Meropenem activity against European isolates: report on the MYSTIC (Meropenem Yearly Susceptibility Test Information Collection) 2006 results

The MYSTIC (Meropenem Yearly Susceptibility Test Information Collection) Program is a longitudinal antimicrobial surveillance study that has been in place since 1997 in centers that are actively prescribing meropenem. This report examines the activity of meropenem and other broad-spectrum antibacterial comparators against the 7124 isolates submitted by 40 European centers during 2006 and compares the results with those obtained in 2002. Cumulative susceptibility rates against all methicillin-susceptible staphylococci were amikacin (99.2%) > meropenem and imipenem (98.1%) > piperacillin + tazobactam (96.6%) > gentamicin (91.8%) > tobramycin (91.1%) > ciprofloxacin (83.1%) > ceftazidime (59.7%). Against all species of Enterobacteriaceae, the rates were meropenem (98.9%) > imipenem (97.9%) > amikacin (97.1%) > gentamicin (91.0%) > piperacillin + tazobactam (83.4%) > ceftazidime (82.3%) > ciprofloxacin (82.2%) > tobramycin (75.1%). The carbapenems were also the most effective class against nonfermenters, although there are increasing numbers of multidrug-resistant (MDR)-Acinetobacter spp. being reported. Overall meropenem is still retaining excellent activity against the majority of isolates studied. The continued need for surveillance studies such as MYSTIC in order that correct clinical decisions concerning antibiotic selection are made is once again demonstrated.