The in vitro activities of moxifloxacin, ciprofloxacin, levofloxacin, gatifloxacin, imipenem, piperacillintazobactam, clindamycin, and metronidazole against 900 surgical isolates were determined using NCCLS testing methods. Moxifloxacin exhibited good to excellent antimicrobial activity against most aerobic (90.8%) and anaerobic (97.1%) microorganisms, suggesting that it may be effective for the treatment of polymicrobial surgical infections.Infections of the abdominal-pelvic vaults and diabetic limbs involve a mixed microbial flora, often characterized by a high level of antimicrobial resistance (5-7). In addition to appropriate antimicrobial spectrum, the ideal antimicrobial agent must also have extensive tissue distribution, as many surgical infections occur in sites where there is significant disruption of tissue plains and vascular supply (7,17,22). Since the introduction of ciprofloxacin in the late 1980s, the fluoroquinolones have been viewed as potent antimicrobials for the treatment of serious gram-negative infections. Newer quinolones have improved in vitro activity against anaerobes, with trovafloxacin, moxifloxacin, and gatifloxacin having more potent activities than levofloxacin and ciprofloxacin (1, 3). Unfortunately, safety and toxicity concerns have limited the potential therapeutic usefulness of many of these agents (11,14,15,21). The present study was undertaken to investigate the in vitro activity of moxifloxacin against aerobic and anaerobic clinical isolates recently obtained from surgical patients with diabetic foot and intra-abdominal infections.Nine hundred sequential, nonduplicated clinical isolates (350 aerobic and 550 anaerobic strains) were collected over a 3-year period (1999 to 2002) from patients with intra-abdominal and diabetic foot infections in a tertiary care medical center in Milwaukee, Wis. (three surgical services: vascular surgery, trauma and critical care, and pancreatobiliary surgery). NCCLS-recommended reference broth and agar dilution methods were used for aerobic and anaerobic susceptibility testing, respectively (18,19). Microbroth and agar dilution plates were prepared on the day of testing and incubated at 35°C for 24 h (aerobes) and 48 h (anaerobes), respectively. Gram-positive and gram-negative aerobic-facultative isolates were tested in Mueller-Hinton broth. Anaerobic strains were tested within an anaerobic chamber on brucella blood agar plates supplemented with 5 g of hemin, 1 g of vitamin K 1 per ml, and 5% lysed sheep blood. The agar dilution plates were inoculated (10 5 CFU/spot) using a 32- The susceptibilities of the aerobic isolates, listed by species, are shown in Table 1. The results are expressed as the MICs at which 50 and 90% of strains were inhibited (MIC 50 and MIC 90 , respectively) and the ranges for all strains. While moxifloxacin, gatifloxacin, and imipenem demonstrated good activity against methicillin-susceptible S. aureus, E. faecalis, and Streptococcus spp., all agents tested failed to provide reliable in vitro activity (based on MIC 90 s) ...
