Hospital cleaning depends on many factors, such as the frequencies, methodology and equipment used, monitoring and training of personnel. How these parameters influence the effectiveness of the cleaning process are nicely discussed by Dancer SJ (1,2).

In previous posts we discussed the choices of disinfectants for manual cleaning, their pros and cons, and the selection of areas to be cleaned. In the current post I would like to review some of the literature that demonstrates that routine cleaning or disinfection in the hospital environment does not result in complete eradication of nosocomial pathogens. In addition that even cleaned surfaces become significantly contaminated quite readily after being disinfected.

There are several reports that show that despite routine cleaning and disinfection, pathogens are not thoroughly eradicated from surfaces. For example, in a large study of 36 acute US hospitals it was found that efficacious cleaning was achieved in less than 50% of the cases, as determined by removal of a fluorescent marker (3). In another study conducted in St. Louis, USA, it was found that one or more sites remained contaminated with either MRSA or A. baumannii in 26.6% of more than 300 rooms sampled following four consecutive rounds of bleach disinfection (4).


Similarly, C. difficile was cultured from 16% of 243 cultures after bleach disinfection implemented during an outbreak (5); C. difficile were cultured from 44% of 54 surfaces after bleach disinfection in 9 rooms and VRE was cultured from 71% of 102 samples after bleach disinfection in 17 rooms (6); MRSA was cultured from 66% of 124 surfaces in MRSA patient rooms after cleaning with a sanitizer (7), from 16% of 65 sites following bleach and steam cleaning during an outbreak on a surgical ward (8); and Norovirus RNA was identified on 31% of 239 surfaces after bleach disinfection, and 16% of surfaces remained contaminated after double bleach disinfection (9).

Clostridium difficile
Clostridium difficile


Fittingly, it has been shown that multiple cleaning practices, despite the use of powerful disinfectants, fail to remove many nosocomial pathogens from a range of sites (e.g. ref 10,11). Although disinfectants have potent broad-spectrum antimicrobial activity, there are some nosocomial pathogens that are resistant to some disinfectants, e.g. C. difficile spores and norovirus (12-14). Furthermore, the hospital environment is complex and often difficult to clean and the use of a cleaning agent that is not effective against the target organism can spread pathogens to other surfaces (e.g. 15).


Nosocomial pathogens surviving in environmental reservoirs despite rigorous cleaning and disinfection was shown to be the cause of HAI outbreaks in several cases. For instance, over a 14-month period, 13 patients acquired MRSA on a dermatology ward that was associated with an environmental reservoir of the pathogen despite routine cleaning measures (16). Another example is the HAI of 30 patients in two ICUs with imipenem-resistant Acinetobacter baumannii, identified from environmental reservoirs throughout both of the affected ICUs (17). In accordance to the above, several controlled studies found that enhanced environmental cleaning routines resulted in lower HAI rates as compared to regular environmental hospital cleaning routines implemented (18,19).

A recent study examined the kinetics of microbial contamination of lockers, left and right bedrails and overbed tables next to 30 bed patients following cleaning with a detergent (20). They found that cleaning reduced the microbial loads below the proposed benchmark standard of infection risk of less than 5 cfu/cm2 (21). Importantly they also found that the detergent-cleaned sites reached the benchmark standard loads ~24 hours after cleaning. The surfaces may be rapidly repopulated by air- or hand-borne bacterial contamination. For example, it has been shown that that when the hospital personnel change the bed linens or patients garments, large quantities of micro-organisms are released into the air contaminating the immediate and non-immediate surroundings of the patients (22,23). Also personnel, when handling contaminated textiles can contaminate their gloves or hands with microorganisms and then contaminate these and other surfaces, such as door knobs, and even patients directly (24).

Thus, it is clear that the hospital environment, which may be routinely and thoroughly cleaned and disinfected, may not be free of nosocomial pathogens loads below the infection transmission rates, and while it may be so shortly after cleaning, these surfaces become quickly re-contaminated before being re-cleaned in many instances, and thus being a potential reservoir of nosocomial pathogens.

