δ溶血素G10S突变与β溶血素联合检测对金黄色葡萄球菌ST59型的鉴定作用

Identification of staphylococcus aureus lineage ST59 by the combined detection of delta hemolysin allelic variant G10S and beta hemolysin

目的探讨δ溶血素G10S突变(HldG10S)与β溶血素(β-toxin)联合检测对金黄色葡萄球菌ST59型的鉴定作用。方法收集中南大学湘雅三医院检验科2017年11月至2018年4月非重复分离的82株金黄色葡萄球菌临床菌株,通过基质辅助激光解吸电离飞行时间质谱(MALDI-TOFMS)对菌株进行常规鉴定并获取菌株的质谱图,根据δ溶血素(Hld)的m/z表达强度,将所有菌株分为HldG10S(3036±2.0)m/z、Hld(3006±2.0)m/z及ND(无δ溶血素质谱峰)3个组,利用多位点序列分型(MLST)方法检测各组ST59型分布情况,并采用反向协同溶血试验进行β-toxin表型测定,比较HldG10S、β-toxin单项和联合检测鉴定ST59的敏感度、特异度和准确度。结果82株菌中21株表达HldG10S毒素,占25.6%;39株表达Hld毒素,占47.6%;22株不表达HldG10S与Hld毒素,占26.8%。HldG10S组中16株为ST59,占76.19%(16/21);Hld与ND两组中均无ST59。HldG10S组中16株ST59菌株均产β-toxin,而5株非ST59菌株均未检测到β-toxin产生。HldG10S与β-toxin联合检测鉴定ST59的特异度(100%)与准确度(100%)显著高于HldG10S、β-toxin单项检测的特异度(92.4%,77.3%)和准确度(80.5%,81.7%)(χ2=19.472,P<0.001;χ2=17.792,P<0.001)。结论HldG10S与β-toxin联合检测能初步快速鉴定ST59,可辅助常规监测金黄色葡萄球菌流行变化趋势。

Objective To investigate the identification of staphylococcus aureus lineage ST59 using the combined detection of delta hemolysin allelic variant G10S(HldG10S) and beta hemolysin(β-toxin). Methods Perspective study.A total of 82 non-duplicate clinical staphylococcus aureus were collected from November 2017 to April 2018 in the department of Clinical laboratory, the Third Xiangya Hospital of Central South University, China.The strains were routinely identified by MALDI-TOF MS and the mass spectra were obtained. According to the m/z expression intensity of delta hemolysin(Hld), all strains were divided into three groups:HldG10S (3 036±2.0)m/z, Hld (3 006±2.0)m/z and ND [no (3 036±2.0)m/z and no (3 006±2.0)m/z]. The distribution of ST59 in the three groups was detected by MLST. Reverse synergic hemolysis test was used to determine the β-toxin phenotype.And the sensitivity, specificity and accuracy of HldG10S,β-toxin and the combined detection of HldG10S and Hld to identify ST59 were compared. Results Among the 82 strains, 21 strains expressed HldG10S toxin, accounting for 25.6%. 39 strains expressed Hld toxin, accounting for 47.6%.22 strains did not express HldG10S and Hld toxin, accounting for 26.8%. In HldG10S group,16 strains were ST59, accounting for 76.19%(16/21).ST59 was not found in both Hld and ND groups. All 16 strains of ST59 in HldG10S group produced β-toxin, while none of the 5 strains of non-ST59 produced β-toxin. The specificity(100%) and accuracy(100%) of the combined detection was significantly higher than that of HldG10S and β-toxin single detection of specificity(92.4%,77.3%) and accuracy(80.5%,81.7%)(χ2=19.472,P<0.001;χ2=17.792,P<0.001). Conclusion The combined detection of HldG10S and β-toxin can preliminarily and rapidly identify ST59, which can assist the routine monitoring of the change trend of staphylococcus aureus epidemic.