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CORRELATING ANTIBIOTIC CONSUMPTION RATE

WITH ANTIMICROBIAL RESISTANCE PATTERN OF

UROPATHOGENS IN THE

LAGOS UNIVERSITY TEACHING HOSPITAL.

BY

DR IFEANYI A. ONWUEZOBE

FOR THE FULFILLMENT OF THE REQUIREMENT BY THE

NATIONAL POSTGRADUATE MEDICAL COLLEGE

FOR PART II EXAMINATION

JULY, 2006.

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CORRELATING ANTIBIOTIC CONSUMPTION RATE

WITH ANTIMICROBIAL RESISTANCE PATTERN OF

UROPATHOGENS IN THE

LAGOS UNIVERSITY TEACHING HOSPITAL.

SUBMITTED BY

DR IFEANYI A. ONWUEZOBE

FOR THE FULFILLMENT OF THE REQUIREMENT BY THE

NATIONAL POSTGRADUATE MEDICAL COLLEGE

FOR PART II EXAMINATION

SUPERVISOR- DR O. O. ODUYEBO

JULY, 2006.

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CERTIFICATION

This is to certify that this work was carried out by Dr Ifeanyi A. Onwuezobe

of the Department of Medical Microbiology and Parasitology of the Lagos

University Teaching Hospital under my supervision.

………………..………………… Dr Ifeanyi A. Onwuezobe

……………….…………. Dr O. O Oduyebo SUPERVISOR

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DEDICATION

I dedicate this work to my family who stood by me especially during the

most difficult times of this project work, and to the Almighty God who made

all things possible.

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ACKNOWLEDGEMENTS

I wish to acknowledge the efforts of my supervisor Dr O. O. Oduyebo in

seeing to the progress of this work and Dr F. T. Ogunsola for her expert

advise and to Mr. Akintunde of the LUTH pharmacy Department for his

assistance and to the resident doctors in the Department of Medical

Microbiology and Parasitology LUTH for their moral support.

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TABLE OF CONTENTS

TITLE PAGE i

CERTIFICATION ii

DEDICATION iii

ACKNOWLEDGEMENT iv

TABLE OF CONTENT v

SUMMARY vii

CHAPTER ONE

INTRODUCTION 1

CHAPTER TWO

LITERATURE REVIEW 4

CHAPTER THREE

MATERIALS AND METHODS 32

CHAPTER FOUR

RESULTS 38

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CHAPTER FIVE

DISCUSSION, CONCLUSION AND RECOMMENDATION

DISCUSSION 47

CONCLUSION 50

RECOMMENDATION 51

REFERENCES 52

APPENDIX I 60

APPENDIX II 61

APPENDIX III 62

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SUMMARY

The study on correlating antibiotic consumption rate with Antimicrobial

resistance pattern of uropathogens was carried out in the Lagos University

Teaching Hospital from January to June 2006. Midstream urine samples of

1520 patients with suspected urinary tract infections (UTI) which were sent

to the Microbiology Laboratory were processed. Cultured specimens with

growth of pathogen greater than 10,000 colony forming units per milliliter of

urine were biochemically identified using the Analytical profile index (API)

test kits. Antibiotic susceptibility testing was done on all identified

uropathogens and all Escherichia coli and Klebsiella pneumoniae resistant to

the third generation cephalosporins were tested for the production of

extended spectrum betalactamases (ESLBs). The antibiotic resistance

pattern of the isolated pathogens was correlated with the antibiotic

consumption pattern of patients in LUTH.

Two hundred and fifteen bacterial pathogens were isolated with Escherichia

coli being the most prevalent (57.2%). Twenty percent were Klebsiella

pneumoniae and 7.9% were Pseudomonas aeroginosa in that order of

prevalence. Other gram negative and gram positive bacteria isolates

constituted 14.9%. About 14% and 11.6% of Escherichia coli and Klebsiella

pneumoniae isolates respectively were found to be producing extended

spectrum betalactamase (ESBLs).

Majority of isolates were resistant to cotrimoxazole and amoxicillin-

clavulanate. There was high sensitivity of the pathogens isolated to

nitrofurantoin, ceftazidime, cefotaxime and cefoxithin.

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For all the antimicrobials, there was an increase in resistance which was

preceded by an increase in antimicrobial consumption. This increasing trend

of resistance of uropathogens to antimicrobials was more with the

Quinolones (ciprofloxacin and ofloxacin), cotrmoxazole (trimethoprim-

sulphamethoxazole) and amoxicillin-clavulanate in the face of increased

consumption of these drugs.

CHAPTER ONE

INTRODUCTION

Urinary tract infection (UTI) is a condition in which microorganisms are

established and multiplying in the bladder, prostate, collecting systems or

the kidneys and could present with symptoms like dysuria, frequency,

urgency and sometimes suprapubic tenderness when the lower tract is

involved and in an adult fever, loin pain and tenderness when the upper

urinary tract is involved (1).

These manifestations occur in cystitis, acute and chronic pyelonephritis and

papillary necrosis. Cystitis describes infection or inflammation of the bladder.

Whereas acute and chronic pyelonephritis are the descriptions used when

the infection involves the pelvis of the kidney, papillary necrosis is a

complication of pyelonephritis, which occur usually in the presence of

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Diabetes mellitus, urinary tract obstruction, sickle cell disease or analgesic

abuse and can occur in the presence or absence of infection.

UTI is caused mainly by bacteria, the commonest agent being Escherichia

coli. Others include Klebsiella pneumoniae, Pseudomonas aeruginosa,

Proteus mirabilis, Acinetobacter baumanii and Enterococcus faecalis and

Staphylococcus sp. In nosocomial UTI the other bacteria like Pseudomonas,

Acinetobacter and Enterococcus play more important roles while E. coli

infection shows a decrease in incidence (2).

UTIs are treated with antibiotics which serve to eliminate the pathogens

causing it as well as preventing mortality and complications associated with

it. So it is necessary to be aware of trends in antibiotic sensitivity and

resistant patterns. Over the years antibiotic susceptibility pattern of the

isolates revealed that for outpatients, first generation cephalosporins,

nitrofurantoin, norfloxacin/ciprofloxacin are effective for treatment of urinary

tract infection but for inpatients, parenteral therapy with newer

aminoglycosides and third generation cephalosporins need to be advocated

as the organisms for nosocomial UTI exhibit a high degree of drug

resistance (3,4). Since patterns of antibiotic resistance in a wide variety of

pathogenic organisms vary even over short periods and depend on site of

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isolation and on different environments, periodic evaluation of antibacterial

activity to update this information is always needed (5, 6, 7).

Recently, trimethoprim/sulphamethoxazole combination which has been a

frontline choice decides for UTI was found to be ineffective for the

treatment of urinary tract infections as all the uropathogens from inpatients

and outpatients showed high degree of resistance to it (8).

A study carried out in Kaduna on susceptibility pattern of uropathogens

showed that all isolates were poorly sensitive to the common first-line drugs

used in UTI isolates including, cotrimoxazole and ampicillin, but exhibited

good sensitivity to nalidixic acid, nitrofurantoin and ofloxacin (9).

Although multiple factors play a role in antimicrobial resistance, the selective

pressures of inappropriate and widespread use of antibiotics are considered

major contributors and rates of use of antibiotics usually correlate with the

level of antibiotic resistance (10, 11). Controlling antibiotic resistance

requires the monitoring of both susceptibility trends and antimicrobial usage

within specific areas of the hospital. Previous studies in Lagos and indeed in

Nigeria show high level resistance of antibiotics to uropathogens (9,12,13),

but these have never been correlated with rates of use of antibiotics.

