Susceptibility of Clinical Isolates of Acinetobacter baumannii and Pseudomonas aeruginosa to Colistin and Polymyxin B in Korea / 감염과화학요법

ABSTRACT

BACKGROUND: The emergence of multidrug-resistant Acinetobacter baumannii and Pseudomonas aeruginosa has become a major problem. The use of nontraditional agents such as colistin and polymyxin B have been tried. The purpose of this study was to evaluate the colistin and polymyxin B susceptibility of A. baumannii and P. aeruginosa isolates in Korea. MATERIALS AND METHODS: According to susceptibility of ceftazidime and imipenem, selected 93 isolates of A. baumannii and 99 isolates of P. aeruginosa were collected from 5 university hospitals in Korea. Susceptibility to colistin and polymyxin B was tested using the reference broth microdilution method. RESULTS: The rates of other beta-lactams, aminoglycosides, and ciprofloxacin susceptibility were high (58-100%, 50-100%, and 75-100%, respectively) in ceftazidime- and imipenem-susceptible isolates but were low (< or =31%, < or =47%, and < or =18%, respectively) in ceftazidime- or imipenem-resistant isolates (P<0.05). Colistin and polymyxin B displayed a nearly identical spectrum of activity, exhibiting excellent potency against A. baumannii (MIC50/90, 1/2 microgram/mL) and P. aeruginosa (MIC50/90, 1/1 microgram/mL). Only one of the A. baumannii isolates was resistant to colistin (MIC, 4 microgram/mL), but the isolate was susceptible to polymyxin B (MIC, 2 microgram/mL). CONCLUSION: In Korea, no A. baumannii and P. aeruginosa isolates were resistant to both colistin and polymyxin B. These data suggested that polymyxins may be alternative drugs for multidrug-resistant A. baumannii and P. aeruginosa isolates.