The prevalence of optrA -carrying Enterococci in the vaginal micro-ecology of pregnant women in late pregnancy

Abstract

The colonization of Enterococcus in the female vagina leads to neonatal and pediatric enterococcal septicemia. Linezolid (LZD) is a kind of mainstream drug for treating multidrug-resistant Gram-positive infections. OptrA is the main LZD-resistance gene at Enterococci in human isolates. It is essential to explore the prevalence of optrA -carrying Enterococcus in vaginal secretions of late pregnant women and the drug resistance of optrA . From May to June 2023, this study recruited 340 volunteers in late pregnancy (35–40 weeks of pregnancy) to provide non-repetitive vaginal discharge samples. Luria-Bertani broth and florfenicol (10 µg/mL) were used to enrich bacteria. Enterococci was identified through time-of-flight mass spectrometry. Additionally, antimicrobial susceptibility, polymerase chain reaction, and next-generation sequencing assays were applied to this study. Fifty-four optrA -carrying Enterococcus strains were obtained, the proportion of the whole vagina of late pregnant women was 15.88% (54 out of 340), and Enterococcus faecalis account the highest proportion. All optrA -carrying Enterococcus were resistant to at least three drugs. Tetracycline, chloramphenicol, erythromycin, and LZD have higher bacterial resistance rates. Genetic environment analysis revealed that IS 1216E , fexA , and erm (A) may synergistically exert multidrug resistance with optrA . It is necessary to strengthen the surveillance of optrA -carrying Enterococcus in pregnant women. This study provides scientific support for controlling hospital infections and managing antibiotic-resistant bacteria, and provides a scientific basis for rational clinical medication. IMPORTANCE The disruption of cervicovaginal microbiota homeostasis is considered a key factor in causing imbalance in the microenvironment, leading to inflammation, transmission of infections, and illness. Enterococcus is considered a major cause of healthcare-related infections globally. It has resistance to multiple antimicrobial drugs, which pose significant challenges for clinical treatment. Therefore, it is crucial to assess the prevalence of optrA -carrying Enterococcus in vaginal secretions of late pregnant women and the drug resistance of optrA . This study detected 15.88% of optrA -carried Enterococci in 340 pregnant women. Furthermore, we found that optrA -carrying Enterococcus strains are highly resistant to tetracycline, chloramphenicol, erythromycin, and Linezolid. Additionally, genetic environment analysis revealed that IS1216E , fexA , and erm (A) may synergistically exert multidrug resistance with optrA . This study provides scientific support for controlling hospital infections and managing antibiotic-resistant bacteria and provides a scientific basis for rational clinical medication.