The objectives of this study therefore are:

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1. T o characterize the bacteria causing urinary tract infection in Lagos

University Teaching Hospital (LUTH).

2. To determine the sensitivity and resistance patterns of bacteria.

3. To correlate the resistance patterns of the bacteria with antibiotic

usage in the hospital.

CHAPTER TWO

LITERATURE REVIEW

DEFINITION

The urinary tract consists of the upper and lower parts. The upper part of

the urinary tract is made up of the kidneys, and the ureters, while the lower

part is made up of the bladder, and the urethra. Therefore, urinary tract

infections (UTI) are anatomically classified into lower tract infections and

upper tract infections (1).

The lower tract infections include cystitis, urethritis, prostatitis and

epididymitis while the upper urinary tract infections include pyelonephritis,

which is the most severe of the UTIs and can be acute or chronic. Acute

pyelonephritis is the inflammation of the renal parenchyma caused by either

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bacteria or fungi. Chronic pyelonephritis refers to a diffuse, interstitial

inflammatory disease of the kidneys which could be caused by either an

infective agent or in some situations noninfective agents

UTIs are also classified as simple or complicated. Simple or uncomplicated

UTI refers to inflammation of the normal urinary tract in which case there is

no structural abnormalities in the urinary tract or associated conditions like

Diabetes mellitus, sickle cell disease or immunosuppression. UTI is said to

be complicated where there are either functional or structural abnormalities

in the diseased urinary tract. These abnormalities could be presence of

indwelling catheter or bladder or renal calculi. Simple UTI mainly refers to

acute cystitis, while pyelonephritis is the main example of complicated UTI.

All areas of the urinary tract above the urethra in a healthy person are

sterile. The transitional epithelium of the urethra is normally colonized by

resident flora which consist of coagulase negative staphylococci (with the

exception of S. saprophyticus), Viridans and nonhemolytic streptococci,

lactobacilli, diphtheriods, nonpathogenic Neisseria sp., anaerobic cocci,

Propionibacterium sp., anaerobic gram negative bacilli, commensal

Mycobacterium sp. and commensal Mycoplasma sp. Bacteriuria is

quantifiable. When the number in the voided urine exceeds the number that

can be expected from contamination from the anterior urethra (i.e.≥105

bacteria/mL), it becomes significant bacteriuria and this is an indication of

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infection (1). Therefore, quantitative cultures popularized by Kass are used

to determine the presence of UTI and diagnosis is not made unless greater

than 105 colony forming units of bacteria per milliliter (CFU/ml) are present

in the urine. This is referred to as significant bacteriuria and is highly

indicative of infection in patients with acute cystitis, pyelonephritis, and

asymptomatic bacteriuria.

AETIOLOGICAL AGENTS

Urinary tract infections are mainly caused by bacteria; however a few fungi

can also cause UTI. The bacterial causes are; Escherichia coli,

Staphylococcus saprophyticus and epidermidis, Protus species,

Streptococcus faecalis, Klebseilla spp, Pseudomonas aerogenosa Serratia

marcescens and other coliforms. The fungal cause of urinary tract infection

is mainly Candida albicans which causes bladder infection predominantly in

diabetics and immunosuppressed patients. Other causes though rare are

Mycobacterium tuberculosis, Salmonella sp., Leptospira sp. and Mycoplasma

sp. Viruses are a very rare cause of UTI, however, genital herpes can cause

urethral syndrome which is sexually transmitted (28).

Most urinary tracts infections are caused by E. coli but only a few

serogroups of E. coli, for example the 01 and 02 among others, cause a

high proportion of infections (3, 15, 29).

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EPIDEMIOLOGY

UTI is one of the most common reasons adults seek medical consultation all

over the world, and it is also one of the most frequently occurring

nosocomial infections. The most common type of UTI is acute simple cystitis

in women (14, 15, 16). The most commonly isolated bacterial pathogen,

globally, both in children and adults is Escherichia coli. Some studies have

shown that this may not always be the case as the predominant isolate in

both inpatients and outpatients in a study done on patients with urinary

tract infection in Ibadan Nigeria in 1994 was Klebsiella species which

accounted for 52.8% of cases (4, 9). This unusual finding was due the fact

that most of the patients were inpatients and Klebsiella species are

frequently nosocomial. Also in Enugu (Eastern Nigeria), in 2005 the

predominant organisms were coliforms, Staphylococcus aureus and Proteus

spp. (13).

In Central African Republic, Escherichia coli was found to be the most

common cause of urinary tract infection in patients followed by Klebsiella

pneumoniae, Citrobacter diversus, Salmonella spp and other

Enterobactereceae in that order. Pseudomonas aeruginosa accounts for less

than 5%. The gram positive organisms isolated are Staphylococcus aureus,

Streptococcus agalactiae, and enterococcus feacalis (18).

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In recurrent urinary tract infections (especially in the presence of structural

abnormalities of the urinary tract) although E. coli is still the commonest

pathogen relative frequency of infection caused by Proteus, Pseudomonas,

Klebsiella, and Enterobacter species and by enterococci and staphylococci

increases greatly. There is also the catheter-associated UTI and indeed it is

the most common nosocomial infection, accounting for greater than 1

million cases in hospitals and nursing homes (17). Coagulase-negative

staphylococci also cause urinary tract infection as reported in some parts of

the world (21). Staphylococcus saprophyticus cause infection in young

women of sexually active age and account for 5% to 15% of acute cystitis

episodes in the United States (1, 3).

Coagulase-positive staphylococcus most often invade the kidney from the

haematogenous route, resulting in intrarenal or perinephric abscesses.

Adenoviruses (particularly type II) have been implicated as causative agents

in haemorragic cystitis in children, especially boys, and in allogenic bone

marrow transplant recipients (22). Cell wall-deficient bacteria

(e.g.,Chlamydia spp) have been isolated in urine of patients with

pyelonephritis particularly in association with therapy using cell wall-active

antibiotics (22,23). Catheter-associated urinary tract infections account for

40 percent of all nosocomial infections and are the most common source of

gram-negative bacteremia in hospitalized patients (24).

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Fungi (particularly candida species) occur in patients with indwelling

catheters who are receiving antimicrobial therapy (25). Mycobacterium

tuberculosis and anaerobes are known to cause urinary tract infection (26).

Candida species have been isolated as a cause of UTI in some patients.

Sex prevalence: Women are significantly more likely to experience UTI

than men due mainly to the anatomical difference in the length of the

urethra in which the female urethra is shorter and more proximal to the

anus than the male urethra. Nearly 1 in 3 women will have had at least one

episode of UTI requiring antimicrobial therapy by the age of 24 years.

Almost half of all women will experience one UTI during their lifetime (27).

Staphylococcus saprophyticus is the second most common cause in young

sexually active women after Escherichia coli.

Age prevalence: Specific age subpopulations are at increased risk of UTI.

The prevalence of UTI in the neonatal period is low and could result from

bacteremia which could lead to pyelonephritis. Infants of up to 3 months

especially boys experience urinary tract infection when they are not

circumcised. Urinary tract infection could also affect children in the

preschool and school age group (20).

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PATHOGENESIS: The urinary tract is normally sterile. In cystitis the

bladder is invaded most often by enteric coliform bacteria (e.g., Escherichia

coli) that inhabit the periurethral vaginal introitus and ascend into the

bladder via the urethra.

Sexual intercourse may promote migration of microorganisms causing

infection to the bladder. This is because the coliform bacteria that colonize

the vaginal introitus could be displaced to the urethra and subsequently to

the bladder following sexual intercourse.

