Group B streptococci (GBS) strains evading molecular diagnostics showed novel chromosomal deletions encompassing the CAMP-factor (cfb) encoding gene

• DOI: 10.1007/s10096-023-04620-x
• Publication Date: 2023-05-10T23:26:33Z
• Authors: Roberta Creti; Monica Imperi; Andrea Stanziale; Giorgia Giuliani; Paolo Fazii; Vincenzo Savini
• Keywords: Hemolysin Proteins; Bacterial Proteins; Whole Genome Sequencing; Molecular Diagnostic Techniques; Streptococcal Infections; Humans; Female; Genome, Bacterial; 3. Good health; Streptococcus agalactiae; Bacterial Typing Techniques

A highly conserved fragment adjacent to the cfb gene encoding the CAMP factor is the target of PCR-based molecular diagnostic systems for the identification of S. agalactiae (group B streptococci (GBS)). Six PCR-negative, culture-positive GBS strains were whole genome sequenced to assess why they escaped molecular diagnostics. GBS strains did not constitute a clonal cluster and presented variably sized chromosomal deletions (from 7 to 33 kb) which always included the cfb gene, a finding never described before. GBS strains that escape molecular diagnostics are considered rare; however, they can cause false-negative results using molecular diagnostics alone, affecting medical decisions.