α-hemolysin activity of methicillin-susceptible Staphylococcus aureus predicts ventilator-associated pneumonia

Lukas Stulik, Stefan Malafa, Jana Hudcova, Harald Rouha, Bence Z. Henics, Donald E. Craven, Agnes M. Sonnevend, Eszter Nagy

Research output: Contribution to journalArticlepeer-review

45 Citations (Scopus)

Abstract

Rationale: Colonization of lower airways by Staphylococcus aureus is a risk factor for the development of ventilator-associated tracheobronchitis (VAT) and ventilator-associated pneumonia (VAP). However, little is known about the virulence factors of methicillin-sensitive and -resistant S. aureus (MSSA and MRSA) that may influence host colonization and progression to VAT and VAP. Objectives: We evaluated MRSA and MSSA endotracheal aspirates (ETA) for genotype and α-hemolysin activity in relation to the development of VAT and VAP. Methods: Serial S. aureus ETA isolates from ventilated patients were analyzed for methicillin resistance, molecular type by Multi-Locus Sequence Typing and spa-typing, and α-hemolysin activity by semiquantitative analysis of hemolysis on sheep blood agar and quantitative measurement of cytolysis ofhumanlung epithelial cells.The virulence of selected strainswas assessed in mice by intranasal challenge. Measurements and Main Results: We detected S. aureus from ETA samples in a quarter of the 231 ventilated patients analyzed; one-third of them developed VAP. VAP patients (n = 15) were mainly infected by MSSA strains (87%), whereas colonized individuals (n = 18) not progressing to disease mainly carried MRSA strains (68%). MSSA isolates from colonized or VAT patients exhibited significantly lower α-hemolysin activity than those from VAP cases; however, no such relationship was found with MRSA strains. α-Hemolysin activity of S. aureus isolates was predictive for virulence inmouse pneumonia model. Conclusions: MSSA strains with strong blood agar hemolysis and high α-hemolysin activity aremarkers for VAP, but not VAT, and might be considered in differential diagnosis and initiation of therapy.

Original languageEnglish
Pages (from-to)1139-1148
Number of pages10
JournalAmerican Journal of Respiratory and Critical Care Medicine
Volume190
Issue number10
DOIs
Publication statusPublished - Nov 15 2014
Externally publishedYes

Keywords

  • Biomarker
  • Staphylococcus aureus
  • Ventilator-associated pneumonia
  • α-hemolysin

ASJC Scopus subject areas

  • Pulmonary and Respiratory Medicine
  • Critical Care and Intensive Care Medicine

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