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Epidemiological and Inducible Resistance in Coagulase Negative Staphylococci

Shadieh Abdollahi1, Rashid Ramazanzadeh, Zahra Delami Khiabani

  • 1. atrop_t51@yahoo.com.

Global Journal of Health Science
|November 18, 2015
PubMed
Abstract

Insights

Coagulase-negative staphylococci (CNS) show inducible clindamycin resistance, with diverse genetic patterns observed. This suggests varied infection sources, impacting hospital-acquired infections and treatment strategies for methicillin-resistant CNS (MRCNS).

Area of Science:

  • Microbiology
  • Infectious Diseases
  • Molecular Epidemiology

Background:

  • Coagulase-negative staphylococci (CNS) are increasingly recognized as significant pathogens, particularly in healthcare settings with a rise in medical implants.
  • Antibiotic resistance, including to macrolide, lincosamide, and streptogramin B (MLSB) agents, poses a therapeutic challenge in treating staphylococcal infections.

Purpose of the Study:

  • To investigate the molecular mechanisms and prevalence of inducible clindamycin resistance in CNS isolates.
  • To characterize the genetic diversity and transmission patterns of CNS strains within hospital environments.
  • To identify specific resistance genes, such as erm (A, B, C, and TR), associated with MLSB resistance.

Main Methods:

  • Isolation and identification of 110 CNS strains from patients in intensive care and infectious wards of two hospitals.
  • Phenotypic detection of methicillin resistance using agar screen tests and inducible clindamycin resistance via the D-Test.
  • Molecular analysis using Multiplex PCR for erm genes and ERIC-PCR for genetic fingerprinting and strain typing.

Main Results:

  • Over half (58.2%) of the CNS isolates were methicillin-resistant (MRCNS).
  • A significant proportion (43.6%) exhibited erythromycin resistance (ERCNS), with 10.4% of these displaying an inducible MLSB (iMLSB) phenotype.
  • Molecular analysis confirmed erm genes in 4 resistant isolates, and ERIC-PCR revealed extensive genetic diversity, with 110 isolates categorized into 90 distinct ERIC-types and 14 main clusters.

Conclusions:

  • The study highlights considerable genetic heterogeneity among CNS isolates, indicating diverse origins of infection.
  • The presence of inducible clindamycin resistance mechanisms in CNS strains necessitates careful antibiotic susceptibility testing and treatment selection.
  • Understanding the genetic patterns of CNS is crucial for controlling the spread of resistant strains in hospital settings.

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