References quoted in this article

  1. Dancer SJ. 2011. Hospital Cleaning in the 21st Century. J. Clin. Microbiol. Infect. Dis. 30:1473–1481.
  2. Dancer SJ. 2014. Controlling hospital-acquired infection: focus on the role of the environment and new technologies for decontamination. Clin Microbiol Rev. 27(4):665-90.
  3. Carling PC, Parry MM, Rupp ME, Po JL, Dick B, Von Beheren S. 2008. Improving cleaning of the environment surrounding patients in 36 acute care hospitals. Infect Control Hosp Epidemiol 29:1035-1041.
  4. Manian FA, Griesenauer S, Senkel D et al. Isolation of Acinetobacter baumannii complex and methicillin-resistant Staphylococcus aureus from hospital rooms following terminal cleaning and disinfection: can we do better? Infect Control Hosp Epidemiol 2011;32:667-672.
  5. Kaatz GW, Gitlin SD, Schaberg DR et al. 1988. Acquisition of Clostridium difficile from the hospital environment. Am J Epidemiol 127:1289-1294.
  6. Eckstein BC, Adams DA, Eckstein EC et al. 2007. Reduction of Clostridium difficile and vancomycin-resistant Enterococcus contamination of environmental surfaces after an intervention to improve cleaning methods. BMC Infect Dis 7:61.
  7. French GL, Otter JA, Shannon KP, Adams NM, Watling D, Parks MJ. 2004. Tackling contamination of the hospital environment by methicillin-resistant Staphylococcus aureus (MRSA): a comparison between conventional terminal cleaning and hydrogen peroxide vapour decontamination. J Hosp Infect 57:31-37.
  8. Jeanes A, Rao G, Osman M, Merrick P. 2005. Eradication of persistent environmental MRSA. J Hosp Infect 61:85-86.
  9. Morter S, Bennet G, Fish J et al. 2011. Norovirus in the hospital setting: virus introduction and spread within the hospital environment. J Hosp Infect 77:106-112.
  10. Sample ML, Gravel D, Oxley C, Toye B, Garber G, Ramotar K. 2002. An outbreak of vancomycin-resistant enterococci in a hematology-oncology unit: control by patient cohorting and terminal cleaning of the environment. Infect Control Hosp Epidemiol. 23(8):468-70.
  11. Strassle P, Thom KA, Johnson JK, Leekha S, Lissauer M, Zhu J, Harris AD. The effect of terminal cleaning on environmental contamination rates of multidrug-resistant Acinetobacter baumannii. Am J Infect Control. 40(10):1005-7.
  12. Dawson LF1, Valiente E, Donahue EH, Birchenough G, Wren BW. 2011. Hypervirulent Clostridium difficile PCR-ribotypes exhibit resistance to widely used disinfectants. PLoS One 6(10):e25754.
  13. Macleod-Glover N, Sadowski C. 2010. Efficacy of cleaning products for C. difficile: environmental strategies to reduce the spread of Clostridium difficile-associated diarrhea in geriatric rehabilitation. Can Fam Physician. 56(5):417-23.
  14. Tuladhar E, Hazeleger WC, Koopmans M, Zwietering MH, Beumer RR, Duizer E. 2012. Residual viral and bacterial contamination of surfaces after cleaning and disinfection. Appl Environ Microbiol. 78(21):7769-75.
  15. Ali S, Moore G, Wilson AP. 2011. Spread and persistence of Clostridium difficile spores during and after cleaning with sporicidal disinfectants. J Hosp Infect;79:97-98.
  16. Layton MC, Perez M, Heald P, Patterson JE. 1993. An outbreak of mupirocin-resistant Staphylococcus aureus on a dermatology ward associated with an environmental reservoir. Control Hosp. Epidemiol. 14:369–375.
  17. Tankovic J, Legrand P, De Gatines G, Chemineau V, Brun-Buisson C, Duval J. Characterization of a hospital outbreak of imipenem-resistant Acinetobacter baumannii by phenotypic and genotypic typing methods. J Clin Microbiol. 32(11):2677-81.
  18. Dancer SJ, White LF, Lamb J, Girvan EK, Robertson C, 2009. Measuring the effect of enhanced cleaning in a UK hospital: a prospective cross-over study. BMC Med. 7:28.
  19. Datta R, Platt R, Yokoe DS, Huang SS. 2011. Environmental cleaning intervention and risk of acquiring multidrug-resistant organisms from prior room occupants. Arch Intern Med. 171(6):491-4.
  20. Bogusz A, Stewart M, Hunter J, Yip B, Reid D, Robertson C, Dancer SJ. 2013. How quickly do hospital surfaces become contaminated after detergent cleaning? Healthcare Infection 18, 3–9.
  21. Dancer SJ. 2004. How do we assess hospital cleaning? A proposal for microbiological standards for surface hygiene in hospitals. J Hosp Infect 56: 10–5.
  22. Shiomori et al, 2002. Evaluation of bedmaking-related airborne and surface methicillin-resistant Staphylococcus aureus contamination. J Hosp.Infect. 50, (1) 30-35.
  23. B. Beggs. 2003. The airborne transmission of infection in hospital buildings: fact or fiction?. Indoor Built Environ  12, 9-18.
  24. J. Morgan et al. 2010. Frequent multidrug-resistant Acinetobacter baumannii contamination of gloves, gowns, and hands of healthcare workers. Infect Control Hosp.Epidemiol. 31, 716-721.

Image references

Acinetobacter-CDC, Clostridium difficile-WSJ