Determination of some genes encoding antibiotic resistance of Salmonella spp. isolates from pigs

Abstract

The study was conducted to detect some genes encoding antibiotic resistance of 60 Salmonella isolates, they were identified from the pigs raising in some Northern and Central highland provinces in 2005 to 2012. These isolates belonged to 7 different serovars, including S. typhimurium (n = 15), S. derby (n = 14), S. choleraesuis (n = 12), S. rissen (n = 6), S. Anatum (n = 5), S. sandow (n = 4) and S. bargny (n = 4). Of which, S. typhimurium and S. derby were 2 serovars having several strains resisted to more antibiotics than other serovars. The S. typhimurium strains resisted to the tested antibiotics with the highest rate, such as: out of 15 tested strains, 14 strains resisted to tetracyclin, accounting for 93.33%; 13/18 strains (86.67%) resisted to ampicillin and streptomycin, 12/15 strains (80%) resisted to kanamycin; 11/15 strains (73.33%) resisted to sulfisoxazole; 9/15 strains (60%) resisted to chloramphenicol; 5/15 strains (33.33%) resisted to gentamycin and 3/15 strains (20%) resisted to ciprofloxacin. The S. derby strains resisted to 8/10 tested antibiotics (am, cm, km, sm, su, tc, cip, cf) with resistant rates ranging from 14.29% to 78.57%. Three antimicrobial resistant genes were identified, such as: blaTEM, aphAI-Iab and tetA (A) in the the studied Salmonella strains, occurred mostly in S. typhimurium and S. derby strains. The blaTEM genes appeared in 26 Salmonella strains, including 13 S. typhimurium, 11 S. derby, 1 S. anatumand 1 S. bargny isolates. The aphAI-Iab genes appeared in 22 strains, including 12 S. typhimurium and 10 S. derby isolates. The tetA (A) genes presented in 28 strains, including 14 S. typhimurium, 9 S. derby, 2 S. rissen, 2 S. anatum and 1 S. bargny isolates