Surveillance and Control

of Hubbard Tank

Bacterial Contaminants

JOHN K. MILLER, M.D. NEIL T. LaFOREST, M.A.

MARY HEDBERG, M.S. and VILMA CHAPMAN, B.S.

During a two-year period, a cultural surveillance of bacterial contaminants of the Hubbard tank was made. A comparative study of the antiseptic value of 17 percent benzalkonium chloride, ortho-phenyl p-pert amyl phenol with potassium ricinol-eate in propyl glycol and alcohol (Amphyl®), acetic acid, and sodium hypochlorite (Clorox®) indicated that two hundred parts per million of chlorine was an effective disinfectant for most bacteria contaminating the tank, the exception be­ing Clostridia. A method for routine surveillance and control of bacterial contamination of the Hub­bard tank is presented.

P, atients requiring hydrother­apy contaminate waters of the Hubbard tank and arm and leg whirlpool baths with bacteria from infected ulcers or burns, from surfaces of the skin, and from fecal flora. Also, at times tap water may contain bacteria such as Pseu-domonas aeruginosa and Flavobacteriwn spe­cies, which thrive in a moist environment. Hence, continual cultural surveillance and con­trol are essential in the management of patients treated with hydrotherapy.

A variety of hospital disinfectants have been employed for the disinfection of hydrotherapy equipment.1 Povidone-iodine * in a concen­tration of three parts per million has been re­ported to be an effective disinfectant for whirl­pool baths.1 Calcium hypochlorite has been used as a disinfectant at fifty-five parts per million for various types of water baths, effec­tive only in an alkaline solution. However, with alteration in the pH, calcium has a tendency to form insoluble salts. Acetic acid in 2.5 percent concentration has been used to reduce gram-negative bacillary contaminants of Puritan

* Betadine®, The Purdue-Frederick Co., Yonkers, New York 10701.

Dr. Miller is Director of the Laboratories for Clinical Research, and Mrs. Hedberg is an Associate Bacteriologist at the Division of Laboratories and Research, New York State Department of Health, Albany, New York 12201. Mr. LaForest and Miss Chapman are Supervisor of Phys­ical Therapy and Supervisor of the Microbiology Labora­tories, respectively, Albany Medical Center Hospital, Albany, New York 12208,

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nebulizers,2,3 inhalation equipment,4 and in­dwelling catheters.5 The authors have found a 2 percent ortho-phenyl p-pert amyl phenol with potassium ricinoleate in propyl glycol and al­cohol t a valuable disinfectant of the drains of hand bowls in which the disinfectant probably remains for long periods of time. Koepke and Christopher found Amphyl® effective in control of bacterial contamination of whirlpool baths.6

Knoepfli and Pedersen report that a combina­tion of Dreft® and 10 percent benzalkonium chloride t is useful for sterilization of hydro­therapy equipment.7

METHODS

Prior to the present study, 17 percent benzal­konium chloride ** was used routinely as a disinfectant for hydrotherapy equipment. Since bacterial contamination persisted the authors decided to evaluate other disinfectants such as 1 percent acetic acid, 2 percent Amphyl®, and sodium hypochlorite solution in a concentra­tion of 5.25 percent as contained in Clorox® solution.

After hydrotherapy treatment in the Hubbard tank of patients with infected ulcers or burns, open wounds, draining sinuses or skin erup­tions, the following disinfection procedure was instituted:

1. While the unit was being drained, the sides and floor of the tank, and the immersed areas of the agitators and thermometer gauge were washed with a clean towel soaked with Roccal®.

2. After the tank was emptied, it was rinsed with tap water.

3. The sides and floor of the tank and im­mersed areas of the fixtures were washed with a clean towel soaked with the disin­fectant under study.

t Amphyl®, Lehn and Fink Products Corporation, 225 Summitt Avenue, Montvale, New Jersey 07645.

t Zephiron®, Winthrop Laboratories, 90 Park Avenue, New York, New York i0016.

** Roccal®, Winthrop Laboratories, 90 Park Avenue, New York, New York 10016.

4. The whole apparatus was rinsed with tap water.

5. The sides and walls of the tank and agi­tators and thermometer gauge were wiped dry with a clean sterile towel.

6. At the end of each day, two hundred cubic centimeters of the disinfectant under study were poured into all drains.

7. At the end of each week (Friday after­noon), the agitators were operated in a container Med with the disinfectant under study for ten minutes (600 seconds) and the thermometer shaft was soaked in the disinfectant for ten minutes (600 seconds).

