title: Development of a non-invasive murine infection model for acute otitis media.
abstract: Otitis media (OM) is one of the most frequent diseases in childhood, and Streptococcus pneumoniae is among the main causative bacterial agents. Since current experimental models used to study the bacterial pathogenesis of OM have several limitations, such as the invasiveness of the experimental procedures, we developed a non-invasive murine OM model. In our model, adapted from a previously developed rat OM model, a pressure cabin is used in which a 40 kPa pressure increase is applied to translocate pneumococci from the nasopharyngeal cavity into both mouse middle ears. Wild-type pneumococci were found to persist in the middle ear cavity for 144 h after infection, with a maximum bacterial load at 96 h. Inflammation was confirmed at 96 and 144 h post-infection by IL-1beta and TNF-alpha cytokine analysis and histopathology. Subsequently, we investigated the contribution of two surface-associated pneumococcal proteins, the streptococcal lipoprotein rotamase A (SlrA) and the putative proteinase maturation protein A (PpmA), to experimental OM in our model. Pneumococci lacking the slrA gene, but not those lacking the ppmA gene, were significantly reduced in virulence in the OM model. Importantly, pneumococci lacking both genes were significantly more attenuated than the DeltaslrA single mutant. This additive effect suggests that SlrA and PpmA exert complementary functions during experimental OM. In conclusion, we have developed a highly reproducible and non-invasive murine infection model for pneumococcal OM using a pressure cabin, which is very suitable to study pneumococcal pathogenesis and virulence in vivo.
authors.affiliation: Department of Pediatrics, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.
authors.forename: K
authors.initials: K
authors.lastname: Stol
authors.affiliation: Department of Pediatrics, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.
authors.forename: S
authors.initials: S
authors.lastname: van Selm
authors.affiliation: Department of Pediatrics, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.
authors.forename: S
authors.initials: S
authors.lastname: van den Berg
authors.affiliation: Department of Pediatrics, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.
authors.forename: H J
authors.initials: HJ
authors.lastname: Bootsma
authors.affiliation: Department of Pathology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.
authors.forename: W A M
authors.initials: WAM
authors.lastname: Blokx
authors.affiliation: Department of Otorhinolaryngology, Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.
authors.forename: K
authors.initials: K
authors.lastname: Graamans
authors.affiliation: Department of Otorhinolaryngology, Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.
authors.forename: E L G M
authors.initials: ELGM
authors.lastname: Tonnaer
authors.affiliation: Department of Pediatrics, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.
authors.forename: P W M
authors.initials: PWM
authors.lastname: Hermans
mesh_terms: D000208:Acute Disease; D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology; D001483:Base Sequence; D002675:Child, Preschool; D017931:DNA Primers / Q000235:genetics; D004269:DNA, Bacterial / Q000235:genetics; D004195:Disease Models, Animal; D004432:Ear, Middle / Q000382:microbiology; D005260:Female; D005798:Genes, Bacterial; D006801:Humans; D007223:Infant; D053583:Interleukin-1beta / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D009154:Mutation; D009305:Nasopharynx / Q000382:microbiology; D010033:Otitis Media / Q000209:etiology* / Q000276:immunology / Q000382:microbiology / Q000473:pathology; D019696:Peptidylprolyl Isomerase / Q000235:genetics / Q000502:physiology; D011008:Pneumococcal Infections / Q000209:etiology* / Q000276:immunology / Q000382:microbiology / Q000473:pathology; D011312:Pressure; D051381:Rats; D013296:Streptococcus pneumoniae / Q000235:genetics / Q000472:pathogenicity / Q000502:physiology; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D014774:Virulence / Q000235:genetics / Q000502:physiology
chemical_list: D001426:Bacterial Proteins; D017931:DNA Primers; D004269:DNA, Bacterial; D053583:Interleukin-1beta; C542808:PpmA protein, Streptococcus pneumoniae; D014409:Tumor Necrosis Factor-alpha; D019696:Peptidylprolyl Isomerase; C508148:SlrA protein, Streptococcus pneumoniae