Pathogenesis of

Pseudomonas
Joanna B. Goldberg, Ph.D.
Emory University School of Medicine

March 1, 2017
Nothing to disclose
Mandell, Douglas, and BenneD's
Principles and PracGce of
InfecGous Diseases,
Updated EdiGon, 221, 2518-2531.e3
P. aeruginosa physiology
•  Ubiquitous
•  Minimal growth requirements
•  Temperature
•  Can grow anaerobically with arginine or nitrate
•  Resistant to anGmicrobials
•  Permeability barrier
•  Numerous efflux pumps
•  Acquired resistance
What is available to the field?
•  Strains
•  First sequenced P. aeruginosa strain, PAO1 (Stover et al. Nature 2000)
•  Large genome, single circular chromosome, ~6.6 Mb
•  >5580 ORF
•  66% G+C
•  BioinformaGc analysis
•  Ordered transposon (Tn) libraries
•  PAO1, Jacobs et al. PNAS 2003
•  PA14, LiberaG et al. PNAS 2006
•  State of the art geneGc tools
•  Reagents for the construcGon of specific mutaGons
•  Tnseq
•  RNAseq
What is available to the field?
•  Strains
•  First sequenced P. aeruginosa strain, PAO1 (Stover et al. Nature 2000)
•  Large genome, single circular chromosome, ~6.6 Mb
•  >5580 ORF
•  66% G+C
•  BioinformaGc analysis
•  Ordered transposon (Tn) libraries
•  PAO1, Jacobs et al. PNAS 2003
•  PA14, LiberaG et al. PNAS 2006
•  State of the art geneGc tools
•  Reagents for the construcGon of specific mutaGons
•  Tnseq
•  RNAseq
What is available to the field?
•  Strains
•  First sequenced P. aeruginosa strain, PAO1 (Stover et al. Nature 2000)
•  Large genome, single circular chromosome, ~6.6 Mb
•  >5580 ORF
•  66% G+C
•  BioinformaGc analysis
•  Ordered transposon (Tn) libraries
•  PAO1, Jacobs et al. PNAS 2003
•  PA14, LiberaG et al. PNAS 2006
•  State of the art geneGc tools
•  Reagents for the construcGon of specific mutaGons
•  Tnseq
•  RNAseq
P. aeruginosa is an opportunis;c pathogen
•  InfecGons generally occur in the context of breach of the innate
immune system
•  Healthy animals like healthy humans are typically resistant to
infecGon
 Ear infecGons Eye infecGons
Chronic respiratory infecGons
(parGcularly, cysGc fibrosis)
Hospital-acquired pneumonia

Bloodstream and
catheter-related infecGons
Intra-abdominal infecGons

Urinary tract infecGons

Skin and sod Gssue infecGons

Pseudomonas aeruginosa
Clinical PresentaGon
 Attachment
to surface ‘Sessile’

Surface-associated Microcolony Biofilm formation Dispersal

Biofilms motility formation
Biofilm formation starts with the attachment of bacteria to a surface, followed by twitching into the biofilm. A gradient of oxygen and nutrients induces the formation of distinct
motility and the formation of microcolonies, which evolve into mature biofilms. Biofilm bacterial subpopulations that vary in their susceptibility to antibiotics; exposure to β-lactams
architecture depends on the production of the biofilm matrix, which consists of the or colistin can induce the production of resistance factors (AmpC β-lactamase and
polysaccharides Pel (synthesized by PelA–PelG), Psl (arranged in a helical pattern around MexA–MexB–OprM efflux pumps). Rhamnolipids on bacteria at the surface induce necrosis
cells) and alginate, extracellular DNA (eDNA), and proteins, including the CupA, CupB of neutrophils. Finally, planktonic bacteria are released from parts of the mature biofilm.
and CupC fimbriae, which mediate bacterial attachment during initial biofilm formation, The steps of biofilm maturation shown here are based on in vitro studies; the corresponding
and the lectin LecB. The extracellular polymeric matrix delays diffusion of some antibiotics steps and biofilms structures that occur during in vivo infections are less clear.

Pyoverdin
Pathogenesis P. aeruginosa
Fe3+ + Fe2+
Pathogenesis in FpvA
Inner membrane
Pyocyanin
P. aeruginosa is Secretion systems Peptidoglycan
mediated by various Elastase Outer membrane
adhesins and secreted Type I Type II Type III Type VI Type IV pili Flagellum
SecYEG
toxins, proteases, Extracellular Flagellin
effector proteins and matrix
LasA protease Type V ? LPS
pigments that
facilitate adhesion, Asialo-GM1 TLR4 CTFR TLR5 Asialo-GM1
modulate or disrupt Disrupted actin Actin SOD1
cytoskeleton Active Pro-inflammatory
host cell pathways 14-3-3 Flagellin inflammasome IL-1
cytokines
ADP
and target the Exotoxin A ExoU PscI IL-18
extracellular matrix. Oxidative ADP ExoS
damage RAS Pilin Pyroptosis
EF2
RAS
Inactive ExoS
Translation inflammasome ExoU Epithelial cell

Further reading: Pseudomonas aeruginosa

Acknowledgements
Hanson, N. D. Antibacterial-resistant Pseudomonas
ct and complex regulation of chromosomally encoded
u Bleves, S. et al. Protein secretion systems in
Pseudomonas aeruginosa: A wealth of pathogenic
u Pier, G. B. & Ramphal, R. in Principles and Practice of
Infectious Diseases (eds Mandell, G. L., Bennett, J. E.Alan Hauser and Egon A. Ozer
We thank the many investigators whose
work is summarized in this poster.
in. Microbiol. Rev. 22, 582–610 (2009).
national Nosocomial Infection Control Consortium (INICC)
weapons. Int. J. Med. Microbiol. 300, 534–543 (2010).
u Harmsen, M., Yang, L., Pamp, S. J. & Tolker-Nielsen, T.
& Dolin, R.) 2835–2860 (Elsevier, Philadelphia, 2010).
u Strateva, T. & Yordanov, D. Pseudomonas aeruginosa
Nature Review Microbiology
Edited by Christiaan van Ooij;
2003–2008, issued June 2009. Am. J. Infect. Control 38, An update on Pseudomonas aeruginosa biofilm – a phenomenon of bacterial resistance. J. Med. Vol. 9 no. 3 March 2011
copy-edited by Lucie Wootton;
 Early (Acute) InfecGon Chronic InfecGon

Secreted toxins and enzymes Decreased secreGon

Flagella
Complete LPS (“Smooth”) DefecGve LPS (“Rough”)

Type IV pili Deacylated lipid A

Auxotrophy

Low level of Overexpression of

alginate alginate

LasR (quroum-sensing) mutants

Adapta&on During Chronic Lung Infec&on In Cys&c Fibrosis

Considera;ons for development of animal
models of P. aeruginosa
•  Normal healthy animals are generally resistant to infecGon
•  Some acute infecGons can disseminate
•  Other infecGons stay localized
•  P. aeruginosa adapts during chronic respiratory infecGons in cysGc
fibrosis (CF)
•  There are >1700 recognized disease-associated mutaGons in CFTR in the
human populaGon (with F508del being most common), but not all are
equivalent
•  Strains from parGcular sources may express disGnct constellaGons of
pathogenic factors that may be essenGal at different infecGon sites

Thanks