Urine is generally a good medium for growth of microorganism but there are

specific factors that are unfavorable to bacterial growth and these include a

low pH (5.5 or less), a high concentration of urea, and the presence of

organic acids derived from a diet that includes fruits and protein. Organic

acids enhance acidification of the urine leading to decreased pH and this

prevents the growth of bacteria.

Frequent and complete voiding has been associated with a reduction in the

incidence of UTI. Normally, a thin film of urine remains in the bladder after

emptying, and any bacteria present are removed by the mucosal cell

production of organic acids. UTI occurs when these mechanisms fail.

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The gram negative rods not only thrive in urine, they are specially adapted

to cause infection by having fimbriae with terminal receptors for specific

glycolipids and glycoproteins in the urinary tract. The E. coli strains which

cause UTI’s typically have fimbriae with a terminal receptor for the “P”

antigen, a blood group marker present on the surface of cells lining the

perineum and urinary tract (4).

The P antigen is also found in vaginal and prostatic secretions: these

secreted P antigens are protective in that they bind to the bacterial receptor,

preventing binding of the organism to the surface epithelium. The

individuals most susceptible to UTI are those who express P antigen on their

cells and lack P antigen in their secretions.

Host defenses of the upper tract include local leukocyte phagocytosis and

renal production of antibodies that kill bacteria in the presence of complement

(3). When these fail pyelonephritis occurs.

Complicated UTI occurs in the setting of underlying structural, medical, or

neurologic disease. Patients with a neurogenic bladder or bladder

diverticulum and postmenopausal women with bladder or uterine prolapse

have an increased frequency of UTI due to incomplete bladder emptying.

This eventually allows residual bacteria to overwhelm local bladder mucosal

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defenses. The high urine glucose content and the defective host immune

factors in patients with diabetes mellitus also predispose to infection (30).

Factors predisposing to UTI: Various risk factors predispose to UTI.

These are pregnancy, old age, spinal cord injuries catheters, diabetes

mellitus, multiple sclerosis, acquired immunodeficiency disease syndrome,

human immunodeficiency virus, and use of diaphragm and spermicides for

contraception in women (3, 17).

Other risk factors include abnormalities of the urinary tract that obstructs or

slows the flow of urine, making it easier for bacteria to grow. A stone in the

kidney or any part of the urinary tract can form such a blockage, creating

the conditions for a UTI. In men, an enlarged prostate gland can obstruct

urine flow and make infection difficult to treat.

CLINICAL MANIFESTATIONS

Cystitis – Infection of the bladder results in dysuria (painful urination),

urgency (the need to urinate without delay), increased frequency of

urination, suprapubic tenderness, small volume voiding, and pyuria. Pelvic

discomfort especially pre- and immediately postvoid which occurs in 20% of

women with uncomplicated UTI (31).

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Hemorrhagic cystitis is characterized by large quantities of visible blood

in the urine as irritative voiding symptoms regardless of the origin which

may be infection or noninfection. When infectious in origin, signs and

symptoms of infection may also be encountered. Hemorrhagic cystitis is

differentiated from glomerulonephritis, by absence of hypertension (4, 22,

32).

ASYMPTOMATIC BACTERIURIA

This condition is due to bacterial presence of more than 100,000 CFU per ml

of voided urine in persons with no symptoms of urinary tract infection. This

is rarely seen in adult healthy men. However it occurs in young and elderly

women. In pregnancy asymptomatic bacteriuria occurs and could be a

danger to the developing fetus hence pregnant women are screened and

treated. The clinical guidelines for the prevention of the complications of

UTI in pregnancy include; the screening of all pregnant women for the

presence of bacteriuria on the first antenatal visit and at the twenty eight-

week, the treatment of asymptomatic bacteriuria with antimicrobials

considered safe in pregnancy and a follow-up cultures at 1 and 4 weeks

following therapy (1, 24).

LABORATORY DIAGNOSIS

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The diagnosis of UTI is based on a quantitative urine culture yielding greater

than 100,000 colony-forming units (105CFU) per milliliter of urine, which is

termed "significant bacteriuria." This value is chosen because of its high

specificity for the diagnosis of true infection, even in asymptomatic persons

(33, 34).

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Specimen collection and transport: There are various methods of

collecting urine from patients suspected of having UTI.

1. Clean catch midstream urine – Here, the patient should void the first

part of the urine stream which cleanses the anterior urethra, and then

the middle stream is collected in a sterile universal bottle making sure

that the external genitalia did not touch the specimen bottle.

2. Catheter specimen – This is a method of urine collection from

patients. Here, urine sample is collected from an indwelling catheter

using a syringe to collect urine sample from the junction between the

catheter tube and the bag after disinfecting the area.

3. Suprapubic aspiration involves collecting urine aseptically from the

suprapubic region for example, in bladder obstructions and in

children.

Urine samples should be transported immediately to the Laboratory for

processing within two hours following collection. Where delay is anticipated,

it should immediately be refrigerated at 4o or preserved with boric acid for

24 hours. A urine transport tube containing boric acid, glycerol and sodium

formate can preserve urine for 24 hours without refridgeration (29).

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Microscopic examination of urine sample

1. Wet mount – this is done to detect the presence of white blood cells

(WBCs) and bacteria in urine sample. When there are more than 10

WBCs per high-power field in centrifuged urine, it is termed pyuria. If

bacteria (more than 20) is present in an unspurn urine, it is an

indication of UTI (28).

2. Gram stain – Here, a drop of uncentrifuged urine is placed to dry on a

microscope slide and then Gram stained. If greater than one

bacterium per oil immersion field is seen, the specimen has >105

bacteria/ml. If one bacterium is seen in 3-4 fields, the specimen has

<104 bacteria/ml (35). Also, centrifuged urine with a finding of 2-5

White Blood Cells (WBCs) or 15 or more bacteria per high power field

in the urine sediment is consistent with UTI (35).

Urine culture

Culture media – for primary isolation of uropathogens, most laboratories use

an enriched medium like 5% blood agar plate and a differential medium like

MacConkey agar (the contents are peptone, lactose, bile salts, sodium

chloride, neutral red, agar) MacConkey agar allows for the detection of

most gram-negative bacilli and some gram positive organisms.

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Some laboratories prefer the use of cystein-lactose electrolyte deficient

(CLED) agar (contents are, peptone, tryptone, lactose, L-cystine,

bromothymol blue, to MacConkey agar because it supports the growth of

Gram negative and Gram positive pathogens (51). Special medium like the

Lowenstein Jensen medium could be used for the growth of mycobacterium

sp. Culture is done using different methods.

The growth of Enterococci spp. and other streptococci spp. may be

enhanced by using selective plates for gram-positive organisms such as

Columbia colistin-nalidixic acid agar (CNA) or phenylethyl alcohol agar.

These are rarely used because of their cost.

Two methods are employed to determine significant bacteriuria.

Quantitative loop method: Here, a calibrated platinum loops is used to

inoculate plates directly and count of bacterial colonies is done after

incubation to determine the number of microorganisms per ml (29).

Dip cultures: Here, special slides coated with media, are dipped in urine

specimen and incubated. Bacterial colony count is done directly (29).

Incubation is done at 350C to 370C for 18 -24 hours.

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Rapid preliminary tests

Chemical tests using dip sticks coated with specific chemicals and/or

substrates – This involves a simple dipping of the sticks in urine and looking

for color changes in a few minutes. Some of the sticks used are; (a) Nitrate

(NO3) sticks in which the production of nitrite with colour change establishes

bacteriuria. Best results are gotten if used on first-void urine (first urination

in morning) specimens because at least 4 hours are required for coliforms to

convert nitrate to nitrite. (b) Leukocyte esterase sticks are used to establish

pyuria (20, 34).

