Prevalence, molecular characteristics and antibiotic susceptibility of clinical isolates of Clostridioides difficile in southeastern Nigeria Prévalence, caractéristiques moléculaires et sensibilité aux antibiotiques des isolats cliniques de Clostridioides difficile dans le sud-est du Nigéria

Abstract

Background: Clostridioides difficile is a major contributor to healthcare-associated infections, exhibiting global variations in its prevalence and resistance. There is an absence of data on its molecular characteristics and antibiotic susceptibility of C. difficile in southeastern Nigeria. This study aims to evaluate its prevalence, molecular features, and resistance patterns to enhance treatment and control strategies. 
Methodology: Stool samples were collected from 450 hospitalized adult patients with persistent diarrhoea and prolonged antibiotic use from selected public and private healthcare facilities across the five States of southeastern Nigeria. The total anaerobes were enumerated using standard bacteriological methods. Clostridioides difficile was cultured on Clostridium difficile differential agar with selective supplements, followed by biochemical testing including catalase, oxidase, and reverse CAMP tests. Genomic bacterial DNA was extracted, purified, and amplified by polymerase chain reaction (PCR) assay. Sequencing of the DNA amplicon was performed and results were blasted on the NCBI database. Virulence (tcdA, tcdB, cdtA, and cdtB) and resistance (tetS, tetA, and ermB) genes were detected by conventional PCR assay. Antibiotic susceptibility of each isolate was determined using the Kirby-Bauer disc diffusion method.
Results: The mean anaerobe counts ranged from 5.61±0.11 log10 CFU/g (Ebonyi) to 5.65±0.07 log10 CFU/g (Enugu). Antibiotic susceptibility test revealed sensitivity to gentamicin, meropenem, and amoxicillin-clavulanic acid, while resistance was observed to tetracycline and erythromycin. The multiple antibiotic resistance (MAR) index of isolates was 0.44. All isolates (100%) harbored tcdB gene while 69.56% harbored tcdA gene. Additionally, 4.34% of isolates contained cdtA and cdtB genes.
Conclusions: This study highlights significant antibiotic resistance and presence of virulence genes in C. difficile isolates in southeastern Nigeria, emphasizing the need for monitoring and tailored treatment strategies.