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Biosensor for Detection of Antibiotic Resistant Staphylococcus Bacteria
14:04

Biosensor for Detection of Antibiotic Resistant Staphylococcus Bacteria

Published on: May 8, 2013

Heteroresistance to glycopeptides in Italian meticillin-resistant Staphylococcus aureus (MRSA) isolates

Floriana Campanile1, Sonia Borbone, Marianna Perez

  • 1Department of Microbiology, University of Catania (I), Catania, Italy.

International Journal of Antimicrobial Agents
|August 24, 2010
PubMed

Insights

Heteroresistant vancomycin-intermediate Staphylococcus aureus (hVISA) are common in Italy. Macro Etest (MET) is a reliable method for detecting hVISA in MRSA infections, aiding early treatment.

Area of Science:

  • Microbiology
  • Infectious Diseases
  • Clinical Science

Background:

  • Methicillin-resistant Staphylococcus aureus (MRSA) poses a significant threat in healthcare settings.
  • Vancomycin is a critical antibiotic for treating MRSA infections.
  • Emergence of vancomycin resistance, including heteroresistant vancomycin-intermediate S. aureus (hVISA), complicates treatment.

Purpose of the Study:

  • To determine the prevalence and molecular characteristics of hVISA strains in Italy.
  • To evaluate the effectiveness of different screening methods for hVISA detection.
  • To assess the susceptibility of hVISA strains to current antibiotics.

Main Methods:

  • Retrospective analysis of 1284 S. aureus strains isolated from documented infections (2005-2007).
  • Screening of 139 strains with vancomycin MICs of 1-2 mg/L for hVISA using three methods, confirmed by Population Analysis Profile (PAP).
  • Molecular characterization including accessory gene regulator (agr) typing and identification of major nosocomial clones.

Main Results:

  • Thirty-six hVISA strains (25.9%) were detected among MRSA isolates with vancomycin MICs of 1-2 mg/L.
  • Macro Etest (MET) showed 100% specificity and 75% sensitivity for hVISA screening.
  • hVISA strains belonged to agr types I and II and major Italian nosocomial clones (ST8, ST239, ST247, ST228).
  • All hVISA strains remained susceptible to newer antibiotics like quinupristin/dalfopristin, linezolid, daptomycin, tigecycline, and dalbavancin.

Conclusions:

  • hVISA is prevalent among Italian MRSA isolates with vancomycin MICs of 1-2 mg/L.
  • MET is a highly specific and sensitive method for early hVISA detection, crucial for managing serious infections.
  • Current anti-Gram-positive agents retain in vitro activity against these hVISA strains.

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