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Linezolid dependence in Staphylococcus epidermidis bloodstream isolates
Spyros Pournaras1, Eleni Ntokou, Olympia Zarkotou
1Department of Microbiology, University of Thessaly Medical School, Larissa, Greece. pournaras@med.uth.gr
Emerging Infectious Diseases
|December 25, 2012
Summary
We found that some Staphylococcus epidermidis strains highly resistant to linezolid (LRSE) actually depend on this antibiotic for growth. This linezolid dependence may explain the increasing emergence of LRSE infections.
Area of Science:
- Microbiology
- Molecular Biology
- Antimicrobial Resistance
Background:
- Linezolid is a crucial antibiotic for treating infections caused by Gram-positive bacteria, including methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE).
- Emergence of linezolid-resistant Staphylococcus epidermidis (LRSE) poses a significant threat to clinical treatment efficacy.
- Mechanisms underlying linezolid resistance and its clinical implications are not fully understood.
Purpose of the Study:
- To investigate the phenomenon of linezolid dependence in highly linezolid-resistant Staphylococcus epidermidis (LRSE) bloodstream isolates.
- To identify the genetic mutations associated with linezolid dependence in these isolates.
- To explore the potential role of linezolid dependence in the increasing emergence of LRSE.
Main Methods:
- Phenotypic characterization of LRSE isolates under varying linezolid concentrations.
- Genomic analysis to identify mutations in 23S rRNA genes and ribosomal protein L3 (rplL).
- Assessment of bacterial growth rates in the presence of linezolid.
Main Results:
- Five highly linezolid-resistant Staphylococcus epidermidis bloodstream isolates exhibited significant growth enhancement in the presence of 32 µg/mL linezolid, indicating linezolid dependence.
- These dependent isolates harbored specific mutations: T2504A and C2534T in multiple 23S rRNA gene copies.
- Additionally, two mutations resulting in amino acid substitutions within the L3 ribosomal protein were identified.
Conclusions:
- Linezolid dependence is a documented phenomenon in highly linezolid-resistant Staphylococcus epidermidis.
- The identified mutations in 23S rRNA and L3 protein are associated with this dependence.
- This linezolid dependence mechanism may contribute to the increasing prevalence of linezolid-resistant Staphylococcus epidermidis infections, necessitating further investigation and surveillance.
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