Resistance Patterns of Frequently Applied Antimicrobials and Occurrence of Antibiotic Resistance Genes in Detected in Edwardsiellosis-Infected Tilapia Species of Fish Farms of Punjab in Pakistan.

is one of the most significant fish pathogens, causes edwardsiellosis in a variety of freshwater fish species, and its antibiotic resistance against multiple drugs has made it a health risk worldwide. In this study, we aimed to investigate the antibiotic resistance (ABR) genes of and establish its antibiotic susceptibility. Thus, 540 fish (299 , 138 , and 103 ) were collected randomly from twelve fish farms in three districts of Punjab in Pakistan. was recovered from 147 fish showing symptoms of exophthalmia, hemorrhages, skin depigmentation, ascites, and bacteria-filled nodules in enlarged liver and kidney. Antimicrobial susceptibility testing proved chloramphenicol, ciprofloxacin, and streptomycin effective, but amoxicillin, erythromycin, and flumequine ineffective in controlling edwardsiellosis. Maximum occurrence of qnrA, blaTEM, and sul3 genes of was detected in 45% in the liver, 58%, and 42% respectively in the intestine; 46.5%, 67.2%, and 55.9% respectively in ; 24%, 36%, and 23% respectively in summer with respect to fish organs, species, and season, respectively. Motility, HS, indole, methyl red, and glucose tests gave positive results. Overall, infected 27.2% of fish, which ultimately caused 7.69% mortality. The Chi-squared test of independence showed a significant difference in the occurrence of ABR genes of with respect to sampling sites. In conclusion, the misuse of antibacterial agents has led to the emergence of ABR genes in , which in association with high temperatures cause multiple abnormalities in infected fish and ultimately resulting in massive mortality.