Antimicrobial therapy for methicillin-resistant Staphylococcus aureus colonization in residents and staff of a Veterans Affairs nursing home care unit.
OBJECTIVE
To evaluate the effect of antimicrobial therapy on patients and staff colonized with methicillin-resistant Staphylococcus aureus (MRSA) in a skilled nursing facility and to assess the role of the environment as a potential reservoir for MRSA in the nursing home setting.


METHODS
As part of a comprehensive program to control an MRSA outbreak in a nursing home, patients and staff colonized with MRSA received 1 of 3 antimicrobial decolonization regimens depending upon the site and extent of colonization. Followup cultures were performed during therapy and on days 2, 7, 14, and 30 following the completion of therapy. Cultures of the patients' inanimate environment (pajamas, sheet, and floor) were obtained during and after therapy. Antimicrobial susceptibility tests were performed on 54 MRSA isolates obtained before and 44 MRSA isolates recovered after therapy.


METHODS
A 120-bed Veterans Affairs nursing home care unit.


METHODS
Thirty-six patients and 7 staff nurses colonized with MRSA at 1 or more sites.


METHODS
Decolonization therapy with rifampin, trimethoprim-sulfamethoxazole, and clindamycin used alone or in various combinations for 5 or 10 days in conjunction with other infection control measures employed to combat the MRSA outbreak.


RESULTS
Twenty (56%) of the 36 NHCU patients were either persistently colonized or became recolonized with MRSA during the 30-day followup period. Positive cultures on day 3 during therapy frequently identified patients who subsequently exhibited persistent or recurrent colonization. Before therapy, 92% of MRSA isolates were susceptible to rifampin, whereas only 43% of the isolates obtained after therapy were susceptible. Sixteen (80%) of 20 patients with persistent or recurrent colonization had rifampin-resistant strains of MRSA isolated after therapy. Twenty-three (18%) of 125 environmental cultures obtained during and after therapy from patients who exhibited persistent or recurrent colonization were positive for MRSA, in contrast to 9 (8%) of 107 from patients who were successfully decolonized.


CONCLUSIONS
The decolonization component of the outbreak control program was judged to be ineffective and potentially hazardous because colonization persisted or recurred in more than half of the patients, and substantial antimicrobial resistance was noted in MRSA stains isolated after therapy. Resistance, especially to rifampin, and possibly re-acquisition of MRSA from other human or environmental sources were 2 factors that appeared to impede the decolonization effort.
Strausbaugh
L J
LJ
Infectious Disease Section, Medical Service, Oregon Health Sciences University, Portland.
Jacobson
C
C
Sewell
D L
DL
Potter
S
S
Ward
T T
TT
D000368:Aged; D000369:Aged, 80 and over; D002981:Clindamycin / Q000627:therapeutic use*; D015169:Colony Count, Microbial; D004197:Disease Reservoirs; D006801:Humans; D017053:Infection Control / Q000379:methods*; D008297:Male; D016106:Methicillin Resistance; D008875:Middle Aged; D009740:Nursing Staff; D009922:Oregon; D012008:Recurrence; D012293:Rifampin / Q000627:therapeutic use*; D012866:Skilled Nursing Facilities; D013203:Staphylococcal Infections / Q000188:drug therapy*; D013211:Staphylococcus aureus / Q000302:isolation & purification; D015662:Trimethoprim, Sulfamethoxazole Drug Combination / Q000627:therapeutic use*; D014481:United States; D014493:United States Department of Veterans Affairs
D002981:Clindamycin; D015662:Trimethoprim, Sulfamethoxazole Drug Combination; D012293:Rifampin