Specimens were collected twice a month with a sterile cotton swab from the following areas of the tank: lower floor near the floor drains, both floor drains, both overflow drains, shaft of the thermometer, water-conducting tube of both agitators, and the walls of the tank. These specimens were collected at the conclusion of the disinfection procedure.

Each swab was placed in a tube of thiogly-colate broth and sent to the laboratory for aerobic and anaerobic culture. All cultures were incubated at 309 degrees Kelvin (36° C) and were observed for fourteen days.

The in vitro bactericidal action of four an­tiseptics, Betadine®, Amphyl®, acetic acid, and sodium hypochlorite was determined for two commonly found bacterial contaminants, Pseu-domonas and Flavobacterium. Roccal® was omitted since earlier experience had shown that it did not control contaminants in the tank.

Concentrations of the antiseptic were pre­pared by dilution of the stock solution in sterile tap water. Dilutions of an eighteen-hour broth culture of the test bacteria were prepared in sterile tap water and added to the various con­centrations of antiseptic solutions to give 104

organisms per cubic centimeter of the final solu­tion. After one, fifteen, and sixty minutes' (60, 900, and 3,600 seconds) contact at room tem­perature, 0.05 cubic centimeters of the culture-antiseptic mixture were uniformly spread on the surface of a blood agar plate. Plates were incu­bated for eighteen hours (64,800 seconds) at 309 degrees Kelvin (36° C) and the colonies were counted. The lowest antiseptic concentra­tion that resulted in no colonies on the agar

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plate was considered the minimal effective bac­tericidal concentration for a given time.

RESULTS

In chronological sequence in 1968, Roccal® was used for three months, 1 percent acetic acid for four and one-half months, 2 percent Amphyl® for three months, and, again, 1 per­cent acetic acid for the last month and one-half of the year. None of these disinfectants con­trolled bacterial contamination of the Hubbard tank.

Table 1 summarizes the sites of bacterial contamination. The most frequent sites were

both agitators, the floor drains, the overflow drains, and the floor of the tank near the drains. Pseudomonas aeruginosa was the most frequent contaminant, followed by Clostridium per-jringens and Flavobacterium species. Other pathogens recovered included Proteus species, Escherichia coli and Aerobacter aerogenes. In order of frequency of isolation, other organisms were Bacillus subtilis (14), Micrococcus tetra-genus (6) and diphtheroids (5).

During 1969, sodium hypochlorite in the strength of two hundred parts per million, was used for disinfection of the Hubbard tank. In this twelve-month period, there were twenty-two contaminants isolated from the tank: Clostridium perfringens, twelve; Micrococcus tetragenus, three; Bacillus subtilis, two; Staphy­

lococcus coagulase positive, two; Neisseria catarrhalis, two; and Streptococcus viridans, one. During seven monthly periods, no con­tamination occurred.

In March 1969, the tank became contam­inated with Clostridium perfringens which was recovered from nine areas of the tank after treatment with two hundred parts per million of sodium hypochlorite. Clostridium was iso­lated on two other occasions. That chlorine does not eliminate the spore-forming bacteria is not surprising. Chlorine, however, does control contamination by such bacteria as the Pseudomonas, Flavobacterium, Escherichia coli, Aerobacter aerogenes, and Proteus species.

T otal

14 14 6

15 15 12

8 11 5 4

104

Table 2 presents the bactericidal concentra­tions of Betadine®, sodium hypochlorite, acetic acid, and Amphyl® required to kill six cultures of Flavobacterium species, and four cultures of Pseudomonas aeruginosa in 15 minutes (900 seconds) of exposure. Sodium hypochlorite in a concentration of 0.02 percent ten parts per million of available chlorine killed all cultures tested. The minimal bactericidal concentration of Betadine® varied between 0.02 and 0.1 per­cent, i.e., two to ten parts per million available iodine. A much higher concentration of acetic acid or Amphyl® was required to effect bac­tericidal action.