Paper strip test – A paper strip test known as the Griess test can be used to

detect the presence of nitrate-reducing enzymes produced by most

uropathogens.

URISCREEN – This is a manual screening system that measures the enzyme

catalase in urine. Hydrogen peroxide when added to the urine produces

bubbles which indicate the presence of aetiologic agents of UTI, as most of

them will produce catalase enzyme except streptococci (29).

Other test

Blood culture – In some patients with pyelonephritis and septicaemic

symptoms, blood culture is necessary for the detection of the aetiologic

agents.

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PRINCIPLE OF ANTIBIOTIC THERAPY

The goal of treatment of a urinary tract infection is sterilization of the urine,

which should occur within hours of the first dose of an appropriately chosen

antimicrobial (31). To accomplish this, selection of a suitable drug is critical.

When choosing empiric therapy one must consider if the infection is

complicated or uncomplicated, the spectrum of activity of the drug against

the likely pathogen, potential untoward effects of the drug, patient

compliance, and cost. The duration of therapy should be guided by the

presumed extent of tissue involvement and concentration of antimicrobial in

the urine (32). It is desirable that the urine concentration of the drug

exceeds the minimum inhibitory concentration (MIC) of the infecting

pathogen by the highest amount for the longest period of time.

ANTIMICROBIALS

Trimethoprim-sulfamethoxazole, a combination that synergistically

interferes with folate metabolism of bacteria, is frequently used in the

treatment of uncomplicated urinary tract infections. With the notable

exceptions of Pseudomonas and Enterococcus species, it is effective against

a broad range of urinary pathogens (35). However, there have been reports

of an increased resistance to this drug (12, 13). The concentration in the

urinary tract is excellent and the effect on the fecal flora is minimal. The

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drug is affordable in developing countries like Nigeria. However, skin rash

and gastrointestinal complaints are the main side effects. Use of this drug in

pregnancy and neonates under one month of age is contraindicated because

of the untoward effects in this age group.

Nitrofurantoin disrupts carbohydrate metabolism and inhibits bacterial cell

wall synthesis. It is effective against most uropathogens except

Pseudomonas and Proteus (34). Since nitrofurantoin reaches high levels in

the urine, but does not concentrate in tissue, it is ineffective in the

treatment of infection involving solid organs such as pyelonephritis or

prostatitis. There is limited interaction with the fecal reservoir resulting in

minimal problems with resistance. It is not used in patients with poor renal

function because of poor concentration ability (3).

Aminopenicillins (i.e. ampicillin and amoxicillin) are frequently used in the

treatment of a wide range of infectious processes including those in the

urinary tract. This frequent use has resulted in up to 30% resistance in

clinical isolates (36). Extended spectrum synthetic penicillins and those

combined with beta-lactamase inhibitors are occasionally used in parenteral

therapy for complicated pyelonephritis.

Aminoglycosides, which inhibit bacterial RNA synthesis, are a useful class

of drugs and, when combined with TMP-SMX or ampicillin, are parts of first

line therapy. They have largely maintained their spectrum of activity and,

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with appropriate monitoring of levels, the danger of renal toxicity can be

minimized. Newer regimes of extended dose therapy which employ single

daily doses of up to 7 mg/kg are equally efficacious as standard dosing but

have a lower risk of nephrotoxicity (37).

Fluoroquinolones are inhibitors of DNA gyrase with a broad spectrum of

activity that is ideal for empiric treatment of urinary tract infection (38).

Coverage against Enterobacteriaceae and Pseudomonas species is high, with

high levels of activity against Staphylococcal species, though Streptococcal

coverage is marginal (39). Fluoroquinolones do have advantages in the

treatment of complicated UTIs, resistant organisms, or difficult-to-treat

pathogens such as Pseudomonas aeruginosa (40). Inappropriate use has

caused an increased incidence of resistant strains (41). Fluoroquinolones are

contraindicated in children because of theoretical danger in cartilage

formation, but side effects are rare in adults. Although as a class

fluoroquinolones are not nephrotoxic, their dosing must be adjusted in

patients with renal failure because of its metabolism in the kidneys.

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MANAGEMENT OF URINARY TRACT INFECTION

In the treatment of UTIs, short-course antibiotic or long-course antibiotic

regimens has been considered

Short-course antibiotic regimens range from a single dose to 3 days

duration while long-course regimens range from 7 to 14 days. The short-

course regimens are used in the treatment of uncomplicated lower UTIs

especially in adults. They are effective, less expensive with fewer side

effects and may prevent reinfection with resistant organism (42). However

the efficacy and advantages of short-course antibiotic treatment of UTI in

adults are not seen in children. The reasons are that by the time UTIs is

identified in children, there is often upper tract involvement that cannot be

easily distinguished clinically from lower tract infection by signs and

symptoms and/or by laboratory tests (42). Also children are more likely to

have anatomic abnormalities predisposing them to pyelonephritis and so

would require longer treatment of up to 7 – 14 days; however, Randomized

Controlled Trials (RCTs) over the last 25 years have not provided evidence

supporting this practice (63). In fact, most of these studies have shown no

statistical significance difference in efficacy between short- and long-course

therapies (42).

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In the past years (between 1970s and 1990s), the drugs mainly used for short-

course therapy are gentamicin, amikacin, cefotaxime, cephalexin and

pivmecillinam. Trimethoprim-sulphamethoxazole, nitrofurantion, sulphamethizole,

amoxicillin, ampicillin, nalidixic acid, sulfisoxazole and cefadroxil were used for

long-course therapy (42).

The use of these drugs over the years has been associated with treatment

failures manifesting as persistence of infection (when there is continued

positive urine culture 1 to 2 days of initiation of therapy) and relapse (when

there is symptoms and signs of infection with the same organism following a

bacteriologic cure) (42,43). None of them has demonstrated superiority over

the others in this respect.

One systematic review and two subsequent RCTs in women with acute

uncomplicated pyelonephritis found no consistent differences in

bacteriologic or clinical cure rates (43). However, there is evidence that

quinolones such as ciprofloxacin, levofloxacin, lomefloxacin and gatifloxacin

are more effective than narrow spectrum antibiotics such as amoxicillin and

trimethoprim-sulphamethoxazole in areas with high prevalence of resistance

(43,44).

Oral ciprofloxacin, levofloxacin, lomefloxacin and gatifloxacin are used for

the treatment of acute pyelonephritis (43).

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CHALLENGES TO TREATMENT

Recurrent cystitis in women

Up to 20 percent of young women with acute cystitis develop recurrent

UTIs. During these recurrent episodes, the causative organism should be

identified by urine culture to help differentiate between relapse (infection

with the same organism) and recurrence (infection with different

organisms). Multiple infections caused by the same organism are, by

definition, complicated UTIs and this require longer courses of antibiotics for

up to 2 weeks (3). Fortunately, most recurrent UTIs in young women are

uncomplicated infections caused by different organisms (36, 45).

Women who have more than three UTI recurrences documented by urine

culture within one year can be managed using one of three preventive

strategies: Acute self-treatment with a three-day course of standard

therapy; Postcoital prophylaxis with trimethoprim-sulfamethoxazole given as

half the strength of a tablet (i.e. 40/200 mg) if the UTIs have been clearly

related to intercourse; and continuous daily prophylaxis with one of these

regimens for a period of six months: trimethoprim-sulfamethoxazole, one-

half tablet per day (40/200 mg); nitrofurantoin, 50 to 100 mg per day;

norfloxacin, 200 mg per day; cephalexin, 250 mg per day; or trimethoprim,

100 mg per day (3, 17, 29).

