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Persistent bacteremia due to methicillin-resistant Staphylococcus aureus infection is associated with agr dysfunction

Vance G Fowler1, George Sakoulas, Lauren M McIntyre

  • 1Department of Medicine, Division of Infectious Diseases, Duke University Medical Center, Durham, NC 27710, USA. vance.fowler@duke.edu

The Journal of Infectious Diseases
|August 21, 2004
PubMed
Abstract

Insights

Persistent bacteremia (PB) from methicillin-resistant Staphylococcus aureus (MRSA) is linked to specific bacterial traits. Isolates from PB patients showed higher in vitro survival, defective delta-lysin, non-agr genotype II, and a distinct PFGE type.

Area of Science:

  • Infectious Diseases
  • Microbiology
  • Clinical Medicine

Background:

  • Persistent bacteremia (PB) caused by methicillin-resistant Staphylococcus aureus (MRSA) has poorly understood origins.
  • This study investigates associations between PB, clinical features, and bacterial characteristics in MRSA isolates.

Purpose of the Study:

  • To identify in vitro bacterial genotypic and phenotypic characteristics associated with persistent bacteremia (PB) in MRSA infections.
  • To compare these characteristics between MRSA isolates from patients with PB and those with resolving bacteremia (RB).

Main Methods:

  • MRSA isolates from 21 PB patients and 18 RB patients were analyzed.
  • Assessed characteristics included pulsed-field gel electrophoresis (PFGE) relatedness, thrombin-induced platelet microbicidal protein (tPMP) susceptibility, accessory gene regulator (agr) genotype and functionality (delta-lysin production), and autolysis phenotypes.

Main Results:

  • Isolates from PB patients showed significantly higher in vitro survival after tPMP exposure (P=.005).
  • PB isolates also exhibited higher rates of defective delta-lysin production (P=.057), non-agr genotype II (P=.037), and a specific PFGE genotype (P=.015) compared to RB isolates.
  • Endocarditis was more frequent in PB patients (43%) than RB patients (0%) (P=.0016).

Conclusions:

  • MRSA isolates from patients with persistent bacteremia exhibit distinct in vitro genotypic and phenotypic characteristics compared to those with resolving bacteremia.
  • These bacterial factors may play a role in the development and persistence of MRSA bacteremia, warranting further investigation into their impact on clinical outcomes.

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