The effect of chlorine solutions in one minute (60 seconds) was the same as that of a fifteen minute (900 second) exposure. Usually twice

TABLE 1 SITES OF CONTAMINATION OF THE HUBBARD TANK, 1968

Bacteria Pseudo­ Flavo­ Other Misc. Site monas Clostridium bacterium pathogens3 bacteria

Agitator—rt 1 c 2 4 3 4 Agitator—It 2 2 2 0 8 Thermometer 4 0 1 1 0 Floor drain—rt 5 2 1 6 1 Floor drain—It 1 5 0 7 2 Overflow drain—rt 6 1 2 1 2 Overflow drain—It 2 0 2 2 2 Floor 3 1 0 7 0 Walls 1 0 0 1 3 Faucet 0 0 0 lc 3

Total 25 13 12 29 25

a Streptococci, Staphylococci, Proteus, Aerobacter aerogenes, Escherichia coli. b Micrococcus tetragenes, Bacillus subtilis, Diphtheroids. c No. of strains isolated.

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as much Betadine® was needed to produce bac­tericidal action in one minute (60 seconds) as fifteen minutes (900 seconds). Exposure of the bacteria to the disinfectants for one hour (3,600 seconds) did not decrease the amount of the agent required to give a bactericidal

effect. Betadine® was not used in this study to con­

trol bacterial contamination of the Hubbard tank because of the significantly greater cost

of this disinfectant.

DISCUSSION

These observations indicate that solutions of sodium hypochlorite to give two hundred parts per million chlorine are an inexpensive and effective disinfectant for the control of bac­terial contamination of the Hubbard tank. The exception is a spore-forming bacterium such as Clostridium perjringens, a member of fecal flora. Sodium hypochlorite is a disinfectant recommended by the American Hospital As­sociation for sterilization of operating room equipment.8

Among the various germicides, only glu-taraldehyde (Cidex), formalin alcohol (5-8 percent formaldehyde, i.e., 12-20 percent formalin), ethylene oxide, and beta propriolac-tone are effective agents against spores. Even these, however, require prolonged exposure. Glutaraldehyde, a chemical relative of formalde­hyde, appears to be somewhat more effective

than formaldehyde in that a 2 percent alkaline solution is the equivalent of 8 percent formalde­hyde in alcohol. Glutaraldehyde kills spores within three hours (10,800 seconds) of ex­posure but it has limited stability and corrodes carbon steel. This latter effect requires thorough flushing of the tank with tap water after ex­posure. Formaldehyde in a moist environment promotes corrosion of metals and produces very irritating fumes.

The use of gas sterilization by agents such as ethylene oxide and beta propriolactone is not applicable to large fixed equipment. In addition to the fact that both are expensive germicides, ethylene oxide is poisonous and beta propriolactone is unstable and a vesicant. Three hours (10,800 seconds) of exposure with 2 percent glutaraldehyde, therefore, would appear to be the preferable germicide for spore sterilization of drains and agitators of the Hub­bard tank contaminated with Clostridia.

Koepke and Christopher found that areas of heaviest bacterial contamination of whirlpool baths were those near the drains and the agi­tators.6 Both their studies and this present study emphasize the importance of routine pe­riodic monitoring of drains and agitators by cultural examinations as a part of the sur­veillance and control of bacterial contamination of hydrotherapy equipment. Collection of cul­tures with cotton swabs placed in thioglycolate medium is an economical and time-saving method. Good hospital practice requires the

TABLE 2

BACTERICIDAL CONCENTRATION OF DISINFECTANTS REQUIRED TO KILL STRAINS OF Pseudomonas AND Flavobacterium WITHIN FIFTEEN MINUTES

Cuture Bactericidal concentration (%) no. Genus Betadine®" Na hypochlorite" Acetic acid Amphyl*®

013 Flavobacterium species 0.05 0.02 0. 12 0.25

014 Flavobacterium species

0.02 0.02 0.12 0.12

015 " 0.05 0.02 0.12 0.12

017 " 0.10 0.02 0.50 0.12

026 " 0.10 0.02 1.0 0. 12

027 " 0.05 0.02 0.5 0.06

008 Pseudomonas aeruginosa 0. 10 0.02 1.0 0.50

009 " 0.05 0.02 >1.0 0.50

011 " 0.05 0.02 >1.0 0.50

012 " 0.10 0.02 >1.0 0.50

"0.1 percent Betadine ® = ten parts per million available iodine. b 0.02 percent sodium hypochlorite = approximately ten parts per million available chlorine.

