title: Nontypeable Haemophilus influenzae inhibits autolysis and fratricide of Streptococcus pneumoniae in vitro.
abstract: Streptococcus pneumoniae (SP) and nontypeable Haemophilus influenzae (NTHi) are common commensals of the human airway and major bacterial pathogens of otitis media (OM) and other upper airway infections. The interaction between them may play an important role in the pathogenesis of polymicrobial infections. Although previous studies suggested NTHi could promote pneumococcal survival and biofilm formation, how NTHi affects pneumococcal activities has not been defined. Our data in the present studies indicated that the outcome of the interaction between SP and NTHi was in a cell-density-dependent manner and the enhancement of pneumococcal survival happened at the later stages of culturing. Using quantitative PCR, we found that the expression of pneumococcal genes regulating autolysis and fratricide, lytA and cbpD, were significantly down-regulated in co-culture with NTHi. We further observed that influence of NTHi was not on direct cell-to-cell contact, but that this contact may contribute to the interaction between these two microorganisms. These results suggest that pneumococcal survival and biofilm formation can be enhanced by down-regulating pneumococcal cell wall hydrolase production thereby inhibiting pneumococcal autolysis and fratricide in the presence of NTHi.
authors.affiliation: Department of Otolaryngology and Communication Sciences, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA. Electronic address: whong@mcw.edu.
authors.forename: Wenzhou
authors.initials: W
authors.lastname: Hong
authors.affiliation: Department of Otolaryngology and Communication Sciences, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA.
authors.forename: Pawjai
authors.initials: P
authors.lastname: Khampang
authors.affiliation: Department of Otolaryngology and Communication Sciences, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA.
authors.forename: Christy
authors.initials: C
authors.lastname: Erbe
authors.affiliation: Department of Pathology, CRI Imaging Core, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA.
authors.forename: Suresh
authors.initials: S
authors.lastname: Kumar
authors.affiliation: Department of Otolaryngology and Communication Sciences, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA.
authors.forename: Steve R
authors.initials: SR
authors.lastname: Taylor
authors.affiliation: Department of Otolaryngology and Communication Sciences, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA; Division of Pediatric Otolaryngology, Medical College of Wisconsin, Children's Hospital of Wisconsin, 9000 W Wisconsin Ave., Milwaukee, WI 53226, USA.
authors.forename: Joseph E
authors.initials: JE
authors.lastname: Kerschner
mesh_terms: D001433:Bacteriolysis / Q000502:physiology*; D018441:Biofilms; D018920:Coculture Techniques; D006193:Haemophilus influenzae / Q000502:physiology*; D056265:Microbial Interactions / Q000502:physiology*; D050296:Microbial Viability; D013296:Streptococcus pneumoniae / Q000502:physiology*
keywords: Autolysis; Fratricide; Inhibit; Nontypeable Haemophilus influenzae; Streptococcus pneumoniae; Survival