Analysis of non-typeable Haemophilus influenzae in invasive disease reveals lack of the capsule locus

T-T Lâm; H Claus; M Frosch; U Vogel

doi:10.1016/j.cmi.2015.09.027

Analysis of non-typeable Haemophilus influenzae in invasive disease reveals lack of the capsule locus

Clin Microbiol Infect. 2016 Jan;22(1):63.e7-63.e8. doi: 10.1016/j.cmi.2015.09.027. Epub 2015 Oct 8.

Authors

T-T Lâm¹, H Claus², M Frosch², U Vogel²

Affiliations

¹ Institute for Hygiene and Microbiology, National Reference Laboratory for Meningococci and Haemophilus influenzae, University of Würzburg, Germany. Electronic address: ttlam@hygiene.uni-wuerzburg.de.
² Institute for Hygiene and Microbiology, National Reference Laboratory for Meningococci and Haemophilus influenzae, University of Würzburg, Germany.

PMID: 26454058
DOI: 10.1016/j.cmi.2015.09.027

Abstract

Among invasive Haemophilus influenzae, unencapsulated strains have largely surpassed the previously predominant serotype b (Hib) because of Hib vaccination. Isolates without the genomic capsule (cap) locus are designated non-typeable H. influenzae (NTHi). They are different from capsule-deficient variants that show deletion of the capsule transport gene bexA within the cap locus. The frequency of capsule-deficient variants in invasive disease is unknown. We analysed 783 unencapsulated invasive isolates collected over 5 years in Germany and found no single capsule-deficient isolate. Invasive unencapsulated strains in Germany were exclusively NTHi. A negative serotyping result by slide agglutination was therefore highly predictive for NTHi.

Keywords: Capsule deficiency; Haemophilus influenzae; Hib; NTHi; epidemiology; serotype.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Agglutination Tests
Bacterial Capsules / genetics*
Germany
Haemophilus Infections / microbiology*
Haemophilus influenzae / classification*
Haemophilus influenzae / genetics*
Haemophilus influenzae / isolation & purification
Serotyping*