Microbial monitoring of the hospital environment: why and how?

Background: The purpose of microbial monitoring of the inanimate environment surrounding a patient can be two-fold; to monitor hygiene standards and also to examine for the presence of specific nosocomial pathogens which may be the source of an outbreak. While both purposes involve routine culture of microorganisms, the methods used for each can differ in order to provide optimal results. The main difference between both purposes is the need for enumeration, site specificity for an aerobic colony count (ACC) for hygiene assessments, and the need to simply detect the presence or absence of multi-resistant nosocomial pathogens for infection control surveillance. Aim: To access current methods used in research studies and during outbreak investigations to detect nosocomial pathogens in the inanimate environment in the clinical setting. Methods: A Pubmed search of published literature was performed. Findings: Microbial monitoring of the environment can involve the use of swabs, sponges, contact plates and dip slides coupled with a variety of enrichment broths and selective media. The use of molecular methods such as polymerase chain reaction (PCR) can potentially provide a faster turnaround time, resulting in the quicker implementation of infection prevention and control cleaning and disinfection regimens. However, the optimal methods for performing a microbial hygiene evaluation or detecting specific bacterial pathogens are not generally agreed. Conclusion: There is a need for agreed standards on the optimal methods, frequency of environmental sampling and acceptable levels of surface contamination within the healthcare system. (C) 2012 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved.