Characterisation of neonatalStaphylococcus capitisNRCS-A isolates compared with non NRCS-AStaphylococcus capitisfrom neonates and adults

Staphylococcus capitisis a frequent cause of Late-Onset Sepsis (LOS) in neonates admitted to Neonatal Intensive Care Units (NICU). The NRCS-A clone ofS. capitishas been isolated from NICUs globally although the reasons for the global success of this clone are not understood.We analysed a collection ofS. capitiscolonising babies admitted to two NICUs, one in the UK and one in Germany as well as corresponding pathological clinical isolates. Genome analysis identified 3 groups; non-NRCS-A isolates, NRCS-A isolates, and a group of ‘proto NRCS-A’ - isolates closely related to NRCS-A but not associated with neonatal infection. All bloodstream isolates belonged to the NRCS-A group and were indistinguishable from strains carried on the skin or in the gut. NRCS-A isolates showed increased tolerance to chlorhexidine and antibiotics relative to the otherS. capitisas well as enhanced ability to grow at higher pH values. Analysis of 138 pangenomes of the clades identified characteristicnsrandtarJgenes in the NRCS-A and proto groups with a CRISPR-cas system only seen in NRCS-A isolates which also showed enrichment of genes for metal acquisition and transport.We found evidence for transmission ofS. capitisNRCS-A within NICU, with related isolates shared between babies and multiple acquisitions by some babies. Our data show NRCS-A strains commonly colonise uninfected babies in NICU representing a potential reservoir for potential infection. This work provides more evidence that adaptation to survive in the gut and on skin facilitates spread of NRCS-A, and that metal acquisition and tolerance may be important to the biology of NRCS-A. Understanding how NRCS-A survives in NICUs can help develop infection control procedures against this clone.