Original article Bacterial etiology of diabetic foot infections in South India E.M. Shankar a , V. Mohan b , G. Premalatha b , R.S. Srinivasan b , A.R. Usha a, * a Bacteriology Laboratory, Department of Microbiology, Dr. ALM PG Institute of Basic Medical Sciences, University of Madras, Taramani Campus, Chennai, India b Dr. V. Mohan’s M.V. Diabetes Specialities Centre, 6B, Conran Smith Road, Gopalapuram, Chennai, India Received 31 December 2004; received in revised form 20 May 2005; accepted 2 June 2005 Abstract Background: Foot infections are a frequent complication of patients with diabetes mellitus, accounting for up to 20% of diabetes-related hospital admissions. Infectious agents are associated with the worst outcomes, which may ultimately lead to amputation of the infected foot unless prompt treatment strategies are ensued. The present study sought to reveal the bacterial etiology of diabetic foot ulcers in South India, the diabetic capital of India. Methods: A 10-month-long descriptive study was carried out to analyse the aerobic and anaerobic bacterial isolates of all patients admitted with diabetic foot infections presenting with Wagner grade 2–5 ulcers. Bacteriological diagnosis and antibiotic sensitivity profiles were carried out and analysed using standard procedures. Results: Diabetic polyneuropathy was found to be common (56.8%) and gram-negative bacteria (57.6%) were isolated more often than gram-positive ones (42.3%) in the patients screened. The most frequent bacterial isolates were Pseudomonas aeruginosa , Staphylococcus aureus , coagulase-negative staphylococci (CONS), and Enterobacteriaceaes. Forty-nine cultures (68%) showed polymicrobial involvement. About 44% of P. aeruginosa were multi-drug-resistant, and MRSA was recovered on eight occasions (10.3%). Bacteroides spp. and Peptostreptococcus spp. were the major anaerobic isolates. Conclusions: Our study supports the viewpoint put forth by previous South Indian authors that the distribution of gram-negative bacteria (57.6%) is more common than that of gram-positive ones (42.3%) and it is contrary to the viewpoint that diabetic foot infections are frequently monomicrobial. Furthermore, recovery of multi-drug-resistant P. aeruginosa isolates is of serious concern, as almost no one has reported the same from the South Indian milieu. D 2005 European Federation of Internal Medicine. Published by Elsevier B.V. All rights reserved. Keywords: Diabetes; Foot infections; Wagner grade 1. Introduction Foot ulceration and infections are a leading cause of morbidity and mortality, especially in developing countries like India [1]. A recent report indicates that India has the largest diabetic population, with about 19 million patients, and that this is expected to increase to 57 million by 2025 [2]. Fifteen percent of all diabetics develop a foot ulcer at some point in their lives that is highly susceptible to infection and that spreads quite rapidly, leading to over- whelming tissue destruction and subsequent amputation [3]. The major predisposing factor to infection is foot ulceration, which is usually related to peripheral neuropathy [4]. Various poorly characterized immunologic disturbances may also increase the risk and severity of foot infections [5]. The Wagner classification [6] classifies the severity and depth of tissue injury into five grades or stages. In the superficial stages 1 and 2, aerobic bacteria are predominant, while anaerobic bacteria add up in Wagner grade 3–5 ulcers [7]. Bacterial involvement in diabetic foot ulcers may be polymicrobial [8]. Chronic wounds develop a more complex colonizing flora, including enterococci, various Enterobac- teriaceae, obligate anaerobes, Pseudomonas aeruginosa and, sometimes, other nonfermentative gram-negative rods [9]. Lipsky et al. [3] have proposed that gram-positive 0953-6205/$ - see front matter D 2005 European Federation of Internal Medicine. Published by Elsevier B.V. All rights reserved. doi:10.1016/j.ejim.2005.06.016 * Corresponding author. Tel.: +91 44 24925317; fax: +91 44 24926709. E-mail address: drushaanand@yahoo.com (A.R. Usha). European Journal of Internal Medicine 16 (2005) 567 – 570 www.elsevier.com/locate/ejim