Antimicrobial spectrum of activity for meropenem and nine broad spectrum antimicrobials: report from the MYSTIC Program (2002) in North America.

The Meropenem Yearly Susceptibility Test Information Collection (MYSTIC) Program provides susceptibility data for participating medical centers where carbapenems are utilized. The activity of meropenem and nine broad-spectrum antimicrobial agents were assessed against 3,047 bacterial isolates collected during 2002 from 16 North American sites. The overall rank order of susceptibility of the 10 antimicrobial agents tested against Gram-negative isolates was: meropenem (98%) > imipenem (97%) > cefepime (95%) > tobramycin (93%) > piperacillin/tazobactam = gentamicin (92%) > ceftazidime (91%) > ciprofloxacin (87%) > aztreonam (86%) > ceftriaxone (74%). These results and those from previous years, demonstrate the continued excellent potency and spectrum of activity for meropenem. The utility of meropenem against Pseudomonas aeruginosa isolates has increased steadily with a rise in percent susceptibility each year from 78.2% in 1999 to a present rate of 93.1% susceptible. Conversely, we showed the susceptibility for ciprofloxacin against these same P. aeruginosa isolates has decreased from 82.9 to 72.3% susceptible over four years. Many medical centers have observed a decreased activity of some aminoglycosides, cephalosporins and fluoroquinolones due to increases in rates of extended-spectrum beta-lactamases, Amp C and other resistance mechanisms. Carbapenem resistance remains rarely documented and these beta-lactamase-stable agents appear to be an alternative treatment option for serious community-acquired or nosocomial infections in high risk patient populations.