Microbial contamination of enteral feeding solution and its prevention i
S. Oie, PhD" A. Kamiya, PhD" K. Hironaga, PhD b A. Koshiro, PhD c Ube, Houfu, and Niigata, Japan
In an investigation of microbial contamination of enteral feeding solutions, all 22 residual solutions obtained immediately after administration were contaminated at concentrations of 103 to 106 viable counts/ml. Major contaminants were glucose-nonfermenting gram-negative bacilli such as Pseudomonas aeruginosa and Acinetobacter calcoaceticus var anitratus. Contamination seemed to have been caused by frequent reuse of bag-type containers and the infusion tubes connected to the bags, neither of which can be washed or dried. Decontamination methods were evaluated by using polypropylene containers that can be washed and disinfected for administration. Few Serratia marcescens on the inside wall of the container were removed by rinsing with tap water, alone or in combination with detergent scrub. Tap water and detergent plus air-drying at 56° C for 1 hour reduced Serratia marcescens only somewhat. Tap water and detergent plus immersion in 0.01% sodium hypochlorite for 1 hour or in water at 70° C for 3 minutes eliminated all 1011cells of Serratia marcescens. (AJIC AMJ INFECT CONTROL1992;20:202-5)
Enteral feeding solution is a d m i n i s t e r e d at a daily v o lu me of b e t w e e n 100 a nd 2000 ml. If the solution is highly contaminated, a large n u m b e r of m i c r o o r g a n i s m s e n t e r the patient's body. Markedly c o n t a m i n a t e d enteral feeding solution, containing 103 to 109 gram-negative bacilli p e r milliliter, has b e e n r e p o r t e d to cause not only d i a r r h e a but also sepsis, pneum oni a , a n d u r i n a r y tract infection. 1-8 I n Japan, however, little attention seems to be p a i d to microbial c o n t a m i n a t i o n of enteral feeding solutions. Reports in ot her countries have s how n that microbial c o n t a m i n a t i o n of enteral feeding solution f r e q u e n t l y oc c ur s during its preparation, 9"1~ p r e s u m a b l y b e c a u s e of c o n t a m i n a t i o n of the m i xer a n d b l e n d e r o r the 'hands of the p r e p a r e r . In contrast, o u r experience suggests that f r e quent reuse of the n u t r i e n t solution a dm i ni s t r at i on container d u r i n g Iong periods m a y be the p r i m a r y From the Department of Pharmacy, Yamaguchi University Hospital,a Ube, the Department of Pharmacy, Yamaguchi Prefectural Central Hospital,b Houfu, and the Department of Pharmaceutics, Niigata College of Pharmacy? Niigata, Japan. Reprint requests: Akira Kamiya, PhD, Department of Pharmacy, Yamaguchi University Hospital, 1144 Kogushi, Ube 755, Japan. 17/47/35679
202
cause of c o n t a m i n a t i o n of solution. We also evaluated m et hods for d e c o n t a m i n a t i n g administ rat i on cont ai ners for reuse. METHODS Identification and counting of m i c r o o r g a n i s m s We analyzed 22 samples of nut ri ent solutions residual after a d m i n i s t r a t i o n to 22 patients at o u r hospital and two affiliated institutions. The nutrient solutions had been p r e p a r e d within 30 minutes before administration. Immediately after administration, for 30 minutes to 2 hours, samples of residual solution were collected f r o m the e n d of the infusion tube (the p o r t i o n c o n n e c t e d to the feeding tube). The samples w ere diluted at 10, 102, 103 , a n d 105 times with n o r m a l saline solution. Pipettes w e r e used to t r a n s f e r 0.2 ml of the undiluted or diluted samples to trypticase soy agar or S a b o u r a u d dextrose agar. Plates w ere streaked with a glass " h o c k e y stick," and incubated at 30 ° C for 24 to 72 hours (trypticase soy agar) a n d at 25 ° C for 2 to 7 days ( S a b o u r a u d dextrose agar). Colonies w e r e c o u n t e d on each plate to d e t e r m i n e colony-forming units (CFU) and organisms w e r e identified by G r a m staining, m o rp h o logic examination, the oxidation-fermentation
Volume 20 Number 4
test, the cytochrome-oxidase test, and the API System (Analytab Products, Plainview, N.Y.). The nutrient product Ensure (Dynabott Co. Ltd., Osaka, Japan) was used in eight cases, Elental (Ajinornoto Co., Inc., Tokyo, Japan) and Sunett-88 (Sanwa Chemicals, Nagoya, Japan) were used in four cases each, and Lifelon (Nikken Chemicals, Tokyo, Japan) and Clinimeal (Eisai Co. Ltd., Tokyo, Japan) were used in three cases each. Only Ensure was an aseptic liquid product requiring no preparation; the others were powder products used in solution. As a control measure, each product was cultured immediately after being prepared. Administration c o n t a i n e r s and their m a i n t e n a n c e
