Molecular characterization of fosfomycin resistance genes in E.coli isolates

In this study, 24 fosfomycin resistant E. coli isolates isolated from urine samples from Ahi Evran University Training and Research Hospital, Microbiology Laboratory were included. Species identification and antibiotic susceptibility studies of isolates were carried out with the automated system of Vitek 2 Compact (bioMérieux, France) and disk diffusion methods. The plasmid-derived fosA, fosA3, fosB, fosC, fosC2, fosX genes, which are known to be responsible for the phosphomycin resistance in the E.coli isolates included in the study, were screened with the aid of PCR using specific primers. E.coli isolates are also responsible for resistance to beta-lactam and quinolone group antibiotics, blaTEM, blaSHV, blaOXA-1, blaPER-1, blaGES, blaVEB, blaCTX-M, qnrA, qnrB, qnrS, aac-(6')-ıb-cr The presence of aac-(6')-ıb-cr genes and Class-1 and Class-2 integron were screened with the aid of PCR using specific primers. Clonal relationships of isolates were studied with the help of REP PCR. The replication origins of conjugative and transformant plasmids obtained from the isolates were determined according to the PCR-based replication origin determination method. As a result of the PCR procedure to determine the phosphomycin resistance, 1 (FF25) of 24 samples was found positive for the fosA3 gene. The presence of blaTEM, gene in 11, blaOXA-1, in 6 and blaSHV gene in 3 were detected. As a result of PCR for the blaCTX-M gene, the products were sent to index analysis and all 14 positive results were found to belong to the CTX-M 15 group. No blaPER-1, blaGES, blaVEB genes were detected in any of the isolates. It was determined that 6 of E. coli isolates contain qnrB and qnrS, 9 of them contain aac-(6^')-ıb-cr gene. None of the isolates contain the qnrA gene. When Class-1 and Class-2 integron contents are researched; It was determined that 3 of the isolates contain Class-1 and 5 of them contain Class-2 integron. In conjugation and transformation situations that caused genetic changes in bacteria, transformation and conjugation experiment was performed on 24 bacterial isolate samples. According to the experimental findings, one of the samples was identified as transconjugant and both were transformant bacteria. As a result of the epidemiological data obtained in the study and literature researches, the resistance rate started to increase with the use of fosfomycin antibiotic as an alternative agent. This study will give very important clues in determining the spread of resistance both in our country and in the world. It will also be a very important database for future studies.