The microbiology laboratory's contribution to the surveillance and control of outbreaks caused by nonfermentative Gram-negative bacilli

Pseudomonas aeruginosa, Acinetobacter baumannii and Stenotrophomonas maltophilia are, among others, the most important nonfermentative Gram-negative bacilli within hospitals. These organisms are able to cause different types of nosocomial infections in predisposed patients, and P. aeruginosa and A. baumannii in particular may cause extensive clonal outbreaks and complex situations in which sporadic isolates may coexist with some epidemic strains. Some common features are their intrinsic resistance to many antimicrobials, their capacity to further develop antimicrobial resistance, and the possibility of environmental reservoirs as sources of these microorganisms in healthcare centers. The microbiology laboratory plays a key role in the detection of potential outbreaks, in the identification of new resistance mechanisms and in the characterization of local epidemiology, by detecting colonized patients and/or environmental reservoirs if needed, appropriately identifying the isolates, phenotypically or genotypically characterizing their mechanisms of resistance, if appropriate, and finally by using different molecular techniques for clonal typing, which are reviewed in this article. Such activities must be performed in the context of the surveillance and control programs of specific institutions and as part of the daily work of multidisciplinary infection control teams. (C) 2010 Elsevier Espana, S.L. All rights reserved.