Antibiotic resistance of Campylobacter spp isolated from chickens and humans in central Italy

Campylobacter jejuni and Campylobacter coli strains, isolated from slaughtered chickens and human feces, were examined for their susceptibility to six antibiotics (ampicillin, cefotaxime, erythromycin, levofloxacin, nalidixic acid and trimethoprim) by broth microdilution, for minimum inhibitory concentration determination, and disc diffusion assays. For the 32 C. jejuni isolates, the highest levels of resistance were to trimethoprim (65.6% of the isolates by broth microdilution and 62.5% by disc diffusion) and cefotaxime (62.5% by both methods). Comparable levels of resistance to these antibiotics were found in the 24 C. coli isolates. Statistically significant differences were found between all C. coli isolates for cefotaxime (P = 0.0043) using disc diffusion. A high proportion of C. jejuni isolates show resistance to nalidixic acid using both the broth microdilution (59.4%) and disc diffusion (56.2%) methods. C. coli strains were resistant to this antibiotic showing proportions of 75% when tested by broth microdilution and 70.8% by disc diffusion. Multidrug resistance was detected in 21.8% and 62.5% of C. jejuni and C. coli strains, respectively, by broth microdilution test and in 28.1% and 75% of C. jejuni and C. coli strains by disc diffusion method. None of the isolates showed the same pattern of multidrug resistance. © 2010 Wiley Periodicals, Inc.. polymorphic DNA (RAPD) analysis and unweighted pairgroup method with arithmetic averages (UPGMA) cluster analysis. Our findings revealed an high diversity of the autochthonous bacterial populationinvestigated, both at species and strain level.