Salmonella spp. isolates causing bloodstream infections in Latin America: report of antimicrobial activity from the SENTRY Antimicrobial Surveillance Program (1997-2000)

Abstract

Recent years have seen a dramatic rise in the incidence and severity of cases of human salmonellosis. In addition, multidrug resistant strains have arisen. The objective of this study was to characterize the antimicrobial susceptibility profile of Salmonella spp. clinical isolates collected from Latin American medical centers as part of the SENTRY Antimicrobial Surveillance System. A total of 144 bloodstream Salmonella spp. isolates were collected between 1997 and 2000. The susceptibility to diverse antimicrobial agents was tested by broth microdilution techniques according to the NCCLS recommendations. The Salmonella spp. strains were more frequently collected from adult patients (67.0%; 21-60 years) and isolated from Chile (28.5%) > Brazil (25.0%) > Mexico (18.8%) > Colombia (11.8%). Ampicillin (MIC(50), 1 microg/ml) showed good in vitro activity (92.4% susceptibility). Meropenem (MIC(50), 0.06 microg/ml) and gatifloxacin (MIC(50), 0.03 microg/ml) were the most potent compounds against the Salmonella spp. isolates (100.0% susceptible) followed by piperacillin/tazobactam (99.3%), ceftazidime (98.6%), ceftriaxone (98.6%), and amoxicillin/clavulanic acid (94.4%). The lowest susceptibility rates were observed for tetracycline (87.5%) and trimethoprim/sulfamethoxazole (91.7%). Four of 144 (2.8%) Salmonella spp. isolates demonstrated an ESBL phenotype; however, only two (1.4%) were confirmed as an inhibitable ESBL producer. The results of this study show that multidrug resistance, especially fluoroquinolone resistance, does not represent a serious problem among Salmonella isolates collected from the Latin American medical centers as monitored by the SENTRY Program.