8. Interaksi Tuan Rumah-Parasit

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Chapter 8.MICROBE-HUMAN INTERACTIONS:

INFECTION AND DISEASE

Tiana Milanda


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DEFINISI

Patogen : organisme yg mampu menimbulkanpenyakit

Patogenisitas : kemampuan organisme utkmenimbulkan penyakit

Virulensi : derajat kemampuan organismemenimbulkan penyakit

Faktor-faktor virulensi : sifat organisme yangmenimbulkan patogenisitasnya

Infeksi : peristiwa masuk dan berkembangbiaknya organisme dalam sel inang sampaimenimbulkan penyakit

Penyakit : respons sel inang terhadap infeksi


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MEKANISME INFEKSI


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FAKTORVIRULENSI

Dapat berupa single

atau multiple factors :

1.Struktur permukaan

sel : fimbriae (pili),kapsul, spike (duri),

flagela, adhesin atau

antifagositosis

2.Produksi protein

toksin atau enzim

ekstraseluler


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MEKANISME ADHESI


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MEKANISME ADHESI


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pa


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Penetration into Host Cells

Invasins: Surface proteins that alter actinfilaments of host cell cytoskeleton, allowing

microbes to enter cells.

Examples: Salmonella typhimurium and E.coli.

Cadherin: A glycoprotein that bridgesjunctions between cells, allowing microbes to

move from one cell to another.


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Antifagosit :

Leukosidin : enzim yang merusak sel darah

putihKapsul


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TOKSIN

Toksin : zat beracun yg dihasilkan mikroorganisme Toksin terdiri dari

1. Eksotoksin : toksin yg diekskresikan

mikroorganisme ke medium atau jaringan di

sekitarnya2. Endotoksin : toksin yang berupa bagian tubuh

mikroorganisme

Toksigenisitas : kemampuan produksi toksin pada saat

bakteri bermultiplikasi Toksinosis : kemampuan toksin merusak struktur atau

fungsi komponen sel inang

Toksikemia : adanya toksin ke dalam darah


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EXOTOXINS

Both Gram + and Gram bacteria produce exotoxins.

Exotoxins are secreted by bacterium or leak intosurrounding fluids following cell lysis.

In most cases, the pathogen must colonize a body surfaceor tissue to produce enough toxin to cause damage.

Exotoxins can act locally, or they may be carried in thebloodstream throughout the body, causing systemic

effects. Exotoxins have very specific damaging effects which are

disease specific.


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EXOTOXINS

Most exotoxins fall into 3 general categories that

reflect their structure and general mechanism of

action:

A-B toxins Membrane-damaging toxins

Superantigens


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The A-B toxins can be grouped into functional categoriesas well:

Neurotoxins

Cause damage to nervous system

Major symptom is paralysis

Enterotoxins

Damage to intestines and tissues of digestive tract

Major symptom is vomiting and diarrhea

Cytotoxins

Damage to variety of cells

Damage caused by interference with cell function

or cell lysis

EXOTOXINS


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EXOTOXINS


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Neurotoxin : Botulinum toxin

Clostridium botulinum causes botulismis a severe type of food poisoning

caused by the ingestion of foods

containing the neurotoxin formed

during growth of this bacteria

C. botulinum can be destroyed, ifheated to 80C for at least 10 minutes.

Weakness and vertigo, followed by

double vision, difficulty in speaking,

swallowing and breathing, muscleweakness, abdominal distention, and

constipation paralysis and death

may follow

BC Yang


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Neurotoxin : Tetanus toxin

Tetanus toxin:

Patient number in Canada

After antitoxin vaccine1941-1995

BC Yang


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Enterotoksin : Cholera toxins, causehyperactivation

Vibrio cholerae

BC Yang


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Cytotoxin : diphteria toxins, inhibition ofprotein synthesis

Corynebacterium diphtheriaeBeta-phage: lysogenic

Subunit A

BC Yang


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EXOTOXINS

Exotoxins are proteins, therefore, the immunesystem can generally produce protective antibodies.

Exotoxins can be inactivated and used to produceantitoxins called toxoids.

The body produces antibodies called antitoxins that

provide immunity to exotoxins. When toxoids are injected into the body as a

vaccine they stimulated antitoxins to be produced,diphtheria and tetanus are examples.


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Phospholipases are group of potent membrane-damaging

toxins

Remove polar heads of phospholipid

Destabilizes membrane

Clostridium perfringens which causes gas gangrene

is a phospholipase.

Disrupt plasma membrane

Cause cell lysis

Can be termed hemolysins or cytolysins.

Some membrane-damaging toxins produce pores that

allow fluids to enter causing cell destruction.

Streptococcus pyogenes on blood agar plates.

MEMBRANE DAMAGING TOXINS


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SUPERANTIGENS

Superantigens short-circuitnormal control mechanisms of

antigen process and

presentation

Superantigens also suspected incontributing to autoimmune

disease

Override specificity of T cellresponse Causes toxic effects due to massive

release of cytokines by large numberof helper T cells


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ENDOTOXINS Endotoxins are

lipopolysaccharides, part ofthe outer leaflet of the outer

membrane of Gram negative

bacteria include Salmonella

typhi, Proteus spp.,Pseudomonas spp., Neisseria

spp.

