Investigation of high-risk ST131 clone, CTX-M-1 and CTX-M-15 genes in ESBL-producing Escherichia coli isolates from clinical samples by real time PCR

Recent studies have revealed the prevalence of Escherichia coli Sequence Type 131 (ST131) clonal group isolates, which are reported to produce extended-spectrum β-lactamase in terms of antimicrobial resistance. The aim of this study was to determine the ratios of ST131 clone and CTX-M-1 and CTX-M-15 genes in extended spectrum β-lactamase producing Escherichia coli isolates isolated from various clinical materials by Real Time PCR. Escherichia coli strains isolated from various clinical materials in the microbiology laboratory of Adıyaman University Training and Research Hospital were included in the study. Identification of species was performed using conventional and automated methods. Antibiotic susceptibility tests and extended spectrum β-lactamase production were determined by automated methods. DNA isolation and Real Time PCR of extended spectrum β-lactamase producing Escherichia coli isolates were performed in the Central Laboratory of Çukurova University Balcalı Hospital Health Application and Research Center. As a result of Real Time PCR analysis of 72 extended spectrum β-lactamase (+) Escherichia coli isolates; 44 (61.1%) isolates were ST131 clone, 28 (38.9%) isolates were not ST131 clone; 84.72% carried CTX-M-1 and 77.78% carried CTX-M-15 genes. In proportion to the number of patients with antibiogram test; the first two antibiotics to which ST131(+) isolates were resistant were 67.4% Ceftazidime and 66.7% Cefuroxime, and the first two antibiotics to which they were susceptible were 66% Amikacin and 65.2% Nitrofurantion. Among the ST131 (-) isolates, the first two antibiotics to which they were resistant were 41.1% Cefixime and 38.6% Cefazolin, the first two antibiotics to which they were susceptible were 34% Amikacin and 33.3% Colistin, respectively, and there was 100% sensitivity to Tigecycline due to the study in one patient. In all extended-spectrum β-lactamase (+) Escherichia coli isolates for which antibiogram tests were performed, Amoxicillin/Clavulanate resistance was 68.1% (49/72) and Gentamicin resistance was 20.8% (15/72). Keywords: β-Lactamase, CTX-M-1, CTX-M-15, E.coli ST131, Real-time PCR