الفهرس 
english coverOnly 14 pages are availabe for public view
 |  | from | 145 |  |  |
| | | from | 145 | | |
Abstract
Antibiotics and disinfectants’ resistant Gram-negative bacteria represent a major risk on the broiler chicks especially during the first ten days of the rearing cycle, mainly Salmonella, E. coli, and Pseudomonas aeruginosa as they contribute as major causes of early mortalities in broiler farms.
We aimed in this study to shed light on these main three bacterial pathogens through detection of their prevalence, sensitivity range against the different antimicrobials, and resistance genes that hinder the efficacy not only of some antibiotics but also of Quaternary Ammonium Compounds that are widely used to eliminate them.
Five hundred samples (liver, yolk sac, cecum, spleen and heart) from freshly dead affected chicks (1-10 days old) were cultured on different media for the isolation of causative agents by conventional and serological methods.
PCR was used for the 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. We found that 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.
The single and mixed experimental bacterial infections of twenty-five one-day-old broiler chicks classified into five groups revealed that the mixed bacterial infection represents a high risk on the broiler chicks than the single infection.
It was concluded that the existence of 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.