Abstract：This study aims to investigate the virulence, antibiotic resistance gene profiles, and molecular types of Staphylococcus aureus small colony variants (SASCVs) in periprosthetic joint infections (PJIs) to provide fundamental data for understanding their pathogenic mechanisms. A total of 19 SASCV strains isolated from synovial fluid samples of PJI patients were collected, and whole genome sequencing, bioinformatics analysis, and database comparison were performed to determine the presence of virulence and antibiotic resistance genes. Multilocus sequence typing (MLST) was employed to classify strain types and a phylogenetic tree was constructed by MEGA software. The results demonstrated that among the 19 SASCV strains, eight were found to coexist with Staphylococcus aureus with a normal phenotype. All 27 strains underwent whole genome sequencing, with genome lengths ranging from 2 696 437 bp to 3 011 803 bp and G＋C content of (32.8±0.05)%. A total of 23 virulence-related genes were detected: 14 adhesin-related genes had detection rates between 21.1% and 100.0%; four immune evasion-related genes had detection rates ranging from 36.8% to 68.4%; and five hemolytic and leukocidin genes were also identified. Twelve resistance genes were detected: blaZ was detected in 78.9% (15/19) of the samples; mecA was detected in 31.6% (6/19) of the samples; resistance genes for macrolide and aminoglycoside antibiotics were detected with varying rates; and methicillin-resistant Staphylococcus aureus (MRSA) had a higher number of detected resistance genes compared to methicillin-sensitive Staphylococcus aureus (MSSA). MLST analysis revealed 10 different sequence types (STs) among the 19 SASCV strains. There were eight groups of phenotypically mixed strains. In two groups SCVs and their normal phenotype (NP) counterparts belonged to different geno-types, with significant differences in virulence and antibiotic resistance genes, while in the remaining six groups SCVs and NP strains belonged to the same genotype. This study revealed that in PJIs, the detection rate of biofilm-related adhesion genes in SASCVs is high, and the prevalence of mecA is relatively elevated. Among the MLST genotypes, ST59 is the most common, followed by ST398 and ST25. When SCVs coexist with normal phenotype strains, they may belong to different genotypes.
魏莹，刘颖，刘薇，郭宇. 金黄色葡萄球菌小菌落变异体在关节假体感染中的分子病原学特征[J]. 微生物与感染, 2023, 18(2): 65-74.
WEI Ying, LIU Ying, LIU Wei, GUO Yu. Molecular pathogenic characteristics of Staphylococcus aureus small colony variants in periprosthetic joint infections. JOURNAL OF MICROBES AND INFECTIONS, 2023, 18(2): 65-74.
2023, Vol. 18 
