In Journal of Food Protection, S. Döhne of the University of Veterinary Medicine Hannover in Germany and co-authors there and at the University of Leipzig report their study to assess the antimicrobial susceptibility rate of Salmonella and Campylobacter spp. isolated from fattening pigs in northern Germany.

From 540 lymph node samples, 16 Salmonella Typhimurium, 1 Salmonella Brandenburg, 37 Campylobacter coli, and 11 Campylobacter jejuni strains were isolated. Antibiotic susceptibility testing was carried out by the broth dilution method.

The 14 tested antibiotics for Salmonella were ampicillin, cefotaxime, ceftazidime, chloramphenicol, ciprofloxacin, colistin, florfenicol, gentamicin, kanamycin, nalidixic acid, streptomycin, sulfamethoxazole, tetracycline and trimethoprim.

The eight tested antibiotics for Campylobacter spp. were ampicillin, ampicillin-sulbactam (2:1), ciprofloxacin, erythromycin, gentamicin, nalidixic acid, sulfamethoxazole-trimethoprim (1:19), and tetracycline.

In total, 93.7 per cent (n=16) of Salmonella Typhimurium, 75.7 per cent (n=37) of C. coli and 54.5 per cent (n=11) of C. jejuni isolates were resistant to at least one of the tested antibiotics.

Multi-resistance to three antibiotics was observed in 75 per cent of Salmonella Typhimurium, 16.2 per cent of C. coli and zero per cent of C. jejuni isolates.

Pan-susceptibility was detected in 6.3 per cent of Salmonella Typhimurium, 24.3 per cent of C. coli, and 45.5 per cent of C. jejuni isolates.

Multi-resistance is defined as resistance to three or more antibiotics, and pan-susceptibility is defined as not having resistance to any antibiotic.

Regarding drugs of last resort, cefotaxime, ciprofloxacin and nalidixic acid-resistance was not common among Salmonella (6.3 per cent).

Döhne and co-authors found that the resistance rate of Campylobacter spp. to last-resort drugs - erythromycin, ciprofloxacin and nalidixic acid - varied between species. The observed trend was not statistically significant. No C. coli isolates and few C. jejuni isolates (9.1 per cent) were resistant to erythromycin. In contrast to C. jejuni, the C. coli isolates were more likely to be resistant to ciprofloxacin (9.1 and 18.9 per cent, respectively) and nalidixic acid (0 and 13.5 per cent, respectively). The researchers added that the same phenomenon was detected for tetracycline (27.3 and 62.2 per cent, respectively), sulfamethoxazole (9.1 and 43.2 per cent, respectively) and ampicillin (9.1 and 21.6 per cent, respectively).

Reference

Döhne S., Merle R., Altrock A.V., Waldmann K., Verspohl, J., Grüning P., Hamedy A. and Kreienbrock L. 2012. Antibiotic susceptibility of Salmonella, Campylobacter coli, and Campylobacter jejuni isolated from Northern German fattening pigs. Journal of Food Protection, 75(10):1839-1845. DOI: http://dx.doi.org/10.4315/0362-028X.JFP-12-051

Further Reading You can view the full report (fee payable) by clicking here.