title: Reliability of Haemophilus influenzae biofilm measurement via static method, and determinants of in vitro biofilm production.
abstract: Information is lacking regarding the precision of microtitre plate (MTP) assays used to measure biofilm. This study investigated the precision of an MTP assay to measure biofilm production by nontypeable Haemophilus influenzae (NTHi) and the effects of frozen storage and inoculation technique on biofilm production. The density of bacterial final growth was determined by absorbance after 18-20 h incubation, and biofilm production was then measured by absorbance after crystal violet staining. Biofilm formation was categorised as high and low for each strain. For the high biofilm producing strains of NTHi, interday reproducibility of NTHi biofilm formation measured using the MTP assay was excellent and met the acceptance criteria, but higher variability was observed in low biofilm producers. Method of inoculum preparation was a determinant of biofilm formation with inoculum prepared directly from solid media showing increased biofilm production for at least one of the high producing strains. In general, storage of NTHi cultures at -80 °C for up to 48 weeks did not have any major effect on their ability to produce biofilm.
authors.affiliation: a Pharmacy Division, School of Medicine, Hobart, University of Tasmania, 7001, Australia.
authors.forename: Najla A
authors.initials: NA
authors.lastname: Obaid
authors.affiliation: b School of Health Sciences, University of Tasmania, Launceston, Tasmania 7250, Australia.
authors.forename: Stephen
authors.initials: S
authors.lastname: Tristram
authors.affiliation: a Pharmacy Division, School of Medicine, Hobart, University of Tasmania, 7001, Australia.
authors.forename: Christian K
authors.initials: CK
authors.lastname: Narkowicz
authors.affiliation: a Pharmacy Division, School of Medicine, Hobart, University of Tasmania, 7001, Australia.
authors.forename: Glenn A
authors.initials: GA
authors.lastname: Jacobson
mesh_terms: D018441:Biofilms / Q000254:growth & development*; D015925:Cryopreservation; D006192:Haemophilus Infections / Q000382:microbiology*; D006193:Haemophilus influenzae / Q000502:physiology*; D006801:Humans; D015203:Reproducibility of Results
keywords: Haemophilus influenzae non typables; NTHi; bacterial isolate storage; biofilm formation; conservation d’isolats bactériens; dosage sur microplaque; formation de biofilm; microtitre plate assay; nontypeable Haemophilus influenzae; reproducibility; reproductibilité