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Microbial adhesion: a source of infection in patients fed by enteral feeding
205
Letters to the Editor References
Alder, V. G., Burman, D., Simpson, R. A., Fysh, J. & Gillespie, W. A. (1980). Comparison of hexachlorophane and chlorhexidine powders in prevention of neonatal infection. Archives of Disease in Childhood 55, 277-280. Ayliffe, G. A. J., Brightwell, K. M., Ball, P. M. and Derrington, M. M. (1972). Staphylococcal infection in cervical glands of infants. Lancet ii, 479-480. Baber, K. G., Comer, B., Duncan, E. H. L., Eades, S. M., Gillespie W. A. &Walker, S. C. B. (1967). Journal of Hygiene Cambridge 65, 381-393. Comer, B. D., Crowther, S. T. & Eades, S. M. (1960). Control of staphylococcal infection in a maternity hospital. British Medical Journal 1, 1927-1929. De Sousa, S. W., Lewis, D. M., Allen, L. & Thomason, F. (1975). Hexachlorophane dusting powder for newborn infants. Lancet i, 860-861. Dixon, R. E., Kaslow, R. A.$ Mallison, G. F. & Bennett, J. V. (1973). Staphylococcal disease outbreaks in hospital nurseries in the United States. December 1971 through March 1972. Puediutrics 51,413-416. Gillespie. W. A.. Simpson, K. & Tozer. R. S. (1958). Stanhvlococcal infection in a maternitv h&&l. E$dem‘iolo& and Control. La&et ii, 107%iO80. Gillesnie. W. A.. Comer. B. D.. Burman. D. & Alder. V. G. (19741. Absomtion of h;xachloropl&ne froi dusting powder, ‘on newborn ihfants’ skin. Jo&al of hygiene, Cambridge 73,311-315. Plueckhahn, V. D. (1973). Infant antiseptic skin care and hexachlorophane. MedicalJournal of Australia 1, 93-100. Simpson, K.., Tozer, R. C. & Gillespie, W. A. (1960). Prevention of staphylococcal sepsis in a matermty hospital by means of hexachlorophane. British Medical Journal 1, 315-317.
Sir, Microbial
adhesion:
a source of infection
in patients
fed by enteral
feeding
Cundidu ulbicans and Cund. tropicalis have been found on enteral feeding tubes removed from the upper intestinal tract of children (Gemeinhardt Sz Kirchberger, 1971) and the development of staphylococcal enterocolitis in neonates has been associated with the passage of the feeding catheter through a nasal or gastronomy site colonized by Staphylococcus uureics (Gutman et al., 1976). It has also been suggested that the transmission of bacteria from the stomach to the respiratory tract may be facilitated by the presence of a nasogastric tube (Atherton & White, 1978). In a previous in 1984u), surface irregularities in which microvitro study (Anderton, organisms could become trapped were observed on the internal walls of a wide range of commercially available tubes. However, the external walls of these tubes were not studied. Since the above reports seem to suggest that may also adhere to and/or become trapped and micro-organisms subsequently colonize the outer walls of these tubes, a further study has been made to determine the adherence of Staph. uureus to the outer surfaces of enteral feeding tubes made of four different materials. The tubes selected were of polyvinylchloride, radio-opaque polyvinylchloride, radio-opaque polyurethane and radio-opaque silicone. Ten 1 -cm lengths of each tube were opened longitudinally with sterile razor blades and the resultant sections of tube were transferred to universal containers
206
Letters
to the Editor
with 20 ml Clinifeed IS0 (Roussel Laboratories Ltd., London) been experimentally contaminated with Staph. aweus (NCTC concc entration of lo* colony forming units (cfu) ml-’ (Bastow, Allis on, 1982; Anderton, 1984b). These samples were incubated
which had 10657) at a Greavc es & for 1 h and
enteral feeding tube after 24 h immers ion in Figur .e 1. Outer surface of polyvinylchloride feed c:xperimentally contaminated with Staphylococcus aureus. Bacterial cells and partic cles of feed q:an be seen on the reticulated surface (+). Figur .e 2. Outer surface of radio-opaque
polyurethane
enteral tube showing deep pit.
Letters
to the Editor
207
Figure 3. Outer surface of radio-opaque polyvinylchloride enteral tube after 24 h immersion in feed experimentally contaminated with Staphylococcus aureus. Bacterial cells and particles of feed are trapped in a pit on the surface (+). Particles of radio-opaque material in PVC tube are also visible.
