Risk factors and molecular typing associated with colonization or infection by a multidrug-resistant (MDR) Pseudomonas aeruginosa in intensive care unit (ICU) patients

Background

Pseudomonas aeruginosa infections are associated with high mortality. Ps. aeruginosa has developed, after many years, multidrug resistance. We conducted a retrospective study to identify risks factors associated with acquisition of MDR Ps. aeruginosa in ICU patients.

Methods

A retrospective study was performed in the 12-bed medico-surgical ICU from January to December 2000. All charts corresponding to acquisition of Ps. aeruginosa were reviewed; among them, we compare patients with or without a MDR strain. The MDR strains were genotyped by pulsed-field gel electrophoresis (PFGE) and were defined as resistance to at least three drugs among ciprofloxacin (CIP), amikacin, ceftazidim and imipenem.

Results

Six hundred and ninety-nine patients were admitted to the ICU during the study period. Fifty-two (7.5%) had a colonization or an infection with Ps. aeruginosa during their ICU stay. Forty (77%) had a susceptible strain and 12 (23%) had a MDR strain. Alcoholism was more frequent in the MDR group (P = 0.047). The previous use of CIP, cefuroxime (CEF) and bitherapy with cefepime (CEP) plus amikacin were identified as a risk factor associated with acquisition of a MDR Ps. aeruginosa (for CIP, P = 0.0012; for CEF, P = 0.03; and for bitherapy, P = 0.026). No clonal strain was identified by PFGE.

Conclusions

The previous use of some broad-spectrum antibiotics was associated with development of MDR Ps. aeruginosa. Control prescriptions and optimizing use of broad-spectrum antibiotics is now established in our hospital to reduce the risk of emergence of MDR strains.