Characterization of genetic and phenotypic diversity of invasive nontypeable Haemophilus influenzae.
The ability of unencapsulated (nontypeable) Haemophilus influenzae (NTHi) to cause systemic disease in healthy children has been recognized only in the past decade. To determine the extent of similarity among invasive nontypeable isolates, we compared strain R2866 with 16 additional NTHi isolates from blood and spinal fluid, 17 nasopharyngeal or throat isolates from healthy children, and 19 isolates from middle ear aspirates. The strains were evaluated for the presence of several genetic loci that affect bacterial surface structures and for biochemical reactions that are known to differ among H. influenzae strains. Eight strains, including four blood isolates, shared several properties with R2866: they were biotype V (indole and ornithine decarboxylase positive, urease negative), contained sequence from the adhesin gene hia, and lacked a genetic island flanked by the infA and ksgA genes. Multilocus sequence typing showed that most biotype V isolates belonged to the same phylogenetic cluster as strain R2866. When present, the infA-ksgA island contains lipopolysaccharide biosynthetic genes, either lic2B and lic2C or homologs of the losA and losB genes described for Haemophilus ducreyi. The island was found in most nasopharyngeal and otitis isolates but was absent from 40% of invasive isolates. Overall, the 33 hmw-negative isolates were much more likely than hmw-containing isolates to have tryptophanase, ornithine decarboxylase, or lysine decarboxylase activity or to contain the hif genes. We conclude (i) that invasive isolates are genetically and phenotypically diverse and (ii) that certain genetic loci of NTHi are frequently found in association among NTHi strains.
Erwin
Alice L
AL
Seattle Biomedical Research Institute, 307 Westlake Ave. N., Suite 500, Seattle, WA 98109-5219, USA. alice.erwin@sbri.org
Nelson
Kevin L
KL
Mhlanga-Mutangadura
Tendai
T
Bonthuis
Paul J
PJ
Geelhood
Jennifer L
JL
Morlin
Gregory
G
Unrath
William C T
WC
Campos
Jose
J
Crook
Derrick W
DW
Farley
Monica M
MM
Henderson
Frederick W
FW
Jacobs
Richard F
RF
Mühlemann
Kathrin
K
Satola
Sarah W
SW
van Alphen
Loek
L
Golomb
Miriam
M
Smith
Arnold L
AL
D018829:Adhesins, Bacterial / Q000235:genetics / Q000276:immunology; D000595:Amino Acid Sequence; D000940:Antigenic Variation / Q000235:genetics / Q000276:immunology*; D000942:Antigens, Bacterial / Q000235:genetics / Q000276:immunology; D015373:Bacterial Typing Techniques; D006193:Haemophilus influenzae / Q000201:enzymology / Q000235:genetics* / Q000276:immunology / Q000472:pathogenicity*; D008070:Lipopolysaccharides / Q000096:biosynthesis; D008780:Methyltransferases / Q000235:genetics; D008969:Molecular Sequence Data; D010641:Phenotype; D012150:Polymorphism, Restriction Fragment Length; D014510:Urease / Q000235:genetics
D018829:Adhesins, Bacterial; D000942:Antigens, Bacterial; D008070:Lipopolysaccharides; D008780:Methyltransferases; C047346:16S rRNA (adenine(1518)-N(6)-adenine(1519)-N(6))-dimethyltransferase; D014510:Urease