Risk Factors, Antibiotic Profile, and Molecular Detection of Virulence and Antibiotic Resistance Genes of Enteric Bacteria in Diarrheic Calves in Egypt

Abstract

Diarrhea caused by different bacterial infections in calves is a serious issue. In the present study, 215 diarrheic animals, including 175 buffalo and 40 cattle calves were examined. The incidence varied amongst farms, ranging from 0 to 27.9%. Among the affected calves, 37.2% were 1 to 7 days old, 55.8% were 7 days to 3 months of age, while 6.9% were more than 3 months old. Bacteriological, antibiogram, and PCR-based detection of specific virulence and antimicrobial resistance genes were performed. E. coli (85.5%), C. perfringens (8.8%), and Salmonella (3.7%) were bacterial infections recovered from affected calves. Various E. coli pathotypes, such as Shiga-toxin-producing E. coli (STEC), enteropathogenic E. coli (EPEC), extraintestinal E. coli (ExPEC), and enterotoxigenic E. coli (ETEC), caused diarrhea in these calves. The most prevalent virulence genes in E. coli were the sta and eaeA genes (60%). All Salmonella strains were found positive for the invA gene, while all C. perfringens strains were tested positive for the cpa gene. Most of the identified strains were resistant to clindamycin, erythromycin, and oxytetracycline. The isolated strains harbored blaTEM, qnrA and tetA. Approximately 96.2% of E. coli and 62.5% of Salmonella isolates were MDR to different antimicrobial classes. Moreover, 10.5% of C. perfringens isolates were extensive drug-resistant (XDR) to seven antimicrobial classes, while 84.2% of them were MDR to various antimicrobial classes. The findings of this study provide a better understanding regarding the epidemiological aspects of bacterial illnesses and for the development of prevention techniques for this problem. The antibiograms recorded in this study highlight the dangers of indiscriminate antibiotic usage in diarrheic calves.