Methicillin-resistant Staphylococcus aureus nasal colonization is a poor predictor of intensive care unit-acquired methicillin-resistant Staphylococcus aureus infections requiring antibiotic treatment.
OBJECTIVE
To test whether intensive care unit (ICU) nasal screening for methicillin-resistant Staphylococcus aureus (MRSA) predicts the presence or absence of MRSA infections requiring antimicrobial treatment.


METHODS
A prospective cohort study.


METHODS
Medical ICU at Barnes-Jewish Hospital, a 1252-bed urban teaching hospital.


METHODS
Seven hundred forty-nine consecutive patients admitted to the medical ICU over a 7-mo period (November 2007 through June 2008).


METHODS
Nasal swabs were obtained at ICU admission and weekly thereafter for MRSA detection by using polymerase chain reaction. All subjects were followed for the development of MRSA infection during their ICU stay.


RESULTS
One hundred sixty-four (21.9%) patients had positive nasal colonization with MRSA at the time of ICU admission. The predictive accuracy of MRSA nasal colonization for ICU-acquired MRSA infections, either lower respiratory tract infection or bloodstream infection, was poor (lower respiratory tract infection: sensitivity, 24.2%; specificity, 78.5%; positive predictive value, 17.7%; and negative predictive value, 84.4%; and bloodstream infection: sensitivity, 23.1%; specificity, 78.2%; positive predictive value, 11.0%; and negative predictive value, 89.7%). Addition of nasal-colonization results obtained during the ICU stay did not appreciably change the predictive accuracy of this test for identification of subsequent lower respiratory tract infections and bloodstream infections attributed to MRSA requiring antimicrobial treatment.


CONCLUSIONS
In this analysis, nasal colonization with MRSA was found to be a poor predictor for the subsequent occurrence of MRSA lower respiratory tract infections and MRSA bloodstream infections requiring antimicrobial treatment. Clinicians should be cautious in using the results of nasal-colonization testing to determine the need for MRSA treatment among patients with ICU-acquired infections.
Sarikonda
Kiran V
KV
Division of Pulmonary and Critical Care Medicine, Washington University School of Medicine, St. Louis, MO, USA.
Micek
Scott T
ST
Doherty
Joshua A
JA
Reichley
Richard M
RM
Warren
David
D
Kollef
Marin H
MH
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D003428:Cross Infection / Q000188:drug therapy / Q000382:microbiology*; D005260:Female; D006801:Humans; D007362:Intensive Care Units / Q000706:statistics & numerical data*; D008297:Male; D055624:Methicillin-Resistant Staphylococcus aureus; D008875:Middle Aged; D009296:Nasal Cavity / Q000382:microbiology*; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012372:ROC Curve; D012680:Sensitivity and Specificity; D013203:Staphylococcal Infections / Q000188:drug therapy* / Q000382:microbiology; D014640:Vancomycin / Q000627:therapeutic use; D055815:Young Adult
D000900:Anti-Bacterial Agents; D014640:Vancomycin