Nontypeable Haemophilus influenzae strains with the capsule-associated insertion element IS1016 may mimic encapsulated strains

• With the elimination of Haemophilus influenzae type b through vaccination, it has been suggested that other types of H. influenzae strains might acquire virulence traits and emerge as important pathogens. The gene sequence IS1016 has been associated with an increased capacity to cause severe infections. It is usually present in encapsulated strains but is sometimes harbored by nontypeable H. influenzae strains. To explore this further, 118 H. influenzae isolates, collected from both patients and healthy carriers, were investigated with PCR with reference to this gene sequence. Isolates positive for the insertion element were bio- and serotyped. The presence of hmw genes for adherence, the genetic profile, and the ability to form biofilm in vitro were investigated. A total of 15 isolates were IS1016-positive, whereof 12 were nontypeable. All 12 nontypeable isolates were obtained from healthy carriers, and 92% of the isolates were biotype I. They cross-reacted to some extent with type-specific antisera or exhibited a restricted genetic diversity like encapsulated strains. Furthermore, they lacked hmw-genes, and their ability to form biofilms was comparable with a capsule-deficient type b strain. Although this subset of strains mimicked traits usually exhibited by encapsulated strains, the isolation frequency did not seem to have been affected by vaccination.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Medicinska och farmaceutiska grundvetenskaper -- Mikrobiologi inom det medicinska området (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Basic Medicine -- Microbiology in the medical area (hsv//eng)

Nyckelord

nontypeable Haemophilus influenzae

serotype

cross-reaction

hmw genes

biofilm

MEDICINE

MEDICIN

cross-reaction

nontypeable Haemophilus influenzae

serotype

genes

biofilm

hmw

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ref (ämneskategori)

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