33

Each of these regimens has been shown to decrease the morbidity of

recurrent UTIs without a concomitant increase in antibiotic resistance and

long-term studies have shown antibiotic prophylaxis to be effective for up to

five years with trimethoprim, trimethoprim-sulfamethoxazole or

nitrofurantoin, without the emergence of drug resistance (29).

Unfortunately, antibiotic prophylaxis does not appear to alter the natural

history of recurrences because forty to sixty percent of these women were

observed to reestablish their pattern or frequency of infections within six

months of stopping prophylaxis (29).

Catheter-Associated UTI

Some patients who are hospitalized receive indwelling Foley catheter which

increase the risk of bacteriuria by approximately 5 percent per day. For

every patient on long-term catheterization, however bacteriuria is inevitable.

The diagnosis of catheter-associated urinary tract infection can be made

when the urine culture shows 100,000 or more CFU per mL of urine from a

catheterized patient.

Symptomatic bacteriuria in a patient with an indwelling Foleys catheter

should be treated with antibiotics that cover potential nosocomial

uropathogens such as E. coli and Proteus, Enterococcus, Pseudomonas,

Enterobacter, Serratia and Candida species. Patients with mild to moderate

34

infections may be treated with one of the oral quinolones, usually for 10 to

14 days. Parenteral antibiotic therapy may be necessary in patients with

severe infections or patients who are unable to tolerate oral medications.

The recommended duration of therapy for severe infections is 14 to 21 days.

Treatment is not recommended for catheterized patients who have

asymptomatic bacteriuria, with the following exceptions: patients who are

immunosuppressed after organ transplantation, patients at risk for bacterial

endocarditis and patients who are about to undergo urinary tract

instrumentation (24). In patients on long term catheterization, catheters

should be changed periodically to prevent the formation of concretions and

obstruction that can lead to infection. Although prophylactic systemic

antibiotics have been shown to delay the onset of bacteriuria in catheterized

patients, this strategy may lead to increased bacterial resistance (24).

Furthermore, antibiotic therapy has been successful in reducing the

frequency of bacteriuria only in patients who can be weaned from indwelling

catheters to intermittent catheterization.

35

Asymptomatic Bacteriuria

Asymptomatic bacteriuria is defined as the presence of more than 100,000

CFU per ml of voided urine in persons with no symptoms of urinary tract

infection. The largest patient population at risk for asymptomatic bacteriuria

is the elderly. Up to 40 percent of elderly men and women may have

bacteriuria without symptoms and should benefit from treatment (20). Other

groups of patients with asymptomatic bacteriuria have been shown to

benefit from treatment: patients with renal transplants, patients who are

about to undergo genitourinary tract procedures and pregnant women.

Between 2 and 10 percent of pregnancies are complicated by UTIs; if left

untreated, some of these women develop pyelonephritis (45, 46).

Pregnant women with asymptomatic bacteriuria should ideally be treated

with a three- to seven-day course of the antibiotics to which the cultured

isolate is sensitive to, and following treatment the urine should subsequently

be cultured to ensure cure and the avoidance of relapse (45). Although

amoxicillin has been the agent of choice, E. coli is now commonly resistant

to ampicillin, amoxicillin and cephalexin. Nitrofurantoin or trimethoprim-

sulfamethoxazole may also be used; however, caution should be exercised

in the third trimester because the sulfonamides compete with bilirubin

binding sites in the newborn (20). Thus, treatment should be based on the

results of susceptibility tests.

36

ANTIMICROBIAL RESISTANCE

Bacterial resistance to antibiotic

The antimicrobial agents traditionally used for treatment of UTI include

trimethoprim, trimethoprim-sulphamethoxazole, nitrofurantion, amoxicillin-

clavulanate, gentamicin and ciprofloxacin. However uropathogens are not

always fully sensitive to them as a report from 30 medical centers in the

United States of America and 10 medical centers from Canada shows an

overall resistance of uropathogens to ampicillin to be 37.7%, followed by

SMX/TMP (21.3%), nitrofurantoin (1.1%), ciprofloxacin (5.5%) and

levofloxacin (5.1%) (47).

Understanding the three main mechanisms by which uropathogenic

organisms manifest resistance to antimicrobials; natural resistance, selection

of resistant mutants, and transferable resistance, can help guide therapy.

Natural chromosomal resistance is exemplified by Proteus, which is never

sensitive to nitrofurantoin. Another examples, is Pseudomonas aeruginosa

which is inherently resistant to sulfonamides, trimethoprim, tetracycline and

chloramphenicol. These families of antibiotic are unable to accumulate in

Pseudomonas aeruginosa to a sufficient intracellular concentration due to

presence of efflux pumps (44, 48). These resistance patterns are predictable

and guide definitive therapy.

37

Selection of resistant mutants represents survival of a resistant strain that

was present prior to therapy but survives due to underdosing. In practice,

selection of resistant clones occurs in up to 10% of patients and can be

mitigated by ensuring the appropriate dosing of the antimicrobial.

Transferable resistance or R-factor resistance is caused by a plasmid-

mediated, transferable element that confers resistance, usually multi-drug

resistance. This manner of resistance is common and can be problematic

with improper use of antimicrobials in the hospital setting (26). The

transmission of R-factor occurs within the fecal reservoir of patients

receiving beta-lactams, trimethoprim-sulfamethoxazole (TMP-SMX),

aminoglycosides, and tetracyclines.

Such plasmids are responsible for β-lactamase-mediated ampicillin

resistance in Escherichia coli and Klebsiella spp. The bacteria undergo

simple point mutations that result in the production of extended-spectrum

β-lactamases (ESBLs) capable of hydrolyzing extended-spectrum

cephalosporins (e.g., cefotaxime, ceftriaxone, ceftizoxime, and ceftazidime)

and aztreonam, as well as older β-lactam drugs (49). Studies have shown

that ESBL-producing isolates are resistant to all extended-spectrum

penicillins, cephalosporins, and monobactams in vivo even if they are

susceptible to these agents invitro (50). The genes that codes for production

38

of ESBLs are often linked to other resistance genes, so that ESBL-producing

isolates are often resistant to many other antibiotic classes (e.g. resistant to

aminoglycosides and trimethoprim-sulfamethoxazole).

Antibiotic consumption and resistance

Resistance to antibiotics is a major public-health problem and antibiotic use

is being increasingly recognised as the main selective pressure driving this

resistance. Thus there have been studies world wide to demonstrate this

association and monitor drug use. In order to facilitate this, various

classification systems for drug consumed were developed. The European

Pharmaceutical Market Research Association (EPhMRA) classification system

was one such system. However due to the difficulties encountered in the

interpretation of results obtained by this system, it was not widely used

internationally. Another classification system, the Anatomical Therapeutic

Chemical (ATC) was developed which in combination with the Defined Daily

Dose (DDD) gained acceptance world wide (51). The ATC/DDD system is

used as a tool for presenting drug utilization statistics with the aim of

improving drug use. The ATC system groups drugs according to the organ

or system on which they act and their chemical, pharmacological and

therapeutic properties. It is especially suitable for evaluation for long term

trends in drug use. The (DDD) is a measurement of drug consumption and

39

is defined as the assumed average maintenance dose per day for a drug

used for its main indication in adults. It has been standardized for use in

hospital and community and data can be compared among hospitals and

regions, nationally and internationally. It can be used to identify possible

overuse, underuse or misuse of individual drugs. This information can then

be used to initiate specific studies or specific educational interventions.

