Identification and antibiotic susceptibility of microorganisms isolated from diabetic foot ulcers: A pathological aspect

Abstract

Diabetic foot ulcers infected with microorganisms increase the risk of amputation. The presence of drug-resistant bacteria in diabetic foot ulcers creates a big challenge during the treatment. The objective of the present study was to determine the bacterial prevalence and antibiotic resistance among bacteria isolated from Chinese patients with diabetic foot ulcers. The present study studied the microbial colonization of diabetic foot ulcers of patients from a single center in China. Wound swabs from 89 patients with diabetic foot ulcers were collected and the presence of microorganisms detected. The isolated microorganisms were subjected to antibiotic susceptibility testing by the disk diffusion method. Of 89 patients, 56 (62.9%) were male and 33 (37.1%) were female, the mean age of patients was 53.2±5.4 years, the mean duration of diabetes was 14.8±2.9 years, the mean random blood sugar was 301±87 mg/dl, mean HbA1c was 7.9±1.4%. Patients with Wanger ulcer grade III (36.0%; P=0.034) and patients within the weight range of 51-75 kg (59.6%; P=0.012) were significantly higher. The prevalence rate of diabetic foot ulcers was 11.3%. Among 153 microorganisms, gram-positive bacteria (52.3%) were more prevalent than gram-negative bacteria (44.4%). Most of the patients with polymicrobial infection were classified to have Wanger III ulcer grade diabetic foot ulcers. Staphylococcus aureus (38.2%) was the most predominant bacteria isolated followed by Staphylococcus epidermidis (29.2%) and Escherichia coli (28.1%). Most of the gram-positive and gram-negative bacteria were resistant to dicloxacillin (73.8%, P=0.021) and cefotaxime (50%), respectively and ~53.4% of the isolates were multi-drug resistance isolates, 61.8% of the Staphylococcus aureus were identified as methicillin-resistant Staphylococcus aureus and 61.8% of the gram-negative bacteria were extended-spectrum β-lactamase producers. Staphylococcus aureus and Escherichia coli were the predominant gram-positive and gram-negative bacteria isolated, respectively. Penicillin resistance was significantly higher among the gram-negative bacteria (P=0.019). Staphylococcus aureus and Escherichia coli were the predominant gram-positive and gram-negative bacteria isolated and levofloxacin and nitrofurantoin were the most effective antibiotics among the gram-positive and gram-negative bacterial isolates, respectively.

Keywords: antibiotic resistance; diabetic foot ulcer; extended-spectrum β-lactamase; gram-negative bacteria; gram-positive bacteria; methicillin-resistant Staphylococcus aureus; polymicrobial infection.