Increasing prevalence of extended-spectrum-betalactamase among Gram-negative bacilli in Latin America: 2008 update from the Study for Monitoring Antimicrobial Resistance Trends (SMART)

ABSTRACT

OBJECTIVES: This analysis of the Study for Monitoring Antimicrobial Resistance Trends (SMART) evaluated the susceptibility patterns of Enterobacteriaceae in Latin America in 2008, with emphasis on susceptibility trends of E. coli and K. pneumoniae. METHODS: Clinical isolates were recovered from intra-abdominal infections (IAI) from 23 centers in 10 Latin American countries. Isolates were sent to a central laboratory for confirmation of identification, antimicrobial susceptibility and ESBL testing, following the Clinical Laboratory Standards Institute (CLSI) guidelines. RESULTS: Of 1,003 Gram-negative bacilli collected from intra-abdominal infections, E. coli and K. pneumoniae were the most commonly isolated organisms, and 26.8 percent of E. coli and 37.7 percent of K. pneumoniae were ESBL positive. Ertapenem and imipenem were the most consistently active agents tested; 99 percent of ESBLpositive E. coli isolates were susceptible to ertapenem and 100 percent to imipenem as well, and 91 percent of ESBL-positive K. pneumoniae were susceptible to ertapenem and 98 percent to imipenem. Quinolones and cephalosporins were less active, achieving 1.5 percent to 76 percent inhibition against ESBL-producing E. coli and 3.5 percent to 61 percent inhibition against K. pneumoniae. CONCLUSIONS: Local and unit-specific surveillance data is particularly important for selection of empiric therapy and in community-acquired infections as they can help the clinician with antibiotic selection by providing guidance regarding the likely pathogens and their resistance profiles. Our data also confirm the increasing frequency with which ESBL-producing organisms are found in the community setting, with 31.4 percent of communityacquired and 24.9 percent of hospital-acquired infections found to produce ESBLs. Imipenem and ertapenem are the most active agents tested for ESBL-positive E. coli and K. pneumoniae.