Prevalence of ESBL and Antibiotic Resistance Profile of Escherichia coli from Diabetic Wound Infections in a Nigerian Tertiary Hospital
Charity Nneka John-Emaimo
Department of Family Medicine, University of Nigeria Teaching Hospital Ituku-Ozalla, Enugu, Nigeria and Department of Applied Microbiology, Ebonyi State University, Abakaliki, Nigeria.
Ikemesit Udeme Peter *
Department of Microbiology, Federal University of Allied Health Sciences, Enugu, Nigeria.
Ifeanyichukwu Romanus Iroha
Department of Applied Microbiology, Ebonyi State University, Abakaliki, Nigeria.
*Author to whom correspondence should be addressed.
Abstract
Background: Diabetes-related foot wounds are frequently complicated by bacterial infection, and antimicrobial resistance can restrict therapeutic options. This study determined the prevalence of phenotypic extended-spectrum beta-lactamase (ESBL) production and described the antibiotic resistance profile of Escherichia coli recovered from diabetic foot wound samples at a tertiary hospital in Abakaliki, Nigeria.
Methods: One hundred wound swab specimens were processed using conventional microbiological methods. Escherichia coli isolates were identified by biochemical testing with VITEK® 2 COMPACT confirmation. Antibiotic susceptibility testing was performed by Kirby-Bauer disk diffusion using the disk contents recorded in the study protocol, and ESBL production was assessed by a double-disk synergy method. Principal proportions were summarised using 95% Wilson confidence intervals, and ward-level proportions were compared using two-sided Fisher's exact tests. Because disk diffusion is not recommended for colistin under CLSI M100-Ed32, the colistin row is retained as an original screening classification but is not used for clinical susceptibility inference.
Results: Escherichia coli was recovered from 46/100 samples (46.0%; 95% CI, 36.6-55.7). Recovery was 37.5% in A&E and 53.8% in GOPD (P = .113). ESBL production was detected in 34/46 isolates (73.9%; 95% CI, 59.7-84.4), including 16/18 A&E isolates (88.9%) and 18/28 GOPD isolates (64.3%); this ward difference was not statistically significant (P = .090). Under the recorded study protocol, all 34 ESBL-producing isolates were classified as resistant to amoxicillin-clavulanic acid, the four tested cephalosporins, three carbapenems, nalidixic acid, trimethoprim-sulfamethoxazole, and tetracycline, whereas all were classified as susceptible to gentamicin. Aztreonam resistance was 88.2%; ciprofloxacin susceptibility was 88.2%; and ofloxacin susceptibility was 61.8%. The MARI recalculated from all 16 recorded categorical results was 0.836 overall, 0.852 for A&E, and 0.823 for GOPD; these values are interpreted descriptively because of the susceptibility-testing limitations noted above.
Conclusion: The study identified a high proportion of phenotypic ESBL-producing Escherichia coli and a broad recorded resistance pattern among isolates from diabetic foot wounds. The extreme carbapenem-resistance pattern warrants confirmation using fully standardised susceptibility procedures and, where feasible, molecular characterisation. The findings support local antimicrobial-resistance surveillance, laboratory quality assurance, and antimicrobial stewardship, but they should not be used alone to select clinical therapy.
Keywords: Antibiotic resistance, diabetes-related foot wound, Escherichia coli, ESBL, multidrug resistance, Nigeria