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    Escherichia coli O157 in fish: Prevalence, antimicrobial resistance, biofilm formation capacity, and molecular characterization
    (Elsevier, 2020) Onmaz, Nurhan Ertas; Yildirim, Yeliz; Karadal, Fulden; Hizlisoy, Harun; Al, Serhat; Gungor, Candan; Disli, H. Burak
    This study was performed to survey the incidence of Escherichia coli O157:H7 contamination in fish samples which were obtained from different fish farms and retail markets. For this purpose, a total of 140 fish samples were analyzed according to ISO 16654 and screened for virulence genes by mPCR. Antibiotic susceptibility tests were performed with the disc diffusion method and isolates were genotyped by using Enterobacterial repetitive intergenic consensus (ERIC) PCR. Of the 140 analyzed sample, two (1.4%), from the same farm, were found to be contaminated with E. coli O157 serogroup, one of which harbored stx1 and the other eaeA gene. E. coli O157 serogroup were resistant to only ciprofloxacin and were not capable of forming biofilm and their ERIC-PCR patterns were different. In conclusion, the existence of pathogenic E. coli O157 serogroup in fish samples might be a significant threat to public health and fish could serve as a vehicle for transmission of these bacteria to consumers in Turkey.
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    Escherichia coli serogroups in slaughterhouses: Antibiotic susceptibility and molecular typing of isolates
    (Elsevier, 2022) Barel, Mukaddes; Hizlisoy, Harun; Gungor, Candan; Dishan, Adalet; Disli, Huseyin Burak; Al, Serhat; Onmaz, Nurhan Ertas
    This study aimed to investigate the contamination of carcasses and slaughterhouse environment with Escherichia coli O157:H7 and non-O157 serogroups (O45:H2, O103:H2, O121:H19, O145:H28, O26:H11, O111:H8). For this purpose, a total of 150 samples (30 carcasses, 30 shredding units, 30 knives, 30 slaughterhouse waste water and 30 wall surfaces) were collected from 5 different slaughterhouses in Kayseri, Turkey. The conventional and molecular methods were performed in order to detect Escherichia coli and its serogroups. Of the 150 samples, 55 (36%) were found to be contaminated with E. coli. Among isolates, E. coli serogroup (O157:H7) were detected in 2 (11%) carcass and 2 (11%) wastewater samples. None of the E. coli isolates harbored tested genes (stx1, stx2, eaeA, and hylA). Effective infection control measures and antibiotic stewardship programs should be adopted to limit the spread of multidrug-resistant bacteria. It was also deduced that these isolates resistance to different antibiotics could be hazardous for public health.
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    From cattle to pastirma: Contamination source of methicillin susceptible and resistant Staphylococcus aureus (MRSA) along the pastirma production chain
    (Elsevier, 2021) Gungor, Candan; Barel, Mukaddes; Dishan, Adalet; Disli, H. Burak; Koskeroglu, Kursat; Onmaz, Nurhan Ertas
    This study was designed to determine the prevalence of Methicillin Susceptible S. aureus (MSSA) and MethicillinResistant S. aureus (MRSA) and their source of contamination in the pastirma production chain. Additionally, this study was focused on the antimicrobial resistance, virulence profiles, biofilm-forming capabilities and phylogenetic relationships of obtained isolates. A total of 400 samples were analyzed and from which 105 (26.25%) were found positive for coagulase-positive with Staphylococci (CPS). Within the 105 CPS samples, 36 (9%) were identified as S. aureus, from which 8 (2%) were MRSA. Four (11.1%) of 36 S. aureus isolates, of which 3 (37.5%) were MRSA, had a multidrug resistance (MDR), and 6 MRSA strains were found positive for one or more SEs genes (seb, sed, and see). According to the ERIC-PCR analysis, only two S. aureus strains (one with personnel origin and one with carcass origin) were genetically identical. This study highlights the detection frequency of S. aureus in samples analyzed observed, while low, can be a significant public health problem, especially due to the identification of MRSA harboring some enterotoxin genes and having MDR.
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    Mycotoxigenic and phylogenetic perspective to the yeasts and filamentous moulds in mould-matured Turkish cheese
    (Elsevier, 2021) Onmaz, Nurhan Ertas; Gungor, Candan; Al, Serhat; Dishan, Adalet; Hizlisoy, Harun; Yildirim, Yeliz; Tekinsen, Filiz Kasap
    This study was conducted to determine the diversity of yeasts and filamentous moulds in mould-matured cheese (MMC) consumed in Turkey. Overall, 120 samples were collected from 12 different geographical locations between March 2016 and April 2017. The morphological observation was applied in combination with matrixassisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and molecular analyses to determine yeasts and filamentous moulds in the cheeses. High-performance liquid chromatography (HPLC) technique was used to evaluate the ability of mycotoxins production of fungal isolates and the presence of mycotoxins in cheese samples. A total of 241 fungi (81 filamentous moulds and 160 yeast) were recovered, and Penicillium roqueforti and Debaryomyces hansenii were the most frequently isolated species in all cheese samples. The rep-PCR results indicated a high level of genetic diversity among fungal isolates, regardless of isolation source or geographical origin. Filamentous mould strains isolated from MMC were found to synthesize at least one mycotoxin (Aflatoxin B1, B2, G1 and G2, citrinine, cyclopiazonic acid, mycophenolic acid, ochratoxin A, penicillic acid and roquefortine C). Although mycotoxin producing ability was observed from all isolates, none of the cheese samples were found positive for these mycotoxins. AFM1 was detected in 8 (6.6%) MMC samples from which 2 (1.6%) were above the legal limits (0.05 mu g/kg) set by the Turkish Food Codex (TFC) and European Commission (EC). In conclusion, Turkish MMCs were found to be contaminated with toxigenic fungi, so a potential public health risk, while low, exists. Therefore, the selection of nontoxigenic filamentous mould strains for cheese manufacturing and control of the ripening conditions is a critical need to ensure the quality and safety of Turkish MMC.