title: An isolate of Haemophilus haemolyticus produces a bacteriocin-like substance that inhibits the growth of nontypeable Haemophilus influenzae.
abstract: Nontypeable Haemophilus influenzae (NTHi) frequently colonises the upper respiratory tract and is an important cause of respiratory infections. Resistance to antibiotics is an emerging trend in NTHi and alternative prevention or treatment strategies are required. Haemophilus haemolyticus is a common commensal occupying the same niche as NTHi and, if able to produce substances that inhibit NTHi growth, may have a role as a probiotic. In this study, ammonium sulphate extracts from broth culture of 100 H. haemolyticus isolates were tested for the presence of substances inhibitory to NTHi using a well diffusion assay. One isolate produced a substance that consistently inhibited the growth of NTHi. The substance was inactivated by protease enzymes and had a molecular size of ca. 30 kDa as determined by size exclusion chromatography. When the substance was tested against bacteria from eight Gram-negative and three Gram-positive genera, only Haemophilus spp. were inhibited. Quantitative PCR testing showed the substance to be different to 'haemocin', the previously described bacteriocin of H. influenzae type b. These molecular characteristics, together with narrow-spectrum activity, suggest the substance may be a novel bacteriocin, and there is potential for this H. haemolyticus isolate to function as a probiotic for reduction of colonisation and subsequent infection with NTHi.
authors.affiliation: University of Tasmania, School of Medicine, Medical Sciences Precinct, Hobart, Tasmania, Australia. Electronic address: roger.latham@utas.edu.au.
authors.forename: Roger D
authors.initials: RD
authors.lastname: Latham
authors.affiliation: University of Tasmania, School of Medicine, Medical Sciences Precinct, Hobart, Tasmania, Australia.
authors.forename: David A
authors.initials: DA
authors.lastname: Gell
authors.affiliation: University of Tasmania, School of Medicine, Medical Sciences Precinct, Hobart, Tasmania, Australia.
authors.forename: Rory L
authors.initials: RL
authors.lastname: Fairbairn
authors.affiliation: University of Tasmania, School of Medicine, Medical Sciences Precinct, Hobart, Tasmania, Australia.
authors.forename: A Bruce
authors.initials: AB
authors.lastname: Lyons
authors.affiliation: University of Tasmania, School of Medicine, Medical Sciences Precinct, Hobart, Tasmania, Australia.
authors.forename: Shakti D
authors.initials: SD
authors.lastname: Shukla
authors.affiliation: University of Tasmania, School of Health Sciences, Launceston, Tasmania, Australia.
authors.forename: Kum Yin
authors.initials: KY
authors.lastname: Cho
authors.affiliation: Royal Hobart Hospital, Hobart, Tasmania, Australia.
authors.forename: David A
authors.initials: DA
authors.lastname: Jones
authors.affiliation: Royal Hobart Hospital, Hobart, Tasmania, Australia.
authors.forename: Nick M
authors.initials: NM
authors.lastname: Harkness
authors.affiliation: University of Tasmania, School of Health Sciences, Launceston, Tasmania, Australia.
authors.forename: Stephen G
authors.initials: SG
authors.lastname: Tristram
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D000898:Antibiosis; D001426:Bacterial Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D001430:Bacteriocins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D006190:Haemophilus / Q000254:growth & development / Q000378:metabolism / Q000502:physiology*; D008970:Molecular Weight; D059748:Proteolysis
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D001430:Bacteriocins
keywords: Bacteriocin; Haemocin; Haemophilus haemolyticus; Haemophilus influenzae; Probiotic