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Types of methicillin-resistant Staphylococcus aureus associated with high mortality in patients with bacteremia
1Department of Clinical Laboratory Medicine, Nagoya University Hospital, Japan.
Abstract:
Forty-seven strains of methicillin-resistant Staphylococcus aureus (MRSA) isolated from 47 patients with bacteremia were analyzed by chromosomal DNA digestion pattern using pulsed-field gel electrophoresis and evaluated for serological coagulase type, enterotoxin type, and toxic shock syndrome toxin-1 production. The mortality rate was significantly higher in the older patients (> or = 51 years of age) than in the younger patients (< or = 50 years of age) (50% vs. 4%, p = 0.0007). Methicillin-resistant Staphylococcus aureus strains of serological coagulase type II were more likely to be associated with mortality in older patients than were strains of the other types (p = 0.037).
Insights
Older patients with bacteremia face higher mortality from methicillin-resistant Staphylococcus aureus (MRSA) infections. Specific MRSA strains, particularly serological coagulase type II, are linked to increased mortality in elderly patients.
Area of Science:
- Medical Microbiology
- Infectious Diseases
- Epidemiology
Background:
- Methicillin-resistant Staphylococcus aureus (MRSA) is a significant cause of hospital-acquired infections.
- Bacteremia due to MRSA is associated with high morbidity and mortality rates.
- Understanding strain characteristics and patient factors influencing outcomes is crucial for effective treatment.
Purpose of the Study:
- To investigate the relationship between MRSA strain characteristics and patient outcomes in bacteremia.
- To identify specific MRSA types associated with increased mortality.
- To analyze the impact of patient age on MRSA bacteremia mortality.
Main Methods:
- Pulsed-field gel electrophoresis (PFGE) for chromosomal DNA fingerprinting of MRSA strains.
- Serological typing for coagulase and enterotoxin types.
- Detection of toxic shock syndrome toxin-1 production.
- Statistical analysis comparing mortality rates based on patient age and MRSA strain characteristics.
Main Results:
- A significantly higher mortality rate was observed in older patients (≥51 years) compared to younger patients (≤50 years) (50% vs. 4%, p=0.0007).
- MRSA strains of serological coagulase type II were significantly associated with mortality in older patients (p=0.037).
- No significant association was found between enterotoxin type or TSST-1 production and mortality in this cohort.
Conclusions:
- Patient age is a critical factor influencing mortality in MRSA bacteremia.
- Specific MRSA serological coagulase types, particularly type II, may represent a higher risk for mortality in elderly patients.
- Further research into MRSA strain virulence factors and host-pathogen interactions is warranted.