As discussed in our previous blogs, surfaces with frequent hand contact and in close proximity to the patients are often the most colonized with pathogens. These pathogens can remain viable on these inanimate surfaces for prolonged periods of time, and over a wide range of environmental conditions.

The contribution of this environmental pathogen contamination to outbreaks of C. difficile, MRSA, VRE, A. baumannii, norovirus and other nosocomial pathogens infections has been already established (1-5).  In this post, I would like to briefly review some of the findings showing that these pathogens, which remain viable on hard surfaces, can directly contribute to HAI.

The most compelling data that suggests  environmental contamination  Previously infected patient in the same room and rates of infection in next patientplays a role in contributing to HAIs are the findings that admission to a room previously occupied by environmentally-associated pathogens increases the risk of infection for incoming patients (6, 7).

For example, MRSA, VRE and C. difficile were cultured from 43%, 13% and 17% of surfaces in rooms used by patients not known to be MRSA, VRE or C. difficile positive, respectively (8-10).

Accordingly, environmental decontamination of patient rooms prior of their reuse was found to reduce the risk of the new patients acquiring multidrug-resistant organisms (MDRO) or other nosocomial pathogens. For instance, patients admitted to rooms, previously used by patients known to be infected or colonized with MDRO, that were decontaminated with hydrogen peroxide vapor (HPV), were significantly less likely to acquire any MDRO (64% reduction) than patients admitted to rooms disinfected using standard methods (11).

Similarly, a retrospective cohort intervention study conducted in 10 ICUs at a US hospital found that improved cleaning and disinfection following room occupancy resulted in 50% and 27% reduction in acquisition of both MRSA and VRE, respectively (12).

Interestingly, a recent study found that patients hospitalized in bed/rooms previously occupied by someone given antibiotics are 22% more likely to develop a C. difficile infection, even if they do not themselves receive antibiotics (13).

The infectious dose for most environmentally-associated nosocomial pathogens is quite low. E.g. <1 CFU/cm2 of C. difficile, a single norovirus particle, and less than 15 S. aureus cells, were sufficient to cause infection in different experimental models (14-16). It has been found that the concentration of nosocomial pathogens on surfaces is generally in the range of <1 to 100 CFU/cm2,(17,18) although higher concentrations of surface contamination were reported (19-21).  Thus, touching a contaminated hard surface may be a risk for transmission. This is further supported by the finding that improved cleaning and disinfection, which reduces the bioburden, reduces the overall infection rates (22).

Studies indicate that transfer from surfaces to hands and vice versa readily occur (23-26). Furthermore, several studies have shown that bacterial pathogens were acquired by hospital personnel through contact with environmental surfaces in the absence of direct patient contact ( 27-30).

In conclusion, there is quite clear evidence that supports the notion that contamination of hard surfaces with nosocomial pathogens in the clinical environment plays an important role in the HAI of both the current occupant of the room, and potentially the next occupant in the room.

 

