A Study of Methicillin Resistant Staphylococcus Aureus and Extended Spectrum Betalactamase Producing Bacteria in Diabetic Foot Ulcer in a Tertiary Care Hospital.

INTRODUCTION : Diabetes Mellitus currently affects more then 19.4 crore people worldwide and the figure is expected to reach 33.3 crore by 2025. India itself harbours over 3.5 crore diabetics which is the highest among the countries of the world and it is expected to touch 7.35 crore by 2025. These staggering figures unfortunately have earned India the title of “DIABETIC CAPITAL OF THE WORLD”. Diabetic foot ulcers are estimated to affect about 25% of all diabetics during their lifetime accounting for 20% of diabetic related hospitalisation. The risk of lower extremity amputation is 15-46 times higher in a diabetic and diabetic foot ulcers precede 85% of all foot amputations . Nine out of ten amputations are instigated by an infection. It is the spark that leads to amputation though circulation is critically important, it only determines the level of amputation. The burden of diabetic foot ulcer is set to rise further in the future since contributory factors such as peripheral neuropathy and peripheral vascular disease are present in more than10% of diabetics at the time of diagnosis. There is little awareness for foot care in patients and there is significant delay in seeking the treatment. Further a significant population in our country is rural and work in the fields barefoot, thus increasing the chances of further infection. There is paucity of data on the frequency of the emerging resistant strains causing infection and the outcome of such infections among diabetic foot ulcers in India. AIMS AND OBJECTIVES : 1. To isolate and identify bacterial pathogen from diabetic foot ulcer. 2. To study the antibiotic sensitivity pattern of the isolated bacterial pathogens. 3. To assess the risk factors predisposing to diabetic foot ulcers. 4. To characterise Methicillin resistant Staphylococcus aureus in the diabetic foot ulcer. 5. To characterise Extended spectrum betalactamase producers among the Gram negative pathogens. MATERIALS AND METHODS : This is a descriptive study for a period of one and half year from July 2008 to Dec 2009 to analyse the bacterial isolates from diabetic foot ulcers of patients attending the Department of diabetology, Kilpauk Medical college & Hospital. A total of 100 diabetic foot ulcer patients from both sexes in age group between 35 to 82 years were studied during this period Inclusion Criteria:- All diabetic patients with foot ulcers attending the department. Exclusion Criteria:- 1. All non-diabetic patients with foot ulcers. 2. All diabetic patients with foot ulcers but on antibiotic therapy. Methodology includes, 1. Collection of samples, 2. Identification of the organisms and antibiotic sensitivity pattern, 3. Selection of resistant strains, 4. Detection of MRSA, 5. Identification of mecA gene, 6. Detection of ESBL production, 7. Identification of CTX-M gene. RESULTS : 100 patients with diabetic foot ulcer were studied and 142 bacterial isolates from the ulcers were isolated, identified and analysed for their antibiotic sensitivity pattern. Resistant strains were identified and studied for Methicillin resistant Staphylococcus aureus (MRSA) and extended spectrum betalactamases (ESBL) producing bacteria by various methods. 100 patients with diabetic foot ulcer were studied. Out of these 100 patients included in the study 53 were male and 47 were female. The male to female ratio was 1: 0.8. Outcome was noted in 62 patients only as the remaining did not come for regular follow up. Out of the 62 patients healing was seen in 18 (29%) patients and among them one (0.5%) was positive for MRSA, two (1.1%) had ESBL in the ulcers and two(1.1%) lodged MDR Pseudomonads and the remaining13(72%) did not harbour any resistant organism .Various flap surgeries depending upon the nature of the ulcer was done in 14(22.5%) of the patients. Out of them 50% had resistant organisms in the ulcers (MRSA-21.4%,ESBL-21.4% and MDR Pseudo-7%). 24(38.7%) patients were on regular dressing at the end of the period of study. Their ulcers did not heal even after regular dressings. Among the patients 15(24%) had resistant organisms in their ulcers (MRSA-33%, ESBL -12%, MDR Pseudo -16%,). Amputation was done in 6 (9.6%) of the patients out of which 3 (50%) showed MRSA, 2 (33%) showed ESBL and one patient did not have any resistant organism. CONCLUSION : We found the diabetic foot ulcers to be polymicrobial in nature and Gram negative bacteria (54.3%) to be more common then gram positive bacteria (45.1%). However Staphylococcus aureus (28.8%) was seen as the most common bacterial pathogen followed by Klebseilla spp (18%) and Pseudomonads. (12%) • Our studies showed the foot ulcers to be higher in patients with diabetes in the family and who had co morbid risk factor of which neuropathy was the most common. Poor glycaemia control also appeared as a significant factor for healing of the ulcer. • On analyzing the antibiotic sensitivity pattern of the isolates we observed an alarming number of multidrug resistant organisms in the diabetic foot ulcers . 44% of S. aureus isolated were MRSA, 39.3% of the enterobactericeae were ESBL producers and 82.3% of Pseudomonads were MBL producers. The high rates of antibiotic resistance observed in the present study may be due to the fact that ours is a tertiary care hospital with widespread usage of broad spectrum antibiotics leading to selective survival advantage of pathogens. • The outcome of the patients depended on a number of factors like grade of the ulcer, associated co-morbid conditions and the presence of resistant pathogen. • Our study showed that resistant isolates to be present in 54 cases of the diabetic foot ulcers. MRSA was seen in 18 cases, ESBL in 22 cases and MBL producing Pseudomonads in 14 cases. • Our study showed that amputation was more common in ulcers which had MRSA(50%).Wound healing was delayed in patients with resistant bacteria-33% MRSA, 12% ESBL and 16% Multidrug resistant Pseudomonads. Healing of wound was maximum in grade I ulcers and those ulcers which did not show the presence of resistant bacteria namely 72% of the ulcers