title: Analysis of non-typeable Haemophilus influenzae in invasive disease reveals lack of the capsule locus.
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.
authors.affiliation: Institute for Hygiene and Microbiology, National Reference Laboratory for Meningococci and Haemophilus influenzae, University of Würzburg, Germany. Electronic address: ttlam@hygiene.uni-wuerzburg.de.
authors.forename: T-T
authors.initials: TT
authors.lastname: Lâm
authors.affiliation: Institute for Hygiene and Microbiology, National Reference Laboratory for Meningococci and Haemophilus influenzae, University of Würzburg, Germany.
authors.forename: H
authors.initials: H
authors.lastname: Claus
authors.affiliation: Institute for Hygiene and Microbiology, National Reference Laboratory for Meningococci and Haemophilus influenzae, University of Würzburg, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Frosch
authors.affiliation: Institute for Hygiene and Microbiology, National Reference Laboratory for Meningococci and Haemophilus influenzae, University of Würzburg, Germany.
authors.forename: U
authors.initials: U
authors.lastname: Vogel
mesh_terms: D000372:Agglutination Tests; D016667:Bacterial Capsules / Q000235:genetics*; D005858:Germany; D006192:Haemophilus Infections / Q000382:microbiology*; D006193:Haemophilus influenzae / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification; D012703:Serotyping
keywords: Capsule deficiency; Haemophilus influenzae; Hib; NTHi; epidemiology; serotype