24 h at 37°C in an orbital incubator at 120 rpm. After incubation each tube segment was washed by gentle manual agitation in sterile distilled water’ and prepared for examination in a scanning electron microscope (Philips PSEM 500) by a standard procedure as described by Anderton (1984~). Samples of unused tubes were also examined. The surface characteristics of the outer walls of the four types of tube examined were quite different. The outer surfaces of the PVC, radioopaque PVC and radio-opaque polyurethane tubes had many surface irregularities including longitudinal ridges, reticulation (Figure l), fissures, pits (Figure 2) and noticeable roughness due to radio-opaque material (Figure 3). After 24 h incubation, bacteria and particles of feed were observed to have lodged in irregularities on the surface of these tubes (Figures 1 & 3). Thus microbial colonization of the outer surfaces of these tubes may occur in the intestine or stomach and it can be hypothesized that subsequent growth may spread up the outside of the tube and present an infection hazard to the patient, particularly if the tube is left in situ for an extended period of time. By contrast, the outer surface of the silicone tube appeared to be fairly smooth and even after 24 h incubation very few adherent bacteria were visible. Botta, Costa & Pugliese (1984) recently stated that with fibre-optic endoscopes, further research is needed to find plastics that are less susceptible to adherence by intestinal bacteria. In studies on coronary catheters Bourassa et al. (1976) suggest that the use of perfectly regular moulds and more adequate extrusion methods would yield catheters with
Letters
208
to the Editor
minimal surface defects. Similar recommendations can be made for enteral feeding tubes. Further research is also needed to explore the possible relationship between the use of enteral feeding tubes and the transmission of bacteria from the stomach to the respiratory tract.
A. Anderton*
Department of Microbiology, University of Glasgow, Glasgow
I thank Professor K. Vickerman for use of the scanning electron microscope in the Zoology Department, Glasgow University: Lawrence Tetley and Helen Hendry of the Zoology Department for advice and assistance and Professor A. C. Wardlaw of the Microbiology Department for helpful discussion. l Present address: Department of Applied Park Drive, Glasgow G3 6PL.
& Life
Sciences,
The Queen’s
College,
Glasgow,
1
References Anderton, A. (1984~). Scanning electron microscopy of the internal wall topography of enteral feeding tubes. Clinical Nutrition 3, 171-176. Anderton, A. (19846). The potential of Escherichia coli in enteral feeds to cause food poisoning: a study under simulated ward conditions. Journal of Hospital Infection 5, 155-163. Atherton, S. T. & White, D. J. (1978). Stomach as source of bacteria colonising respiratory tract during artificial ventilation. Lancet ii, 968-969. Bastow, M. D., Greaves, P. & Allison, S. P. (1982). Microbial contamination of nasogastric feeds. Human Nutrition: Applied Nutrition 36A, 213-217. Botta, G. A., Costa, A. G. M. A. & Pugliese, V. (1984). Bacterial adherence to plastics: a role in endoscope-transmitted infections. Lancet i, 398-399. Bourassa, M., Cantin, M., Sandbom, E. B. & Pederson, E. (1976). Scanning electron microscopy of surface irregularities and thrombogenesis of polyurethane and polyethylene coronary catheters. Circulation 53, 992-996. Gemeinhardt, H. & Kirchberger, E. R. (1971). Zum Vorkommen von Soor-Pilzen auf Nahrungsdauersonden nach der Entnahme aus dem oberen Intestinaltrakt von Kindern. Piidiatrie und Grenzgebiete 10, 41-46. Gutman, L. T., Idriss, A. H., Gehlbach, S. & Blackman, L. (1976). Neonatal staphylococcal enterocolitis: Association with indwelling feeding catheters and Staphylococcus aureus colonization. Journal of Pediatrics, 88, 836-839.
