Prevalence and genetic characteristics of lincosamide resistance genes ) and ) in group B from southern China.

Lincosamides serve as alternative therapeutic agents for penicillin-allergic patients with [group B (GBS)] infections, but the escalating antibiotic resistance has severely compromised their clinical efficacy. This study investigated the epidemiological characteristics of antibiotic resistance and the co-transfer mechanisms of lincosamide resistance genes and in 631 clinical GBS isolates from southern China. The results showed that 98.3% of isolates carried at least one antibiotic resistance gene, with lincosamide resistance genes detected in 76.1% of isolates. The and were identified as prevalent lincosamide resistance determinants alongside , with 18.7% of isolates co-carrying and , and double-positive isolates predominantly distributed in high-risk clonal complexes (CCs): CC10 (15.4%), CC17 (21.7%), CC19 (17.9%) and CC103 (35.5%). Genomic analyses revealed that formed composite resistance modules by integrating into resistance gene clusters within integrative and conjugative elements (ICEs), with insertion sequence-mediated mobilization increasing their dissemination risk. In CC10 and CC17, ICE served as the primary ICE harbouring , while novel genetic contexts for were identified in CC19, CC23 and CC103. This study highlights the high prevalence of resistance clusters in GBS clinical isolates from southern China and their ICE-mediated dissemination mechanisms, providing critical molecular epidemiological evidence for resistance surveillance and precision therapeutic strategies.