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Ventilator-associated pneumonia by Staphylococcus aureus. Comparison of methicillin-resistant and
Abstract:
All episodes of ventilator-associated pneumonia (VAP) caused by Staphylococcus aureus were prospectively analyzed for a 30-mo period. Methicillin-sensitive S. aureus (MSSA) was isolated in 38 episodes and methicillin-resistant S. aureus (MRSA) in 11 others. The two groups were similar regarding sex, severity of underlying diseases, prior surgery, and presence of renal failure, diabetes, cardiopathy, and coma. MRSA-infected persons were more likely to have received steroids before developing infection (relative risk [RR] = 3.45, 95% confidence interval [CI] = 1.38-8.59), to have been ventilated > 6 d (RR = 2.03, 95% CI = 1.36-3.03), to have been older than 25 yr (RR = 1.50, 95% CI = 1.09-2.06), and to have had preceding chronic obstructive pulmonary disease (RR = 2.76, 95% CI = 0.89-8.56) than MSSA-infected patients. MSSA-infected persons were more likely than MRSA-infected patients to have cranioencephalic trauma (RR = 1.94, 95% CI = 1.22-3.09). All patients with MRSA VAP had previously received antibiotics, compared with only 21.1% of those with MSSA infection (p < 0.000001). The incidence of empyema was similar in both groups; nevertheless, the presence of bacteremia and septic shock was more frequent in the MRSA group. Finally, mortality directly related to pneumonia was significantly higher among patients with MRSA episodes (RR = 20.72, 95% CI = 2.78-154.35). This analysis was repeated for monomicrobial episodes, and the difference remained statistically significant. We conclude that MRSA and MSSA strains infect patients with different demographic profiles; previous antibiotic therapy is the most important risk factor for developing MRSA infection.(ABSTRACT TRUNCATED AT 250 WORDS)
Insights
Methicillin-resistant Staphylococcus aureus (MRSA) ventilator-associated pneumonia (VAP) is linked to different patient profiles and higher mortality than methicillin-sensitive S. aureus (MSSA) VAP. Previous antibiotic use is a key risk factor for MRSA VAP.
Area of Science:
- Infectious Diseases
- Critical Care Medicine
- Microbiology
Background:
- Ventilator-associated pneumonia (VAP) poses a significant threat in intensive care settings.
- Staphylococcus aureus, both methicillin-sensitive (MSSA) and methicillin-resistant (MRSA), are common VAP pathogens.
- Understanding distinct risk factors and outcomes for MSSA vs. MRSA VAP is crucial for targeted treatment.
Purpose of the Study:
- To compare the demographic profiles, clinical characteristics, and outcomes of VAP caused by MSSA versus MRSA.
- To identify specific risk factors associated with MRSA VAP.
- To evaluate the impact of MRSA VAP on mortality.
Main Methods:
- Prospective analysis of all VAP episodes caused by Staphylococcus aureus over 30 months.
- Comparison of patient characteristics, comorbidities, ventilation duration, and prior treatments between MSSA and MRSA VAP groups.
- Statistical analysis including relative risk (RR) and confidence intervals (CI) to assess differences.
Main Results:
- MRSA VAP patients were more likely to have received steroids, been ventilated longer (>6 days), be older (>25 years), and have prior chronic obstructive pulmonary disease.
- MSSA VAP patients were more likely to have cranioencephalic trauma.
- All MRSA VAP patients received prior antibiotics versus 21.1% of MSSA VAP patients (p < 0.000001).
- MRSA VAP was associated with higher rates of bacteremia, septic shock, and significantly increased mortality (RR = 20.72).
Conclusions:
- MRSA and MSSA strains infect patients with distinct demographic and clinical profiles.
- Previous antibiotic therapy is the most significant risk factor for developing MRSA VAP.
- MRSA VAP is associated with poorer outcomes, including higher mortality, compared to MSSA VAP.