CAMP-negative <i>Streptococcus agalactiae</i> strains exhibited complete or partial chromosomal deletions of the CAMP-factor encoding gene <i>cfb</i>

Our work makes several novel contributions to the field. (i) We report the first documented case of a C-terminal deletion of the <i>cfb</i> gene in a CAMP-negative GBS strain, demonstrating that both N-terminal and C-terminal regions are essential for cohemolytic activity. (ii) Our findings reveal that CAMP-negative GBS strains (3.6% of isolates) are more prevalent than previously recognized, with most cases resulting from complete chromosomal deletions of the <i>cfb</i> gene. (iii) We provide evidence that single-target molecular assays targeting only the <i>cfb</i> gene may miss GBS detection, highlighting the necessity for multi-target approaches in clinical diagnostics. (iv) We demonstrate a unique antibiotic resistance pattern in CAMP-negative strains, showing significantly lower resistance to certain antibiotics compared to CAMP-positive strains.