Molecular Characterization Of Pathogenic From Raw Beef In Karachi, Pakistan.

The aim of the present study was to estimate the prevalence of and investigate the dominant serovars distribution in raw beef and to screen the isolated serovars for the prescense of beta-lactamases and virulence genes. A total of 150 samples of raw beef sold at butcher shops ( = 75) and supermarkets ( = 75) in Karachi city were collected (50 samples each from muscles, lymph nodes, and minced beef). The samples were cultured according to the ISO-6579-1guidlines. The overall prevalence of strains was found to be 21.34%. A total of 56 isolates of belonging to four serogroups ( Pullorum, Enteritidis, Typhimurium and Choleraesuis) were isolated from beef muscles (12%), lymph nodes (24%) and minced beef (28%) samples collected from butcher shops (av. 21.34%). No was detected in beef samples collected from supermarkets. . Enteritidis contamination was highest (37.5 %), followed by . Choleraesuis (30.4%), . Pullorum (19.6%) and . Typhimurium (12.5 %). Antibiotic susceptibility testing revealed that isolates were highly resistant to Oxytetracycline (90%), Ampicillin (90.5%), Amoxicillin (81.1%), Tetracycline (76%), Neomycin, (79.8%) and Ciprofloxacin (61.4%). The isolates examined were more susceptible to the Cephalosporin antibiotics such as Cefixime (43.2%), Cefepime (48.2) and Cefoxitin (49.8%). PCR based screening of bla, bla and bla revealed that bla and bla were the dominant resistant genes in . Enteritidis and . Typhimurium followed by . Pullorum and . Choleraesuis whereas bla was the least detected beta-lactamase in isolates. Virulence genes screening revealed that at least five genes were present in all the serovars, highest being present in . Enteritidis (12/17) and . Typhimurium (12/17). . Cholerasuis (5/17) carried the least number of virulence genes followed by . Pullorum (6/17). The present data suggest that beef samples from butcher shops of Karachi city are heavily contaminated with MDR . The presence of resistance and virulence genes in MDR strains of may play a significant role in transmission and development of infection in humans.