Co-selection and Cross-resistance Mechanisms Promoting the Antibiotic Resistance in E.Coli

Abstract

Heavy metal pollution in water is one of the most serious environmental problems. These findings have prompted the idea that metal-exposed bacteria may have altered resistance to antibiotics. One hundred water samples were collected including 50 freshwater form Tigris River, were positive for bacterial growth.  Besides, fifty samples from sewage were also positive for bacterial growth in Al-Kut, Wasit. Aliquots of the samples were used for selective isolation of E coli.  Heavy metals and antibiotic resistance of 100 E. coli from sewage and fresh water were detected by polymerase chain reaction (PCR). Minimum inhibitory concentrations (MICs) of heavy metals were determined by the broth micro dilution method. Antibiotic discs used the frequency of different heavy metals resistance genes in E. coli ranged from 1 to 67 %. While prevalence of ESBL genes ranged from 5 to 17 % in freshwater isolates, and 54-96 % in swage isolates. Sewages isolates show a prevalence of ESBL resistance genes, in comparison with corresponding results of freshwater isolates. MICs of heavy metals for E. coli ranged from ≤ 8.0-1500 mg/L., heavy metal resistance genes (PbRT, cadD arsB, PcoA, czrc, and chrA) were found associated with one or more ARGs (blaOXA, blaTEM, blaSHV and blaCTX) (P < 0.05).