Molecular characterization of antibiotic resistance genes in Enterobacteriaceae isolated from urinary tract infections (UTI)

In this thesis, it was aimed to determine the genes that cause resistance to beta lactam and quinolone antibiotics in clinical Enterobacteriaceae isolates that cause urinary tract infections and to show the transferability of these genes on conjugative plasmids. Seventy Gram-negative Enterobacteriaceae isolates, which were identified with the Vitek-2 automated system and isolated by culture methods from the urine samples taken from the patients who applied with the complaint of Urinary Tract Infection, were obtained from the Medical Microbiology Laboratory of Kırşehir Ahi Evran University Training and Research Hospital between September and December 2018. As a result of antibiogram tests, 13 Enterobacteriaceae isolates were found to have multidrug resistance and these isolates were included in the study. Molecular identification of isolates was performed using 16S rRNA gene sequences. Plasmid-mediated β-lactamase (blaTEM, blaSHV, blaCTX-M1, blaCTX-M2, blaOXA-1, blaPER-1) that provides resistance to beta-lactam antibiotics and plasmid-mediated quinolone resistance genes (aac(6)′-Ib-cr, qnrA, qnrB, qnrS) were determined by PCR. Conjugation experiments were performed to determine the transferability of resistance genes. As a result of molecular identification, the isolates were identified as Proteus mirabilis (Pr3, 6, 8, 9, 11 and 17), Citrobacter koseri (Pr4 and Pr5), E. coli (Pr10, 12 and 13), Proteus sp. (Pr19) and Klebsiella pneumoniae (Pr20). All of the isolates were found to have multidrug resistance. All Enterobacteriaceae isolates were found to be resistant to ampicillin, sulbactam/ampicillin, nalidixic acid and trimethoprim/sulfamethoxazole antibiotics, which are β-lactam, β-lactam/β-lactamase inhibitor, quinolone and sulfonamide group antibiotics, respectively. When the presence of plasmid-mediated resistance genes was examined, it was determined that all of the isolates (100%) were positive for blaCTX-M1 and aac(6′)-Ib-cr genes. 85%, 38% and 8% of the isolates were positive for blaTEM, blaCTX-M2 and blaSHV gene, respectively. The blaOXA-1 and blaPER-1 genes were not detected in the isolates. As a result of conjugation experiments, it was determined that Proteus mirabilis Pr17 isolate contained a conjugative plasmid. PCR studies have shown that; the resistance genes blaTEM, blaCTX-M1, qnrA and aac(6′)-Ib-cr and the Class-1 integron gene cassette structure are carried in this conjugative plasmid. In terms of public health, it is thought that demonstrating antibiotic resistance with molecular methods in our province will help to understand the mechanism of resistance and to develop effective prevention and control measures against resistant bacteria.