Download The Polymicrobial Nature of Otitis Media

THE POLYMICROBIAL NATURE
OF OTITIS MEDIA INFECTIONS
Michael Dorrington
Bowdish 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
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COLONIZATION OF URT  INFECTION OF
MIDDLE EAR
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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