Focused microbiological surveillance and gram-negative beta-lactamase--mediated resistance in an intensive care unit

To evaluate the use of focused surveillance in following resistance patterns within an intensive care unit (ICU).

Antibiograms of 167 gram-negative isolates from ICU patients were compared to the hospitalwide antibiograms. ICU isolates were examined for the newer forms of beta-lactamase resistance. An outbreak of multiresistant Pseudomonas aeruginosa during the survey illustrated the usefulness of focused surveillance in early intervention and containment.

A 700-bed adult tertiary care hospital with a 16-bed medical and surgical ICU.

Hospitalwide and ICU antibiograms of the Enterobacteriaceae were similar. However, resistance of P aeruginosa in the ICU was underestimated by hospitalwide rates. Susceptibility of ICU isolates to ceftazidime, ciprofloxacin, and piperacillin was 54%, 54%, and 42%, compared with 81%, 77%, and 85%, respectively, in the hospital at large. Thirty-five percent of isolates exhibited one of the newer forms of beta-lactamase-mediated resistance, with 17% of isolates exhibiting Class I cephalosporinase production.

Targeted survey of high antibiotic-use hospital units should be used to study bacterial epidemiology, rather than relying on general hospital data to evaluate patterns of antimicrobial resistance. Monitoring of potential problem areas leads to prompt identification of changes in resistance and allows early intervention.