The three container types shown in Fig. 1 were each investigated. The methods of washing, disinfecting, and storing the containers and the infusion tubes were also studied. Evaluation of d e c o n t a m i n a t i o n
In this experiment, cylindrical polypropylene containers were used (Fig. 1) because bag-type and semibottle-type containers are structurally difficult to wash. Serratia m a r c e s c e n s (10 2 CFU/ml) were placed in the containers with Elental solution (600 ml) and incubated at 30 ° C for 24 hours. The Elental soIution was removed and the container was disinfected by one of the following five methods: (1) rinsing with tap water alone for 30 seconds, (2) scrubbing with tap water and detergent for 30 seconds, (3) scrubbing with tap water and detergent for 30 seconds and then drying in a hot-air dish drier (KD-6F; Hitachi Medical Corp., Tokyo) at about 56 ° C for 1 hour, (4) scrubbing with tap water and detergent for 30 seconds plus immersion in 0.01% sodium hypochlorite for 1 hour, and (5) scrubbing with tap water and detergent for 30 seconds plus immersion in water at 70 ° C for 3 minutes. After the decontamination procedure was complete, sterile physiologic saline solution (200 ml) was placed in the container, which was vibrated with a recipro shaker (SR-1; Taiyo Industry Ltd., Tokyo, Japan) at a frequency of 250 cycles/min and an amplitude of 50 m m for 30 minutes. The decontamination effects of the five methods were then compared by counting microorganisms in the saline solution. The count was done by the method described previously. The experiment was done in triplicate and the mean value of the three trials was obtained. The Serratia marcescens used
Contamination of enteral feeding solutions
203
in this experiment had been isolated from contaminated Elental solution. The strain was maintained on nutrient agar slants, stored at 4 ° C, and transferred monthly. RESULTS
The colony counts and major organisms identified are shown in Table 1. The major contaminants were glucose nonfermentative bacilli such as the Pseudomonas group, represented by Pseudomonas aeruginosa and Acinetobacter calcoaceticus var anitratus, which were detected in 20 of the 22 samples. Although yeastlike fungi were identified along with bacteria in six samples, their colony counts (102 to 103 CFU/ml) were lower than were those of bacteria. As a control measure, each freshly prepared product was cultured. The degree of contamination of the products was low, with a microorganism count of no more than 1 CFU/ml or CFU/gm in all products except Sunett-88. The main contaminant was Bacillus species. In Sunett-88 the microorganism count was 60 CFU/ml and the primary contaminant was also Bacillus species. For enteral feeding, bag-type container (made of polyvinylchloride) were used in 20 cases and semibottle-type containers (made of polyethylene) were used in two; cylindrical containers were not used in any cases. In all cases administration containers were rinsed with tap water after administration while remaining connected to their infusion tubes (made of polyvinylchloride) and left at room temperature until next use . . . . The effects of the five decontamination methods are compared in Table 2. Immersion in 0.01% sodium hypochlorite for 1 hour or in water at 70 ° C for 3 minutes after scrubbing with tap water and detergent eliminated nearly all of these microorganisms. DISCUSSION
Our experiment revealed microbial contamination (10 a to 106) CFU/ml in all 22 samples of residual enteral feeding solutions. In the eight cases in which Ensure, an aseptic liquid preparation, was used, contamination during preparation may be excluded because the product required no processing and was poured directly into the nutrient' solution container. The interval between the initiation of the preparation and the termination of administration was 21/2 hours or less in all cases. Microbial growth during this period would be expected to be negligible if the sources of contamination were other than the apparatus used
AJIC
204
August 1992
Oie et al.
