Tigecycline antimicrobial activity tested against clinical bacteria from Latin American medical centres: results from SENTRY Antimicrobial Surveillance Program (2011-2014)

Abstract

Bacterial organisms (n = 13,494) were consecutively collected in 2011-2014 from 21 Latin American medical centres (11 nations). Antimicrobial susceptibility was determined by broth microdilution at a central laboratory. Tigecycline was very active against Gram-positive organisms, with MIC50/90 values of 0.06/0.06 µg/mL for Staphylococcus aureus (n = 2878), 0.06/0.12 µg/mL for coagulase-negative staphylococci (n = 880), 0.06/0.06 µg/mL for enterococci (n = 708) and ≤0.03/≤0.03-0.06 µg/mL for streptococci (n = 1352). All Gram-positive species exhibited 100.0% susceptibility (FDA and/or EUCAST criteria), except for Streptococcus pneumoniae (99.8% susceptible). The S. aureus oxacillin resistance rate varied from 28.0% (Brazil) to 55.0% (Argentina), and the overall vancomycin resistance rate was 15.5% (Enterococcus faecium, 50.3%; and Enterococcus faecalis, 2.3%). The E. faecium vancomycin resistance rate varied from a low (26.3%) in Argentina to a high (71.7%) in Brazil. Against Enterobacteriaceae (n = 4543), tigecycline MIC50/90 values were 0.25/1 µg/mL; 98.3% and 94.2% of strains were considered susceptible according to FDA and EUCAST breakpoints, respectively. Overall, 37.7% and 57.3% of Escherichia coli and Klebsiella pneumoniae exhibited the CLSI ESBL screening phenotype. The highest CLSI ESBL screening phenotype rates among E. coli and Klebsiella spp. strains were observed for isolates collected from Mexico (69.9%) and Chile (69.9%), respectively. Occurrence of carbapenem-resistant Enterobacteriaceae was substantially higher in Brazil (9.0%) and Argentina (6.3%) compared with Chile and Mexico (0.4-0.7%). Tigecycline was also active against Acinetobacter spp. (MIC50/90, 1/2 µg/mL; 92.3/72.1% inhibited at ≤2/≤1 µg/mL) and Stenotrophomonas maltophilia (MIC50/90, 0.5/2 µg/mL; 91.5/83.0% inhibited at ≤2/≤1 µg/mL).

Keywords: Antimicrobial resistance; Carbapenem-resistant Enterobacteriaceae (CRE); Meticillin-resistant Staphylococcus aureus (MRSA); Surveillance; Vancomycin-resistant enterococci (VRE).