Plasmid Mediated Extended Spectrum Beta-Lactamase producing strains of Enterobacteraceae Isolated from Diabetic Foot Infections in Egypt.
Extended spectrum beta- lactamases (ESBLs) are heterogeneous group of plasmid mediated β-lactamases enzymes that confer resistant to oxyimino cephalosporins (3rd generation), monobactam (aztreonam) and usually show co-resistance to other classes such as quinolones, aminoglycosides and tetracycline. As the frequency of ESBL producing bacteria is increasing worldwide among diabetic foot infections, we conducted this study to identify the most common plasmid mediated ESBL genes in Egypt and characterize them at molecular level by using PCR and sequencing analysis.
Methods and findings
A total of 135 Gram negative bacterial isolates were recovered from 91 diabetic foot ulcers specimens of patients attending governmental hospitals and private clinics in Cairo, Egypt. Isolates were identified to genus and/or species level by conventional methods (macroscopical, microscopical and biochemical tests). Furtherly, the antibiogram analysis revealed a remarkable high resistance pattern towards different classes of tested antimicrobial agents, especially β-lactam. Based on Clinical and Laboratory Standards Institute (CLSI), a total of 114 isolates out of 135 were considered potential ESBLs producer by initial screening tests (disc diffusion and broth microdilution) followed by the phenotypic confirmatory test, double disc synergy test (DDST). 58 out of 114 isolates were ESBLs producers and almost 14% (8 out of 58), were plasmid-mediated as determined by plasmid screening and transformation experiments.
PCR was used for molecular characterization of plasmid mediated ESBLs genes, where plasmids (templates) and universal primers of bla SHV, bla TEM and bla CTX-M were used. The results revealed that the majority of the tested plasmids (6 out of 8) carried 2 or more genes on the same plasmid. The most common combination was bla CTX-M and bla TEM(n=3/8; 37.5%), followed by bla SHV and bla CTX-M(n=2/8; 25%) and bla CTX-M+ bla TEM+ bla SHV (n=1/8;12.5%). One E. coli isolate harbored a plasmid named pECDF16 coding for the three ESBLs genes. The final nucleotide sequences of bla TEM-1 and bla SHV-8 were deposited in the GenBank database under accessions coder JX976326, and JX976327, respectively.
High prevalence of plasmid-mediated ESBLs was detected among DFIs in Egypt. Therefore, new guidelines should be undertaken in Egypt to limit or prevent the misuse and abuse of antimicrobial agents.
via Archives of Clinical Microbiology http://imedpub.com/ojs/index.php/acmicrob/article/view/621