Active surveillance testing and decontamination strategies in intensive care units to reduce methicillin-resistant Staphylococcus aureus infections.
BACKGROUND
Active surveillance testing (AST) and decontamination strategies (DS) using a topical methicillin-resistant Staphylococcus aureus (MRSA) cleansing agent was introduced in July 2007 in a medical intensive care unit (MICU) and a surgical ICU (SICU) of a tertiary care hospital to reduce the incidence of MRSA infection.


METHODS
Data on ICU admissions between July 1, 2007, and June 30, 2008, was analyzed. All subjects, excluding known MRSA status, had an ICU length of stay (LOS) of more than 24 hours and nasal swabs performed on ICU admission, every 7 days during the ICU stay, and on discharge. MICU and SICU specimens were sent for culture and in-house real-time polymerase chain reaction, respectively. MRSA-colonized (MRSAc) patients were subjected to contact isolation precautions and DS for 5 days or until ICU discharge. Data recorded included demographics, LOS, and antibiotic use. Results were analyzed using SPSS. Control charts were used to determine special cause variation.


RESULTS
Of 653 eligible patients admitted to the ICU, 85 (13%) were determined to be MRSAc on ICU admission. A further 15% (52 of 351) were determined to be MRSAc during the ICU stay or at discharge. Thus, AST detected MRSA in at least 137 of the 653 patients (21.0%). In contrast, clinical cultures for MRSA were positive in only 12 patients (1.8%). Compared with noncolonized patients, MRSAc patients at any screening point had a longer pre-ICU LOS (P =.001), received more antibiotics (P = .004), and had a longer ICU LOS (P = .003). Compared with the preintervention period of July 2006 to June 2007, there was no significant reduction in mean MRSA infection incidence rate in both ICUs (3.8 to 3.0 per 1000 patient-days [P = .057] in the SICU and 1.4 to 1.7 per 1000 patient-days in the MICU) following intervention.


CONCLUSIONS
In ICUs, AST detected 11 times more MRSA than clinical cultures. The lack of reduction in MRSA infection rates in the ICUs does not negate the roles of AST and DS, but does argue for better study design and outcome measures like MRSA transmission incidence, which perhaps would have demonstrated a true benefit of AST and DS.
Kurup
Asok
A
Department of Infectious Diseases, Singapore General Hospital, Singapore. asok.kurup@sgh.com.sg
Chlebicka
Nidhi
N
Tan
Kwee Yuen
KY
Chen
Eileen Xueqin
EX
Oon
Lynette
L
Ling
Tan Ai
TA
Ling
Moi Lin
ML
Hong
Jenny Low Guek
JL
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003428:Cross Infection / Q000453:epidemiology / Q000517:prevention & control*; D003666:Decontamination / Q000379:methods*; D004866:Equipment Contamination; D005260:Female; D006801:Humans; D007362:Intensive Care Units; D008297:Male; D055624:Methicillin-Resistant Staphylococcus aureus / Q000302:isolation & purification*; D008875:Middle Aged; D010356:Patient Isolation; D013203:Staphylococcal Infections / Q000453:epidemiology / Q000517:prevention & control*; D055815:Young Adult