Drug consumption is presented as numbers of DDDs/1000 inhabitants/day

or DDDs per 100 bed days in case of hospital use (51). Statistical packages

such as the Antibiotic Consumption Calculator (ABC CALC) have been

developed and successfully used for the calculations. The use of antibiotic

consumption data in DDDs in correlation to antibiotic resistance displayed by

microorganisms is not yet popular in developing countries like Nigeria,

however, it is widely used in Europe. For example, in an international

multicenter study of antimicrobials consumption and resistance in

Staphylococcus aureus isolated from 15 hospitals in 14 countries in Europe,

significant correlations were found between resistance and consumption of

antimicrobials in hospitals with MRSA prevalence of between 0% and 63%

(52). By calculating the DDDs of antibiotics, the trends of their usage over

time can be obtained and matched with the resistance of organisms to the

drugs. The use is not limited to drug resistance, but can be applied to

40

adverse drug reactions (53). For example in a Swedish study on adverse

drug reactions, the DDD was applied to the prescription data of drugs like

phenformin and metformin and this was used accurately in determining the

relative incidence in their adverse reactions by converting prescribed daily

doses of this drug consumed by the study population and the differences

between means were tested statistically (53).

41

CHAPTER THREE

MATERIALS AND METHODS

This study was carried out in the Medical Microbiology Laboratory of the

Lagos University Teaching Hospital for a period of six months (January to

June, 2006). All isolates obtained from the urine specimens of patients sent

to the Microbiology Laboratory were characterized and antimicrobial

susceptibility testing carried out on them. Antibiotic susceptibility data of

uropathogens isolated from LUTH laboratory for the periods January to

December 2005 was also reviewed. Data on antibiotic consumption pattern

for the periods January to December 2005 and January to June 2006 were

obtained from the in-patients Pharmacy department of the hospital and

correlated with the susceptibility patterns.

Ethical consideration

The study proposal was approved by the Ethics and Research committee of

the Lagos University Teaching Hospital.

Sampling Method

All urine specimen which grew cultures with greater than 100,000 colony

forming units (CFU) per milliliter of a single organism on MacConkey or

blood agar (significant bacteriuria) (54), were included in the study.

42

Procedure

All isolates cultured from consecutive specimens with significant bacteriuria

were analyzed. Isolates obtained were subcultured on MacConkey agar

(oxoid) and blood agar (45, 46). Incubation was done at 37oC for 18-24

hours. Subcultures were characterized by standard laboratory methods (55).

Gram negative bacilli

All isolate were stained by the Gram method. All gram negative bacilli were

tested for motility and oxidase (55). All gram negative bacilli that were

oxidase negative (whether motile or non motile) were further characterized

with API 20E (Biomerieux, France) to the specie level. The oxidase positive

gram negative bacilli were further characterized with API 20 NE

(Biomerieux) (56).

Gram positive cocci

All gram positive cocci were further identified by catalase test. Catalase

positive gram positive cocci were identified as Staphylococcus and further

characterized by coagulase test. Coagulase positive Staphylococcus was

identified as Staphylococcus aureus (56). Coagulase negative

Staphylococcus was further characterized by Urease, and Mannitol tests,

Bacitracin and Novobiocin disk test. Urease positive, mannitol negative,

Bacitracin variable and Novobiocin resistant coagulase negative

43

Staphylococus was identified as Staphylococcus saprophyticus. Novobiocin

sensitive, urease negative, Bacitracin negative and Mannitol variable

coagulase negative Staphylococcus was identified as coagulase negative

Staphylococcus (56).

The catalase negative gram positive cocci subculture on blood agar was

examined for hemolysis. The gamma or non hemolytic catalase negative,

gram positive cocci were identified as Enterococcus.

Other gram positive cocci and/or gram negative bacilli when isolated were

identified by standard methods to their specie levels (55).

Control organisms: ATCC 25922- E. coli and ATCC 27853- Pseudomonas

aerugenosa (for Gram negative controls), ATCC 460701- Staphylococcus

aureus (for Gram positive control) were used as standard controls for the

API systems and antibiotic sensitivity testings.

Antibiotic susceptibility testing

Sensitivity of the organisms was performed using the modified Kirby-Bauer

disk diffusion method on Mueller Hinton agar plates (56).

Plates were inoculated within 15 minutes of preparation of suspensions

using sterile cotton swab to streak on the entire surface.

44

Single antibiotic discs, six per plate were applied using forceps and

incubated for 18-24 hours at 370C.

The antibiotic discs and their concentrations per disk (µg) included:

Trimethoprim-sulfamethoxazole 25µg, nitrofurantoin 30µg, nalidixic acid

30µg gentamicin 10µg, ofloxacin 5µg, amoxicillin-clavulanic acid 30µg

ciprofloxacin 5µg, cefuroxime 30µg, ceftazidime 30µg, cefoxithin 30µg, and

cefotaxime 30µg.The diameters of the zones of inhibition were measured

using a milliliter rule. Organisms resistant to any of the third generation

cephalosporins (ceftazidime, cefotaxime) were tested for extended spectrum

beta-lactamases (ELBS) using the Double-Disk Synergy Test (DDST) method

(57, 58).

Interpretation of results

Each zone size was interpreted, by reference to an interpretive table of the

Clinical Standard for Laboratory Institute (CSLI) (formerly National

Committee for Clinical and Laboratory Standards (NCCLS) (19).

Detection of Extended spectrum beta-lactamase producers (ESBLs).

Isolates showing resistance to ceftazidime (≤22mm for 30µg disk) were

tested for the production of ESBLs by the DDST as described by Jarlire et al

(57) with the modifications suggested by Thompson and Sanders (58).

45

After inoculating Mueller-Hinton agar plates as for routine disk-difusion

method, 30µg, disks of cefoxithin, ceftazidime and cefotaxime were placed

20mm (34) center to center from an amoxicillin-clavulanate (20:10µg) disk

(Oxford UK). Accurate placement of each disk was expedited by melting

holes in the lid of a petri-dish plate and using the lid as a template to mark

the bottom of the agar plate (59). Inoculated media was incubated

overnight at 37oC. An enhanced zone of inhibition between any one of the

beta-lactam disks and the amoxicillin clavulanic acid disk was interpreted as

evidence of the presence of an extended spectrum beta-lactamase producer

(ESBL) (60).

Antimicrobial consumption data: Data on the antimicrobial usage was

obtained from the hospital in-patient pharmacy and analysed using ABC

CALC (10, 51).

Antimicrobial usage in LUTH in-patient wards from January to December

2005 were collected from the Pharmacy Department for parenteral and oral

drugs in grams and number of packages and doses or as defined daily doses

(DDD). These raw data were entered into a spreadsheet (ABC CALC) and

converted into DDD. The World Health Organisation (WHO) Anatomic

Therapeutic Classification (ATC) system to identify antibiotics and their DDD

46

was used (51). The DDD is based on the average daily doses used for the

main indication of the drug. The following ATC antibiotic subgroups were

used because the drugs were consumed in the hospital: Beta-lactam

combinations (amoxicillin + clavulanic acid, ampicillin-cloxacillin);

aminoglycosides ( gentamicin); fluoroquinolones (ciprofloxacin, ofloxacin,

perfloxacin, sparfloxacin, and levofloxacin); penicillins (benzylpenicillin);

second generation cephalosporins (cefuroxime, cefoxithin); third generation

cephalosporins (cefotaxime, ceftaxidime, and ceftriaxone); combinations

(sulfamethoxazole-trimethoprim).

