Antibiotic Susceptibility Profiles of Bacteria from Diabetic Foot Infections in Selected Teaching Hospitals in Southwestern Nigeria

Abstract

One of the serious complications associated with diabetes is foot ulcer and this condition affects the quality of life in patients in all classes, races and ages. Chronic wounds are prone to colonization by wide array of microorganisms which could be extremely hazardous to patients if effective and timely therapeutic intervention is not made. This study was conducted to determine the antibiotic susceptibility profiles of bacteria from diabetic foot infections in southwestern Nigeria. Samples were collected from a total of 142 diabetic foot ulcer patients with moistened sterile cotton swabs. Nutrient agar, Mac-Conkey agar, blood agar and mannitol salt agar media were used for the isolation of total viable bacteria, Gram-negative non-spore forming lactose fermenters, fastidious bacteria and staphylococci, respectively. Morphological and biochemical characteristics of pure cultures were determined in accordance with standard laboratory criteria. API 20 E and API 20 NE were used for the confirmation of identity of the bacterial isolates. The disc diffusion technique was employed for the determination of antibiotic susceptibility of bacterial isolates in accordance with standard procedures. The antibiotics investigated included amikacin, amoxicillin, ampicillin, ceftazidime, cefazolin, ceftriaxone, chloramphenicol, ciprofloxacin, clindamycin, gentamicin, imipenem, linezolid, methicillin, netilmicin, ofloxacin, oxacillin, penicillin, piperacilin, sulfamethoxazole, trimethoprim and vancomycin. One hundred and seventy-seven isolates were encountered and these were characterized into eleven bacterial species. These included Staphylococcus aureus (22.03%), Pseudomonas aeruginosa (16.95%), Staphylococcus epidermidis (12.43%), Proteus mirabilis (8.48%), Klebsiella pneumoniae (7.91%), E. coli (7.35%), Staphylococcus saprophyticus (6.78%), Streptococcus pyogenes (5.65%), Morganella morganii (5.09%), Citrobacter freundii (4.52%) and Acinetobacter baumannii (2.83%). Gram-negative bacteria showed 76.99% susceptibility to the antibiotics while 22.85% was resistant. Gram-positive bacteria showed 93.75% susceptibility and 5.01% resistance to the antibiotics. This study revealed that there is no definite aetiologic bacterial agent for diabetic foot infections and many of the associated bacteria are sensitive to certain antibiotics.