Characterization of Escherichia coli and other bacteria isolated from condemned broilers at a Danish abattoir

Genetic Complexity of CC5 Staphylococcus aureus Isolates Associated with Sternal Bursitis in Chickens: Antimicrobial Resistance, Virulence, Plasmids, and Biofilm Formation

Sternal bursitis, a common inflammatory condition in poultry, poses significant challenges to both animal welfare and public health. This study aimed to investigate the prevalence, antimicrobial resistance, and genetic characteristics of Staphylococcus aureus isolates associated with sternal bursitis in chickens. Ninety-eight samples were collected from affected chickens, and 24 S. aureus isolates were identified. Antimicrobial susceptibility testing revealed resistance to multiple agents, with a notable prevalence of aminoglycoside resistance genes. Whole genome sequencing elucidated the genetic diversity and virulence profiles of the isolates, highlighting the predominance of clonal complex 5 (CC5) strains. Additionally, biofilm formation assays demonstrated moderate biofilm production capacity among the isolates. These findings underscore the importance of vigilant monitoring and targeted interventions to mitigate the impact of sternal bursitis in poultry production systems.

Current status of β-lactam antibiotic use and characterization of β-lactam-resistant Escherichia coli from commercial farms by integrated broiler chicken operations in Korea

β-Lactam antibiotics are one of the most clinical importance in human and veterinary medicine because they are used for both preventive and therapeutic purposes against several gram-positive, gram-negative, and anaerobic organisms. In this study, it was confirmed that β-lactams (81.1%) were found to be significantly prescribed the most among 74 farms in 5 integrated broiler operations, and single prescription (84.6%), 2-day (41.5%) or 3-day (40.0%) administration, and 15 to 22 d of age (67.7%) administration was significantly higher in the farms (P < 0.05). Among the E. coli isolated from 74 farms in 5 integrated broiler operations, β-lactam-resistant E. coli isolates were detected more frequently in fecal sample (94.6%) than in dust sample (60.8%) (P < 0.05). The prevalence of MDR in β-lactam-resistant isolates, ranging from 88.1 to 96.5%, was significantly higher than that in non-β-lactam-resistant isolates (P < 0.05), without significant differences among operations. Of 466 β-lactam-resistant isolates, 432 (92.7%) isolates harbored β-lactamase genes. The non-extended-spectrum β-lactamase (ESBL) gene blaTEM-1 (81.8%) showed the highest prevalence among isolates, followed by the non-ESBL gene blaTEM-135 (6.4%) (P < 0.05). Five ESBL genes, SHV-12, OXA-1, CTX-M-27, CTX-M-55, and CTX-M-65, were found in 0.9 to 6.0% of the isolates. The pAmpC gene blaCMY-2 was detected in 17 isolates (3.6%). These results suggest that feces and dust are important reservoirs of antimicrobial-resistant bacteria, highlighting the need to strengthen farm management regulations, such as cleaning, disinfection, and litter disposal and to reduce the use of antibiotics in broiler operations.