本研究旨在了解关节假体周围感染(periprosthetic joint infection，PJI)中金黄色葡萄球菌小菌落变异体(Staphylococcus aureus small colony variant，SASCV)的毒力、耐药基因携带情况及分子型别，为探讨其致病机制提供基础数据。收集从19例PJI患者关节液中分离出的SASCV，进行全基因组测序、生物信息学分析及数据库比对，以了解其毒力相关基因和耐药基因的携带情况；采用多位点序列分型(multilocus sequence typing，MLST)分析菌株型别，并构建系统发育树。结果显示，19株SASCV中，有8株与正常形态金黄色葡萄球菌混合生长。对全部27株菌株进行全基因组测序，基因组长度为 2 696 437～3 011 803 bp，G＋C 含量为(32.8±0.05)%。共检出23种毒力相关基因：其中14种黏附素相关基因的检出率较高，为21.1%～100.0%；4种与免疫逃逸相关基因的检出率为36.8%～68.4%；5种溶血及杀白细胞素基因也有检出。耐药基因检出12种：blaZ检出率为78.9%(15/19)；mecA检出率为31.6%(6/19)；大环内酯类及氨基糖苷类抗生素耐药基因也有不同比例的检出。耐甲氧西林金黄色葡萄球菌中耐药基因的检出数量高于甲氧西林敏感金黄色葡萄球菌。MLST分析结果显示，19株SASCV共分10个型别。8组表型混合生长的菌株中，2组SCV与正常表型菌株分属不同型别，且毒力及耐药基因差异较大，其余6组为同一型别。本研究还发现，PJI中SASCV的生物膜相关黏附素基因检出率高，耐药基因中mecA检出率较高，MLST以ST59最多，其次为ST398和ST25。SCV与正常表型菌株混合生长时可分属不同型别。

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.