Sensitivity and Specificity of prior Methicillin-Resistant Staphylococcus aureus Nasal Swab Results for Predicting...

Area of Science:

• Infectious Diseases
• Clinical Microbiology
• Hospital Epidemiology

Background:

• Methicillin-resistant Staphylococcus aureus (MRSA) remains a significant global pathogen, frequently necessitating empiric treatment in hospitalized patients.
• Previous studies indicate that MRSA nasal swab colonization has a high negative predictive value (NPV) for MRSA infections, particularly in respiratory cases.
• The predictive value of a prior MRSA nasal swab for subsequent infections in intensive care unit (ICU) settings requires further investigation.

Purpose of the Study:

• To evaluate the predictive value of a previous ICU MRSA nasal swab result on subsequent ICU admissions within the same patient.
• To assess the predictive accuracy of a prior MRSA nasal swab for MRSA infection during a later ICU stay.

Main Methods:

• Retrospective chart review of adult patients admitted to a tertiary care hospital with MRSA nasal swabs and ICU stays exceeding 24 hours.
• Patients were matched to individuals admitted to the same ICU within the following year.
• Data collected included demographics, clinical information, MRSA swab results, and MRSA infection status during both hospitalizations. Predictive values were calculated using 2x2 tables.

Main Results:

• Seventy-seven patients with MRSA swabs on two separate ICU admissions were successfully matched.
• The negative predictive value (NPV) of a prior MRSA nasal swab for predicting MRSA infection during a subsequent ICU stay was 96%.

Conclusions:

• A previous negative MRSA nasal swab demonstrated a high NPV for predicting the absence of MRSA infection in a subsequent ICU admission within a one-year period.
• These findings suggest that a prior negative MRSA nasal swab may be a useful tool for risk stratification and management decisions regarding MRSA in hospitalized patients.