Phenotypic Resistance of Campylobacter Isolates to an Extended Panel of Antibiotics

Because of the global increase in resistance of Campylobacter to both fluoroquinolones and macrolides, we explored phenotypic resistance using traditional Kirby-Bauer methods in human- and animal-derived Campylobacter isolates that were concurrently resistant to both azithromycin and ciprofloxacin to an expanded panel of antimicrobials, including clindamycin, fosfomycin, ampicillin and sulbactam, amoxicillin and clavulanic, fosfomycin, tigecycline, and imipenem. Of 235 Campylobacter isolates resistant to ciprofloxacin and azithromycin, more than 94.8% of Campylobacter jejuni and Campylobacter coli were resistant to clindamycin, 68.5% were resistant to ampicillin and sulbactam, 2.6% were resistant to amoxicillin and clavulanic, and 36.2% were resistant to fosfomycin. Less than 2% of isolates were resistant to tigecycline, and there was no observed resistance to imipenem. The results suggest that amoxicillin and clavulanic warrant further evaluation for use in Campylobacter enteritis in ambulatory patients, but it points to no clear alternative oral therapies. Study findings were reassuring in demonstrating continued universal susceptibility to carbapenems.