title: Clonal spread of catalase-negative ST5/SCCmec II Staphylococcus aureus carrying the staphylococcal enterotoxin A (sea), staphylococcal enterotoxin b (seb), and toxic shock toxin (tst) virulence genes.
abstract: 17 catalase-negative methicillin-resistant Staphylococcus aureus (MRSA) isolates were recovered from respiratory specimens of patients at a 700-bed hospital in Korea. The goal of this study was to determine the molecular characteristics of catalase-negative MRSA strains in Korea for the first time. Characteristics that we explored included kat A gene mutation sequence, sequence type, staphylococcal cassette chromosome (SCC) mec subtype classification, and toxin gene profiles. All 17 isolates showed similar pulsed field gel electrophoresis (PFGE) pattern. Four mutations were identified in the kat A gene of a representative catalase-negative MRSA strain: A602G causing a histidine 201 to arginine change, A695T causing a glutamic acid 232 to valine change, T778A causing a tryptophan 260 to arginine change, and G1438A causing a glycine 480 to serine change. Previous studies suggest that the A695T and T778A mutations may have strong effects on the catalase activity of catalase-negative MRSA. The sequence type (ST) and SCCmec type of this isolate were ST 5 and SCCmec type II, respectively. All 17 isolates harbored toxic shock toxin (tst), staphylococcal enterotoxin A (sea), and staphylococcal enterotoxin B (seb) virulence genes. The mortality rate of the present study was 11.8%, suggesting that the clinical relevance of catalase-negative MRSA requires further study in the future.
authors.affiliation: Department of Laboratory Medicine, College of Medicine, The Catholic University of Korea, Seoul.
authors.forename: Hae Kyung
authors.initials: HK
authors.lastname: Lee
authors.affiliation: Division of Health Research & Planning, Gyeonggi-do Research Institute of Health & Environment.
authors.forename: Jung-Beom
authors.initials: JB
authors.lastname: Kim
authors.affiliation: Department of Laboratory Medicine, College of Medicine, The Catholic University of Korea, Seoul.
authors.forename: Hyunjung
authors.initials: H
authors.lastname: Kim
authors.affiliation: Department of Laboratory Medicine, College of Medicine, The Catholic University of Korea, Seoul.
authors.forename: Dong Wook
authors.initials: DW
authors.lastname: Jekarl
authors.affiliation: Department of Internal Medicine, College of Medicine, The Catholic University of Korea, Seoul, Korea.
authors.forename: Yang Ree
authors.initials: YR
authors.lastname: Kim
authors.affiliation: Department of Laboratory Medicine, College of Medicine, The Catholic University of Korea, Seoul.
authors.forename: Jin Kyung
authors.initials: JK
authors.lastname: Yu
authors.affiliation: Department of Laboratory Medicine, College of Medicine, The Catholic University of Korea, Seoul yjpk@catholic.ac.kr.
authors.forename: Yeon-Joon
authors.initials: YJ
authors.lastname: Park
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001427:Bacterial Toxins / Q000235:genetics*; D004252:DNA Mutational Analysis; D016521:Electrophoresis, Gel, Pulsed-Field; D004768:Enterotoxins / Q000235:genetics*; D005260:Female; D006801:Humans; D008297:Male; D055624:Methicillin-Resistant Staphylococcus aureus / Q000235:genetics* / Q000302:isolation & purification; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D009154:Mutation / Q000235:genetics; D056910:Republic of Korea; D013203:Staphylococcal Infections / Q000473:pathology; D018089:Superantigens / Q000235:genetics*
chemical_list: D001427:Bacterial Toxins; D004768:Enterotoxins; D018089:Superantigens; C030107:enterotoxin F, Staphylococcal; C026066:enterotoxin A, Staphylococcal; C031818:enterotoxin B, staphylococcal
keywords: SCCmec II type; catalase-negative methicillin-resistant Staphylococcus aureus; kat A gene mutation; virulence genes