Nosocomial spread of meticillin-resistant Staphylococcus aureus with β-lactam-inducible arbekacin resistance.
A meticillin-resistant Staphylococcus aureus (MRSA) strain with additional β-lactam-inducible aminoglycoside resistance was previously reported by a group at the Kitasato University in Japan. In addition to gentamicin, the 'Kitasato strain' was resistant to arbekacin (ABK), which is primarily used as an anti-MRSA aminoglycoside. No further studies regarding the spread of MRSA strains with the newly identified resistance mechanism have been reported to date. To obtain epidemiological data on MRSA strains with the antagonistic resistance and to analyse their genetic features, we examined the emergence of β-lactam-inducible ABK-resistant MRSA strains at our university hospital using longitudinal analysis. Among the 396 isolates, 35 (8.8 %) were found to be ABK-resistant MRSA strains (the resistance being induced by β-lactams). Moreover, based on the pulsed-field gel electrophoresis profiles, the clonality of those MRSA strains changed at different time periods. In the Kitasato strain, the antagonistic mechanism was clearly demonstrated by the integration of transposable elements; a Tn4001-IS257 hybrid structure that contained an aminoglycoside resistance gene cointegrated into a region downstream of the β-lactamase gene. In most of the MRSA strains detected in our study, the antagonistic interaction was explained by the same mechanism as that found in the Kitasato strain. Interestingly, sequence analysis showed that all of our strains carried IS257 insertion sites which were different from those of the Kitasato strain. This study shows that MRSA strains with the additional antagonistic resistance are not uncommon and have been increasingly disseminating in clinical settings.
Medicine and Biosystemic Science, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan.
Yukiko
Y
Harada
Medicine and Biosystemic Science, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan.
Yong
Y
Chong
Center for the Study of Global Infection, Kyushu University Hospital, Fukuoka, Japan.
Nobuyuki
N
Shimono
Medicine and Biosystemic Science, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan.
Noriko
N
Miyake
Department of Infection Control, Hamanomachi General Hospital, Fukuoka, Japan.
Yujiro
Y
Uchida
Department of Clinical Chemistry and Laboratory Medicine, Kyushu University Hospital, Fukuoka, Japan.
Masako
M
Kadowaki
Medicine and Biosystemic Science, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan.
Koichi
K
Akashi
Medicine and Biosystemic Science, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan.
Shinji
S
Shimoda
D000900:Anti-Bacterial Agents / Q000378:metabolism; D003428:Cross Infection / Q000453:epidemiology / Q000382:microbiology*; D004251:DNA Transposable Elements; D003982:Dibekacin / Q000031:analogs & derivatives* / Q000378:metabolism; D024881:Drug Resistance, Bacterial; D016521:Electrophoresis, Gel, Pulsed-Field; D006801:Humans; D007564:Japan / Q000453:epidemiology; D055624:Methicillin-Resistant Staphylococcus aureus / Q000145:classification / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D008969:Molecular Sequence Data; D058889:Molecular Typing; D017422:Sequence Analysis, DNA; D013203:Staphylococcal Infections / Q000453:epidemiology / Q000382:microbiology*; D015533:Transcriptional Activation / Q000187:drug effects*; D047090:beta-Lactams / Q000378:metabolism*
D000900:Anti-Bacterial Agents; D004251:DNA Transposable Elements; D047090:beta-Lactams; D003982:Dibekacin; C031986:arbekacin