European Journal of Cardiovascular Medicine

Diabetes mellitus is the most common metabolic disease in India. Diabetes mellitus is a major cause of morbidity, can lead to ulcer formation, non-healing ulcers and lead to gangrene and finally amputation of the limb¹. Foot wounds are an increasingly common problem with diabetes and now constitute the most frequent diabetes related cause of hospitalization. People with diabetes have about 15-25% chance of developing a foot ulcer in their lifetime². Rate of amputation of a limb is estimated to be forty times greater in infected non-healing ulcer in diabetic patients than in trauma patients. According to International Working Group on the Diabetic Foot, Diabetic Foot Ulcer is defined as a full-thickness wound penetrating the dermis located below ankle in a diabetic patient³.

Proper management of these infection requires appropriate antibiotic selection based on culture and antimicrobial susceptibility results; however, initial management comprises empirical antimicrobial therapy, which is often based on susceptibility data extrapolated from studies performed on general clinical isolates⁴.

The most important characteristic of the infection in non-healing ulcer in diabetes is polymicrobial in nature. In superficial wounds, aerobic bacteria are predominant pathogens. Anaerobic organisms are found more frequently in deeper wounds⁵.

Aims and Objectives: To evaluate the bacteriological profile of diabetic foot with special reference to the antimicrobial susceptibility pattern to formulate the policy of empirical antimicrobial therapy to minimise the diabetes associated mortality & morbidity.

The cross-sectional study was conducted in the Department of Microbiology, Government Medical College, Kadapa for a duration of 3 months from October 2022 to December 2022.

Inclusion criteria

• Age 0-80
• Patients presenting with diabetic foot ulcers (IDSA Classification).

Exclusion criteria

• Ulcers other than in
• Vasculitis

150 samples were analyzed. Wound swabs were taken before starting empirical antibiotic therapy. Wound was thoroughly washed with Normal saline and swab collected from the deep tissues and from the base of ulcers. One swab was used for Gram staining and the other was used for culture. A direct Gram stained smear of the specimen was examined. The specimens were inoculated onto Blood agar, Chocolate agar, Mac Conkey’s agar.  The organisms were identified by standard laboratory methods, and Antibiotic susceptibility pattern was performed by Kirby Bauer disc diffusion method. The phenotypic test for the detection of MRSA was done by using a cefoxitin (30 μg) disc. ESBL production was confirmed by using discs of Ceftazidime (30 μg) and Ceftazidime Clavulanic acid (30/10 μg). Carbapenemase production was detected by using the Modified Hodge test.

Out of 150, 80 were females and 70 males. Out of 150 test samples, 80 (53.3%) were culture positive. Amongst them, Pseudomonas aeruginosa was most common organism isolated (35%) followed by Escherichia coli (18.75%). MRSA (Methicillin resistant Staphylococcus) was seen in 10 cases(12.5%) {Figure 1}. Monomicrobial growth was sen in 50 cases (62.5%) and polymicrobial growth was in 30 (37.5%) {Figure 2}. In polymicrobial infection, most common organisms in combination were Pseudomonas and E.coli followed by E.coli and Staphylococcus. Positivity was more among females (56.25%) as compared to males (50%) {Table 1}. Out of 80 positives, 50 were Gram negative bacteria. Among 50 isolated Gram negative bacteria, 23 (46%) produced ESBL whereas 17 (33.33%) were AmpC beta lactamase producers and 4 (8%) were carbapenemase producers; 33 gram negative isolates were resistant to fluoroquinolones (66%). All of the Carbapenemase producers were exclusively Pseudomonas aeruginosa whereas the Amp C β lactamase producers were Pseudomonas aeruginosa followed by Klebsiella pneumoniae and Klebsiella oxytoca. On the other hand, the ESBL (Extended spectrum beta lactamase) producing population comprised of Escherichia coli followed by Pseudomonas aeruginosa{Figure 4}

Figure 1: Isolated organisms

Figure2: Pattern of monomicrobial and polymicrobial growth

Table 1: Age wise distribution of cases and positivity

Figure 4: Resistant pattern in Gram negative bacteria

Diabetic foot ulcers are one of the most common complications of Diabetes mellitus. It is a major medical and socioeconomic problem. People walking and working barefoot mainly due to poverty and lack of education don’t have a proper foot care and acquire infection due to low immune status caused by diabetes and poor glycemic control.

In our study, we have found 62.5% monomicrobial infection. The findings of this study correlate with findings of Pappu et al⁶. Most common organism isolated was Pseudomonas aeruginosa (35%) followed by Escherichia coli (18.75%) and Klebsiella pneumonia (17.5%) and Methicillin resistant Staphylococcus aureus (12.5%). Our study correlates with study of Mohd Zubair et al⁷ and Anandi et al⁸. Gram negative bacilli were more prevalent as in the study by Rama Kant et al⁹. M.B Girish et al¹⁰ reported that 15% of the MRSA strains were resistant to Ampicillin, Cephalosporins and Gentamicin and that they were sensitive to Amikacin, Vancomycin, Teicoplanin and Linezolid but in our study we have found 36. 84% of the isolated S. aureus was Methicillin resistant. This is in accordance with the findings of Raja NS¹¹. Multidrug resistant Gram negative strains have been isolated in a large number; 46% isolates were ESBL producers, mainly Pseudomonas and E. coli, 33.33% were AmpC β lactamase producers, mainly Pseudomonas and Klebsiella and 8% were Carbapenemase producers were exclusively Pseudomona, similar to the study by Alavi SM et al^12-14

Our study concluded that the most common organisms occurring in diabetic foot ulcers are Gram negative aerobes followed by Gram positive cocci being the most prevalent. Piperacillin-tazobactam, Amikacin and third generation cephalosporins were the effective antibiotics.

Multidrug resistant monomicrobial and polymicrobial infections profile of diabetic foot ulcer, in this present study recommends the use of Meropenem or Imipenem to treat the AmpC β- lactamase producers and use of Tigecycline and/or Colistin and/or Polymyxin-B to treat carbapenemase producers however, emergence of resistance to Tigecycline and or Colistin is at the doorstep. Proper education about foot care of diabetic patients is needed to prevent the development of ulcers. Regular self-examination of skin of feet for cracks or small ulcerations and use of appropriate footwear and strict glycemic control should be advised and is recommended for diabetic patients. When a diabetic patient develops foot ulcer proper education is essential for early health care access with regular debridements, dressing, use of appropriate antibiotics and diabetic control to reduce the disease and socioeconomic burden on diabetic patients.

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