Linezolid-resistant Staphylococcus aureus isolated from 2006 through 2008 at six hospitals in Japan.
Limited use of linezolid for treating methicillin-resistant Staphylococcus aureus (MRSA) infection was approved in Japan in 2006. We report here the status of linezolid-resistant MRSAs in Japan. Eleven linezolid-resistant clinical isolates from 11 patients at six hospitals were collected from 2006 through 2008. The minimal inhibitory concentration (MIC) of linezolid in these strains varied from 8 to 64 μg/ml. All strains had at least one G2576T mutation in the chromosomal gene(s) encoding domain V of the 23S ribosomal RNA (rRNA). Chromosomal DNA encoding five copies of the domain V region was analyzed by polymerase chain reaction (PCR). Strains with the linezolid MICs of 64, 32, 16, and 8 μg/ml had the G2576T mutation(s) in four, three (or four), two, and one copy of the 23S rRNA genes, respectively. These results suggest that the level of linezolid resistance seems to be roughly correlated with the number of mutations in the genes encoding 23S rRNA. DNA samples from all 11 strains were subjected to pulsed-field gel electrophoresis and were classified into seven independent clones having >92% identity. Among the 11 patients, five had been treated with linezolid and the remainder, in two hospitals, had no history of prior linezolid use. The results suggested possible nosocomial infections by linezolid-resistant MRSA.
Ikeda-Dantsuji
Yurika
Y
Research Center for Anti-Infectious Drugs, Kitasato Institute for Life Sciences, Kitasato University, Tokyo, Japan.
Hanaki
Hideaki
H
Sakai
Fuminori
F
Tomono
Kazunori
K
Takesue
Yoshio
Y
Honda
Junichi
J
Nonomiya
Yuriko
Y
Suwabe
Akira
A
Nagura
Osanori
O
Yanagihara
Katsunori
K
Mikamo
Hiroshige
H
Fukuchi
Kunihiko
K
Kaku
Mitsuo
M
Kohno
Shigeru
S
Yanagisawa
Chie
C
Nakae
Taiji
T
Yoshida
Koichiro
K
Niki
Yoshihito
Y
D000081:Acetamides / Q000494:pharmacology* / Q000627:therapeutic use; D000900:Anti-Bacterial Agents / Q000494:pharmacology* / Q000627:therapeutic use; D003428:Cross Infection; D004269:DNA, Bacterial / Q000235:genetics; D024901:Drug Resistance, Multiple, Bacterial; D016521:Electrophoresis, Gel, Pulsed-Field; D006761:Hospitals; D006801:Humans; D007564:Japan; D000069349:Linezolid; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects* / Q000235:genetics; D008826:Microbial Sensitivity Tests; D023303:Oxazolidinones / Q000494:pharmacology* / Q000627:therapeutic use; D016133:Polymerase Chain Reaction; D012338:RNA, Ribosomal, 23S / Q000235:genetics; D013203:Staphylococcal Infections / Q000188:drug therapy / Q000382:microbiology*
D000081:Acetamides; D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D023303:Oxazolidinones; D012338:RNA, Ribosomal, 23S; D000069349:Linezolid