Survey of high- and low-level mupirocin-resistant strains of methicillin-resistant Staphylococcus aureus in 15 Japanese hospitals.
BACKGROUND
The extent of mupirocin-resistant methicillin-resistant Staphylococcus aureus (MRSA) in countries using mupirocin only for the eradication of nasal carriage of MRSA is unknown.


METHODS
During 1997, 1998, 1999, 2000, and 2001, 1368 strains of MRSA were isolated from 15 general hospitals in the Tohoku area of Japan and tested for susceptibility to mupirocin.


RESULTS
The isolation of low-level mupirocin resistance was 0.8% in 1997, 1.1% in 1998, 0.7% in 1999, 4.0% in 2000, and 2.4% in 2001. For the first 3 years it was about 1%. However, the isolation rate of low-level mupirocin resistance in MRSA increased dramatically in 2000. High-level mupirocin resistance was not detected during these years.


CONCLUSIONS
Most patients from whom low-level mupirocin resistant MRSA were found in 2000 and 2001 had previously received mupirocin treatment for eradicating nasal carriage of MRSA, and these strains were isolated from sputum or the pharynx. This result indicates that mupirocin treatment is likely to be one of the causes of mupirocin resistance and, therefore, the development of low-level mupirocin resistance in MRSA isolated from sputum or the pharynx should be considered when using mupirocin in order to improve the control of the spread of MRSA in hospitals.
Fujimura
Shigeru
S
Department of Microbiology, Miyagi University, Miyagi, Japan. hujimura@myu.ac.jp
Watanabe
Akira
A
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D003428:Cross Infection / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology*; D024901:Drug Resistance, Multiple, Bacterial / Q000187:drug effects* / Q000235:genetics; D006769:Hospitals, General / Q000706:statistics & numerical data; D006801:Humans; D007564:Japan / Q000453:epidemiology; D016106:Methicillin Resistance / Q000235:genetics; D008826:Microbial Sensitivity Tests; D016712:Mupirocin / Q000494:pharmacology*; D009296:Nasal Cavity / Q000382:microbiology; D010614:Pharynx / Q000382:microbiology; D011159:Population Surveillance; D013183:Sputum / Q000382:microbiology; D013203:Staphylococcal Infections / Q000188:drug therapy* / Q000453:epidemiology / Q000382:microbiology; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D013492:Suppuration / Q000382:microbiology; D014556:Urine / Q000382:microbiology
D000900:Anti-Bacterial Agents; D016712:Mupirocin