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Published on: February 15, 2013
Evaluating Methicillin-Resistant Staphylococcus aureus Polymerase Chain Reaction Nasal Screening as a Tool for
Kristy Bono1, Jorge A Caceda1, Merry Zhai1
1Rutgers New Jersey Medical School, Newark, New Jersey.
Introduction:
Initiation of broad-spectrum empiric antibiotics is common when infection is suspected in hospitalized adults. The benefits of early utilization of effective antibiotics are well documented. However, the negative effects of inappropriate antibiotic use have led to antimicrobial stewardship mandates. Recent data demonstrate the utility of methicillin-resistant Staphylococcus aureus (MRSA) polymerase chain reaction (PCR) nasal screening to steward anti-MRSA empiric antibiotics in pneumonia. We hypothesize that MRSA PCR nasal swabs would also be effective to rule out other MRSA infection to effectively limit unnecessary antibiotics for any infectious source.
Methods:
We performed a single-center retrospective chart review of all adult patient encounters from October 2019-July 2021 with MRSA PCR nasal testing. We then reviewed all charts to evaluate for the presence of infections based on source cultures results, as the gold standard. Sensitivity, specificity, negative predictive value, and positive predictive value were calculated from 2 × 2 contingency tables.
Results:
Among all patients with MRSA nasal screening, 1189 patients had any infection. Prevalence of MRSA nasal carriage among patients screened was 12%. Prevalence of MRSA infection among all infections was 7.5%. MRSA nasal swabs demonstrated a negative predictive value of 100% for MRSA urinary tract infection, 97.9% for MRSA bacteremia, 97.8% for MRSA pneumonia, 92.1% for MRSA wound infection, and 96.6% for other MRSA infections. Overall, MRSA PCR nasal swabs had a sensitivity of 68.5%, specificity of 90.1%, positive predictive value of 23.7%, and negative predictive value of 98.5% for any infections.
Conclusions:
MRSA PCR nasal swabs have a high negative predictive value for all infections. Our data support the use of MRSA PCR nasal swabs to rule out MRSA infection and thereby allow early de-escalation of MRSA coverage in hospitalized patients requiring empiric antibiotics. Implementation of MRSA screening could decrease antibiotic-associated morbidity, resistance, and costs. More studies should be conducted to validate these results and support these findings.
Insights
Methicillin-resistant Staphylococcus aureus (MRSA) PCR nasal swabs effectively rule out MRSA infections in hospitalized patients. This supports early antibiotic de-escalation, reducing resistance and costs.
Area of Science:
- Infectious Diseases
- Clinical Microbiology
- Hospital Epidemiology
Background:
- Broad-spectrum antibiotics are frequently initiated for suspected infections in hospitalized adults.
- Antimicrobial stewardship is crucial due to negative effects of inappropriate antibiotic use.
- Methicillin-resistant Staphylococcus aureus (MRSA) polymerase chain reaction (PCR) nasal screening shows utility in pneumonia management.
Purpose of the Study:
- To evaluate the effectiveness of MRSA PCR nasal swabs in ruling out MRSA infections across all sources in hospitalized patients.
- To assess the potential of MRSA nasal screening to guide the de-escalation of empiric anti-MRSA antibiotics.
Main Methods:
- A single-center retrospective chart review of adult patient encounters from October 2019 to July 2021.
- MRSA PCR nasal testing was performed on all included patients.
- Infections were identified via source cultures, serving as the gold standard; diagnostic accuracy metrics were calculated.
Main Results:
- MRSA nasal swabs demonstrated a high negative predictive value (NPV) for various MRSA infections, including 100% for urinary tract infections and 97.8% for pneumonia.
- Overall, MRSA PCR nasal swabs showed a sensitivity of 68.5%, specificity of 90.1%, and an overall NPV of 98.5% for any MRSA infection.
- The prevalence of MRSA nasal carriage was 12%, and MRSA infection was present in 7.5% of all infections.
Conclusions:
- MRSA PCR nasal swabs possess a high NPV, supporting their use to rule out MRSA infections.
- Implementing MRSA nasal screening can facilitate early de-escalation of MRSA coverage, potentially decreasing antibiotic-associated morbidity, resistance, and healthcare costs.
- Further studies are recommended to validate these findings and support broader implementation.
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