Microbiology of Hospital Washrooms

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Microorganisms in Washrooms

A bacteriological survey is commonly conducted following a disease outbreak to identify the etiology of the infection. Several studies have traced the source of infection to toilets1; thus, understanding the microbiology of toilets is necessary to the prevention of bacterial infections. A study was conducted in which 130 washrooms from various premises were sampled to characterize the bacterial community (Figure 1) and infection “hotspots”(Figure 2). Human feces contain large populations of enteric facultative anaerobic bacteria such as Escherichia coli and Streptococcus faecalis. On the other hand, obligate anaerobes and non-spore forming bacteria do not play a role in cross-infections in washrooms as they cannot survive on open surfaces1.

Urinals and toilet seats contained the greatest concentration of fecal bacteria (Figure 2), and are likely to be sources of infection. Surfaces that are normally dry, such as cubical door locks and flush handles, were rarely contaminated. On the other hand, inside handles of the entrance door and tap handles showed a greater degree of contamination since moisture from hands provides a more favourable environment for microorganisms1. These surfaces are often touched by people after hand washing, which would re-contaminate their hands.

Groundwater serves as water for more than 50% of people living in North America therefore a significant public resource. To date, major contamination of groundwater in North America are due to the release and use of chlorinated ethenes by industry. Examples of such toxic compounds are perchloroethene (PCE), trichloroethene (TCE). Carbon tetrachloride (CT) is also a major groundwater pollutant [4]. These compounds were widely used as solvents for dry cleaning and in textile manufacturing. They are sufficiently water soluble and can travel through soil where they reach the groundwater. The relative high concentration of them here can be harmful [6].

Disease Transmission

Methods of infection reported include splashing during defecation2, direct inhalation and ingestion3, as well as through the contaminated environment via the surface-to-hand-to-mouth contact4. Microorganisms have been recovered in large enough numbers on various surfaces of the washroom such that all these methods of infection are possible1,2.

The release of microorganisms into the air is most likely immediately after first flushing, i.e. the concentration of bacteria recovered from air samples is greatest. Even though each subsequent flush allowed a 2 to 3-log reduction in the concentration of microbes, it caused a further dissemination of airborne particles4. Surface contamination occurred within 90 min of flushing5.

Clinical Relevance

Prevalence of Microbes in Hospital Toilets

The risk of infection arising from microorganisms breeding in hospital toilets has been evaluated; interestingly, opposing views exist on the likelihood and severity of such an infection. One of the first studies to evaluate the risk of infection from hospital toilets was conducted by Newsom in 1972. A low number of fecal bacteria were cultivated from the air, water, and surfaces of hospital toilets, indicating a low risk of infection. Free aerobic bacteria were too low in numbers, compared to the 1011 required to produce a bacterial aerosol 6, to be of concern. However, more recent studies have pointed out that Newsom did not account for either anaerobes or spore-forming bacteria. Newsom’s study predated the first case of Clostridium difficile infection, a species of spore-forming bacteria5. Furthermore, Escherichia coli were used as the only indicator of fecal contamination1 when in reality there are many other types of enteric bacteria present. Therefore, the concentration of fecal bacteria in hospital toilets is likely to have been underestimated in Newsom’s study.

Antibiotic Resistant Pathogenic Species

Because of the heavy use of antibiotics, many of the organisms found in hospital environments are resistant to antibiotics7. Bacteria like methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus (VRE), and Clostridium difficile are becoming more prevalent in hospitals worldwide and pose a severe threat to immunocompromised patients and children8.

Methicillin-resistant Staphylococcus aureus

A study has recovered MRSA from 63% of cultures sampled from the environment near patients with heavy gastrointestinal (GI) colonization with MRSA compared to 33% from patients without GI colonization of MRSA. Furthermore, it was found that routine cleaning of contaminated environmental surfaces does not always eliminate MRSA from surfaces frequently touched by patients9, e.g. the toilet. Another study was conducted at a children’s hospital in 2009 to determine whether sharing toilet facilities could be a source of fomite transmission. MRSA was recovered at low colony counts on 3.3% of the toilets that were not cleaned with alcohol wipes. This was the first case in which MRSA was found on public toilets in outpatient areas of a hospital10.

