Horizontal gene conjugative transmission acquisition and transfer of antibiotic-resistance genes in bacteria

Abstract

Objective: are isolation and identification of test bacteria, detection the sensitivity of bacteria to antibiotics, detection of the plasmids profiles patterns of the resistant strains and determination of the different plasmids bands by gel electrophoresis method. Methods: Thirty specimen have been isolated from different sources ( urine, hospital instruments, and wound) in Sadder Medical City and Al-Zahraa hospital in Najaf governorate, isolation and identification by the automated VITEK-2 compact system. The antibiotic sensitivity test was studied on 4 isolates by the disk diffusion technique on MHA, total DNA was extracted from colonies grown on agar plates by boiling method, and plasmid detection and conjugation assay with standard E. coli MM 294. Results: the results shows high frequency of conjugation occurs between E. coli (EC1, EC2, EC3 and EC 4 ) and E. coli MM 294 as recipient cells strain had acquired resistance to the follow antibiotics and that the isolates were resistance to: rifampin , gentamycin, metronidazole, chloramphenicol, trimethoprim, ampicillin, amoxicillin, tetracycline, co-trimoxazol, cephalexin, cefixime, ceftriaxon, streptomycin, cephalothin, clarthromycin, and carbenicillin. The frequency of conjugation that’s ranging from 8.625 X 10-3 _ 1.25 X 10-3 transconjugants/recipients, non-B-lactam antibiotics resistance was also transferred from donor to recipient cells, resistance to tetracycline and rifampin were appeared in all transconjugants, which indicated that the resistance to these antibiotics was carried on a plasmid that transferred during conjugation. The resistance to tetracycline, rifampin, and erythromycin co-transferred with the gene encoding ESBL resistance, and the encoding resistance to these non-B-lactam antibiotics was transferable to the standard E. coli MM294, and mediated by a plasmid. Conclusion: The in vitro frequency suggests that horizontal gene transfer of conjugative antibiotic resistance plasmids' gene mediated may be significant among resistant bacteria, and revealed a high resistance rate for antibiotics by isolated strains E. coli this corroborates antibiotics misuse.