single-nucleotide polymorphism genotyping identifies a locally endemic clone of methicillin-resistant staphylococcus aureus单核苷酸多态性的基因识别本地流行克隆耐甲氧西林金黄色葡萄球菌.pdf

Single-Nucleotide Polymorphism Genotyping Identifies a Locally Endemic Clone of Methicillin-Resistant Staphylococcus aureus ¨ 1 2 1 1 1 Ulrich Nubel *, Andreas Nitsche , Franziska Layer , Birgit Strommenger , Wolfgang Witte ¨ 1 Fachgebiet Nosokomiale Infektionen, Robert Koch-Institut, Wernigerode, Germany, 2 Zentrum fur Biologische Sicherheit, Robert Koch-Institut, Berlin, Germany Abstract We developed, tested, and applied a TaqMan real-time PCR assay for interrogation of three single-nucleotide polymorphisms that differentiate a clade (termed ‘t003-X’) within the radiation of methicillin-resistant Staphylococcus aureus (MRSA) ST225. The TaqMan assay achieved 98% typeability and results were fully concordant with DNA sequencing. By applying this assay to 305 ST225 isolates from an international collection, we demonstrate that clade t003-X is endemic in a single acute-care hospital in Germany at least since 2006, where it has caused a substantial proportion of infections. The strain was also detected in another hospital located 16 kilometers away. Strikingly, however, clade t003-X was not found in 62 other hospitals throughout Germany nor among isolates from other countries, and, hence, displayed a very restricted geographical distribution. Consequently, our results show that SNP-typing may be useful to identify and track MRSA clones that are specific to individual healthcare institutions. In contrast, the spatial dissemination pattern observed here had not been resolved by other typing procedures, including multilocus sequence typing (MLST), spa typing, DNA macrorestriction,