Sir, Pseudo-outbreak
of Bacillus
species:
related
to fibreoptic
bronchoscopy
We read with interest the article by Goldstein & Abrutyn (1985) concerning a pseudo-outbreak of Bacillus spp. related to fibreoptic bronchoscopy. We wish to report two similar ‘pseudo-outbreaks’ that we have observed since October 1984. The first incident occurred between October 1984 and January 1985, when we isolated Bacillus spp. from bronchial washings obtained from six
Letters to the Editor References
Alder, V. G., Burman, D., Simpson, R. A., Fysh, J. & Gillespie, W. A. (1980). Comparison of hexachlorophane and chlorhexidine powders in prevention of neonatal infection. Archives of Disease in Childhood 55, 277-280. Ayliffe, G. A. J., Brightwell, K. M., Ball, P. M. and Derrington, M. M. (1972). Staphylococcal infection in cervical glands of infants. Lancet ii, 479-480. Baber, K. G., Comer, B., Duncan, E. H. L., Eades, S. M., Gillespie W. A. &Walker, S. C. B. (1967). Journal of Hygiene Cambridge 65, 381-393. Comer, B. D., Crowther, S. T. & Eades, S. M. (1960). Control of staphylococcal infection in a maternity hospital. British Medical Journal 1, 1927-1929. De Sousa, S. W., Lewis, D. M., Allen, L. & Thomason, F. (1975). Hexachlorophane dusting powder for newborn infants. Lancet i, 860-861. Dixon, R. E., Kaslow, R. A.$ Mallison, G. F. & Bennett, J. V. (1973). Staphylococcal disease outbreaks in hospital nurseries in the United States. December 1971 through March 1972. Puediutrics 51,413-416. Gillespie. W. A.. Simpson, K. & Tozer. R. S. (1958). Stanhvlococcal infection in a maternitv h&&l. E$dem‘iolo& and Control. La&et ii, 107%iO80. Gillesnie. W. A.. Comer. B. D.. Burman. D. & Alder. V. G. (19741. Absomtion of h;xachloropl&ne froi dusting powder, ‘on newborn ihfants’ skin. Jo&al of hygiene, Cambridge 73,311-315. Plueckhahn, V. D. (1973). Infant antiseptic skin care and hexachlorophane. MedicalJournal of Australia 1, 93-100. Simpson, K.., Tozer, R. C. & Gillespie, W. A. (1960). Prevention of staphylococcal sepsis in a matermty hospital by means of hexachlorophane. British Medical Journal 1, 315-317.
Sir, Microbial
adhesion:
a source of infection
in patients
fed by enteral
feeding
Cundidu ulbicans and Cund. tropicalis have been found on enteral feeding tubes removed from the upper intestinal tract of children (Gemeinhardt Sz Kirchberger, 1971) and the development of staphylococcal enterocolitis in neonates has been associated with the passage of the feeding catheter through a nasal or gastronomy site colonized by Staphylococcus uureics (Gutman et al., 1976). It has also been suggested that the transmission of bacteria from the stomach to the respiratory tract may be facilitated by the presence of a nasogastric tube (Atherton & White, 1978). In a previous in 1984u), surface irregularities in which microvitro study (Anderton, organisms could become trapped were observed on the internal walls of a wide range of commercially available tubes. However, the external walls of these tubes were not studied. Since the above reports seem to suggest that may also adhere to and/or become trapped and micro-organisms subsequently colonize the outer walls of these tubes, a further study has been made to determine the adherence of Staph. uureus to the outer surfaces of enteral feeding tubes made of four different materials. The tubes selected were of polyvinylchloride, radio-opaque polyvinylchloride, radio-opaque polyurethane and radio-opaque silicone. Ten 1 -cm lengths of each tube were opened longitudinally with sterile razor blades and the resultant sections of tube were transferred to universal containers
206
Letters
to the Editor
with 20 ml Clinifeed IS0 (Roussel Laboratories Ltd., London) been experimentally contaminated with Staph. aweus (NCTC concc entration of lo* colony forming units (cfu) ml-’ (Bastow, Allis on, 1982; Anderton, 1984b). These samples were incubated
which had 10657) at a Greavc es & for 1 h and
enteral feeding tube after 24 h immers ion in Figur .e 1. Outer surface of polyvinylchloride feed c:xperimentally contaminated with Staphylococcus aureus. Bacterial cells and partic cles of feed q:an be seen on the reticulated surface (+). Figur .e 2. Outer surface of radio-opaque
polyurethane
enteral tube showing deep pit.
Letters
to the Editor
207
Figure 3. Outer surface of radio-opaque polyvinylchloride enteral tube after 24 h immersion in feed experimentally contaminated with Staphylococcus aureus. Bacterial cells and particles of feed are trapped in a pit on the surface (+). Particles of radio-opaque material in PVC tube are also visible.
