AUTHOR=Sun Zhewei , Zhou Danying , Zhang Xueya , Li Qiaoling , Lin Hailong , Lu Wei , Liu Hongmao , Lu Junwan , Lin Xi , Li Kewei , Xu Teng , Bao Qiyu , Zhang Hailin 

TITLE=Determining the Genetic Characteristics of Resistance and Virulence of the “Epidermidis Cluster Group” Through Pan-Genome Analysis

JOURNAL=Frontiers in Cellular and Infection Microbiology

VOLUME=10

YEAR=2020

URL=https://www.frontiersin.org/journals/cellular-and-infection-microbiology/articles/10.3389/fcimb.2020.00274

DOI=10.3389/fcimb.2020.00274

ISSN=2235-2988

ABSTRACT=<p><italic>Staphylococcus caprae, Staphylococcus capitis</italic>, and <italic>Staphylococcus epidermidis</italic> belong to the “Epidermidis Cluster Group” (ECG) and are generally opportunistic pathogens. In this work, whole genome sequencing, molecular cloning and pan-genome analysis were performed to investigate the genetic characteristics of the resistance, virulence and genome structures of 69 ECG strains, including a clinical isolate (<italic>S. caprae</italic> SY333) obtained in this work. Two resistance genes (<italic>blaZ</italic> and <italic>aadD2</italic>) encoded on the plasmids pSY333-41 and pSY333-45 of <italic>S. caprae</italic> SY333 were confirmed to be functional. The <italic>bla</italic> region in ECG exhibited three distinct structures, and these chromosome- and plasmid-encoded <italic>bla</italic> operons seemed to follow two different evolutionary paths. Pan-genome analysis revealed their pan-genomes tend to be “open.” For the virulence-related factors, the genes involved in primary attachment were observed almost exclusively in <italic>S. epidermidis</italic>, while the genes associated with intercellular aggregation were observed more frequently in <italic>S. caprae</italic> and <italic>S. capitis</italic>. The type VII secretion system was present in all strains of <italic>S. caprae</italic> and some of <italic>S. epidermidis</italic> but not in <italic>S. capitis</italic>. Moreover, the <italic>isd</italic> locus (iron regulated surface determinant) was first found to be encoded on the genomes of <italic>S. caprae</italic> and <italic>S. capitis</italic>. These findings suggested that the plasmid and chromosome encoded <italic>bla</italic> operons of ECG species underwent different evolution paths, as well as they differed in the abundance of virulence genes associated with adherence, invasion, secretion system and immune evasion. Identification of <italic>isd</italic> loci in <italic>S. caprae</italic> and <italic>S. capitis</italic> indicated their ability to acquire heme as nutrient iron during infection.</p>