Genomic analysis of Staphylococcus capitis isolated from neonates at a neonatal intensive care unit in Sweden

ObjectivesEmergence of a genetically distinct multidrug resistant Staphylococcus capitis clone (NRCS-A) present in neonatal intensive care units has recently been extensively reported. The aim of the present study was to investigate which clones of S. capitis isolated from blood in a Swedish single centre NICU have been present since 1987 and to investigate if the NRCS-A clone has disseminated in SwedenMethodsAll S. capitis isolates from blood cultures of neonates (=28 days of age) between 1987 and 2017 (n=46) were whole genome sequenced and core genome multi-locus sequence typing (cgMLST) performed. SNP-based phylogenetic relationships between the S. capitis isolates and in silico predictions of presence of genetic traits specific to the NRCS-A clone was done. Furthermore, antibiotic susceptibility testing including screening for heterogeneous glycopeptide-intermediate resistance was performed. Results Thirty-five isolates clustered closely to the isolates previously determined as belonging to the NRCS-A clone and had less than 81 core genome loci differences out of 1,063. Twenty-one of these isolates were multidrug resistant. The NRCS-A clone was found in 2001. Six pairs of isolates had differences of less than 2 SNPs. Genetic traits associated to the NRCS-A clone such as nsr, ebh, tarJ and CRISPR were found in all 35 isolates.Conclusions The increasing incidence of S. capitis blood cultures of neonates is predominantly represented by the NRSC-A clone at our NICU in Sweden. Furthermore, there were indications of transmission between cases, adherence to basic hygiene procedures and surveillance measures is thus warranted.