Antimicrobial resistance rates of Campylobacter species isolated from clinical samples during 2010–2011 and 2023–2024 in Serbia

Campylobacteriosis is the most frequent zoonosis in Europe and its most important human pathogens are Campylobacter jejuni and Campylobacter coli. Resistance of Campylobacter to fluoroquinolones and tetracyclines, previously recommended for treatment of prolonged or complicated disease, has been emerging. We examined phenotypic resistance to erythromycin, tetracycline, ciprofloxacin, gentamicin, amoxicillin-clavulanic acid and imipenem in 150 Campylobacter isolates from human stool during 2010-2011 and the same number of strains during 2023-2024, using the antimicrobial gradient method in both periods, to determine minimum inhibitory concentration (MIC). Comparing the two periods, resistance rate of C. jejuni increased by 35% and 38.43% to tetracyclin and ciprofloxacin, respectively and decreased by 0.83% to erythromycin. Prevalence of resistance in C. coli increased by 42.59% and 42.01% against tetracyclin and ciprofloxacin, respectively and all isolates were sensitive to erythromycin. Resistance of C. jejuni to amoxicillin-clavulanic acid decreased by 0.96% and increased by 3.70% in C. coli. All isolates showed sensitivity for imipenem in both periods, while only 2% of C. jejuni strains were resistant to gentamicin in 2023-2024. The difference of mean MICs for all antibiotics was statistically significant in two examined periods, with exception of those for erythromycin both in C. jejuni and C. coli. In 2023-2024, 79 isolates of C. jejuni and 22 isolates of C. coli were resistant against two and more antibiotics, most frequently tetracycline and ciprofloxacin. The present study provides evidence that in Campylobacter spp. the antimicrobial resistance to ciprofloxacin and tetracycline is on rise in Serbia. Our findings are in accordance with recent reports from countries geographically close to Serbia.