Antimicrobial use and methicillin-resistant Staphylococcus aureus in a large nursing home.
BACKGROUND
In 1997, 18% of Staphylococcus aureus clinical isolates at the Wisconsin Veterans Home were resistant to methicillin. By 2002, 51% were resistant.


METHODS
We determined the antibiotic sensitivity pattern of our methicillin-resistant S. aureus (MRSA) isolates as well as changes in utilization of specific antibiotics between two time periods. We reasoned that antibiotics with activity against methicillin-sensitive S. aureus (MSSA), but not MRSA, might be driving the overgrowth of MRSA.


RESULTS
In our facility, MRSA is usually resistant to quinolones; MSSA is usually sensitive. Both MSSA and MRSA are usually sensitive to TMP-sulfa. An increased percentage of S. aureus resistant to methicillin (18%) was associated with a 42% increase in quinolone use and a 37% decrease in TMP-sulfa use.


CONCLUSIONS
Our analysis and previous reports suggest that replacement of TMP-sulfa by quinolones could be selecting MRSA in our facility. This conclusion, however, is speculative, based on association, and requires confirmation.
Drinka
Paul J
PJ
Wisconsin Veterans Home, King, Wisconsin 54946-0620, USA. Paul.Drinka@dva.state.wi.us
Gauerke
Cathy
C
Le
Debbie
D
D000368:Aged; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D004352:Drug Resistance, Microbial; D005260:Female; D006801:Humans; D008134:Long-Term Care; D008297:Male; D016106:Methicillin Resistance; D008826:Microbial Sensitivity Tests; D009735:Nursing Homes; D013203:Staphylococcal Infections / Q000188:drug therapy* / Q000382:microbiology; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000302:isolation & purification / Q000472:pathogenicity*; D014922:Wisconsin
D000900:Anti-Bacterial Agents