Molecular typing of enterotoxigenic strains of Staphylococcus aureus by pulsed-field gel electrophoresis, ribotyping and random amplified polymorphic DNA anaylsis

金黄色葡萄球菌凝固酶VII型菌株是日本爆发的金黄色葡萄球菌食物中毒最常见的菌株。应用SMAL酶切染色体DNA的脉冲场凝胶电泳法(PFGE)对129株凝固酶III型菌株进行了鉴定。这些病毒是从东京35个区16年间(1980-1995年)暴发的129例病例中分离出来的。129株暴发毒株分为3种类型，分别为A(n=115)、B(n=10)和C(n=4)。A型和C型分别分为33个亚型(A1~A33)和4个亚型(C1~C4)。从同一地区的食物中毒病例中分离到相同亚型的菌株，时间间隔为1年或2~5年。在金黄色葡萄球菌食物中毒的流行病学调查中，凝固酶分型和PFGE分型相结合，可提供比单独应用前一种方法更详细的信息。在一九九八年一月至六月期间，食环署在兵库县一间超级市场共抽取180个生肉样本，包括100个鸡肉样本和80个猪肉样本，化验是否含有金黄色葡萄球菌。结果发现，70份(70%)鸡肉和29份(36%)猪肉样品被金黄色葡萄球菌污染。用PFGE对分离株进行流行病学分析。70株鸡分离株产生15种不同的(A-O)型。在鸡体内发现了不同的金黄色葡萄球菌基因类型。29株猪肉分离株产生3种(A，O，Q)带型。有趣的是，在鸡肉(n=18)和猪肉(n=24)中最常见的是具有相同模式A的金黄色葡萄球菌。此外，在整个调查过程中，从鸡肉和猪肉中反复分离到A型。

Staphylococcus aureus coagulase type VII strains have been the strains most frequently isolated from staphylococcal food poisoning outbreaks in Japan. We applied pulsed-field gel electrophoresis (PFGE) of chromosomal DNA digested with Smal to characterize 129 coagulase type VII strains. These were isolated from 129 cases occurring in outbreaks in 35 districts of Tokyo during a 16-year period (1980-1995). The 129 outbreak strains were classified into three types, designated A(n=115), B(n=10), and C(n=4). Types A and C were further divided into 33(A1 to A33) and 4(C1 to C4) subtypes, respectively. Strains of the same subtypes were isolated from food poisoning cases in the same districts at time intervals of 1 or 2 to 5 years. PFGE typing appears to be a useful method for subdividing strains of S.aureus coagulase type VII.A combination of coagulase typing and PFGE typing would provide more detailed information than the former method alone in epidemiologic investigations of staphylococcal food poisoning. During the period from January to June in 1998, a total of 180 raw meat samples comprising 100 chicken and 80 pork samples purchased from a supermarket in Hyogo Prefecture were examined for the presence of S.aureus. It was found that 70 (70%) chicken and 29(36%) pork samples were contaminated with S.aureus. PFGE was applied for epidemiological analysis of the isolates. Seventy chicken isolates produced 15 (A-O) different patterns. Various genotypes of S.aureus were found in the chicken. Twenty-nine pork isolates produced 3(A, O, Q) patterns. Interestingly, S.aureus showing the same pattern A was detected most frequently in both the chicken (n=18) and the pork (n=24). In addition, pattern A was isolated repeatedly from the chicken and pork throughout the investigation.