Comparative antimicrobial potency of meropenem tested against Gram-negative bacilli: report from the MYSTIC surveillance program in the United States (2004).
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.
Rhomberg
P R
PR
JMI Laboratories, North Liberty, Iowa 52317, USA. paul-rhomberg@jmilabs.com
Fritsche
T R
TR
Sader
H S
HS
Jones
R N
RN
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D024881:Drug Resistance, Bacterial; D016905:Gram-Negative Bacterial Infections / Q000188:drug therapy*; D006801:Humans; D008137:Longitudinal Studies; D000077731:Meropenem; D008826:Microbial Sensitivity Tests; D011159:Population Surveillance; D013845:Thienamycins / Q000494:pharmacology*
D000900:Anti-Bacterial Agents; D013845:Thienamycins; D000077731:Meropenem