Information on bed-days in LUTH in 2006 was obtained and entered into the

spread sheet and all antibiotic consumption data were calculated as number

of DDD/100 bed-days for each therapeutic subgroup.

Statistical analysis

Analysis was done using SPSS software. Association was determined with

Pearson’s correlation coefficient.

47

CHAPTER FOUR

RESULTS

During the six months period of the study, 215 bacteria were isolated from

1520 urine samples sent to the Microbiology Laboratory in LUTH

corresponding to a rate of isolation of 14.4%. Urine samples of the in-

patients were 913 with significant bacterial isolates of 174, while that of out-

patients were 607 with significant bacterial isolates of 41. As shown in Table

I, Escherichia coli was most prevalent making up 57.2% (123 isolates) of

the total. Klebsiella pneumoniae (subspecies pneumoniae, oxytoca and

ozoanae) was the second most prevalent (43 isolates, 20%) followed by

Pseudomonas aeruginosa (17 isolates, 7.9%). Many other gram negative

bacteria were isolated. The gram positive bacteria isolated were

Staphylococcus aureus (9 isolates, 4.2%), coagulase negative

Staphylococcus (5 isolates, 2.3%), Enterococcus faecalis (1 isolate, 0.5%),

and Enterobacter aerogens (3 isolates, 1.4%).

Many isolates of Escherichia coli were sensitive to nitrofurantion (74.8%),

ceftazidime (74%), cefotaxime (70.7%) and cefoxitin (76.4%) while many

were resistant to cotrimoxazole (95.9%), amoxicillin-clavulanate (84.4%),

gentamicin (61%), ofloxacin (52.8%), cefuroxime (58.5%), ciprofloxacin

48

(54.5%) and nalidixic acid (66.7%). The overall resistance rate ranged from

23.6% (cefoxitin) to 95.9% (cotrimoxazole), (Table 2).

As shown in Table 2, the sensitivity rates of Klebsiella pneumoniae to the

various antimicrobials were nitrofurantoin (55.8%), ceftazidime (55.8%),

cefotaxime (60.5%) and cefoxitin (79.1%), while the resistance rates of the

other antimicrobials were ofloxacin (55.8 %), ciprofloxacin (55.8%),

cotrimoxazole (95.3%), gentamicin (72.1%), cefuroxime (72.1%),

amoxicillin clavulanate (90.7%) and nalidixic acid (69.8%).

Pseudomonas aeruginosa isolates were mainly sensitive to ceftazidime

(70.2%) and ofloxacin (58.8%). Resistance to ciprofloxacin was 52.9%. The

isolates were resistant to nitrofurantoin (100%) and cotrimoxazole (100%),

cefuroxime (88.2%), gentamicin (76.5%), amoxicillin-clavulanate, nalidixic

acid, and cefotaxime (82.4% respectively) and cefoxitin (70.6%), (Table 2).

The sensitivity rates of other gram negative bacilli were nitrofurantion

(42.9%), gentamicin (57.1%), ceftazidime (57.1%), cefotaxime (57.1%),

ofloxacin (50%), ciprofloxacin (42.9%) and cefoxitin (50%). Many of them

were resistant to cotrimoxazole (100%), amoxicillin-clavulanate (78.6%),

and nalidixic acid (64.2%), (Table 2).

49

The gram positive cocci isolated showed a high rate of resistance of 80%

and above to Cotrimoxazole, Nalidixic acid, Cloxacillin and Cefoxithin, (Table

2).

The resistance rates of the isolates from urine of patients sent to the

Microbiology Laboratory in LUTH in 2005 from January to June and July to

December (124 and 198 isolates respectively) are shown in Table 3, with

the organisms being more resistant to Clotrimoxazole and Amoxicillin –

clavulanate.

Also shown are the drugs that were dispensed by the LUTH pharmacy and

consumed by patients diagnosed of having infection including UTI included

cotrimoxazole, gentamicin, ofloxacin, cefuroxime, ceftazidime, ciprofloxacin

and amoxicillin-clavulanate.

Overall amoxicillin-clavulanate was the most consumed while ceftazidime

was the least consumed; (Table 3). Co-trimoxazole showed the highest

resistance rates (96 – 98%), followed by amoxicillin clavulanic acid.

Generally, the resistance rates to the antibiotics were high. For all the

antimicrobials except cotrimoxazole, there was an increase in the rates of

consumption from the first and second periods which were accompanied by

an increase in the resistance from the second to the third period. These

50

associations were statistically significant. The rate of consumption of

ciprofloxacin increased steadily over the three 6 monthly periods and this

was significantly associated with a steady increase in resistance. Also

associated with a steady increase in resistance is the increase in the

consumption of ofloxacin in the first two periods.

Seventeen of the 123 isolates of Escherichia coli (13.8%) that were resistant

to Ceftazidime and Cefotaxime were found to produce extended spectrum

beta lactamases (ESBLs), while all the 5 Klebsiella spp. (11.6%) that were

resistant to Ceftazidime and Cefotaxime were found to produce ESBLs

(figure 1).

51

Table I: Uropathogens isolated at the Microbiology Laboratory of the Lagos

University Teaching Hospital (LUTH) from January to June 2006.

Organisms Isolated Frequency Percentage

Escherichia coli 01 102 47.4

Escherichia coli 02 21 9.8

Klebsiella pneumo pneumoniae 39 18.1

Klebsiella pneumo oxytoca 1 0.5

Klebsiella pneumo ozaenae 3 1.4

Hafnia alvei 01 1 0.5

Citrobacter fruendi 2 0.9

Serratia marcesens 3 1.4

Serrtia odorifera 1 0.5

Acinetobacter baumanni 1 0.5

Flavimonas oryzihabitans 1 0.5

Salmonella sp. 1 0.5

Salmonella pullorum 1 0.5

Enterobacter cloaca 1 0.5

Aeromonas hydrophilia 1 0.5

Pasturella sp. 1 0.5

Staphylococcus aureus 9 4.2

Coagulase negative Staphylococcus 5 2.3

Enterococcus faecalis 1 0.5

Enterobacter aerogens 3 1.4

Pseudomonas aeroginosa 17 7.9

TOTAL 215 100

52

Table 2: The antibiotic sensitivity pattern of various bacteria isolated from urine samples of patients with UTI. 2006.

Organisms No.

isolated

Nit (%) Cot

(%)

Gen

(%)

Ofl (%) Cxm

(%)

Caz (%) Amc

(%)

Cip (%) Nal (%) Ctx (%) Fox (%) Cxc

(%)

Escherichia

coli

123 92(78.8) 5(4.1) 48(39) 58(47.2) 51(41.5) 91(74) 19(15.4) 56(45.5) 41(33.3) 87(70.7) 94(76.4) 0

Klebsiella

pneumoniae

43 24(55.8) 2(4.7) 12(27.9) 19(44.2) 12(27.9) 24(55.8) 4(9.3) 19(44.2) 13(30.2) 26(60.5) 34(79.1) 0

Pseudomonas

aerogenosa

17 0 0 4 (23.5) 10(58.8) 2(11.8) 12(70.2) 3(17.6) 8(47.1) 3(17.8) 3(17.6) 5(29.4) 0

Other Gram

negative bacilli

14 6(42.9) 0 8(57.1) 7(50) 5(35.7) 8(57.1) 3(21.4) 6(42.9) 5(35.7) 8(57.1) 7(50) 0

Gram positive

organisms

18 6(37.3) 1(5.6) 5(27.8) 10(55.6) 5(27) 6(33.3) 4(22.2) 7(38.9) 2(11.1) 7(38.9) 15(83.3) 2(11.1)

Key: Nit – Nitrofurantion, Cot – Cotrimoxazole, Gen – Gentamicin, Ofl – Ofloxacin, Cxm – Cefuroxime, Caz – Ceftazidime, Amc – Amoxicillin, Cip – Ciprofloxacin, Nal – Nalidixic acid, Ctx – Cefotaxime, Fox - Cefoxithin

53

Table 3: The LUTH 6 monthly antimicrobial resistance patterns of 2005 and 2006 with the antibiotic

consumption (in DDD/100 bed days).

