Ducks infected with duck circovirus (DuCV) exhibit feathering disorder, growth retardation, and low body weight. The virus can induce immunosuppressi

Campylobacter is a food-borne zoonotic pathogen that causes human gastroenteritis worldwide. Campylobacter bacteria are commensal in the intestines of many food production animals, including ducks and chickens. The objective of the study was to determine the prevalence of Campylobacter species in domestic ducks, and the agar dilution method was used to determine resistance of the isolates to eight antibiotics. In addition, multilocus sequence typing (MLST) was performed to determine the sequence types (STs) of selected Campylobacter isolates. Between May and September 2012, 58 duck farms were analyzed, and 56 (96.6%) were positive for Campylobacter . Among the isolates, 82.1% were Campylobacter jejuni , 16.1% were C. coli , and one was unidentified by PCR. Of the 46 C. jejuni isolates, 87.0%, 10.9%, and 21.7% were resistant to ciprofloxacin, erythromycin, and azithromycin, respectively. Among the C. coli isolates, all 9 strains were resistant to ampicillin, and 77.8% and 33.3% were resistant to ciprofloxacin and azithromycin, respectively. The majority of the Campylobacter isolates were classified as multidrug resistant. Twenty-eight STs were identified, including 20 STs for C. jejuni and 8 STs for C. coli . The most common clonal complexes in C. jejuni were the ST-21 complex and the ST-45 complex, while the ST-828 complex predominated in C. coli . The majority of isolates were of STs noted in ducks and humans from earlier studies, along with seven STs previously associated only with human disease. These STs overlapped between duck and human isolates, indicating that Campylobacter isolates from ducks should be considered potential sources of human infection.

The aim of the present study was to investigate variation in antimicrobial resistance in Clostridium perfringens (C. perfringens) isolated from chickens after withdrawal of antimicrobial growth promoters (AGPs); and to investigate the correlation between the presence of toxin genes (cpb2, netB, and tpeL) and antimicrobial resistance. Altogether, 162 isolates of C. perfringens were obtained from chickens displaying clinical signs of necrotic enteritis (n = 65) and from healthy chickens (n = 97) in Korea during 2010–2016. Compared to before AGP withdrawal, increased antimicrobial resistance or MIC₅₀/MIC₉₀ value was observed for nine antimicrobials including penicillin, tetracycline, tylosin, erythromycin, florfenicol, enrofloxacin, monensin, salinomycin, and maduramycin. Significantly (p < 0.05) higher resistance to gentamicin, clindamycin, and virginiamycin was found in isolates from chickens with necrotic enteritis compared to those from healthy chickens. tpeL gene was not detected in C. perfringens isolates from healthy chickens. A correlation between toxin gene prevalence and antibiotic resistance was found in the C. perfringens isolates. Because the usage of antimicrobials may contribute to the selection of both resistance and toxin genes, these can potentially make it challenging to control antimicrobial resistance in pathogenic colonies. Therefore, a more complete understanding of the interplay between resistance and virulence genes is required.