Association between Microbial Colonization and Spontaneous Abortion: A Clinical Study of Post-Curettage Patients

Introduction Spontaneous abortion causes approximately 50,000 maternal deaths annually, primarily due to microbial infection and hemorrhage, accounting for 8–13% of global maternal deaths. This study aimed to investigate the association between microbial infections, bacterial diversity, and patterns related to spontaneous abortion in two groups of women. Methods A total of 156 bacterial isolates were recovered from 48 patient samples, while 67 isolates were obtained from 48 healthy controls. All samples were cultured under aerobic and anaerobic conditions on enrichment and selective media, including Blood agar, MacConkey agar, and Chocolate agar. Results Gram-positive bacteria predominated among total isolates (53.84%) compared to Gram-negative bacteria (46.15%). The primary Gram-positive pathogens were S. aureus (29.16%), L. acidophilus (27.08%), Peptostreptococcus spp. (22.91%), and C. perfringens 20.83%. Among Gram-negative isolates, E. coli was most prevalent (47.91%), followed by P. aeruginosa (18.75%) and K. pneumonia (16.6%). In the control group, L. acidophilus (43.75%) and E. coli (18.75%) were most common. Diversity analyses showed no significant difference in α-diversity, but β-diversity revealed clear distinctions between groups. Linear Discriminant Analysis identified specific biomarkers differentiating the microbial compositions of the two cohorts. Discussion These findings indicate a Gram-positive predominance, with Staphylococcus aureus and E. coli identified as the primary pathogenic drivers in the study groups. Although species richness remained consistent across cohorts, β- diversity and Linear Discriminant Analysis biomarkers confirmed distinct microbial shifts and bacterial signatures between the examined groups. Conclusion L. acidophilus appears to help maintain vaginal health and reduce the risk of spontaneous abortion, as β- diversity and biomarker analyses revealed a shift from beneficial to pathogenic bacteria in women with spontaneous abortion.