Fig, 1. Three kinds of feeding apparatus and infusion tube. Left to right: bag type, semibottle type, cylindrical, infusion tube.
for preparation or the nutrient solution container used for administration. At least in cases in which Ensure was used, potential contamination sources other than the container used for administration need not be considered. All three types of containers (Fig. 1) are disposable, but they are frequently used for more than 7 days in Japan for economic reasons. The same is true of the infusion tube connected to the container. However, the bag-type and semibottle-type containers and the infusion tube cannot be washed, disinfected, or dried for structural reasons and are thus readily contaminated. Once the container is contaminated, microorganisms adhere to its inside wall and can not be removed by rinsing with tap water alone. 12 In all 22 cases studied in our experiment, a bag-type or semibottle-type container was used repeatedly with tap-water rinsing alone between uses. After being rinsed with tap water, containers were left connected to the infusion tube. The insides of container and tube were wet until the next use. This m a i n t e n a n c e pattern seems to have provided good conditions for microbial contamination and growth. The m a r k e d contamination of the enteral feeding solutions m a y therefore have been due to the use of contaminated administration containers and infusion tubes. In the United States, there
have been no reports on contamination of enteral feeding solution by contaminated administration containers. This m a y be because of the r e c o m m e n dation that such containers and tubes be replaced at 24-hour intervals. 13 The concentration of gram-negative bacilli in the samples of enteral feeding solutions was 103 to 106 CFU/ml, markedly exceeding the permissible level (102 CFU/ml or less) determined by Anderton and associates in England. ~4 Enteral feeding solution contaminated with about 103 to 109 CFU/ml of gram-negative bacilli has been reported to cause various clinical symptoms. 2" 3, 6-8, 15 The microbial concentration observed in this experim e n t is therefore at the critical level. In our studies of cylindrical containers, adequate decontamination was not achieved even after scrubbing with detergent and drying in a dish drier. S e r r a t i a m a r c e s c e n s placed in the containers multiplied, adhering to the inner wall secreting a substance to protect themselves against scrubbing and drying. 164s Once a container has become contaminated, decontamination is difficult to achieve by rinsing with tap water or even by scrubbing with detergent plus hot-air drying. When a cylindrical container is used repeatedly, immersion in 0.01% sodium hypochlorite for 1 h o u r or in waterat 70 ° C for
Volume 20 Number 4
3 minutes o r at 80 ° C for 1 minute is necessary to disinfect it, ~%20 . . . . . To prevent contamination of enteral feeding solution, attention should be paid not only to cleanliness of the apparatus used for preparation of powder products, as has been suggested, but also to the cleanliness of nutrient fluid containers used for administration. The bag-type container and the infusion tube, both of which are difficuk to wash and disinfect, should be used only once or only in one patient for a m a x i m u m of 24 hours. If containers are to be used frequently, cylindrical containers, which are readily washed and disinfected, should be used with washing and disinfection at each use. The infusion tube should still be used only for 1 day. Availability of liquid products in disposable packaging that can also be used as the administration container is awaited. 21 References 1. Pottecher B, Goetz ML, Jacquemaire MA, Reeb E, Lavillaurcix J. Ent6rocolites infectieuses chez des malades de r6animation aliment6s par sonde nasogastrique. Ann Anesthesiol Fr 1979;20:595-602. 2. Casewell MW, Cooper JE, Webster M. Enteral feeds contaminated with Enterobacter cloacae as a cause of septicaemia. BMJ 1981;282:973. 3. Gill KJ, Gill P. Contaminated enteral feeds [Letter]. BMJ 1981;282:1971. 4. de Vries EGE, Mulder NH, Houwen B, de Vries-Hospers HG. Enteral nutrition by nasogastric tube in adult patients treated with intensive chemotherapy for acute leukemia. Am J Clin Nutr 1982;35:1490-6. 5. Baldwin BA, Zagoren AJ, Rose N. Bacterial contamination of continuously infused enteral alimentation with needle catheter jejunostomy-clinical implications. JPEN J Parenter Enter Nutr 1983;8:30-3. 6. Freedland CP, Roller RD, Wolfe BM, Flynn NM. Microbial contamination of continuous drip feedings. JPEN J Parenter Enter Nutr 1989;13:13-22. 7. Levy J, Laethem YV, Verhaegen G, Perpete C, Butzler JP,
