Outer membrane vesicles shield Moraxella catarrhalis β-lactamase from neutralization by serum IgG.
Författare
Summary, in English
OBJECTIVES: The aim of this study was to detect the presence of IgG against Moraxella catarrhalis β-lactamase in healthy adults, and to determine whether outer membrane vesicles (OMVs) could protect the enzyme from inhibition by anti-β-lactamase IgG. METHODS: Transmission electron microscopy was used to detect the presence of β-lactamase in OMVs. Sera were examined by ELISA for specific IgG directed against recombinant M. catarrhalis β-lactamase in addition to the outer membrane adhesins MID/Hag, UspA1 and A2. Binding of anti-β-lactamase IgG from serum to OMVs was analysed by flow cytometry. The chromogenic substrate nitrocefin was used to quantify β-lactamase enzyme activity. RESULTS: The presence of β-lactamase was determined in OMVs from a 9-year-old child suffering from M. catarrhalis sinusitis. Furthermore, anti-β-lactamase IgG was detected in sera obtained from healthy adults. Out of 40 adult blood donors (aged 18-65 years) tested, 6 (15.0%) carried anti-β-lactamase IgG. No correlation between IgG titres against β-lactamase and the adhesins was found. Flow cytometry analyses revealed that anti-β-lactamase IgG from serum bound to β-lactamase-positive OMVs. By comparing the β-lactamase activity of intact OMV with OMV that were permeabilized with saponin we found that OMVs shielded active β-lactamase from the anti-β-lactamase IgG. CONCLUSIONS: Moraxella catarrhalis β-lactamase is found in, or associated with, OMVs, providing clinical relevance for the vesicles in the spread of antibiotic resistance. Furthermore, OMVs protect β-lactamase from specific IgG.
Avdelning/ar
Publiceringsår
2013
Språk
Engelska
Sidor
593-600
Publikation/Tidskrift/Serie
Journal of Antimicrobial Chemotherapy
Volym
68
Issue
3
Fulltext
- Available as PDF - 498 kB
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Länkar
Dokumenttyp
Artikel i tidskrift
Förlag
Oxford University Press
Ämne
- Pharmacology and Toxicology
Status
Published
Forskningsgrupp
- Clinical Microbiology, Malmö
ISBN/ISSN/Övrigt
- ISSN: 1460-2091