Impact of β-Lactam Inoculum Effect on Staphylococcus aureus Endocarditis Outcomes
Author Information
Author(s): Jean Baptiste MD, Crolle Maelys PharmD, Pollani Candice PharmD, Le Guilloux Adèle, Martin-Blondel Guillaume PhD, Tattevin Pierre PhD, Le Bot Audrey MD, Luque Paz David MD, Guérin François PhD, Cattoir Vincent PhD, Armand-Lefevre Laurence PhD, Gueye Signara, Lescure François-Xavier PhD, Duval Xavier PhD, Massip Clémence PhD, Delobel Pierre PhD
Primary Institution: Centre Hospitalier Universitaire (CHU) de Toulouse, Université Paul Sabatier Toulouse III, Toulouse, France
Hypothesis
Is the clinical outcome of methicillin-susceptible Staphylococcus aureus (MSSA) infective endocarditis associated with some underappreciated phenotypic characteristics of the bacterial strains and the β-lactam used?
Conclusion
The presence of an inoculum effect to the β-lactam received was a risk factor for death in the first month of treatment for MSSA infective endocarditis.
Supporting Evidence
- First-month mortality in infective left-sided endocarditis due to MSSA strains was associated with the presence of blaZ and an inoculum effect.
- One-month mortality was higher in patients infected with blaZ-positive strains compared to blaZ-negative strains.
- The presence of an inoculum effect was independently associated with first-month mortality.
Takeaway
This study found that certain bacteria characteristics can affect how well treatments work for heart infections caused by Staphylococcus aureus, suggesting that doctors might need to choose treatments based on these characteristics.
Methodology
This retrospective case series evaluated MSSA infective endocarditis cases treated at 3 French hospitals, analyzing the association between bacterial characteristics and patient outcomes.
Potential Biases
Potential bias due to clinical severity influencing treatment choice and lack of systematic therapeutic drug monitoring.
Limitations
The study is retrospective and observational, which may introduce selection and information bias, and the sample size for subgroup analyses was limited.
Participant Demographics
Median age was 65 years, with 70.4% male and 14.8% intravenous drug users.
Statistical Information
P-Value
P = .01
Confidence Interval
95% CI, 1.28-6.30
Statistical Significance
p<0.05
Digital Object Identifier (DOI)
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