OBJECTIVETo explore the risk factors for nosocomial infection caused by imipenem-resistant Pseudomonas aeruginosa (IRPA).

METHODSA case-control study was carried out for the comparison of 2 groups of 'case' patients with 'controlled' patients. The first group of 'case' patients had nosocomial isolation of IRPA, and the second group had imipenem-susceptible Pseudomonas aeruginosa (ISPA). 'Control' patients were selected from the same medical or surgical services from which 'case' patients were receiving care when isolation of IRPA or ISPA occurred. Risk factors analyzed included the use of antimicrobials, comorbid conditions, and demographic variables. IRPA was recovered from 67 patients, and ISPA from 150 patients while the control case were 200 and 159 respectively. All patients were from Renmin Hospital of Wuhan University during Jan 2002 to Dec 2003. Data were analyzed with unconditional logistic regression and principal component analysis.

RESULTSData from multivariate unconditional logistic regression analysis showed that the independent risk factors for IRPA nosocomial infection were: time at risk (OR = 1.03, 95% CI: 1.01-1.04), imipenem (OR = 4.65, 95% CI: 1.35-11.52), PIP/TAZ (OR = 3.37, 95% CI 1.85-9.43) and quinolones (OR = 1.85, 95% CI: 1.25-5.34) while the third cephalosporins (OR = 2.54, 95% CI: 1.26-5.23) and aminoglycoside antibiotics (OR = 1.86, 95% CI 1.42-3.26) time at risk (OR = 1.05, 95% CI: 1.03-1.05) were associated with isolated ISPA.

CONCLUSIONNosocomial infection of IRPA could be caused by the use of imipenem and other antibiotics, suggesting that to limit the use of imipenem was not sufficient to contain the increasing incidence of IRPA.