Comparative Antimicrobial Potency of Meropenem Tested Against Gram-Negative Bacilli: Report from the MYSTIC Surveillance Program in the United States (2004)

• Published in: Journal of chemotherapy (Florence) 2005-10, Vol.17 (5), p.459-469
• Main Authors: Rhomberg, P.R., Fritsche, T.R., Sader, H.S., Jones, R.N.
• Format: Article
• Language: English
• Subjects: Anti-Bacterial Agents - pharmacology; antimicrobial resistance; carbapenems; Drug Resistance, Bacterial; Gram-Negative Bacterial Infections - drug therapy; Humans; Longitudinal Studies; meropenem; Microbial Sensitivity Tests; MYSTIC Program; Population Surveillance; surveillance; Thienamycins - pharmacology
• ISSN: 1120-009X; 1973-9478
• DOI: 10.1179/joc.2005.17.5.459

The Meropenem Yearly Susceptibility Test Information Collection (MYSTIC) Program is a longitudinal resistance surveillance network of more than 100 medical centers worldwide monitoring the susceptibility of bacterial pathogens to carbapenems and other broad-spectrum agents. In 2004 (year six), the antimicrobial activity of 12 broad-spectrum agents was assessed against 2,799 Gram-negative bacterial isolates submitted from 15 United States (USA) medical centers using Clinical and Laboratory Standards Institute (CLSI; formerly NCCLS) recommended methods. Meropenem continued to demonstrate a high potency with MIC90 values 4- to 32- fold lower than imipenem against the Enterobacteriaceae. The wide spectrum of activity for meropenem against all Gram-negative isolates was demonstrated by the overall rank order of percentage susceptibility at CLSI breakpoints: amikacin (96.5%) > meropenem (96.0%) > imipenem (95.8%) > piperacillin/tazobactam (91.5%) > tobramycin (91.4%) > cefepime (91.2%) > ceftazidime (89.0%) > gentamicin (88.0%) > aztreonam (81.5%) > levofloxacin (80.5%) > ciprofloxacin (80.2%) > ceftriaxone (69.1%). Only the aminoglycosides (84.5%) and carbapenems (76.1 - 83.8%) exhibited acceptable levels of susceptibility against the Acinetobacter spp. isolates as this species group became more resistant to all antimicrobial classes. A continued increase in the resistance rate for both ciprofloxacin and levofloxacin over the six years was observed, most alarming among Escherichia coli (20.2 - 20.7%) and indole-positive Proteus species (34.4 - 42.2%) isolates, some documented as clonal. Continued surveillance of these broad-spectrum antimicrobial agents appears warranted to monitor the potency and spectrum of activity against Gram-negative pathogens causing serious infections and the emergence of new or novel resistance mechanisms that could compromise carbapenem therapy.