A clinico-microbiological study of diabetic foot ulcers in an Indian tertiary care hospital.

OBJECTIVE

To determine the microbiological profile and antibiotic susceptibility patterns of organisms isolated from diabetic foot ulcers. Also, to assess potential risk factors for infection of ulcers with multidrug-resistant organisms (MDROs) and the outcome of these infections.

RESEARCH DESIGN AND METHODS

Pus samples for bacterial culture were collected from 80 patients admitted with diabetic foot infections. All patients had ulcers with Wagner's grade 3-5. Fifty patients (62.5%) had coexisting osteomyelitis. Gram-negative bacilli were tested for extended spectrum beta-lactamase (ESBL) production by double disc diffusion method. Staphylococcal isolates were tested for susceptibility to oxacillin by screen agar method, disc diffusion, and mec A-based PCR. Potential risk factors for MDRO-positive samples were explored.

RESULTS

Gram-negative aerobes were most frequently isolated (51.4%), followed by gram-positive aerobes and anaerobes (33.3 and 15.3%, respectively). Seventy-two percent of patients were positive for MDROs. ESBL production and methicillin resistance was noted in 44.7 and 56.0% of bacterial isolates, respectively. MDRO-positive status was associated with presence of neuropathy (P = 0.03), osteomyelitis (P = 0.01), and ulcer size >4 cm(2) (P < 0.001) but not with patient characteristics, ulcer type and duration, or duration of hospital stay. MDRO-infected patients had poor glycemic control (P = 0.01) and had to be surgically treated more often (P < 0.01).

CONCLUSIONS

Infection with MDROs is common in diabetic foot ulcers and is associated with inadequate glycemic control and increased requirement for surgical treatment. There is a need for continuous surveillance of resistant bacteria to provide the basis for empirical therapy and reduce the risk of complications.