24 h at 37°C in an orbital incubator at 120 rpm. After incubation each tube segment was washed by gentle manual agitation in sterile distilled water’ and prepared for examination in a scanning electron microscope (Philips PSEM 500) by a standard procedure as described by Anderton (1984~). Samples of unused tubes were also examined. The surface characteristics of the outer walls of the four types of tube examined were quite different. The outer surfaces of the PVC, radioopaque PVC and radio-opaque polyurethane tubes had many surface irregularities including longitudinal ridges, reticulation (Figure l), fissures, pits (Figure 2) and noticeable roughness due to radio-opaque material (Figure 3). After 24 h incubation, bacteria and particles of feed were observed to have lodged in irregularities on the surface of these tubes (Figures 1 & 3). Thus microbial colonization of the outer surfaces of these tubes may occur in the intestine or stomach and it can be hypothesized that subsequent growth may spread up the outside of the tube and present an infection hazard to the patient, particularly if the tube is left in situ for an extended period of time. By contrast, the outer surface of the silicone tube appeared to be fairly smooth and even after 24 h incubation very few adherent bacteria were visible. Botta, Costa & Pugliese (1984) recently stated that with fibre-optic endoscopes, further research is needed to find plastics that are less susceptible to adherence by intestinal bacteria. In studies on coronary catheters Bourassa et al. (1976) suggest that the use of perfectly regular moulds and more adequate extrusion methods would yield catheters with
Letters
208
to the Editor
minimal surface defects. Similar recommendations can be made for enteral feeding tubes. Further research is also needed to explore the possible relationship between the use of enteral feeding tubes and the transmission of bacteria from the stomach to the respiratory tract.
A. Anderton*
Department of Microbiology, University of Glasgow, Glasgow
I thank Professor K. Vickerman for use of the scanning electron microscope in the Zoology Department, Glasgow University: Lawrence Tetley and Helen Hendry of the Zoology Department for advice and assistance and Professor A. C. Wardlaw of the Microbiology Department for helpful discussion. l Present address: Department of Applied Park Drive, Glasgow G3 6PL.
& Life
Sciences,
The Queen’s
College,
Glasgow,
1
References Anderton, A. (1984~). Scanning electron microscopy of the internal wall topography of enteral feeding tubes. Clinical Nutrition 3, 171-176. Anderton, A. (19846). The potential of Escherichia coli in enteral feeds to cause food poisoning: a study under simulated ward conditions. Journal of Hospital Infection 5, 155-163. Atherton, S. T. & White, D. J. (1978). Stomach as source of bacteria colonising respiratory tract during artificial ventilation. Lancet ii, 968-969. Bastow, M. D., Greaves, P. & Allison, S. P. (1982). Microbial contamination of nasogastric feeds. Human Nutrition: Applied Nutrition 36A, 213-217. Botta, G. A., Costa, A. G. M. A. & Pugliese, V. (1984). Bacterial adherence to plastics: a role in endoscope-transmitted infections. Lancet i, 398-399. Bourassa, M., Cantin, M., Sandbom, E. B. & Pederson, E. (1976). Scanning electron microscopy of surface irregularities and thrombogenesis of polyurethane and polyethylene coronary catheters. Circulation 53, 992-996. Gemeinhardt, H. & Kirchberger, E. R. (1971). Zum Vorkommen von Soor-Pilzen auf Nahrungsdauersonden nach der Entnahme aus dem oberen Intestinaltrakt von Kindern. Piidiatrie und Grenzgebiete 10, 41-46. Gutman, L. T., Idriss, A. H., Gehlbach, S. & Blackman, L. (1976). Neonatal staphylococcal enterocolitis: Association with indwelling feeding catheters and Staphylococcus aureus colonization. Journal of Pediatrics, 88, 836-839.
Sir, Pseudo-outbreak
of Bacillus
species:
related
to fibreoptic
bronchoscopy
We read with interest the article by Goldstein & Abrutyn (1985) concerning a pseudo-outbreak of Bacillus spp. related to fibreoptic bronchoscopy. We wish to report two similar ‘pseudo-outbreaks’ that we have observed since October 1984. The first incident occurred between October 1984 and January 1985, when we isolated Bacillus spp. from bronchial washings obtained from six