Results from the Survey of Antibiotic Resistance (SOAR) 2015–17 in Latin America (Argentina, Chile and Costa Rica): data based on CLSI, EUCAST (dose-specific) and pharmacokinetic/pharmacodynamic (PK/PD) breakpoints

Abstract Objectives To determine antibiotic susceptibility of Streptococcus pneumoniae and Haemophilus influenzae isolates from community-acquired respiratory tract infections (CA-RTIs) collected in 2015–17 from Argentina, Chile and Costa Rica. Methods MICs were determined by CLSI broth microdilution and susceptibility was assessed using CLSI, EUCAST (dose-specific) and pharmacokinetic/pharmacodynamic (PK/PD) breakpoints. Results A total of 170 S. pneumoniae and 218 H. influenzae isolates were collected at five centres in Argentina, Chile and Costa Rica in 2015–17. Small S. pneumoniae isolate numbers from Costa Rica (n = 2) meant that these could only be included in the penicillin susceptibility analysis; they were excluded from further country analyses. Around one-third of pneumococcal isolates from Argentina and two-thirds from Chile were non-susceptible to penicillin by CLSI oral or EUCAST low-dose IV breakpoints, but most (≥89%) were susceptible by CLSI IV or EUCAST high-dose breakpoints. Amongst pneumococci from Argentina, about 80% or more were susceptible to most other antibiotics except cefaclor (all breakpoints), cefixime (PK/PD breakpoints), cefuroxime (EUCAST breakpoints) and trimethoprim/sulfamethoxazole (CLSI and PK/PD breakpoints). S. pneumoniae isolates from Chile showed significantly lower susceptibility (P