Browsing by Author "Hamed S.M."

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    Multiple mechanisms contributing to ciprofloxacin resistance among Gram negative bacteria causing infections to cancer patients
    (Nature Publishing Group, 2018) Hamed S.M.; Elkhatib W.F.; El-Mahallawy H.A.; Helmy M.M.; Ashour M.S.; Aboshanab K.M.A.; Department of Microbiology and Immunology; Faculty of Pharmacy; October University for Modern Sciences and Arts; 6th of October; Giza; Egypt; Department of Microbiology and Immunology; Faculty of Pharmacy; Ain Shams University; African Union Organization St. Abbassia; Cairo; 11566; Egypt; Department of Clinical Pathology; National Cancer Institute; Cairo University; Cairo; Egypt; Department of Microbiology and Immunology; Faculty of Medicine; Zagazig University; Zagazig; Egypt; Department of Microbiology and Immunology; Faculty of Pharmacy; Al-Azhar University; Cairo; Egypt
    Fluoroquinolones have been used for prophylaxis against infections in cancer patients but their impact on the resistance mechanisms still require further investigation. To elucidate mechanisms underlying ciprofloxacin (CIP) resistance in Gram-negative pathogens causing infections to cancer patients, 169 isolates were investigated. Broth microdilution assays showed high-level CIP resistance in 89.3% of the isolates. Target site mutations were analyzed using PCR and DNA sequencing in 15 selected isolates. Of them, all had gyrA mutations (codons 83 and 87) with parC mutations (codons 80 and 84) in 93.3%. All isolates were screened for plasmid-mediated quinolone resistance (PMQR) genes and 56.8% of them were positive in this respect. Among PMQR genes, aac(6?)-Ib-cr predominated (42.6%) while qnr genes were harbored by 32.5%. This comprised qnrS in 26.6% and qnrB in 6.5%. Clonality of the qnr-positive isolates using ERIC-PCR revealed that most of them were not clonal. CIP MIC reduction by CCCP, an efflux pump inhibitor, was studied and the results revealed that contribution of efflux activity was observed in 18.3% of the isolates. Furthermore, most fluoroquinolone resistance mechanisms were detected among Gram-negative isolates recovered from cancer patients. Target site mutations had the highest impact on CIP resistance as compared to PMQRs and efflux activity. � 2018, The Author(s).
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    Plasmid-mediated quinolone resistance in gram-negative pathogens isolated from cancer patients in Egypt
    (Mary Ann Liebert Inc., 2018) Hamed S.M.; Aboshanab K.M.A.; El-Mahallawy H.A.; Helmy M.M.; Ashour M.S.; Elkhatib W.F.; Department of Microbiology and Immunology; Faculty of Pharmacy; October University for Modern Sciences and Arts; Egypt; Department of Microbiology and Immunology; Faculty of Pharmacy; Ain Shams University; African Union Organization; Abbassia; Cairo; 11566; Egypt; Department of Clinical Pathology; National Cancer Institute; Cairo University; Cairo; Egypt; Department of Microbiology and Immunology; Faculty of Medicine; Zagazig University; Zagazig; Egypt; Department of Microbiology and Immunology; Faculty of Pharmacy; Al-Azhar University; Cairo; Egypt
    Fluoroquinolones (FQs) are the drugs of choice for prophylaxis of bacterial infections in immunocompromised cancer patients. This study aimed to investigate FQ resistance and the prevalence of plasmid-mediated quinolone resistance (PMQR) determinants in 239 Gram-negative isolates collected at a tertiary care cancer hospital in Cairo, Egypt. Disc diffusion and broth microdilution tests showed that 70.7% of the isolates were nonsusceptible to ciprofloxacin (MIC50 = 64 ?g/ml). Polymerase chain reaction (PCR) revealed that 53.6% of the isolates carried at least one PMQR determinant, of which 23.4% were susceptible to ciprofloxacin. The most prevalent gene, aac(6?)-Ib-cr, was identified in 36.8% of the isolates, while qnr genes were harbored by 31.0% (qnrS, 24.3%; qnrB, 7.1%, and qnrA, 0.4%). The oqxAB genes were only detected in Klebsiella sp. isolates (92.5%). PMQR determinants were more likely detectable among isolates recovered from pediatric patients than adults (59.3% vs. 43.8%) and were significantly associated with ceftriaxone and gentamicin resistance. A combined genetic analysis using random amplified polymorphic DNA-PCR and enterobacterial repetitive intergenic consensus-PCR showed that most of the qnr-positive isolates were not clonal. Findings of the current study raised concerns about the efficacy of prophylactic use of FQs in cancer patients in our region. It also demonstrates the possible role of PMQR-positive ciprofloxacin-susceptible isolates in the dissemination of resistance to other antimicrobial agents and the urgent need to reconsider the existing FQ breakpoints defined by the Clinical and Laboratory Standards Institute. � Copyright 2018, Mary Ann Liebert, Inc., publishers 2018.