Antimicrobial susceptibility patterns for pathogens isolated from patientsin Latin American medical centers with a diagnosis of pneumonia: Analysis of results from the SENTRY Antimicrobial Surveillance Program (1997)

Pneumonia is the mosi common fatal hospital-acquired infection, with attrib utable mortality rates ranging from 30 to 60%. Rapid initiation of optimal antimicrobial therapy is essential for obtaining treatment success. In this report the antimicrobial susceptibility of 556 strains from the lower resp iratory tract were collected by the SENTRY Antimicrobial Surveillance Progr am (1997). These strains were isolated from hospitalized patients with pneu monia in 10 Latin American centers (6 countries) as part of this 68-center worldwide program. The isolates were susceptibility tested against more tha n 70 drugs (35 reported by) the reference broth microdilution method. Klebs iella pneumoniae and Escherichia coli phenotypically consistent with extend ed spectrum beta-lactamase (ESBL) production were characterized further by ribotyping and pulsed-field gel electrophoresis. The five most frequently i solated species mere (n/%): Pseudomonas aeruginosa (149/26.8%), Staphylococ cus aureus (127/22.8%), Acinetobacter spp. (66/11.9%), Klebsiella spp. (56/ 10.1%), and Enterobacter spp. (40/7.2%). P. aeruginosa demonstrated high ra tes of resistance to a majority of the antimicrobial drugs tested. Carbapen ems, amikacin, and piperacillin/tazobactam demonstrated the highest suscept ibility rates (73.8-77.2%) against P. aeruginosa, however the lowest resist ance rate was observed for cefepime (6.7%). Acinetobacter spp, also showed very high rates of resistance and the most active compounds were imipenem a nd meropenem (89.0% susceptibility) followed by the tetracyclines. Cephalos porin susceptibilities among Klebsiella spp. were low: cefoxitin, 73.0%; ce ftazidime, 69.4%; and ceftriaxone, 65.9%. Approximately 37% and 28% of K. p neumoniae and E. coli isolates, respectively, were considered ESBL producer s based on NCCLS criteria. Ceftriaxone was active against only 52.5% of Ent erobacter spp. isolates, whereas cefepime uns active against 90.0% of isola tes (MIC50, less than or equal to 0.12 mu g/mL). Oxacillin resistance was d etected in nearly 50% of S. aureus isolates. The most active drugs against S. aureus were vancomycin, teicoplanin, and quinupristin/dalfopristin (MIC9 0, 1 mu g/mL). In summary, our study of pneumonias in Latin American medica l centers demonstrated a greatly increased prevalence of Acinetobacter spp, and higher resistance rates among Gram-negative bacilli when compared with similar controlled studies from North America. (C) Elsevier Science Inc.