Aerobic bacteria isolated from diabetic foot ulcers of Egyptian patients: types, antibiotic susceptibility pattern and risk factors associated with multidrug-resistant organisms.

Abstract

Diabetic foot infection (DFI) is one of the common diabetic complications. Pathogens causing DFI and their antibiotic susceptibility vary with location. Therefore, empirical antibiotic therapy should be based on the pathogens that are most likely to be present. Aim: To identify the frequent aerobic bacteria causing DFI with detection of their antibiotic susceptibility to help clinicians in our community choose the best empirical antibiotic for DFI. Swabs were collected from 104 diabetic foot ulcers (DFUs). Aerobic bacterial cultures were done followed by bacterial identification and antibiotic susceptibility testing on VITEK® 2 system. Extended-spectrum beta-lacatamase (ESBL) detection was performed phenotypically and confirmed by multiplex-PCR for bla CTX-M, bla TEM, and bla SHV genes. Aerobic bacterial infection was detected in 82/104 (78.8%) of the DFUs. Gram-negative bacilli (GNB) were isolated more frequently (56.1%) than Gram-positive cocci (GPC) (43.9%). The most common single-isolated bacteria were K. pneumoniae (26.8%), S. aureus and coagulase negative staphylococci (22% for each). The only significant independent predictors of DFI with GNB or GPC were long DM duration and frequent hospitalizations, respectively. The most active antibiotics were amikacin, tigecycline and meropenem for GNB, and linezolid and vancomycin for staphylococci. Multidrug-resistance prevalence was 95.1%. ESBL was detected in 52.6% of Enterobacteriaceae; the bla CTX-M gene was the most common (90%), followed by bla TEM (65%) and bla SHV (35%). Peripheral neuropathy was the single independent predictor for DFI with ESBL producers (adjusted OR=15.5). There is a notable local pattern of DFI bacteriology in our community. Our findings could be valuable in developing the future empirical treatment guidelines for DFIs.