Pattern of anaerobic bacterial infection of diabetic foot

 

 

Abstract               Background: Diabetic foot is a common cause of hospital admission in diabetic patients in India. The trio of problems leading onto diabetic foot is neuropathy, vascular changes and infections, which constitute the diabetic foot syndrome. Objectives: To determine prevalence of anaerobic pathogens in diabetic foot lesion. Methods: Tissue samples were taken from the affected foot of 109 diabetic patients and processed by routine anaerobic microbiological methods. Results: A total of 32 organisms were isolated from 100 cases. Of these organisms, Bacteroides species (62.5%) was predominant followed by Peptostreptococcus species (28.12%) and Clostridium species (9.37%). Conclusion: Diabetic foot infections are polymicrobial in nature. The isolation of anaerobes increased as the grade of the ulcer increased. Bacteroides species were the major anerobes isolated. Hence it is utmost important to screen all elderly patients for diabetes and moniter blood sugur levels regularly and educate them about foot care and identify the risk factors and insitute the appropriate treatment on time to avoid amputation.

Key Word: Anerobic, Diabetic foot ulcer, Polymicrobial, Bacteroides species, Peptostreptococcus species, Clostridium species.

 

 

INTRODUCTION

Diabetic foot is most simply defined as any infra-malleolar infection in a person with diabetes mellitus.¹ Diabetes is rightly called a “disease of complications” and “Iceberg disease”. India homes 33 million diabetics, ranking highest in the world and has a prevalence of about 8% in urban India. 20% of all diabetic complications involve feet.² Diabetes and foot problem are almost synchronous.³

• major factors are considered important in the development of “diabetic foot”.
• Peripheral neuropathy causing sensory impairment and weakness of intrinsic muscles of the foot and joint that leads to foot deformities.
• Macro and microangiopathy occurring frequently and leading to ischaemia of foot tissues.          
• Wounds become infected 5 times more often in diabetic than in nondiabetic patients and the rate of infection parallels blood glucose levels.⁴

Complication associated with development of infection and diabetic foot syndrome are main cause of morbidity and non-traumatic lower extremity amputation.5Bacteroides melaninogenicus and Bacteroides fragilis are the most commonly isolated anaerobes.⁶ Thus this study was undertaken to determine types and prevalance of anaerobes in diabetic foot lesions.

 

MATERIALS AND METHODS

The present study included 109 cases of patients diagnosed with diabetes having foot ulcers. A detailed history of the patient regarding age and sex, duration of diabetes, type of diabetes, duration of foot ulcer, smoking, hypertension, peripheral neuropathy, peripheral vascular disease, antibiotic usage was taken and recorded. The temperature of the patient was also recorded.

Inclusion criteria:

• Foot ulcers of Grade I or more.
• Evidence of purulent exudates and or oedema.

Exclusion criteria:

• Diabetic patients with a foot lesions of grade 0 and/or limb amputation.

Sample collection: The tissue samples was immediately inoculated into Robertson’s cooked meat media, liquid paraffin was overlayed under sterile conditions to prevent the contamination and labelled. The liquid paraffin was sterilized prior to usage in a hot air oven at 160o C for 1 hour. The inoculated Robertson cooked meat broth was incubated till it was turbid, not earlier than 48 hours. Smears of each specimen from Robertson cooked meat broth was made and stained with Gram stain. It was then subcultured onto 1% Neomycin blood agar plate and a Gentamicin disc (10 μg) was placed at the junction of primary and first streaking while a Metronidazole disc was placed at the junction of first and second streaking to identify the anaerobes presumptively as all the anaerobes are known to be resistant to gentamicin.7 The neomycin blood agar plates were immediately incubated anaerobically for 48 hours at 37oC in an anaerobic jar (Hi media Anaerobic System Mark II LE 002 3.5L) with Gaspak( Anaerogas Pack 3.5 L LE 002A-5NO LOT 06-192). The organisms were identified using Gram staining and colony morphology.

OBSERVATIONS

The present study was carried out in the Department of Microbiology, M. R. Medical College and Basweshwar Teaching and General Hospital, Gulbarga. A total of 109 clinically diagnosed cases of diabetic foot lesions were studied. The specimens from 109 cases were subjected to bacteriological investigations and following observations were made. Of the 109 cases studied, most of the patients belonged to fifth and sixth decades of life (33%). Males were more affected compared to females with a ratio 2.3:1

Table 1: Age and Sex wise distribution of Patients

 

Table 2: Grading ofdiabetic foot and isolates detected

Grade II ulcers were seen in 66 patients, with an average of 2.65 bacteria per sample. Maximum average anaerobes per sample were found in Grade V ulcers.

Table 3: Number and Percentage of Anaerobes isolated.

Bacteroides species were predominantly isolated (62.5%).

DISCUSSION

The present study was carried out, on the patients in M.R. Medical College and Basweshwara Hospital, consisted of one hundred and nine patients of diabetic foot          lesions. In the present study, the average age of patients was 51 with a range of 24-78 years. Age group of 51-60 years accounted for maximum number of patients that is 36 (33%). Ramani et al⁸ reported the mean age of patients in their study as 58 years with a range of 28-87 years. Pathare et al⁹ reported the mean age of patients in their study as                 75.02 years. Dipali et al¹⁰ reported the age range from 30 years to 86 years with an average of 58 years. Anandi et al¹¹ observed the mean age to be 43 years. Gadepalli et al¹² reported that mean age of patients to be 53.9 years. Bansal et al¹³ reported mean age to be 57.04 years. In the present study, the maximum average number of anaerobes were isolated from Grade V ulcers. It can be concluded that, the avg/sample in anaerobes is increasing with the increase in grade of ulcer.

 

CONCLUSION

Diabetic foot ulcers are one of the most common and dreaded complications of diabetes. It is more common in the 5th and 6th decades of life. Males are found to be more common victims. Majority of the patients with diabetic foot ulcers had diabetes for 11-15 years. The isolation of anaerobes increased as the grade of the ulcer increased. Bacteroides species were the major anaerobes isolated. It is utmost important to screen all elderly patients for diabetes and monitor blood sugar levels regularly and educate them               about foot care. Early identification of the risk factors and timely institution of appropriate treatment is indispensable to avoid amputations.

 

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