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Antimicrobial Resistance and Molecular Characteristics of Nasal Staphylococcus aureus Isolates From Newly Admitted

Xu Chen1, Kangde Sun1, Danfeng Dong2

  • 1Department of Laboratory Medicine, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine (SJTUSM), Shanghai, China.

Annals of Laboratory Medicine
|February 27, 2016
PubMed

Insights

Newly admitted patients carry epidemic methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-sensitive S. aureus (MSSA) strains. Understanding nasal S. aureus carriage is key to controlling MRSA transmission in hospitals.

Area of Science:

  • Medical Microbiology
  • Infectious Diseases
  • Molecular Epidemiology

Background:

  • Staphylococcus aureus, including methicillin-resistant strains (MRSA), poses a significant threat in healthcare and community settings.
  • Community-associated MRSA (CA-MRSA) strains exhibit multi-drug resistance and can infiltrate hospitals.
  • Nasal carriage of S. aureus is a critical reservoir for transmission.

Purpose of the Study:

  • To determine the prevalence of antimicrobial resistance in nasal S. aureus isolates from newly admitted inpatients.
  • To characterize the molecular features of these S. aureus isolates, including MRSA and MSSA.
  • To investigate the role of inpatients in the transmission of epidemic MRSA strains.

Main Methods:

  • Screening of 292 newly admitted patients for nasal S. aureus carriage.
  • Isolation and identification of S. aureus, categorizing into HA-MRSA, CA-MRSA, and MSSA.
  • Antimicrobial susceptibility testing, D-test, and erm gene detection.
  • Molecular typing including spa-typing, sequence typing (ST), and SCCmec typing.

Main Results:

  • 66 S. aureus isolates (10 HA-MRSA, 8 CA-MRSA, 48 MSSA) were identified from 62 patients.
  • High resistance rates to penicillin and erythromycin were observed; all isolates were sensitive to linezolid, teicoplanin, and quinupristin/dalfopristin.
  • Specific molecular profiles were identified: HA-MRSA strains belonged to ST239-SCCmec III, and CA-MRSA strains included t437-ST59-SCCmec V.

Conclusions:

  • Newly admitted patients serve as crucial reservoirs for transmitting epidemic CA-MRSA and HA-MRSA strains.
  • Understanding nasal carriage is essential for developing effective infection control strategies.
  • Molecular characterization aids in tracing the origins and spread of MRSA strains within healthcare settings.
Keywords:
Antimicrobial resistanceCA-MRSAMolecular characteristicsNasal carriageStaphylococcus aureus

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