Impact of gamma rays and certain natural products on the virulence of some metallo-β-lactamase producing gram-negative pathogenic bacteria

Abstract

In this study 107 ceftazidime resistant Gram-negative bacilli were collected from different sites of 98 cancer and non-cancer patients visits central microbiological laboratory of El-Demerdash hospital in Cairo, Egypt. Susceptibility test were applied to 19 antibiotics with different mode of action. All the obtained GNB Isolates were subjected to screening test for detection of metallo-β-lactamase (MBL) using the combined disc test (CDT) and double disk synergy test (DDST), imipenem (IPM, 10 μg) disc and ceftazidime (CAZ, 30 μg) as a substrates and ethylene diamine tetra-acetic acid (EDTA) and 2-mercapto propunic acid (MPA) as inhibitors. Fourteen isolates were selected because they had a capability to produce MBL, they showed positive with four combinations (CAZ+EDTA, CAZ+MPA, IPM+EDTA, IPM+MPA) by the two phenotypic detection tests CDT and DDST. Fourteen MBL-producers were identified using Api 20E strips. They were identified as; four isolates Pseudomonas SUMMARY 187 fluorescence, 3 isolates Klebsiella pneumoniae, 2 isolates Pseudomonas aeruginosa, one isolate of each Pseudomonas spp, Proteus mirabilis, Enterobacter cloacae, Escherichia coli and Acinetobacter baumannii. Confirm the presence of MBL-blagenes by Polymerase chain reaction (PCR) using primers of six common MBL-blagenes (IMP, VIM, SPM, GIM, SIM and NDM), resulted in the detection of the examined bla-genes in 13\14 (92.86%) isolates. Pseudomonas fluorescence (83) carrying four genes of MBL, three isolates carrying 3 different MBL- blagenes and six isolates carrying. IMP gene was not detected in local isolates. The prevalence of genes could be ranked as; blaSPM> blaVIM> blaSIM> blaGIM and blaNDM ; 9\13(69.2%), 8\13 (61.5%), 5\13(38.55), 4\13(30.8%) and 2\13(15.4%) respectively.