Enhanced clinical microbiology methods in outbreak management.

Conventional microbiological investigations, including pathogen detection, antibiotic susceptibility testing and molecular epidemiological testing, are valuable tools in helping to manage nosocomial outbreaks. However, the microbiology laboratory, by using other techniques, can investigate additional microbiological aspects of outbreaks, which are often overlooked. Bacterial isolates (n=6) from an outbreak of Pseudomonas aeruginosa bacteraemia in a neonatal intensive care unit (NICU) in Belfast were examined. Enhanced microbiology testing included: (1) susceptibility of outbreak strains to biocides in common use in the unit; (2) effect of organic soils relevant to the area of the outbreak and their effect on the efficacy of biocide; and (3) the persistence of outbreak strains in organic soils. By emulating bespoke conditions of the outbreak, these methods were able to demonstrate that: (1) biocides were effective against the outbreak strains; (2) the critical concentration of soil which rendered biocide ineffective; and (3) how long the outbreak strains could persist. Enhanced microbiological analysis outside the conventional repertoire of testing may therefore offer valuable data that may help guide outbreak management teams.