Contamination o f enteral feeding solutions
205
Wenzel RP. Contaminated enteral nutrition solutions as a cause of nosocomial blood stream infection: a study using plasmid fingerprinting. JPEN J Parenter Enter Nutr 1989;13:228-34. 8. Thurn J, Crossley K, Gerdts A, Maki M, Johnson J. Enteral hyperalimentation as a source of nosocomial infection. J Hosp Infect 1990;15:203-17. 9, Allwood MC. Microbial contamination of parenteral and enteral nutrition solutions. Acta Chir Scand 1981; 507(Suppl):383-7. 10. Casewell MW. Bacteriological hazards of contaminated enteral feeds. J Hosp Infect 1982;3:329-31. 11. Paauw JD, Fagerman KE, McCamish MA, Dean RE. Enteral nutrient solutions. Am Surg 1984;50:312-6. 12. Grunow JE, Christenson JC, Moutos D. Contamination of enteral nutrition systems during prolonged intermittent use. JPEN J Pareuter Enter Nutr 1989; 13:23-5. 13. Van Enk RA, Furtado D. Bacterial contamination of enteral nutrient solutions: intestinal colonization and sepsis in mice after ingestion. JPEN J Parenter Enter Nutr 1986; 10:503-7. 14. Anderton A, Howard JP, Scott DW. Microbiological control in enteral feeding. Hum Nutr Appl Nutr 1986;40: 163-7. 15. Botsford KB, Weinstein RA, Boyer KM, Nathan C, Carman M, Paton JB. Gram-negative bacilli in human milk feedings: quantitation and clinical consequences for premature infants. J Pediatr 1986;109:707-10. 16. Marrie TJ, Costerton JW. Prolonged survival of Serratia marcescens in chlorhexidine. Appl Environ Microbiol 1981;42:1093-102. 17. Miller MJ, Ahearn DG. Adherence of Pseudomonas aeruginosa to hydrophilic contact lenses and other substrata. J Clin Microbiol 1987;25:1392-7. 18. Price D, Ahearn DG. Incidence and persistence of Pseudomonas aeruginosa in whirlpools. J Clin Microbiol 1988;26:1650-4. 19. Shanson D. Could you comment about "percentage', in connection with the strengths of hypoehlorite solutions in hospital? [Letter] J Hosp Infect 1980; 1:88-9. 20. Babb JR. Methods of reprocessing complex medical equipment. J Hosp Infect 1988;I 1(Suppl):285-91. 2 i. Vaughan LA, Manore M, Winston DH. Bacterial safety of a closed-administration system for enteral nutrition solutions. J Am Diet Assoc 1988;88:35-7.
S. Oie, PhD" A. Kamiya, PhD" K. Hironaga, PhD b A. Koshiro, PhD c Ube, Houfu, and Niigata, Japan
In an investigation of microbial contamination of enteral feeding solutions, all 22 residual solutions obtained immediately after administration were contaminated at concentrations of 103 to 106 viable counts/ml. Major contaminants were glucose-nonfermenting gram-negative bacilli such as Pseudomonas aeruginosa and Acinetobacter calcoaceticus var anitratus. Contamination seemed to have been caused by frequent reuse of bag-type containers and the infusion tubes connected to the bags, neither of which can be washed or dried. Decontamination methods were evaluated by using polypropylene containers that can be washed and disinfected for administration. Few Serratia marcescens on the inside wall of the container were removed by rinsing with tap water, alone or in combination with detergent scrub. Tap water and detergent plus air-drying at 56° C for 1 hour reduced Serratia marcescens only somewhat. Tap water and detergent plus immersion in 0.01% sodium hypochlorite for 1 hour or in water at 70° C for 3 minutes eliminated all 1011cells of Serratia marcescens. (AJIC AMJ INFECT CONTROL1992;20:202-5)
Enteral feeding solution is a d m i n i s t e r e d at a daily v o lu me of b e t w e e n 100 a nd 2000 ml. If the solution is highly contaminated, a large n u m b e r of m i c r o o r g a n i s m s e n t e r the patient's body. Markedly c o n t a m i n a t e d enteral feeding solution, containing 103 to 109 gram-negative bacilli p e r milliliter, has b e e n r e p o r t e d to cause not only d i a r r h e a but also sepsis, pneum oni a , a n d u r i n a r y tract infection. 1-8 I n Japan, however, little attention seems to be p a i d to microbial c o n t a m i n a t i o n of enteral feeding solutions. Reports in ot her countries have s how n that microbial c o n t a m i n a t i o n of enteral feeding solution f r e q u e n t l y oc c ur s during its preparation, 9"1~ p r e s u m a b l y b e c a u s e of c o n t a m i n a t i o n of the m i xer a n d b l e n d e r o r the 'hands of the p r e p a r e r . In contrast, o u r experience suggests that f r e quent reuse of the n u t r i e n t solution a dm i ni s t r at i on container d u r i n g Iong periods m a y be the p r i m a r y From the Department of Pharmacy, Yamaguchi University Hospital,a Ube, the Department of Pharmacy, Yamaguchi Prefectural Central Hospital,b Houfu, and the Department of Pharmaceutics, Niigata College of Pharmacy? Niigata, Japan. Reprint requests: Akira Kamiya, PhD, Department of Pharmacy, Yamaguchi University Hospital, 1144 Kogushi, Ube 755, Japan. 17/47/35679
