Diabetic Foot Infection : Microbiological Causes with Special Reference to Their Antibiotic Resistance Pattern

Abstract

Background: Foot infections are one of the major complications of diabetes mellitus and are a significant risk factor for lower extremity amputation. Providing effective antimicrobial therapy is an important component in treating these infections. Objectives: This study investigates the microbial causes of diabetic foot infections and their antibiotic susceptibility pattern. Methodology: A prospective study of 80 patients with diabetic foot infections admitted to Cairo university hospitals was undertaken. Samples were collected by using sterile swabs and they were processed. Detailed antimicrobial susceptibility testing was performed according to CLSI guidelines 2014, including testing for Methicillin Resistant Staphylococcus aureus (MRSA), ESBL and carbapenemase production. Results: In the present study, a single organism was isolated from 48.75% patients and mixed bacterial growths were seen in 51.15% patients. Gram- negative bacteria (56.08%), were more commonly isolated compared with Gram-positive bacteria (27.7%), while gram-negative anaerobes accounted for (8.1%),and Candida species (8.1%). The commonest isolate was Proteus mirabilis (16.8%) followed by Escherichia coli (13.5%), Methicillin Sensitive Staphyloccus aureus (MSSA) (11.4%), Pseudomonas spp (10.8%), and MRSA (10.1%). Among the gram-negative bacteria 49% were ESBL producers and 3.6%were carbapenemases producerswhile46.8% Staphylococcus aureus were methicillin resistant Staphylococcus aureus. Overall 42.5% isolates were identified as MDR. Vancomycin was found to be the most effective against Gram-positive bacteria, whereas imipenem, amikacin and colistin were most effective against Gram-negative bacteria. Conclusion: This study showed a preponderance of gram negative bacilli among the isolates from the diabetic foot ulcers. Knowledge on the antibiotic sensitivity pattern of the isolates will be helpful in determining the drugs for the empirical treatment of diabetic ulcers