Bevin Cohen, Catherine Crawford Cohen, Borghild Løyland, Elaine L Larson

Pathogens that cause health care-associated infections (HAIs) are known to survive on surfaces and equipment in health care environments despite routine cleaning. As a result, the infection status of prior room occupants and roommates may play a role in HAI transmission. We performed a systematic review of the literature evaluating the association between patients' exposure to infected/colonized hospital roommates or prior room occupants and their risk of infection/colonization with the same organism. A PubMed search for English articles published in 1990-2014 yielded 330 studies, which were screened by three reviewers. Eighteen articles met our inclusion criteria. Multiple studies reported positive associations between infection and exposure to roommates with influenza and group A streptococcus, but no associations were found for Clostridium difficile, methicillin-resistant Staphylococcus aureus, Cryptosporidium parvum, or Pseudomonas cepacia; findings were mixed for vancomycin-resistant enterococci (VRE). Positive associations were found between infection/colonization and exposure to rooms previously occupied by patients with Pseudomonas aeruginosa and Acinetobacter baumannii, but no associations were found for resistant Gram-negative organisms; findings were mixed for C. difficile, methicillin-resistant S. aureus, and VRE. Although the majority of studies suggest a link between exposure to infected/colonized roommates and prior room occupants, methodological improvements such as increasing the statistical power and conducting universal screening for colonization would provide more definitive evidence needed to establish causality.