References cited in this article

  1. Boyce JM, Opal SM, Chow JW et al. Outbreak of multidrug-resistant Enterococcus faecium with transferable vanB class vancomycin resistance. J Clin Microbiol 1994;32:1148-1153;
  2. Wu HM, Fornek M, Schwab KJ et al. A norovirus outbreak at a long-term-care facility: the role of environmental surface contamination. Infect Control Hosp Epidemiol 2005;26:802-810;
  3. Denton M, Wilcox MH, Parnell P et al. Role of environmental cleaning in controlling an outbreak of Acinetobacter baumannii on a neurosurgical intensive care unit. J Hosp Infect 2004;56:106-110;
  4. Jeanes A, Rao G, Osman M, Merrick P. Eradication of persistent environmental MRSA. J Hosp Infect 2005;61:85-86;
  5. Kaatz GW, Gitlin SD, Schaberg DR et al. Acquisition of Clostridium difficile from the hospital environment. Am J Epidemiol 1988;127:1289-1294
  6. Otter JA, Yezli S, French GL. The role played by contaminated surfaces in the transmission of nosocomial pathogens. Infect Control Hosp Epidemiol 2011;32:687-699;
  7. Otter JA, Yezli S, Salkeld JA, French GL. Evidence that contaminated surfaces contribute to the transmission of hospital pathogens and an overview of strategies to address contaminated surfaces in hospital settings. Am J Infect Control 2013;41:S6-S11
  8. French GL, Otter JA, Shannon KP, Adams NM, Watling D, Parks MJ. 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 2004;57:31-37;
  9. Trick WE, Temple RS, Chen D, Wright MO, Solomon SL, Peterson LR. Patient colonization and environmental contamination by vancomycin-resistant enterococci in a rehabilitation facility. Arch Phys Med Rehab 2002;83:899-902;
  10. Dubberke ER, Reske KA, Noble-Wang J et al. Prevalence of Clostridium difficile environmental contamination and strain variability in multiple health care facilities. Am J Infect Cont 2007;35:315-318)
  11. Passaretti CL, Otter JA, Reich NG et al. An evaluation of environmental decontamination with hydrogen peroxide vapor for reducing the risk of patient acquisition of multidrug-resistant organisms. Clin Infect Dis 2013;56:27-35
  12. Datta R, Platt R, Yokoe DS, Huang SS. Environmental cleaning intervention and risk of acquiring multidrug-resistant organisms from prior room occupants. Arch Intern Med 2011;171:491-494.
  13. Daniel E. Freedberg, Hojjat Salmasian, Bevin Cohen, et al. Receipt of Antibiotics in Hospitalized Patients and Risk for Clostridium difficile Infection in Subsequent Patients Who Occupy the Same Bed. JAMA Intern Med. 2016;176(12):1801-1808
  14. Lawley TD, Clare S, Deakin LJ et al. Use of purified Clostridium difficile spores to facilitate evaluation of health care disinfection regimens. Appl Environ Microbiol 2010;76:6895-6900;
  15. Teunis PF, Moe CL, Liu P et al. Norwalk virus: how infectious is it? J Med Virol 2008;80:1468-1476;
  16. Foster WD, Hutt MS. Experimental staphylococcal infections in man. Lancet 1960;2:1373-1376
  17. Boyce JM, Havill NL, Otter JA et al. Impact of hydrogen peroxide vapor room decontamination on Clostridium difficile environmental contamination and transmission in a healthcare setting. Infect Control Hosp Epidemiol 2008;29:723-729;
  18. Rutala WA, Katz EB, Sherertz RJ, Sarubbi FA, Jr. Environmental study of a methicillin-resistant Staphylococcus aureus epidemic in a burn unit. J Clin Microbiol 1983;18:683-688
  19. Boyce JM, Havill NL, Otter JA, Adams NM. Widespread environmental contamination associated with patients with diarrhea and methicillin-resistant Staphylococcus aureus colonization of the gastrointestinal tract. Infect Control Hosp Epidemiol 2007;28:1142-1147;
  20. Schmidt MG, Attaway HH, Sharpe PA et al. Sustained reduction of microbial burden on common hospital surfaces through introduction of copper. J Clin Microbiol 2012;50:2217-2223;
  21. Cooper RA, Griffith CJ, Malik RE, Obee P, Looker N. Monitoring the effectiveness of cleaning in four British hospitals. Am J Infect Control 2007;35:338-341
  22. Dancer SJ. The role of environmental cleaning in the control of hospital-acquired infection. J Hosp Infect 2009;73:378-385
  23. Barker J, Vipond IB, Bloomfield SF. Effects of cleaning and disinfection in reducing the spread of Norovirus contamination via environmental surfaces. J Hosp Infect 2004;58:42-49;
  24. Rusin P, Maxwell S, Gerba C. Comparative surface-to-hand and fingertip-to-mouth transfer efficiency of gram-positive bacteria, gram-negative bacteria, and phage. J Appl Microbiol 2002;93:585-592;
  25. Rheinbaben F, Schunemann S, Gross T, Wolff MH. Transmission of viruses via contact in a household setting: experiments using bacteriophage straight phiX174 as a model virus. J Hosp Infect 2000;46:61-66;
  26. Jiang X, Dai X, Goldblatt S et al. Pathogen transmission in child care settings studied by using a cauliflower virus DNA as a surrogate marker. J Infect Dis 1998;177:881-888
  27. Ray AJ, Hoyen CK, Taub TF, Eckstein EC, Donskey CJ. Nosocomial transmission of vancomycin-resistant enterococci from surfaces. JAMA 2002;287:1400-1401;
  28. Bhalla A, Pultz NJ, Gries DM et al. Acquisition of nosocomial pathogens on hands after contact with environmental surfaces near hospitalized patients. Infect Control Hosp Epidemiol 2004;25:164-167;
  29. Guerrero DM, Nerandzic MM, Jury LA, Jinno S, Chang S, Donskey CJ. Acquisition of spores on gloved hands after contact with the skin of patients with Clostridium difficile infection and with environmental surfaces in their rooms. Am J Infect Control 2012;40:556-558;
  30. Stiefel U, Cadnum JL, Eckstein BC, Guerrero DM, Tima MA, Donskey CJ. Contamination of hands with methicillin-resistant Staphylococcus aureus after contact with environmental surfaces and after contact with the skin of colonized patients. Infect Control Hosp Epidemiol 2011;32:185-187