Study on Microbiome of Chronic Non Healing Diabetic Ulcers with Special Reference to Biofilm and Multidrug Resistant Strains

Abstract

Introduction: Diabetic Foot Ulcers (DFU) represent a silent epidemic and are the leading cause of 80% of non traumatic lower-limb amputations. Anaemia in diabetes may have adverse effects on systemic diseases and predict the progression of diabetes complications. Biofilms act as a mechanical barrier to antimicrobials and immune system cells and contribute to Multidrug Resistance (MDR). Aim: To determine the bacteriome and mycobiome of diabetic ulcers and the associated biofilm formation and anti-microbial resistance profile of the pathogens. Also, to determine the molecular characterisation of biofilm-forming resistant isolates by Polymerase Chain Reaction (PCR). Materials and Methods: This cross-sectional study was done on 150 diabetic patients with non healing ulcers and was chosen and studied from January-December 2019. Pus and tissue bit samples were processed as per standard microbiological procedures. Antimicrobial susceptibility test was performed as per Clinical and Laboratory Standards Institute (CLSI) guidelines. Biofilm formation was detected by the tissue culture plate method. Molecular characterisation of resistant pathogens was done by PCR. Variables were expressed as proportions or percentages. Results: Out of 150 diabetic patients, 17.3% of patients underwent amputation. A 90% of patients were associated with anaemia. Most ulcers were polymicrobial in nature. Predominantly isolated pathogens were Pseudomonas aeruginosa 37 (17.1%) and Staphylococcus aureus 33 (15.2%) among aerobic bacteria, Peptostreptococcus 10 (4.6%) among the anaerobes and Candida albicans 20 (9.2%) in fungus. Gram negative bacteria showed high sensitivity to piperacillintazobactam, meropenem, and gram positive cocci to vancomycin and linezolid. A 82% of bacterial isolates and 50% of fungal isolates were biofilm producers. Staphylococcus aureus was a strong biofilm producer. On molecular characterisation, blaCTX-M, blaTEM, blaNDM-1, blaOXA-23, mecA genes were present in resistant biofilm-forming isolates. Conclusion(s): Polymicrobial wound infection and biofilm formation in DFU confers antibiotic resistance and contributes to Multidrug Resistant Organisms (MDRO's). However, proper antibiotic surveillance and antibiotic policy, and preventive strategies can curtail the spread of resistant strains.

Keywords

• anaemia
• antimicrobial susceptibility
• multidrug resistant organism