Antimicrobial %

resistance Jan-June

2005

% resistance July-Dec.

2005

(%) resistance Jan-June

2006

Nr. DDD/100 bed days Jan.-June

2005

Nr.DDD/100 bed days

July-Dec.2005

Nr.DDD/100 bed days

Jan.-June 2006

Pearsons

correlation

coefficient

Cotrimoxazole 96.8% 98% 96.3% 0.685 0.596 0.939 -0.876

Gentamicin 54% 60.6% 64.2% 0.164 0.205 0.082 -0.519

Ofloxacin 12.1% 32.8% 52.6% 0.272 0.478 0.249 0.806

Cefuroxime 58.9% 59.1% 65.1% 0.333 0.888 0.297 -0.522

Ceftazidime 56.5% 27.3% 34.4% 0.032 0.053 0.085 -0.639

Ciprofloxacin 20.2% 52.5% 55.3% 2.015 2.363 2.842 0.856

Amoxicillin-clavulanate

87.9% 78,3% 84.7% 2.532 3.305 2.153 -0.789

54

11.6%

13.8%

10.50% 11.00% 11.50% 12.00% 12.50% 13.00% 13.50% 14.00%

Klebsiella pneumoniae

Escherichia coli

Escherichia coli

Klebsiella pneumoniae

Figure 1: Prevalence of Extended Spectrum Beta-lactamases (ESBLs) in

Escherichia coli and Klebsiella pneumoniae isolated from the urine specimen

submitted to the Microbiology Laboratory of Lagos University Teaching Hospital,

from January to June of 2006.

46

55

CHAPTER FIVE

DISCUSSION

In this study, over 80% of the uropathogens isolated were from in-patients,

and Escherichia coli was the most prevalent making up 57.2% while the

other pathogens made up 43.8%. This pattern fits the trend observed in

hospital based patients. Although the prevalence of Escherichia coli in

community acquired UTI is higher, and could be as high as 85%, it is

relatively lower in hospitalized patients in which case the other pathogens

play a more significant role compared with community acquired infection (4,

61). Klebsiella pneumoniae was found to be the second and Pseudomonas

aeruginosa the third most prevalent. This pattern has been well documented

(12, 21).

Other isolates which are Hafnia alvei, Citrobacter fruendii, Serratia

marcescens, Serratia odorifera, Acinetobacter baumanni, Flavimonas

oryzihabitans, Salmonella sp., Salmonella pullorum, Enterobacter cloaca,

Aeromonas hydrophylia, Pastuerella sp., and Enterococcus aerogens are not

frequently reported in our environment due to the fact that Analytical Profile

Index (API) kits used for their identification in this study are not always

used. It is noteworthy that these organisms could cause septicaemia

associated with high rate of mortality in improperly treated patient, (1, 55).

56

The sensitivity pattern of Escherichia coli which was the most prevalent

uropathogen in this study suggests that antibiotics like ceftazidime,

cefotaxime and nitrofurantion would be useful for empiric therapy of in-

patients because over 70% of isolates were sensitive. Cotrimoxazole,

amoxicillin-clavulanate and gentamicin which were traditionally the first line

drugs for UTI are no longer useful as such because only 39-45% of isolates

were sensitive to them. Studies carried out in the past recommended that

the quinolones which were quite active then, be kept in reserve to combat

resistance problems, but as found in this study, and various others, overuse

has led to increase in resistance (9, 12, 13).

Fourteen percent and 11.6% respectively of cephalosporin resistant E. coli

and K. pneumoniae produce ESBLs. Such isolates cannot be treated with

cefotaxime, ceftriazone and ceftazidime. ESBLs are associated with

overuse. ESBLs producers spread easily and can cause outbreaks in

hospitals especially because the transferable resistance conferred is plasmid

mediated (3).

As found in this study, the treatment of UTI caused by the other gram

negative bacilli and the gram positive cocci should be based on the result of

57

sensitivity patterns because they showed high rates of resistance to all the

antibiotics tested.

For all antibiotics consumed in this study except cotrimoxazole, increased

consumption correlated with increased resistance and on the hand, the

uropathogens were highly sensitive to nitrofurantoin and cefoxitin which

were not consumed during the study period. Studies around the world have

correlated drug overuse with increased antimicrobial resistance and a much

clearer picture of this would be painted in the hospital of study if this trend

is allowed to continue (62). To discontinue this trend, the hospital needs to

stop the use of the relevant antibiotics especially cotrimoxazole and

amoxicillin clavulanate for the treatment of UTI in hospitalized patients. An

antibiotic policy should be developed to reduce or restrict the use of other

antibiotics. There is also need to continue to monitor resistance of the

relevant antibiotics in order to demonstrate a reduction in response to

reduced consumption. The classical case of upward trend in the resistance

of pathogens due to upward trend in the consumption of ciprofloxacin was

seen in this study. And if the consumption is discontinued, the resistance

rate will be reduced in response as shown by a study (63).

CONCLUSION

58

(1). Escherichia coli was the pathogen most commonly isolated from the

urine of hospitalized patients in Lagos University Teaching Hospital.

(2). Majority of isolates were resistant to cotrimoxazole and amoxicillin-

clavulanate and this resistance appear to be endemic. They also

showed high sensitivity nitrofurantoin, ceftazidime, cefotaxime and

cefoxithin

(3). Fourteen percent of Escherichia coli and 11.6% of Klebsiella

pneumoniae were found to be ESBLs producers.

(4). For all the antimicrobials, there was an increase in resistance which

was preceded by increased antimicrobial consumption.

(5). There was a trend of increased resistance of uropathogens to

antimicrobials especially to the Quinolones (ciprofloxacin and

ofloxacin), gentamicin, cefuroxime, ceftazidime and amoxicillin-

clavulanate in the face of increased consumption of these drugs.

There is urgent need for intervention to stop this trend.

RECOMMENDATION

59

(1). The medical personnel prescribing antibiotics in LUTH should be

educated on the current trend and the need for intervention.

(2). The use of co-trimoxazole and amoxicillin-clavulanate should be

stopped. They should be replaced by the more sensitive antimicrobials.

(3). The hospital needs to have an antibiotic policy to ensure rational use

and restrict the use of antibiotics to combat future resistance problems.

(4). That further research should be conducted on the resistance of

uropathogens to antibiotics in relation to the consumption of such drugs in

LUTH over time to monitor the intervention instituted.

60

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69

APPENDIX I

THE ANALITICAL PROFILE INDEX (API) 20E SHOWING A TYPICAL

REACTION OF ENTEROBACTERIACEAE (E. Coli)

70

APPENDIX II

THE ANALITICAL PROFILE INDEX (API) 20NE SHOWING A TYPICAL

REACTION OF NON-ENTEROBACTERIACEAE (Pseudomonas aeroginosa)

71

APPENDIX III

DEMONSTRATION OF EXTENDED SPECTRUM BETA LACTAMASE

PRODUCING ENZYMES (ESBLS) REACTION OF A TYPICAL KLEBSIELLA

PNEUMONIAE AND E. COLI AS SEEN ON MUELLER HINTON PLATE