Descriptive review: global spectrum of invasive group B streptococcal disease in nonpregnant adults: epidemiology, risk factors and clinical presentations

Streptococcus agalactiae, or Group B Streptococcus (GBS), is a historical cause of perinatal infections and neonatal sepsis. While routine screening programs in high-income countries have led to a steady decline in neonatal complications, GBS remains a frequent colonizer of the adult gastrointestinal and urogenital tracts. Over recent decades, the incidence of invasive GBS infections in nonpregnant adults has increased substantially, leading to significant morbidity and mortality. This shifting epidemiological landscape is further complicated by the troubling emergence of multidrug-resistant lineages and hypervirulent genomic clones, such as ST283, which demonstrate severe invasive potential and unique zoonotic transmission capabilities. Because collective data on this growing threat remains fragmented, this review synthesizes global literature on invasive adult GBS, encompassing its changing epidemiology, patient risk factors, and its expanding clinical spectrum. The primary objective is to collate updated evidence to raise clinical awareness, support antimicrobial stewardship, and direct future research toward effective preventive measures and strategies.