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Genotyping of Staphylococcus aureus by Ribosomal Spacer PCR (RS-PCR)
08:51

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Conventional and molecular characterization of coagulase-negative staphylococcus in hospital isolates

Poonam Sharma1, Kunal K Lahiri, Ketoki Kapila

  • 1Department of Microbiology, Armed Forces Medical College, Pune, Maharashtra, India. poonam136@rediffmail.com

Indian Journal of Pathology & Microbiology
|March 12, 2011
PubMed
Abstract

Insights

Coagulase-negative staphylococci (CoNS) are a growing cause of hospital infections. Specific genes (ica and mecA) and biofilm formation effectively distinguish invasive CoNS strains from harmless ones.

Area of Science:

  • Microbiology
  • Infectious Diseases
  • Medical Diagnostics

Background:

  • Coagulase-negative staphylococci (CoNS) are increasingly implicated in nosocomial infections, particularly device-related sepsis.
  • These bacteria are part of normal flora but pose diagnostic and therapeutic challenges.
  • CoNS infections are often associated with medical devices like catheters.

Purpose of the Study:

  • To evaluate the phenotypic and genotypic characteristics of CoNS from nosocomial infections.
  • To identify genetic markers differentiating invasive CoNS strains from saprophytic ones.
  • To assess the role of specific genes in CoNS pathogenicity and biofilm formation.

Main Methods:

  • Analysis of 150 CoNS strains (100 invasive, 50 saprophytic) from a tertiary care hospital.
  • Selection of strains based on colony morphology, antibiotic resistance, and biofilm formation.
  • Multiplex PCR used to detect ica, mecA, and atlE genes.

Main Results:

  • Invasive, biofilm-forming CoNS strains showed high resistance to multiple antibiotics, including over 80% resistance to methicillin.
  • The ica and mecA genes were significantly more prevalent in pathogenic strains (P<0.0001).
  • The atlE gene was detected in all strains, while ica and mecA correlated with antibiotic resistance and biofilm formation.

Conclusions:

  • The presence of ica and mecA genes, along with biofilm formation, can distinguish virulent, invasive CoNS from saprophytic strains.
  • These genetic markers offer potential for improved diagnosis of CoNS infections.
  • Understanding CoNS virulence factors is crucial for managing hospital-acquired infections.

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