202
cause of c o n t a m i n a t i o n of solution. We also evaluated m et hods for d e c o n t a m i n a t i n g administ rat i on cont ai ners for reuse. METHODS Identification and counting of m i c r o o r g a n i s m s We analyzed 22 samples of nut ri ent solutions residual after a d m i n i s t r a t i o n to 22 patients at o u r hospital and two affiliated institutions. The nutrient solutions had been p r e p a r e d within 30 minutes before administration. Immediately after administration, for 30 minutes to 2 hours, samples of residual solution were collected f r o m the e n d of the infusion tube (the p o r t i o n c o n n e c t e d to the feeding tube). The samples w ere diluted at 10, 102, 103 , a n d 105 times with n o r m a l saline solution. Pipettes w e r e used to t r a n s f e r 0.2 ml of the undiluted or diluted samples to trypticase soy agar or S a b o u r a u d dextrose agar. Plates w ere streaked with a glass " h o c k e y stick," and incubated at 30 ° C for 24 to 72 hours (trypticase soy agar) a n d at 25 ° C for 2 to 7 days ( S a b o u r a u d dextrose agar). Colonies w e r e c o u n t e d on each plate to d e t e r m i n e colony-forming units (CFU) and organisms w e r e identified by G r a m staining, m o rp h o logic examination, the oxidation-fermentation
Volume 20 Number 4
test, the cytochrome-oxidase test, and the API System (Analytab Products, Plainview, N.Y.). The nutrient product Ensure (Dynabott Co. Ltd., Osaka, Japan) was used in eight cases, Elental (Ajinornoto Co., Inc., Tokyo, Japan) and Sunett-88 (Sanwa Chemicals, Nagoya, Japan) were used in four cases each, and Lifelon (Nikken Chemicals, Tokyo, Japan) and Clinimeal (Eisai Co. Ltd., Tokyo, Japan) were used in three cases each. Only Ensure was an aseptic liquid product requiring no preparation; the others were powder products used in solution. As a control measure, each product was cultured immediately after being prepared. Administration c o n t a i n e r s and their m a i n t e n a n c e
The three container types shown in Fig. 1 were each investigated. The methods of washing, disinfecting, and storing the containers and the infusion tubes were also studied. Evaluation of d e c o n t a m i n a t i o n
In this experiment, cylindrical polypropylene containers were used (Fig. 1) because bag-type and semibottle-type containers are structurally difficult to wash. Serratia m a r c e s c e n s (10 2 CFU/ml) were placed in the containers with Elental solution (600 ml) and incubated at 30 ° C for 24 hours. The Elental soIution was removed and the container was disinfected by one of the following five methods: (1) rinsing with tap water alone for 30 seconds, (2) scrubbing with tap water and detergent for 30 seconds, (3) scrubbing with tap water and detergent for 30 seconds and then drying in a hot-air dish drier (KD-6F; Hitachi Medical Corp., Tokyo) at about 56 ° C for 1 hour, (4) scrubbing with tap water and detergent for 30 seconds plus immersion in 0.01% sodium hypochlorite for 1 hour, and (5) scrubbing with tap water and detergent for 30 seconds plus immersion in water at 70 ° C for 3 minutes. After the decontamination procedure was complete, sterile physiologic saline solution (200 ml) was placed in the container, which was vibrated with a recipro shaker (SR-1; Taiyo Industry Ltd., Tokyo, Japan) at a frequency of 250 cycles/min and an amplitude of 50 m m for 30 minutes. The decontamination effects of the five methods were then compared by counting microorganisms in the saline solution. The count was done by the method described previously. The experiment was done in triplicate and the mean value of the three trials was obtained. The Serratia marcescens used
Contamination of enteral feeding solutions
203
in this experiment had been isolated from contaminated Elental solution. The strain was maintained on nutrient agar slants, stored at 4 ° C, and transferred monthly. RESULTS
