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Multiplex PCR Assay for Typing of Staphylococcal Cassette Chromosome Mec Types I to V in Methicillin-resistant Staphylococcus aureus
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Molecular Markers of Antimicrobial Resistance in Methicillin-Resistant Staphylococcus aureus SCCmec IV Presenting

Pricilla Dias Moura de Matos1, Tamara Lopes Rocha de Oliveira1, Fernanda Sampaio Cavalcante1

  • 11 Department of Medical Microbiology, Institute of Microbiology , Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil .

Microbial Drug Resistance (Larchmont, N.Y.)
|April 6, 2016
PubMed

Insights

Methicillin-resistant Staphylococcus aureus (MRSA) SCCmec IV isolates in Rio de Janeiro hospitals show high resistance to common antibiotics. The USA400/ST1 lineage exhibits significant multiresistance, while USA800/ST5 is linked to specific resistance genes, indicating potential for hospital persistence.

Area of Science:

  • Microbiology
  • Infectious Diseases
  • Molecular Epidemiology

Background:

  • Methicillin-resistant Staphylococcus aureus (MRSA) carrying SCCmec type IV is a growing global hospital concern.
  • Understanding the antimicrobial resistance profiles and genetic backgrounds of these MRSA strains is crucial for infection control.

Purpose of the Study:

  • To evaluate the phenotypic and molecular characteristics of antimicrobial resistance in MRSA SCCmec IV isolates from Rio de Janeiro hospitals.
  • To identify associations between specific MRSA lineages and resistance mechanisms.

Main Methods:

  • Disk diffusion and minimum inhibitory concentration (MIC) tests were used to assess antimicrobial resistance in 128 MRSA SCCmec IV isolates.
  • Mutations in the parC gene (ciprofloxacin resistance) and genes conferring macrolide-lincosamide-streptogramin B (MLSb) resistance were investigated.
  • Isolates were characterized by their genetic lineages, including USA400/ST1, USA800/ST5, and USA1100/ST30.

Main Results:

  • High rates of resistance were observed for erythromycin (68%), ciprofloxacin (56%), and clindamycin (50%).
  • The USA400/ST1 lineage showed the highest antimicrobial resistance rates and frequently carried the erm(C) gene and parC mutations.
  • The msr(A) gene was more prevalent in USA800/ST5 isolates.

Conclusions:

  • Multiresistance in MRSA SCCmec IV isolates from Rio de Janeiro hospitals is associated with the USA400/ST1 lineage, involving parC gene mutations.
  • The msr(A) gene association with the USA800/ST5 lineage suggests distinct evolutionary paths for resistance.
  • These specific MRSA lineages may have a greater capacity for persistence within hospital settings, necessitating targeted surveillance and control strategies.
Keywords:
MRSASCCmec IVlineagesmacrolidesquinolonesresistance genes

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