Clostridium difficile

Clostridium difficile, an anaerobic Gram-positive rod7, is the most important cause of antibiotic-associated colitis (AAC), a condition caused by the overgrowth and toxin production of antibiotic-resistant organisms in the intestines11. In the environment where patients with colitis were treated, around 10% of the 1086 cultures obtained from inanimate objects were positive for C. difficile. In the washroom, C. difficile was recovered in samples from the toilet (31% of cultures were positive), bathroom floor (16%), and sinks (5%)11. Thus, a major vehicle of spread for C. difficile is infected patients with diarrhea7.

A study showed that C. diffcile was recovered from settle plates placed on the floor, cistern, and toilet seat during 90 min after flushing. Large droplets were released from the toilet and contaminated the surrounding environment quickly5. Other researchers conducted an experiment in which the floor of the hospital room was inoculated with C. difficile and they were recovered for as long as five months. Clostridium difficile produces heat- and acid-resistant spores that can be inhaled or ingested11. Not only do the spores deposit quickly onto surrounding surfaces, but also remain viable for a long time. More is yet to be learned about the epidemiology and prevention of antibiotic-associated colitis in hospitals11.

Hygiene

Prevention

Some researchers suggest that cleaning of toilets once a day is sufficient to prevent the spread of disease provided that the toilets are cleaned immediately when obviously soiled12. However, more recent studies have shown that routine cleaning of contaminated environmental surfaces does not always eliminate pathogenic bacteria (e.g. MRSA) from surfaces frequently touched by patients. It has also been shown that enhanced cleaning methods, such as using hydrogen peroxide vapour, has resulted in a decrease of C. difficile contamination9. Furthermore, the lidless toilets commonly seen in hospitals increase the risk of C. difficile contamination5.

Handwashing

Besides maintaining the hospitals washroom facilities clean, appropriate hand hygiene is paramount in preventing nosocomial infections6. Inadequate hand hygiene is the leading cause of hospital-associated infections and spread of antibiotic-resistant microorganisms13. However, the hand hygiene compliance among healthcare workers (only males were observed) is below 50%, lower than users of public washrooms13. In another study, it was shown that only 30% of physicians adhered to hand-hygiene practices, compared to 48% of the average healthcare worker. Furthermore, the proportion of compliance was lower in intensive care units, during procedures with a high risk of contamination, and when more patients needed treatment14. It is speculated that the low compliance rate is due to understaffing14, and that the relatively clean hospital environment gives a false impression of safety to healthcare workers13.

References

(1) Luesken, F. a, van Alen, T. a, van der Biezen, E., Frijters, C., Toonen, G., Kampman, C., Hendrickx, T. L. G., et al. (2011). Diversity and enrichment of nitrite-dependent anaerobic methane oxidizing bacteria from wastewater sludge. Applied microbiology and biotechnology, 92(4), 845–54. doi:10.1007/s00253-011-3361-9

(2) Mahler, R. L., Colter, A., & Hirnyck, R. (2007). Nitrate and Groundwater. University of Idaho Extension.

(3) Peterson, B. C. (1999). Aerobic Degradation of Trichloroethylene. Brigham Young University.

(4) Semkiw, E. S., & Barcelona, M. J. (2011). Field Study of Enhanced TCE Reductive Dechlorination by a Full-Scale Whey PRB, (1), 68–78. doi:10.1111/j1745

(5) Sepúlveda-Torre, L., Huang, A., Kim, H., & Criddle, C. S. (2002). Analysis of regulatory elements and genes required for carbon tetrachloride degradation in Pseudomonas stutzeri strain KC. Journal of molecular microbiology and biotechnology, 4(2), 151–61. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/11873910

(6) Smith, L. H., Yang, Y., & De-fg-er, D. O. E. G. N. (2003). Biodegradation of chlorinated solvents: Reactions near DNAPL and enzyme functions, (70063), 1–15.

(7) T. Wilson James. (n.d.). Remediation Apparatus and Method for organic contamination in soil and groundwater.pdf.