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[Molecular study of 6 episodes of nosocomial infections produced by methicillin resistant Staphylococcus aureus]
G Kaltwasser1, M L Rioseco, A M Salinas
1Laboratorio de Microbiología Clínica CEDIUC, Facultad de Medicina, P Universidad Católica de Chile, Santiago de Chile.
Abstract:
A critical step in any epidemiologic research concerning nosocomial infections is the precise identification of the responsible pathogen. The present work utilized a molecular approach -plasmids identification, restriction length polymorphism DNA analysis, and random amplified polymorphic DNA- for the characterization of 6 nosocomial outbreaks due to 52 strains of methicillin-resistant Staphylococcus aureus (MRSA). In these episodes, the clinic-epidemiologic and phenotypic analysis (antibiotype) pointed to a nosocomial infection. Through molecular analysis it was possible to establish, in a very precise way, clonality due to MRSA strains in 2 of the studied outbreaks; the same type of analysis allowed to eliminate a MRSA clonal origin in the remainder 4 episodes. The antibiogram was not an useful analytic tool due to its poor discriminatory power. Also, through a PCR procedure, it was possible to identify the presence of the gen mecA in every of the 52 MRSA strains studied.
Insights
Molecular methods precisely identified methicillin-resistant Staphylococcus aureus (MRSA) clonality in nosocomial outbreaks. Antibiotype analysis proved ineffective for distinguishing MRSA strains, highlighting the utility of molecular techniques in infection control.
Area of Science:
- Microbiology
- Epidemiology
- Molecular Biology
Context:
- Nosocomial infections pose significant healthcare challenges.
- Accurate pathogen identification is crucial for effective epidemiologic research.
- Methicillin-resistant Staphylococcus aureus (MRSA) is a common cause of hospital-acquired infections.
Purpose:
- To characterize 6 nosocomial outbreaks caused by 52 MRSA strains using molecular techniques.
- To evaluate the utility of molecular methods versus traditional antibiotype analysis in outbreak investigations.
- To confirm the presence of the mecA gene in all studied MRSA strains.
Summary:
- Molecular approaches, including plasmid identification, restriction fragment length polymorphism (RFLP) DNA analysis, and random amplified polymorphic DNA (RAPD), were employed.
- Molecular analysis confirmed clonality in 2 MRSA outbreaks and ruled it out in 4 others.
- Antibiogram analysis showed poor discriminatory power, while PCR confirmed the presence of the mecA gene in all 52 MRSA strains.
Impact:
- Demonstrates the superiority of molecular typing over antibiograms for precise MRSA strain characterization in nosocomial outbreaks.
- Provides valuable insights into the clonal spread of MRSA within healthcare settings.
- Highlights the importance of molecular tools for accurate infection control and epidemiology.