The lipid A component is

responsible for the toxicproperties of LPS.

If the lipid A is systemic,

such as a septicemia, the

reactions can result in septic

shock or endotoxic shock.


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ENDOTOXINS

All endotoxins produce the same signs and symptoms,regardless of the species of microorganism, although

not to the same degree.

Responses by the host include fever, weakness, and

generalized. If the lipid A is in a localized region themagnitude of the reaction is small.

Medical equipment that has been sterilized may still

contain endotoxins.

Limulus amoebocyte assay (LAL) is a test used todetect tiny amounts of endotoxin.


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Endotoxins and the Pyrogenic (Fever)Response


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COMPARISON OF EXOTOXINS

AND ENDOTOXINS


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COMPARISON OF EXOTOXINS

AND ENDOTOXINS


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ENZIM EKSTRASELULAR

Hialuronidase : membantu bakteri patogen menembusjaringan sel inang dgn menghidrolisis asam hialuronatyg berfungsi melekatkan sel-sel menjadi satu dihasilkan Staphylococcus, Streptococcus danClostridium

Lesitinase : enzim yg menghancurkan berbagaijaringan, terutama melisis sel-sel darah merah Clostridium perfringens penyebab gangrens gas(kelemayuh), suatu infeksi jar disertai gas & nanah

Kolagenase : enzim penghancur kolagen (serabut jarpada otot, tulang & tulang rawan) serta membentukstruktur jala meningkatkan virulensi Clostridiumperfringens


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ENZIM EKSTRASELULER

Koagulase : enzim yg bekerja sama dgn aktivator pdplasma utk mengubah fibrinogen mjd fibrin

menyebabkan endapan fibrin di sekitar sel bakteri yg

melindunginya dari sel fagosit inang.

Contoh : pembentukan dinding pd bisul yg disebabkanS. aureus

Leukosidin : enzim yg menghancurkan leukosit

dihasilkan bbrp Staphylococcus dan Streptococcus


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ENZIM EKSTRASELULER

Hemolisin : enzim pelisis sel darah merah danmembebaskan hemoglobinnya.

Ada 2 tipe yaitu :

1. Hemolisin ekstraseluler

Contoh : Streptolisin O dan S yg dihasilkan bbrpStreptococcus

2. Hemolisin penyebab perubahan warna agar darah,

tdr dari :

- -hemolisis (merah tdk berwarna, krn sel drhmerah lisis & Hb diubah mjd senyawa tdk

berwarna)

- -hemolisis (merah hijau, krn sel drh

merah lisis & Hb diubah mjd metemoglobin


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FAKTOR-FAKTOR LAIN YGMEMPENGARUHI INFEKSI

Afinitas jaringan

Gerbang masuk (Portal of of entry)

Penyebarluasan (Transmisi)


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AFINITAS JARINGAN

Bbrp mikroorganisme mempunyai afinitas ttt thd sel &jar ttt dirusak timbul penyakit

Contoh :

Brucella penyebab bruselosis (keguguran) pada ternakmenyerang plasenta ternak, krn plasenta inimempunyai gula eritritol yg dibutuhkan Brucella

S. typhi menyerang jar limfoid dd usus

Virus polio menyerang sel syaraf

Bbrp protozoa spt parasit malaria menyerang eritrositmanusia, namun pada stadium ttt tumbuh dalam jarnyamuk


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GERBANG MASUK Gerbang masuk : rute tertentu

masuknya patogen ke dalamtubuh sel inang

Contoh :

Saluran pencernaan utk bakteri

tifoid, disentri dan kolera tahan thd enzim mulut dan cairanlambung

Saluran pernafasan : bakteri TBC,pneumokokus dan difteri

Saluran kemih-kelamin :gonokokus & spiroketa

Goresan/luka pada kulit :stafilokokus

Retakan kulit : basil antraks

Gigitan artropoda atau hewan-hewan besar : protozoa penyebabmalaria dan virus rabies


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GERBANG MASUK

Gerbang masuk racun menentukan kemampuanmenyebabkan penyakit pada sel inang

Contoh :

Toksin botulinum menyebabkan keracunanparah atau kematian, bila termakan

Toksin mikrokokus menyebabkan reaksigastrointestinal gawat, bila termakan

Toksin Clostridium tetani dan streptokokushemolitik yg masuk lwt sistem pencernaan tdkmenimbulkan penyakit, ttp menimbulkankejang parah bila melalui kulit atau otot


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Transmission

1. Contact transmission Direct (physical contact)

Indirect (via

contaminated objects)

Droplets2. Vehicle Transmission

Waterborne

Airborne

Foodborne

3. Vector transmission :

mechanical and biological


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CONTACT TRANSMISSION

DIRECT CONTACT reservoir to host

INDIRECT CONTACT contaminated object tohost.

