Phenotypic and Genotypic Characteristics of Antimicrobial and Disinfectant Resistance of Gram-negative Bacteria Involved in Early Broiler Chick Mortality

One of the most challenges facing the poultry industry in Egypt is the early mortality among broiler chicks during the first ten days of the rearing cycle, especially which caused by antimicrobial resistant Gram-negative bacteria. This study was conducted for the determination of the prevalence of Gram-negative bacteria involved in early mortality among broiler chicks. Antibiogram profile and antibiotic and disinfectant resistance genes were also performed. Five hundred samples (liver, yolk sac, cecum, spleen, and heart) from freshly dead affected chicks were cultured on different media for isolation of causative agents.by conventional and serological methods. PCR was used for detection of resistance genes. The Bacteriological examination revealed the presence of Salmonella spp., E. coli, and P. aeruginosa in the percentages of 23, 25 and 8%, respectively. Single and mixed infections were observed as 41, and 7%, respectively. 86.9% of Salmonella serovars were resistant to colistin sulphate, 48% of E. coli strains showed resistance against norfloxacin, and 87.5% of P. aeruginosa showed resistance against florfenicol. The mcr1 gene was found in 86.9% of all Salmonella serovar, qnrS gene was detected in 16% of E. coli, and floR gene was present in 100% of P. aeruginosa isolates. PCR screening for qacED1 revealed that all bacterial isolates under test were positive. It was concluded that results of current study assert the existence mcr1, qnrS, floR, and qacED1 genes among (Salmonella spp., E. coli, and P. aeruginosa) which were isolated from early aged broiler dead chicks; that represents a high risk on the poultry industry in Egypt.