Regional and global antimicrobial susceptibility among isolates of Streptococcus pneumoniae and Haemophilus influenzae collected as part of the Tigecycline Evaluation and Surveillance Trial (T.E.S.T.) from 2009 to 2012 and comparison with previous years of T.E.S.T. (2004-2008)

Abstract

Background: We report here on 14438 Streptococcus pneumoniae and 14770 Haemophilus influenzae isolates collected from 560 centres globally between 2004 and 2012 as a part of the Tigecycline Evaluation and Surveillance Trial (T.E.S.T.). Methods: MIC testing was performed using broth microdilution methods as described by the Clinical and Laboratory Standards Institute (CLSI) using CLSI-approved breakpoints; US Food and Drug Administration breakpoints were used for tigecycline as CLSI breakpoints are not available. Results: At least 99% of S. pneumoniae isolates globally were susceptible to levofloxacin, linezolid, tigecycline or vancomycin. Penicillin resistance was observed among 14.8% of S. pneumoniae and was highest in Asia/Pacific Rim (30.1%) and Africa (27.6%); 23.4% of S. pneumoniae isolates were penicillin-intermediate, which were most common in Africa (37.6%). Minocycline susceptibility among S. pneumoniae decreased by 20% between 2004-2008 and 2009-2012. High (>98.5%) susceptibility was reported among H. influenzae to all antimicrobial agents on the T.E.S.T. panel excluding ampicillin, to which only 78.3% were susceptible. β-lactamase production was observed among 20.2% of H. influenzae isolates; 1.5% of isolates were β-lactamase negative, ampicillin-resistant. Conclusions: S. pneumoniae remained highly susceptible to levofloxacin, linezolid, tigecycline and vancomycin while H. influenzae was susceptible to most antimicrobial agents in the testing panel (excluding ampicillin).