Comparative antimicrobial activity of gatifloxacin tested against Campylobacter jejuni including fluoroquinolone-resistant clinical isolates

Campylobacter jejuni is an important pathogen that causes gastroenteritis, as well as other disease states such as meningitis and septic arthritis. In this study, the Etest (AB BIODISK, Solna, Sweden) results were compared to a reference agar dilution method using gatifloxacin, a new 8-methoxyfluoro quinalone. A total of 53 strains of C. jejuni initially isolated from patie nts in California and Mexico were tested. Results demonstrated a high corre lation (r = 0.88) between the two utilized in vitro dilution methods. In ad dition, gatifloxacin activity was compared to that of ciprofloxacin, metron idazole, amoxicillin, erythromycin, chloramphenicol, gentamicin, tetracycli ne, and trimethoprim/sulfamethaxazole using the Etest. Gatifloxacin (MIC90, 4 mu g/ml) was approximately eight- to 16-fold more potent than ciprofloxa cin (Mic(90), > 32 mu g/ml), a commonly used fluoroquinolone for Campylobac ter infections. Eight strains highly resistant to ciprofloxacin (MIC90, > 3 2 mu g/ml) were tested for cross resistance against the newer fluoroquinolo nes (gatifloxacin, levofloxacin, trovafloxacin) and the rank order of poten cy was: gatifloxacin (MIC50, 16 mu g/ml) > trovafloxacin = levofloxacin (MI C50, > 32 mu g/mL). However, only 25% ciprofloxacin-resistant strains were inhibited by less than or equal to 1 mu g/mL of gatifloxacin or trovafloxac in. These results for gatifloxacin against C. jejuni strains must be furthe r assessed in the context of in vivo trials before the clinical role of thi s new fluoroquinolone can be determined. The Etest appears to be a simple a nd precise susceptibility test method for testing C. jejuni isolates agains t fluoroquinolones and other alternative therapeutic agents. (C) 1999 Elsev ier Science Inc.