THE POLYMICROBIAL NATURE OF OTITIS MEDIA INFECTIONSMichael DorringtonBowdish Lab

MY INTEREST IN THE HUMAN MICROBIOME Infectious disease models involving the

upper respiratory tract Streptococcus pneumoniae

Relationships among different bacterial species and how these affect colonization and infection as well as disease outcome

Development of intranasal vaccine strategies to prevent colonization of common pathogens

TOPICS OF DISCUSSION Upper respiratory tract microbial

communities and otitis media Laufer et al. “Microbial Communities of the Upper

Respiratory Tract and Otitis Media in Children” Feb 2011

The role of quorum signaling in establishing and maintaining infectious biofilms in otitis media infections Armbruster et al. “Indirect Pathogenicity of

Haemophilus influenzae and Moraxella catarrhalis in Polymicrobial Otitis Media Occurs via Interspecies Quorum Signaling” July 2010

OTITIS MEDIA Inflammation of the

middle ear From tympanic membrane

to the cochlea and including the eustachian tube

Caused by viral, bacterial, and fungal pathogens S. pneumoniae Haemophilus influenzae Moraxella catarrhalis

More common in children <7 years old

http://www.dizziness-and-balance.com/images/master-ear.jpg

COLONIZATION OF URT INFECTION OF MIDDLE EAR

http://www.atlasaviation.com/medical/Ear.jpg

http://www.mhhe.com/biosci/ap/dynamichuman2/content/gifs/0164.gif

CHILDREN WITH OTITIS MEDIA

COLONIZATION VS. INFECTION

POLYMICROBIAL INFECTIONS The majority of infectious diseases have

more than one causative agent Modulation of host responses Passive antibiotic resistance Quorum signaling

Otitis Media Haemophilus influenzae + Moraxella catarrhalis

BIOFILMS A complex community of microbes adhering

to a surface that comes in regular contact with a fluid

Can be made up of numerous species of bacteria, fungi, and/or protazoa

Embedded in a self-produced extracellular matrix

Normally very resistant to antibiotic treatment

QUORUM SIGNALING Bacteria within a biofilm can communicate

via signaling molecules Autoinducers

N-acyl homoserine lactones (Gram-negative) Oligopeptides (Gram-positive)

Signaling molecules can co-ordinate activities between and among different species

Signaling often based on threshold population densities

BIOFILM FORMATION IN OTITIS MEDIA

PASSIVE ANTIBIOTIC RESISTANCE

luxS AI-2

THOUGHTS The addition of a single pathogen can induce

changes in resident populations of bateria as well as the host This can promote competition or synergism

among bacterial species Intranasal probiotics?

Upper respiratory tract infections are often polymicrobial in nature Important to gain further understanding of the

interactions between commensals and pathogens and how these affect disease outcome