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assignment of patients with suspected or known areas of infection to the last period of the day's program of hydrotherapy.

SUMMARY

A method of surveillance and control of bac­terial contamination of the Hubbard tank has been presented. The effect of Roccal®, Amphyl®, acetic acid, and sodium hypochlorite on the control of bacterial contamination of the tank was studied. The in vitro minimal bactericidal concentration of Betadine®, Amphyl®, acetic acid, and sodium hypochlorite required to kill cultures of Pseudomonas and Flavobacterium, common contaminants of the Hubbard tank, was determined. Ten parts per million of chlorine, 0.02 percent sodium hypo­chlorite, was effective in vitro within fifteen minutes (900 seconds) and two hundred parts per million of chlorine was a very effective dis­infectant for most bacteria contaminating the tank. The exception was the spore-forming bacterium, Clostridium, a common inhabitant of fecal flora, which requires exposure, as long as three hours (10,800 seconds), to a germi­cide such as glutaraldehyde or formalin-alcohol

solutions.

REFERENCES

1.Zigenfus RW: Povidone-iodine as a bactericide in hy­drotherapy equipment. Phys Ther 49:582-585, 1969

2. Parker RH, Hoeprich PD: In vitro effect of buffered solutions of acetic acid, ti iclobisonium chloride, chlor-

hexidine diacetate, and chlorhexidine digluconate on urinary tract pathogens. Antimicrobial Agents & Chem­otherapy, pp 26-34, 1962

3. Edmonson EB, Reinarz JA, Pierce AK, et al: Nebuliza-tion equipment, a potential source of infection in gram-negative pneumonias. Amer J Dis Child 111:357-360, 1966

4. Reinarz JA, Pierce AK, Mays BB, et al: The potential role of inhalation therapy in nosocomial pulmonary infection. J Clin Invest 44:831-839, 1965

5. Kass EH, Sosser BS: Prevention of infection of urinary tract in presence of indwelling catheters: Description of electromechanical valve to provide intermittent drain­age of the bladder. J Amer Med Ass 169:1181-1183, 1959

6. Koepke GH, Christopher RP: Contamination of whirl­pool baths during treatment of infected wounds. Arch Phys Med 46:261-263, 1965

7. Knoepfli I, Pederson T: An effective method of steril­izing hydrotherapy equipment. J Amer Phys Ther Ass 42:514, 1962

8. American Hospital Association: Infection Control in Hospital. Chicago, American Hospital Association, 1968, p 94

SELECTED READINGS

1. Perkins JJ: Principles and Methods of Sterilization in Health Sciences 2d ed. Springfield, Illinois, Charles C Thomas, Publisher, 1969, Chapter 14, part 1, Chemical Disinfection, pp 327-344

2. Sykes JH: Calcium hypochlorite for disinfection of hy­drotherapy equipment. J Amer Phys Ther Ass 43:345-347, 1963

the authors ———— —

John K. Miller, M.D., is associate professor of medicine at the Albany Medical College and recently retired as chief of the Division of In­fectious Diseases. He received M.A. and M.D. degrees from the University of Nebraska. Dr. Miller is a Fellow of the American Col­lege of Physicians and a Member of the Royal Society of Health. He is director of the Laboratories for Clinical Research in the Division of Laboratories and Research of the New York State Department of Health.

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Neil T. LaForest is currently chief of physical therapy and supervisor of Physical Medicine and Rehabilitation at the Albany Medical Center Hospital. He received his B.A. degree from Syracuse University and his Certificate and Master of Arts in Physical Therapy from New York University.

Mary Hedberg is an associate bacteriologist in charge of the Sanitary Bacteriology Laboratory of the Division of Laboratories and Research, New York State Department of Health. She earned her B.S. degree from Russell Sage College and the M.S. degree from Brown University. Mrs. Hedberg was senior bacteriologist in the Clinical Research Lab­oratory of the Infectious Disease Center at the Division of Laboratories and Research when the work described was done.

Vilma Chapman is supervisor of the Microbiology Diagnostic Labora­tory of the Albany Medical Center Hospital. She received her B.S. degree from Russell Sage College.

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