Abstract
Using MacConkey agar, E. coli were isolated from 285 samples including 125 tonsil swabs (4-6 weeks old healthy pigs from 5 farms), 80 tissue samples from different slaughter houses (20 each intestine, liver, meat and kidney), and 80 samples from super-and wet-markets (each 20 meat and liver) collected both in summer and winter. Isolates were tested for 15 antibiotics (CRO, AMX, GEN, STR, TET, CHL, CLR, LVX, OFX, GAT, CIP, SXT, AMP, LIN and AZM) according to the disc diffusion method and antibiotic resistant genes {tet(A), tet(B), tet(C), strA/strB, aadA, aac(3)IV), aadB, sul1, sul2 and sul3, blaCMY-2, blaTEM and blaSHV} using mPCR. Resistance for LIN was the highest in overall (96.3%, 77/80) isolates as well as from pig farms (100%, 20/20) and different markets (100%, 20/20, 85%, 17/20). Resistance for other antibiotics such as AMX, TET, AMP and SXT was found 82.5% (66/80), 63.7% (51/80), 58.7% (47/80) and 50% (40/80), respectively. The most prevalent ARGs in the isolates recovered from pig farms was blaTEM (100%, 20/20), followed by blaCMY-2 (80%, 16/20), tetA and tetB (60%, 12/20) and tetC (50%, 10/20). E. coli became more and more diverse along the PSCP with group B2 being the most prevalent. Besides multiple drug resistance, they share many traits with the human pathogenic isolates based on virulence gene contents that may pose a potential threat to public health.