Everybody nose: molecular and clinical characteristics of nasal colonization during active methicillin-resistant Staphylococcus aureus bloodstream infection

Erika Reategui Schwarz, Adriana van de Guchte, Amy C. Dupper, Ana Berbel Caban, Devika Nadkarni, Lindsey Fox, Alexandra Mills, Ajay Obla, Kieran I. Chacko, Irina Oussenko, Flora Samaroo, Jose Polanco, Richard Silvera, Melissa L. Smith, Gopi Patel, Melissa Gitman, Bremy Alburquerque, Marilyn Chung, Mitchell J. Sullivan, Harm van BakelDeena R. Altman

Research output: Contribution to journalArticlepeer-review

Abstract

Background: Healthcare-associated infections pose a potentially fatal threat to patients worldwide and Staphylococcus aureus is one of the most common causes of healthcare-associated infections. S. aureus is a common commensal pathogen and a frequent cause of bacteremia, with studies demonstrating that nasal and blood isolates from single patients match more than 80% of the time. Here we report on a contemporary collection of colonizing isolates from those with methicillin-resistant S. aureus (MRSA) bloodstream infections to evaluate the diversity within hosts, and detail the clinical features associated with concomitant nasal colonization. Methods: Swabs of the bilateral anterior nares were obtained from patients diagnosed with MRSA bacteremia. A single colony culture from the blood and an average of 6 colonies from the nares were evaluated for MRSA growth. For the nares cultures, we typed multiple isolates for staphylococcal protein A (spa) and derived the clonal complexes. Demographic and clinical data were obtained retrospectively from the electronic medical record system and analysed using univariate and multivariable regression models. Results: Over an 11-month period, 68 patients were diagnosed with MRSA bloodstream infection, 53 were swabbed, and 37 (70%) were colonized with MRSA in the anterior nares. We performed molecular typing on 213 nasal colonies. Spa types and clonal complexes found in the blood were also detected in the nares in 95% of the cases. We also found that 11% of patients carried more than one clone of MRSA in the nares. Male sex and history of prior hospitalization within the past 90 days increased odds for MRSA colonization. Conclusion: The molecular epidemiological landscape of colonization in the setting of invasive disease is diverse and defining the interplay between colonization and invasive disease is critical to combating invasive MRSA disease.

Original languageEnglish
Article number400
JournalBMC Infectious Diseases
Volume22
Issue number1
DOIs
StatePublished - Dec 2022

Keywords

  • Bloodstream infections
  • Colonization
  • Methicillin-resistant Staphylococcus aureus
  • Molecular epidemiology

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