Clinico Microbiological Profile of Diabetic Foot Ulcers: A Retrospective Study

Abstract

Introduction and aim: Diabetic foot ulcer (DFU) is a frequent and critical complication associated with diabetes mellitus. They carry a higher risk of infection, longer hospital stays, and increased healthcare costs. This study aimed to identify the microbiological profile and antibiotic susceptibility pattern of organisms isolated from infected diabetic foot ulcers.

Material and methods: A retrospective, record-based, cross-sectional study was conducted by retrieving data on culture isolates obtained from diabetic foot ulcers and the clinical data of these patients over a period of two years (from August 2022 to August 2024) at a tertiary care hospital. The demographic, clinical, and laboratory data were retrieved from the laboratory information system; all data were entered into an Excel spreadsheet (Redmond, WA: Microsoft Corp.), and the variables were analyzed.

Results: A total of 100 patients with DFUs, and the details of 156 samples obtained from the diabetic foot ulcers of these patients, were included in the study. Among the 100 patients, the majority were male (76%, 76/100), and the age group most commonly affected was 50-60 years (40%, 40/100). Pus was the predominant sample (41.7%, 65/156) among the total 156 samples collected. Among the 156 samples collected, 62.2% (97/156) showed mono-microbial growth, and 37.8% (59/156) showed poly-microbial growth. The total number of bacterial and fungal isolates was 213 and five, respectively. All fungal isolates were identified to be Candida tropicalis. The most common bacterial isolates were Pseudomonas aeruginosa (18.8%, 40/213), Klebsiella pneumoniae (17.8%, 38/213), Escherichia coli (14.1%, 30/213), and Enterococcus spp. (12.7%, 27/213), and Staphylococcus aureus (11.7%, 25/213). The most effective antibiotics for Pseudomonas aeruginosa were carbapenems, imipenem (90%, 36/40) and meropenem (80%, 32/40), followed by piperacillin-tazobactam (75%, 30/40) and amikacin (75%, 30/40). Imipenem (55%, 21/38) was the most sensitive antibiotic for Klebsiella pneumoniae followed by gentamicin (45%, 17/38). For Gram-positive isolates, Enterococcus spp. was most sensitive to teicoplanin and linezolid (100%, 27/27), followed by ampicillin (96.3%, 26/27) and vancomycin (77.8%, 21/27). Staphylococcus aureus isolates were most sensitive to vancomycin and teicoplanin (92%, 23/25), followed by daptomycin (84%, 21/25). A total of 25 Staphylococcus aureus isolates were obtained, of which 92% (23/25) were found to be methicillin-resistant Staphylococcus aureus (MRSA).

Conclusion: This study has enhanced our understanding of the epidemiology of diabetic foot ulcers by identifying common pathogens. The antibiotic susceptibility pattern of the pathogens will help clinicians provide better empirical therapy, thereby promoting faster wound healing.

Keywords: antibiotic susceptibility; diabetes mellitus; diabetic foot ulcers; gram negative; gram positive.

Figure 1. Flowchart representing the total number of patients with diabetic foot ulcers included in the study (n=100).

Figure 2. Specimen-wise distribution (in percentage) of clinical isolates obtained from DFU (n=156).

DFU: diabetic foot ulcer

Figure 3. Distribution of bacterial pathogens isolated from clinical samples of diabetic foot ulcers illustrating both Gram-negative and Gram-positive bacteria (n=213).

*Others denotes Proteus mirabilis, Enterobacter aerogenes, Morganella morganii, Citrobacter freundii, Serratia marcescens, Sphingomonas paucimobilis, and Streptococcus anginosus, which together constitute 15% (n=213).

Figure 4. Antibiotic susceptibility pattern of commonly isolated Gram-negative bacteria from DFU (n=159).

DFU: diabetic foot ulcers

Figure 5. Antibiotic susceptibility pattern of commonly isolated Gram-positive bacteria from DFU (n=54).

DFU: diabetic foot ulcers