The colony counts and major organisms identified are shown in Table 1. The major contaminants were glucose nonfermentative bacilli such as the Pseudomonas group, represented by Pseudomonas aeruginosa and Acinetobacter calcoaceticus var anitratus, which were detected in 20 of the 22 samples. Although yeastlike fungi were identified along with bacteria in six samples, their colony counts (102 to 103 CFU/ml) were lower than were those of bacteria. As a control measure, each freshly prepared product was cultured. The degree of contamination of the products was low, with a microorganism count of no more than 1 CFU/ml or CFU/gm in all products except Sunett-88. The main contaminant was Bacillus species. In Sunett-88 the microorganism count was 60 CFU/ml and the primary contaminant was also Bacillus species. For enteral feeding, bag-type container (made of polyvinylchloride) were used in 20 cases and semibottle-type containers (made of polyethylene) were used in two; cylindrical containers were not used in any cases. In all cases administration containers were rinsed with tap water after administration while remaining connected to their infusion tubes (made of polyvinylchloride) and left at room temperature until next use . . . . The effects of the five decontamination methods are compared in Table 2. Immersion in 0.01% sodium hypochlorite for 1 hour or in water at 70 ° C for 3 minutes after scrubbing with tap water and detergent eliminated nearly all of these microorganisms. DISCUSSION
Our experiment revealed microbial contamination (10 a to 106) CFU/ml in all 22 samples of residual enteral feeding solutions. In the eight cases in which Ensure, an aseptic liquid preparation, was used, contamination during preparation may be excluded because the product required no processing and was poured directly into the nutrient' solution container. The interval between the initiation of the preparation and the termination of administration was 21/2 hours or less in all cases. Microbial growth during this period would be expected to be negligible if the sources of contamination were other than the apparatus used
AJIC
204
August 1992
Oie et al.
Fig, 1. Three kinds of feeding apparatus and infusion tube. Left to right: bag type, semibottle type, cylindrical, infusion tube.
for preparation or the nutrient solution container used for administration. At least in cases in which Ensure was used, potential contamination sources other than the container used for administration need not be considered. All three types of containers (Fig. 1) are disposable, but they are frequently used for more than 7 days in Japan for economic reasons. The same is true of the infusion tube connected to the container. However, the bag-type and semibottle-type containers and the infusion tube cannot be washed, disinfected, or dried for structural reasons and are thus readily contaminated. Once the container is contaminated, microorganisms adhere to its inside wall and can not be removed by rinsing with tap water alone. 12 In all 22 cases studied in our experiment, a bag-type or semibottle-type container was used repeatedly with tap-water rinsing alone between uses. After being rinsed with tap water, containers were left connected to the infusion tube. The insides of container and tube were wet until the next use. This m a i n t e n a n c e pattern seems to have provided good conditions for microbial contamination and growth. The m a r k e d contamination of the enteral feeding solutions m a y therefore have been due to the use of contaminated administration containers and infusion tubes. In the United States, there
have been no reports on contamination of enteral feeding solution by contaminated administration containers. This m a y be because of the r e c o m m e n dation that such containers and tubes be replaced at 24-hour intervals. 13 The concentration of gram-negative bacilli in the samples of enteral feeding solutions was 103 to 106 CFU/ml, markedly exceeding the permissible level (102 CFU/ml or less) determined by Anderton and associates in England. ~4 Enteral feeding solution contaminated with about 103 to 109 CFU/ml of gram-negative bacilli has been reported to cause various clinical symptoms. 2" 3, 6-8, 15 The microbial concentration observed in this experim e n t is therefore at the critical level. In our studies of cylindrical containers, adequate decontamination was not achieved even after scrubbing with detergent and drying in a dish drier. S e r r a t i a m a r c e s c e n s placed in the containers multiplied, adhering to the inner wall secreting a substance to protect themselves against scrubbing and drying. 164s Once a container has become contaminated, decontamination is difficult to achieve by rinsing with tap water or even by scrubbing with detergent plus hot-air drying. When a cylindrical container is used repeatedly, immersion in 0.01% sodium hypochlorite for 1 h o u r or in waterat 70 ° C for
