Thesis (Ph.D.) - Cairo University - Faculty of Pharmacy - Department of Microbiology and Immunology

Healthcare-associated infections caused by antimicrobial-resistant microorganisms represent a major global threat. Thus, we aimed to evaluate two different molecular typing methods, to investigate the clonal relatedness for carbapenemase-producing Enterobacteriaceae strains that might contribute to a major hospital outbreak among high-risk patients. Gram-negative isolates were obtained from cancer patients. Bacterial isolates were identified using conventional and automated microbiological methods. Antimicrobial susceptibilities were determined using both disc diffusion method, however, minimum inhibitory concentration was determined by Vitek 2 and E-test. Phenotypic detection for carbapenemases producing isolates was performed. Detection for both carbapenemases and ESBLs encoding genes by PCR and DNA sequencing. Klebsiella pneumoniae was the most prevalent among other Enterobacteriaceae isolates.Thus, it was selected for clonal relationship determination especially for those isolates that harbour blaOXA-48 gene. Clonal relatedness was performed using both Enterobacterial repetitive intergenic consensus (ERIC)-PCR and pulsed-field gel electrophoresis (PFGE).The blaOXA-48 was the most common gene compared to, blaNDM-1, blaIMP and blaVIM genes in the carbapenem resistant (CR) isolates. However, blaTEM was prevalent among ESBLs genes compared to blaCTX-M and blaSHV were identified. Some of the carbapenem resistant Enterobacteriaceae (CRE) isolates co-harboured at least 2 different resistant determinates. Dendrogram analysis for ERIC and PFGE genotyping revealed 3 possible related clones harbouring blaOXA-48 gene with similarity coefficient {u2265}85%, respectively.The study findings underlined an increased circulation of some closely related clones of multidrug-resistant K. pneumoniae harbouring carbapenem resistance determinants

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