Non-susceptibility trends among enterococci and non-pneumococcal streptococci from bacteraemias in the UK and Ireland, 2001-06

Objectives: To describe the current patterns and trends in antimicrobial susceptibility in enterococci and streptococci (excepting pneumococci) from bacteraemia in the UK and Ireland from 2001 to 2006. Methods: In each year 2001-06, blood culture isolates were collected by 25 laboratories distributed across the UK and Ireland. In total, there were 1408 isolates of enterococci, 1332 of beta-haemolytic streptococci and 1012 of alpha- and non-haemolytic streptococci. A single central laboratory re-identified the isolates and measured MICs by the BSAC agar dilution method. Results: The prevalence of reduced susceptibility in streptococci and enterococci did not change significantly for most antibiotics, but trends were noted to increased ampicillin, imipenem and vancomycin resistance in Enterococcus faecium. The prevalence of reduced susceptibility to macrolides and tetracycline in streptococci, to tetracycline and gentamicin (high level) in enterococci and to beta-lactams and glycopeptides in E. faecium were all high, with some differences in the prevalence among species or groups. Conclusions: Reduced susceptibility to some antimicrobial agents among streptococci and enterococci remains common and continued surveillance is warranted.