The prevalence of phylogenetic group of Shiga toxin-producing Escherichia coli strain isolated from farm animals in Iran: a meta-analysis study

Background: The study of the prevalence of the phylogenetic group in the Shiga toxin-producing Escherichia coli (STEC) strain isolated from farm animals is valuable for epidemiology aspects; therefore, the current systematic review and meta-analysis aimed to investigate the prevalence of the phylogenetic group in STEC isolates obtained from farm animals in Iran. Methods: A systematic literature search was conducted in the Web of Science, PubMed, Scopus, and Embase electronic databases. The search investigated articles published by Iranian authors to the end of December 2020. Analysis of data was conducted using the Comprehensive Meta-Analysis Software (Biostat Company). To estimate the pooled prevalence and the corresponding 95% confidence interval (CI), the random-effects model was used. Results: Our comprehensive search identified nine studies with eligibility criteria subjected to the meta-analysis. The pooled prevalence of phylogroup A was 21% (95% CI: 10–38). There was significant heterogeneity among the nine studies (χ2 = 92.52; P < 0.001; I2 = 91.35%). Additionally, the pooled prevalence of phylogroups B1, B2 and D among the nine studies was 63, 3, and 9%, respectively. The subgroup analysis results based on healthy and diarrheic cases indicated that the rate of phylogroup A in healthy and diarrheic samples was 27 and 2%, respectively. For phylogroup B1, this rate was 55 and 88% in healthy and diarrheic samples, respectively. Conclusion: In summary, our results demonstrated that domestic animals might be the possible reservoirs of STEC in the studied population. Comparison of the phylogroup characteristics of the STEC strain obtained from different sources exhibited a partial genetic diversity in isolates, and there was heterogeneity among the studies in terms of phylogenetic groups. This study provides important information about STEC regarding the phylogenetic characteristics