FRIEDLAND IR, HARM S, STINSON L, GALLAGHER D; Interscience Conference on Antimicrobial Agents and Chemotherapy (41st : 2001 : Chicago, Ill.).

Abstr Intersci Conf Antimicrob Agents Chemother Intersci Conf Antimicrob Agents Chemother. 2001 Dec 16-19; 41: abstract no. E-805.

Merck & Co, West Point, PA

ISS (ICU Surveillance Study) is a multicenter, longitudinal study monitoring antimicrobial susceptibility of ICU isolates. ETP is a carbapenem with a unique antibacterial spectrum undergoing clinical investigation. 1739 unique initial P. aeruginosa isolates were obtained in 84 centers in the USA in 1999. Antibiotic susceptibility was determined by microdilution MIC using customized Microscan panels. RESULTS: Resistance rates in P. aeruginosa (MIC definition in microg/ml) were: IMI 12% (>/=16); ETP 39% (>/=16, tentative); piperacillin/tazobactam (P/T) 11.3% (>/=128); ceftazidime (CTZ) 12% (>/=32); ciprofloxacin (CIP) 22% (>/=4); and amikacin (AMK) 3% (>/=64). Resistance rates (%) for each antibiotic were higher in IMI-resistant vs IMI-susceptible/intermediate strains: ETP 92 vs 31; P/T 35 vs 8; CTZ 30 vs 9; CIP 51 vs 18; and AMK 7 vs 2. Only 2% of strains were multiply resistant to IMI, CTZ, P/T and CIP. Linear regression showed a strong positive correlation between IMI MICs and geometric mean MICs of other antibiotics. The strongest correlation was between the beta-lactams but correlation was observed across antibiotic classes. Only 4% of IMI-resistant strains were susceptible to ETP but 70% of ETP-resistant strains were susceptible or intermediate to IMI. CONCLUSIONS: Among P. aeruginosa strains in ICUs: 1) Resistant strains were common, but almost all strains remained susceptible to at least one anti-pseudomonal agent. 2) ETP is likely to be of limited usefulness for ICU-acquired Pseudomonas infection. 3) The majority of ETP resistant strains were susceptible to IMI suggesting P. aeruginosa has at least one mechanism that confers resistance to ETP but not IMI. 4) The mechanism conferring resistance to IMI (probably D2 porin loss) affects ETP similarly.

Publication Types:

• Meeting Abstracts

Keywords:

• Amikacin
• Anti-Bacterial Agents
• Carbapenems
• Ceftazidime
• Ciprofloxacin
• Imipenem
• Intensive Care Units
• Lactams
• Longitudinal Studies
• Microbial Sensitivity Tests
• Multicenter Study
• Penicillanic Acid
• Piperacillin
• Pseudomonas Infections
• Pseudomonas aeruginosa
• beta-Lactams
• ertapenem
• tazobactam

Other ID:

• GWAIDS0029307

UI: 102268939

From Meeting Abstracts