A van G-type locus in Clostridium argentinense.

Objectives: The objective was to study a new vanG-type locus in Clostridium argentinense vanG_Car and to determine its impact on glycopeptide susceptibility of the host. Methods: The whole genome of C. argentinense NCIB 10714 was sequenced using Illumina single-reads sequencing technology. The presence of vanG_Car in seven C. argentinense strains was tested by PCR and its expression was tested by quantitative RT-PCR (qRT-PCR). Glycopeptide susceptibility was determined by the Etest procedure. Results: The vanG_Car locus contained four genes encoding a carboxypeptidase, a D-alanine:D-serine ligase, a serine transporter and a serine racemase, and was present in the seven C. argentinense studied. An AraC-type transcriptional regulator was found upstream from the genes. C. argentinense NCIB 10714 was susceptible to vancomycin and to teicoplanin. qRT-PCR experiments revealed that vanG_Car was not expressed without or with induction by a subinhibitory concentration of vancomycin. Conclusions: The new vanG_Car locus was cryptic in C. argentinense and intrinsic to this species. Emergence of vancomycin resistance in C. argentinense due to decryptification of the vanG_Car gene cluster could occur. [ABSTRACT FROM AUTHOR]