AUTHOR=Zhang Jing , Suo Yujuan , Zhang Daofeng , Jin Fangning , Zhao Hang , Shi Chunlei 

TITLE=Genetic and Virulent Difference Between Pigmented and Non-pigmented Staphylococcus aureus

JOURNAL=Frontiers in Microbiology

VOLUME=9

YEAR=2018

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2018.00598

DOI=10.3389/fmicb.2018.00598

ISSN=1664-302X

ABSTRACT=<p>Staphyloxanthin (STX), a golden carotenoid pigment produced by <italic>Staphylococcus aureus</italic>, is suggested to act as an important virulence factor due to its antioxidant properties. Restraining biosynthesis of STX was considered as an indicator of virulence decline in pigmented <italic>S. aureus</italic> isolates. However, it is not clear whether natural non-pigmented <italic>S. aureus</italic> isolates have less virulence than pigmented ones. In this study, it is aimed to compare the pigmented and non-pigmented <italic>S. aureus</italic> isolates to clarify the genetic and virulent differences between the two groups. Here, 132 <italic>S. aureus</italic> isolates were divided into two phenotype groups depending on the absorbance (OD<sub>450</sub>) of the extracted carotenoids. Then, all isolates were subjected to <italic>spa</italic> typing and multilocus sequence typing (MLST), and then the detection of presence of 30 virulence factors and the gene integrity of <italic>crtN</italic> and <italic>crtM</italic>. Furthermore, 24 typical <italic>S. aureus</italic> isolates and 4 <italic>S. argenteus</italic> strains were selected for the murine infection assay of <italic>in vivo</italic> virulence, in which the histological observation and enumeration of CFUs were carried out. These isolates were distributed in 26 sequence types (STs) and 49 <italic>spa</italic> types. The pigmented isolates were scattered in 25 STs, while the non-pigmented isolates were more centralized, which mainly belonged to ST20 (59%) and ST25 (13%). Among the 54 non-pigmented isolates, about 20% carried intact <italic>crtN</italic> and <italic>crtM</italic> genes. The <italic>in vivo</italic> assay suggested that comparing with pigmented <italic>S. aureus</italic>, non-pigmented <italic>S. aureus</italic> and <italic>S. argenteus</italic> strains did not show a reduced virulence in murine sepsis models. Therefore, it suggested that there were no significant genetic and virulent differences between pigmented and non-pigmented <italic>S. aureus</italic>.</p>