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    Occurrence of antimicrobial resistance, integrons and virulence genes in Escherichia coli isolated from drinking water in Van, Turkiye: a cross-sectional study
    (Bmc, 2025) Rakici, Erva; Aydin, Elif; Tanriverdi, Elif Seren; Ozgumus, Osman Birol
    Background Escherichia coli is one of the recommended freshwater indicator organisms for faecal contamination and can be associated with the pool of genes encoding antibiotic resistance. The aim of this study was to investigate the molecular characterisation of antibiotic resistance and to identify the virulence genes in E. coli isolated from drinking water samples collected for the purpose of monitoring microbial drinking water quality. Methods The E. coli isolates (n = 244) from municipal tap water samples collected in Van province in Turkiye over a five-month period in 2018 were examined in this study. Antimicrobial susceptibility testing was performed using the standard disc diffusion method with 12 antibiotics. Integron content, the resistance genes such as bla(TEM), bla(SHV), bla(CTX-M) groups, tetA-E genes, qnrA, qnrB, qnrS, qepA, and aac(6')-Ib-cr were screened and the virulence genes (afa, sfa, fimA, hly, iroN, aer, cnf, iutA and pap) were assessed by specific PCRs. The fingerprinting of the isolates harbouring the integron was evaluated using dendogram analysis of the band patterns obtained from the enterobacterial repetitive intergenic consensus (ERIC) PCR. Results Ampicillin, tetracycline, streptomycin, nalidixic acid and trimethoprim/sulfamethoxazole were the most common resistances. MAR index of 18.03% of the isolates was greater than 0.2. The two isolates produced ESBL. Thirty seven (15.16%) isolates carried the class 1 or class 2 integrons harboured the gene cassettes such as aadA, sat, estX and unnamed protein gene. Thirty two (21.47%) isolates were found to carry bla(TEM), 5 (3.33%) isolates carried bla(SHV) and 2 (1.3%) isolates carried the bla(CTX-M) group genes. tetA (81.25%) and tetB (91.66%) were present in tetracycline-resistant isolates. qnrS (29.92%), qnrB and aac(6')-Ib-cr (3.84%) were present in the nalidixic acid resistant isolates. Most of the isolates carried the virulence genes such as fimA, iutA, iroN, aer and sfa. Isolates belonged to 65.57% B1, 15.98% A, 9.42% D and 9.01% B2 phylogroups. A statistically significant difference was found between the phylogenetic groups of the isolates and the integron content (p < 0.001). Fingerprinting showed the 25 different phylotypes in four clusters. Conclusions Molecular epidemiological findings in such a five-month period in the 11 sampled districts in the city of Van appearently showed us that the tap waters in public use was continuously contaminated by the antibiotic resistant and virulent E. coli isolates. This could pose a serious public health risk and, thus need the serious precautions for the infrastructures.
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    Stenotrophomonas maltophilia outbreak originating from a pull-out faucet in a pediatric intensive care unit in Turkey: Insights from clinical records and molecular typing
    (Mosby-Elsevier, 2024) Yashar, Meltem; Basarir, Kerem E.; Tanriverdi, Elif S.; Celep, Selcuk; Sirekbasan, Leyla; Rakici, Erva; Ejder, Nebahat
    Background: Nosocomial Stenotrophomonas maltophilia-related cases are rising and pose a threat to immunocompromised patients. Twelve patients from our pediatric intensive care unit (PICU) presented with S maltophilia-associated bloodstream infection. Methods: This outbreak investigation includes 12 patients from PICU between the ages of 2 months and 4 years (mean 16 months, 7 male). To identify the origin, samples from all possible sources throughout the hospital were collected and ran through DNA isolation and Pulse Field Gel Electrophoresis. Results: 120 samples were collected during the outbreak. 31 samples (26%) were positive for S maltophilia. 30 S maltophilia isolates were analyzed, 10 different genotypes were identified. Clustering isolates were grouped into 3 different clusters (tolerance and optimization 1.0, cutoff 90%). The largest cluster was genotype 1, which included 19 isolates, those belong to patients' samples and a sample from a pull -out faucet inside the PICU. The Pull -out faucet was the origin of the bloodstream infection. Discussion: Pull -out faucets allow biofilm production, due its structure. Pulse Field Gel Electrophoresis identifies the transmission dynamics of the outbreak, with its high discriminatory power. Conclusions: Water sources should be monitored on a regular basis. Pull -out faucets enable bacterial overgrowth; therefore, we recommend water surveillance during outbreak investigations. (c) 2023 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.