Volume 20 Number 4
3 minutes o r at 80 ° C for 1 minute is necessary to disinfect it, ~%20 . . . . . To prevent contamination of enteral feeding solution, attention should be paid not only to cleanliness of the apparatus used for preparation of powder products, as has been suggested, but also to the cleanliness of nutrient fluid containers used for administration. The bag-type container and the infusion tube, both of which are difficuk to wash and disinfect, should be used only once or only in one patient for a m a x i m u m of 24 hours. If containers are to be used frequently, cylindrical containers, which are readily washed and disinfected, should be used with washing and disinfection at each use. The infusion tube should still be used only for 1 day. Availability of liquid products in disposable packaging that can also be used as the administration container is awaited. 21 References 1. Pottecher B, Goetz ML, Jacquemaire MA, Reeb E, Lavillaurcix J. Ent6rocolites infectieuses chez des malades de r6animation aliment6s par sonde nasogastrique. Ann Anesthesiol Fr 1979;20:595-602. 2. Casewell MW, Cooper JE, Webster M. Enteral feeds contaminated with Enterobacter cloacae as a cause of septicaemia. BMJ 1981;282:973. 3. Gill KJ, Gill P. Contaminated enteral feeds [Letter]. BMJ 1981;282:1971. 4. de Vries EGE, Mulder NH, Houwen B, de Vries-Hospers HG. Enteral nutrition by nasogastric tube in adult patients treated with intensive chemotherapy for acute leukemia. Am J Clin Nutr 1982;35:1490-6. 5. Baldwin BA, Zagoren AJ, Rose N. Bacterial contamination of continuously infused enteral alimentation with needle catheter jejunostomy-clinical implications. JPEN J Parenter Enter Nutr 1983;8:30-3. 6. Freedland CP, Roller RD, Wolfe BM, Flynn NM. Microbial contamination of continuous drip feedings. JPEN J Parenter Enter Nutr 1989;13:13-22. 7. Levy J, Laethem YV, Verhaegen G, Perpete C, Butzler JP,
Contamination o f enteral feeding solutions
205
Wenzel RP. Contaminated enteral nutrition solutions as a cause of nosocomial blood stream infection: a study using plasmid fingerprinting. JPEN J Parenter Enter Nutr 1989;13:228-34. 8. Thurn J, Crossley K, Gerdts A, Maki M, Johnson J. Enteral hyperalimentation as a source of nosocomial infection. J Hosp Infect 1990;15:203-17. 9, Allwood MC. Microbial contamination of parenteral and enteral nutrition solutions. Acta Chir Scand 1981; 507(Suppl):383-7. 10. Casewell MW. Bacteriological hazards of contaminated enteral feeds. J Hosp Infect 1982;3:329-31. 11. Paauw JD, Fagerman KE, McCamish MA, Dean RE. Enteral nutrient solutions. Am Surg 1984;50:312-6. 12. Grunow JE, Christenson JC, Moutos D. Contamination of enteral nutrition systems during prolonged intermittent use. JPEN J Pareuter Enter Nutr 1989; 13:23-5. 13. Van Enk RA, Furtado D. Bacterial contamination of enteral nutrient solutions: intestinal colonization and sepsis in mice after ingestion. JPEN J Parenter Enter Nutr 1986; 10:503-7. 14. Anderton A, Howard JP, Scott DW. Microbiological control in enteral feeding. Hum Nutr Appl Nutr 1986;40: 163-7. 15. Botsford KB, Weinstein RA, Boyer KM, Nathan C, Carman M, Paton JB. Gram-negative bacilli in human milk feedings: quantitation and clinical consequences for premature infants. J Pediatr 1986;109:707-10. 16. Marrie TJ, Costerton JW. Prolonged survival of Serratia marcescens in chlorhexidine. Appl Environ Microbiol 1981;42:1093-102. 17. Miller MJ, Ahearn DG. Adherence of Pseudomonas aeruginosa to hydrophilic contact lenses and other substrata. J Clin Microbiol 1987;25:1392-7. 18. Price D, Ahearn DG. Incidence and persistence of Pseudomonas aeruginosa in whirlpools. J Clin Microbiol 1988;26:1650-4. 19. Shanson D. Could you comment about "percentage', in connection with the strengths of hypoehlorite solutions in hospital? [Letter] J Hosp Infect 1980; 1:88-9. 20. Babb JR. Methods of reprocessing complex medical equipment. J Hosp Infect 1988;I 1(Suppl):285-91. 2 i. Vaughan LA, Manore M, Winston DH. Bacterial safety of a closed-administration system for enteral nutrition solutions. J Am Diet Assoc 1988;88:35-7.
