Abstract

The purpose of this study was to determine and evaluate the current status of antimicrobial resistance, both phenotypically and genotypically, of the most common aerobic pathogenic bacteria recovered from diabetic foot ulcers (DFUs) in Egypt. Standard methods were used for culture identification, sensitivity testing and extended spectrum β-lactamases (ESBLs) detection. PCR for bla genes was performed and the obtained PCR products were verified by DNA sequencing. A total of 206 clinical bacterial isolates were recovered from DFU specimens, of which 135 (65.5%) were Gram negative and 71 (34.5%) were Gram positive. Gram negative isolates were mainly Proteus spp. (49; 24.4%), Escherichia coli (24; 11.6%), Pseudomonas spp. (19; 9.2%) and Klebsiella spp. (17; 8.2%) while, Gram positive isolates were mostly Staphylococcus aureus (26; 12.6%) and coagulase-negative staphylococci (25; 12.13%). The antibiogram analysis of Gram negative isolates revealed a remarkable high resistance pattern towards most of the tested antibiotics particularly, 3^rd, 4^th generation cephalosporins and fluroquinolones. About, 50.87% of Gram negative isolates were ESBL producers of which 14% were plasmid-mediated. Upon molecular characterization of plasmid-mediated ESBLs by PCR, bla_CTX-M showed 100% positivity, followed by bla_TEM (50%) and bla_SHV (37.5%). For further detection of variants within genes, only one E. coli isolate that harbored a plasmid coding for three genes was sent for DNA sequencing. The results revealed presence of bla_TEM-1 (accession number JX976326), bla_SHV-8 (accession number JX976327) and bla_CTX-M on a single plasmid coded pECDF16 as deposited in GenBank. The majority of ESBLs recovered from DFUs, showed resistance to more than one class of antimicrobial agents and hence new guidelines should be addressed in Egypt to rationalize and prevent the misuse and overuse of antimicrobial agents.

Key words: Diabetic foot ulcers, extended spectrum β-lactamase (ESBL), plasmid, bla_CTX-M, bla_TEM-1, bla_SHV-8.