title: Methodology optimization and diversification for the investigation of virulence potential in Haemophilus influenzae clinical strains.
abstract: Ten Haemophilus influenzae strains were isolated from patients aged between 1.6 - 24 years, with various diagnoses (acute meningitis, acute upper respiratory infection, otitis media and acute sinusitis). Identification was based on phenotypic and molecular characteristics; antibiotic susceptibility testing was performed by diffusion method according to CLSI standards 2011 for seven antibiotics. The results of molecular testing showed that all the studied strains produced an amplicon of 1000 bp with ompP2 primers indicating that all strains were H. influenzae. For six strains, the PCR amplicon obtained with bexA specific primers, proving that the strains were capsulated. The results of phenotypic testing showed that four strains were ampicillin nonsusceptible and (beta-lactamase-positive. The virulence potential of H. influenzae clinical strains was investigated by phenotypic methods, including the assessment of the soluble virulence factors on specific media containing the biochemical substratum for the investigated enzymatic factor, as well as the adherence and invasion capacity to HeLa cells monolayer using Cravioto modified method. The studied strains exhibited mainly a diffuse adherence pattern and different adherence indexes. Interestingly, two strains isolated from the same pacient (blood and CSF) showed a different degree of invasiveness, the strain isolated from blood being 20 times more invasive than the one isolated from CSF.
authors.affiliation: "Cantacuzino" National Institute of Research-Development for Microbiology and Immunology, Bucharest. giucamihaela@yahoo.com
authors.forename: Mihaela Cristina
authors.initials: MC
authors.lastname: Giucă
authors.forename: Monica
authors.initials: M
authors.lastname: Străuţ
authors.forename: Maria
authors.initials: M
authors.lastname: Surdeanu
authors.forename: Maria
authors.initials: M
authors.lastname: Nica
authors.forename: Vasilica
authors.initials: V
authors.lastname: Ungureanu
authors.forename: Grigore
authors.initials: G
authors.lastname: Mihăescu
mesh_terms: D000328:Adult; D001422:Bacterial Adhesion; D002648:Child; D002675:Child, Preschool; D005260:Female; D006193:Haemophilus influenzae / Q000472:pathogenicity*; D006367:HeLa Cells; D006801:Humans; D007223:Infant; D008297:Male; D010641:Phenotype; D016133:Polymerase Chain Reaction / Q000379:methods*; D014774:Virulence