Abstract

Background: Diabetic foot ulcer is the leading cause of non-traumatic lower extremity amputations. A prospective case–control study was carried out on 50 patients with diabetic foot ulcers (cases) and 50 with non-diabetic foot ulcers (controls) to determine the microbiological profile, their antibiotic sensitivity patterns along with different demographic parameters. The prevalence of extended-spectrum beta-lactamases (ESBLs) producers, carbapenemase producers, and methicillin-resistant Staphylococcus aureus among the isolates and the potential risk factors for infection of ulcers with these multidrug-resistant organisms (MDROs) was also studied along with the outcome of these infections.

Objectives: The present study aims at identifying the microbiological spectrum in these diabetic foot infections and their antibiotic sensitivity pattern in a developing country, like India.

Materials and Methods: Clinical specimens were taken from each patient with diabetic and non-diabetic foot ulcers. These specimens were processed for culture (aerobic and anaerobic), further identification and antibiotic sensitivity testing. ESBL and carbapenemase production was detected by phenotypic methods and automated VITEK-2 system, and the results were mutually compared by the two methods.

Results: A total of 158 organisms (155 bacteria and 3 fungi) were isolated giving an average of two organisms/patient. Cases were mostly positive for polymicrobial growth (77%) as compared to controls, and tissue was the most yielding sample. Gram-negative aerobes were predominantly isolated, followed by Gram-positive aerobes. Anaerobic Gram-negative (3%) and fungal (3%) isolates were also seen in the case samples.

Conclusion: Escherichia coli among the Gram-negative (33%) and S. aureus among the Gram-positive (7%) were the predominantly isolated organisms, while Candida was the most predominantly isolated fungus. A strong association of peripheral vascular disease (PVD), smoking (P = 0.001), as well as neuropathy (P < 0.001) was seen in the case samples ESBL (44%) and carbapenemase (37%) producers were significantly more in cases as compared to controls. CTX-M like was the most common ESBL phenotype of the isolates. One isolate (3.2%) was detected as resistant due to AmpC enzyme by the VITEK-2 system and four were also positive for metallo-B-Lactamase production. MDRO infection was associated with the presence of neuropathy, PVD, ulcer size >5 cm2, and osteomyelitis (P

Key words: Carbapenemase Production; CTX-M Phenotype; Diabetic Foot Ulcer; Phenotypic Methods, VITEK-2