Vancomycin-resistant enterococci in Iran: A systematic review and meta-analysis of non-clinical studies

Abstract Environmental contamination with fecal antibiotic-resistant enterococci can increase the risk of antibiotic resistance gene transfer among different species, and ultimately spreading resistant bacteria to the community and hospital. The current study was the first systematic review and meta-analysis on the prevalence of antibiotic-resistant Enterococcus species, particularly vancomycin-resistant species, isolated from non-clinical sources in Iran. Two authors conducted literature search on the antibiotic resistance of enterococci in national and international databases until February 2021. Data were extracted from 38 qualified articles based on the pre-defined criteria, and meta-analysis was performed using Comprehensive Meta-Analysis software. The pooled prevalence of vancomycin-resistant enterococci (VRE) in non-clinical sources was 26.8% (95% CI: 17.9–38) in Iran. The frequency of VRE strains in foods, hospital environment and also sewage and surface water were 33.4%, 26.4% and 13.1%, respectively. In addition, the most predominant vancomycin resistance genotypes were vanA (35.1%), followed by vanB (6.6%) and vanC (2.2%). Enterococci had higher rates of resistance to erythromycin (56.6%), ampicillin (30.4%), gentamicin (37.4%), ciprofloxacin (35.3%), tetracycline (35.6%), streptomycin (60.1%), quinupristin/dalfopristin (30.5%), trimethoprim/sulfamethoxazole (58.7%), penicillin (52%) and amikacin (59.4%), while showing low resistance rates to linezolid (2.8%), nitrofurantoin (4.6%), teicoplanin (10.2%), chloramphenicol (13.3%) and amoxicillin (14.4%). Our results suggest that inhibition of the excessive prevalence of VRE strains and other drug-resistant enterococci in Iran requires appropriate antibiotic use in clinics, proper disinfection of hospitals, management of the wastewater and hygienic preparation and distribution of food products.