DROPLET reservoir to air (short distance)to host
http://www.dpd.cdc.gov/dpdx/HTML/Trichomoniasis.asp?body=Frames/S-Z/Trichomoniasis/body_Trichomoniasis_page1.htm


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Direct-C

ontactTransmission
http://www.dpd.cdc.gov/dpdx/HTML/Trichomoniasis.asp?body=Frames/S-Z/Trichomoniasis/body_Trichomoniasis_page1.htm


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Indirect-Contact Transmission

Door knobs areanother goodexample of a

fomite.

Influenzavirus?
http://www.recyclingthepast.com/hardware.htm


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Droplet Transmission

Measles?
http://www.econ.ucla.edu/doepke/spontax/disease/rb.htm


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VEHICLE TRANSMISSION

Common vehicle transmissionrefers to the transmission ofdisease agents by a commoninanimate reservoir (food,

drugs, blood) to an individual.

Airborne transmission refers tothe spread of agents by droplet

nuclei or dust at a distance ofmore than 1 meter from thereservoir to host.


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Airborne Transmission

Mycobacteriumtuberculosis?
http://helios.bto.ed.ac.uk/bto/biology/imagmem3.htm


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Airborne Transmission

Contact with air from small

room containing 12 people.

Contact with air from clean,

empty room.


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Waterb

orneTransmission

Cryptosporidium

parvum?


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Waterb

orneTransmission

Giardiasis

from

water.


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FoodborneTr

ansmission

Hepatitis A


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FoodborneTr

ansmission

Balantidium coli


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VECTORS

A vector, animals that

carry pathogens from

one host to another.

Biological: bite or feces

Mechanical:transported

on feet


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CHARACTERISTICS OF INFECTIOUSDISEASE

An infection that results in disease is called

infectious disease.

Diseases are characterized by symptoms and

signs.

SYMPTOMSsubjective evidence of disease as

sensed by the patient.

SIGNSobjective evidence of disease as noted byan observer.

SYNDROMESa specific group of symptoms or

signs which accompany a particular disease.


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CHARACTERISTICS OF INFECTIOUS

DISEASE Infectious diseases that spread from one host

to another are called communicable or

contagious diseases.

The ease of spread of a contagious disease

partly reflects the infectious dose, or the

number of microbes necessary to establish

an infection. The infectious dose is expressed as the ID50 ,

which indicates the number of microbes that

results in disease in 50% of the population.

PATTERN OF DISEASE


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Fig. 13.p398

PATTERN OF DISEASE


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INCUBATION PERIOD Incubation period is the time

from initial contact with the

infectious agent to the

appearance of the first

symptoms. During this period the agent is

multiplying at the portal of

entry but has not yet caused

enough damage to elicitsymptoms.

Incubation periods range

between 2 and 30 days

usually.


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PRODROMIAL STAGE

The prodromial stage is the

period when symptoms

develop.

The symptoms tend to bevague feelings of discomfort

such as head and muscle

aches, fatigue, and general

malaise.


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PERIOD OF INVASION

During the period of invasion

the infectious agent

multiplies at high levels,

exhibits its greatest toxicity,and becomes well

established.

This period is often marked

by fever and otherprominent and more specific

signs and symptoms.

The length of this period is

extremely variable.


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PERIOD OF CONVALESCENT

The period of convalescent is the time when

the patient recovers his strength and health

gradually returns.


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PRINCIPLES OF INFECTIOUS

DISEASE Duration of symptoms

Acute

Symptoms have rapid

onset and last only shorttime

Chronic

Symptoms develop slowly

and persist

Latent

Infection never

completely eliminated

Infection becomes

reactive


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EXTENT OF HOST INVOLVEMENT

A PRIMARY INFECTIONis

an acute infection that

causes the initial illness.

A SECONDARYINFECTIONis one caused

by an opportunist

microbe or is the result of

the primary infection. A SUBCLINICAL

INFECTIONis one that

does not cause any

noticeable illness.


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LOCALIZED INFECTION

microbes enters body &

remains confined to a

specific tissue.

FOCAL INFECTION when

infectious agent breaksloose from a local

infection and is carried

to other tissues.

SYSTEMIC INFECTION

infection spreads to

several sites and tissue

fluids usually in the

bloodstream.


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BACTEREMIAthe presence of bacteria

in the blood.

SEPTICEMIAif bacteria are multiply inthe blood.

TOXEMIApresence of toxins in the

blood. VIREMIApresence of viruses in the

blood.


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OCCURRENCE OF DISEASE

INCIDENCE measures the number of

new cases over a certain time period,

as compared with the general healthypopulation.

PREVALENCE total number of existing

cases with respect to the entirepopulation usually represented by a

percentage of the population.


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OCCURRENCE OF DISEASE

SPORADIC when occasionalcases are reported at irregular

intervals.

ENDEMIC disease that exhibits

a relatively steady frequencyover a long period of time in a

particular geographic locale.

EPIDEMIC when prevalence of

a disease is increasing beyondwhat is expected.

PANDEMIC epidemic across

continents

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