Fourth Belgian multicentre survey of antibiotic susceptibility of anaerobic bacteria

Abstract

Objectives: To collect recent data on the susceptibility of anaerobes to antimicrobial agents with known activity against anaerobes, and to compare them with results from previous Belgian multicentre studies. Methods: Four hundred and three strict anaerobic clinical isolateswere prospectively collected fromFebruary 2011 to April2012 in eight Belgian university hospitals. MICswere determined byonecentral laboratory for 11antimicrobial agents using Etest methodology. Results: According to EUCAST breakpoints, >90% of isolates were susceptible to amoxicillin/clavulanate (94%), piperacillin/tazobactam (91%), meropenem (96%), metronidazole (92%) and chloramphenicol (98%), but only 70% and 40% to clindamycin and penicillin, respectively. At CLSI recommended breakpoints, only 71% were susceptible tomoxifloxacin and79%to cefoxitin. MIC50/MIC90 values for linezolid and for tigecyclinewere 1/4 and 0.5/4 mg/L, respectively. When compared with survey data from 2004, no major differences in susceptibility profiles were noticed. However, the susceptibility of Prevotella spp. and other Gram-negative bacilli to clindamycin decreased from91%in1993-94and82%in2004to69%in this survey. Furthermore, the susceptibility of clostridia to moxifloxacin decreased from 88% in 2004 to 66% in 2011-12 and that of fusobacteria from 90% to 71%. Conclusions: Compared with previous surveys, little evolution was seen in susceptibility, except a decline in activity of clindamycin against Prevotella spp. and other Gram-negative bacteria, and of moxifloxacin against clostridia. Since resistance was detected to all antibiotics, susceptibility testing of anaerobic isolates is indicated in severe infections to confirm appropriateness of antimicrobial therapy. © The Author 2013. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved.