Nationwide epidemiological study revealed the dissemination of meticillin-resistant Staphylococcus aureus carrying a specific set of virulence-associated genes in Japanese hospitals.
To study comprehensive toxin profiles and the chromosomal diversity of current Japanese hospital-associated meticillin-resistant Staphylococcus aureus (HA-MRSA) strains, we conducted PCR-based identification of 28 toxin genes, and staphylococcal cassette chromosome mec (SCCmec) typing and PFGE analysis of 208 MRSA strains isolated from 100 hospitals throughout Japan. Of the tested HA-MRSA strains, 80.3 % were tst-positive. The most frequent toxin gene profile was characterized by the carriage of 13 genes, tst, sec, seg, sei, sel, sem, sen, seo, lukED, hla, hlb, hld and hlg-2. Ninety of the 208 strains had this profile, which was named pattern A. Among the 118 non-pattern A strains, 100 had similar toxin gene profiles, the concordance rates to pattern A of which were more than 80 %. Consequently, 91.3 % of the examined HA-MRSA strains carried similar toxin profiles, although PFGE patterns showed a wide variation. These strains belonged to SCCmec type II, agr II and coagulase type II. We concluded that, unlike MRSA from many other countries, most of the Japanese HA-MRSA strains belonged to, or were related to, a specific group carrying the set of 13 toxin genes, irrespective of chromosomal diversity. In addition, among the 13 toxin genes, the coexistence rates of tst, sec and sel, and those of seg, sei, sem, sen and seo, were higher than for the other toxin genes. High coexistence rates of tst, sec and sel genes suggested the presence of the pathogenicity island SaPIn1 in these strains.
Ohkura
Teruko
T
Department of Bacteriology, Nagoya University Graduate School of Medicine, Nagoya, Aichi, Japan.
Yamada
Keiko
K
Department of Bacteriology, Nagoya University Graduate School of Medicine, Nagoya, Aichi, Japan.
Okamoto
Akira
A
Department of Bacteriology, Nagoya University Graduate School of Medicine, Nagoya, Aichi, Japan.
Baba
Hisashi
H
Department of Infectious Diseases, Nagoya University Hospital, Nagoya, Aichi, Japan.
Ike
Yasuyoshi
Y
Department of Bacteriology and Bacterial Infection Control, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan.
Arakawa
Yoshichika
Y
Department of Bacterial Pathogenesis and Infection Control, National Institute of Infectious Diseases, Musashimurayama, Tokyo, Japan.
Hasegawa
Tadao
T
Department of Bacteriology, Nagoya City University, School of Medical Sciences, Nagoya, Aichi, Japan.
Ohta
Michio
M
Department of Bacteriology, Nagoya University Graduate School of Medicine, Nagoya, Aichi, Japan.
D001427:Bacterial Toxins / Q000235:genetics; D001483:Base Sequence; D002876:Chromosomes, Bacterial / Q000235:genetics; D003428:Cross Infection / Q000188:drug therapy / Q000453:epidemiology* / Q000382:microbiology*; D017931:DNA Primers / Q000235:genetics; D004269:DNA, Bacterial / Q000235:genetics; D016521:Electrophoresis, Gel, Pulsed-Field; D005798:Genes, Bacterial; D006801:Humans; D007564:Japan / Q000453:epidemiology; D016106:Methicillin Resistance / Q000235:genetics*; D055624:Methicillin-Resistant Staphylococcus aureus / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification / Q000472:pathogenicity; D017720:Molecular Epidemiology; D013203:Staphylococcal Infections / Q000188:drug therapy / Q000453:epidemiology* / Q000382:microbiology*; D014774:Virulence / Q000235:genetics
D001427:Bacterial Toxins; D017931:DNA Primers; D004269:DNA, Bacterial