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Pseudomonas Aeruginosa 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 • Bioinformac analysis • Ordered transposon (Tn) libraries • PAO1, Jacobs et al. PNAS 2003 • PA14, Libera et al. PNAS 2006 • State of the art geneGc tools • Reagents for the construcGon of specific mutaons • 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 • Bioinformac analysis • Ordered transposon (Tn) libraries • PAO1, Jacobs et al. PNAS 2003 • PA14, Libera et al. PNAS 2006 • State of the art geneGc tools • Reagents for the construcGon of specific mutaons • 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 • Bioinformac analysis • Ordered transposon (Tn) libraries • PAO1, Jacobs et al. PNAS 2003 • PA14, Libera et al. PNAS 2006 • State of the art geneGc tools • Reagents for the construcGon of specific mutaons • Tnseq • RNAseq P. aeruginosa is an opportunisc pathogen • InfecGons generally occur in the context of breach of the innate immune system • Healthy animals like healthy humans are typically resistant to infecon Ear infecGons Eye infecons 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 Presentaon Pseudomonas aeruginosa Alan R. Hauser and Egon A. Ozer Pseudomonas aeruginosa is an opportunistic pathogen that infects humans with for the success of P. a e r u g i n o s a . It can utilize a broad spectrum of nutrients compromised natural defences. Predisposing conditions include a disrupted and can thus grow in hospital drains, sinks and even disinfectant solutions. epithelial barrier (as found in a patient with a burn wound), a depletion of P. aeruginosa is intrinsically resistant to a large number of antibiotics and can neutrophils (for example, in a cancer patient receiving chemotherapy), the acquire resistance to many others, making treatment difficult. The propensity presence of a foreign body (a patient with a central venous catheter) and altered of P. aeruginosa to form biofilms further protects it from antibiotics and from mucociliary clearance (in an individual with cystic fibrosis). Many P. a e r u g i n o s a the host immune system. In addition, a large arsenal of pathogenicity factors is MICROBIOLOGY infections occur after patients have been hospitalized. Several factors account used to interfere with host defences. Supplement to Nature Publishing Group Transposons and integrons Plasmid Clinical disease Quorum sensing O H N Biofilm O Eye infections Three quorum sensing systems in P. a e r u g i n o s a regulate biofilm architecture and a O O LasR Chromosome P. a e r u g i n o s a infections most commonly involve the large number of virulence determinants. Cross regulation of the three systems provides lasI 3-O-C12-HSL Aminoglycoside Phagocyte O H ampC Colistin cornea (keratitis) but may occasionally involve the an additional level of complexity. N Penicillin rhIl C4-HSL O RhlR Cephalosporin intraocular cavity (endophthalmitis). Bacteria are Quorum u N -(3-oxododecanoyl)-l-homoserine lactone (3-O-C -HSL) production is controlled O Gyrase Topoisomerase IV sensing 12 Carbapenem Penicillin pqsABCDE phnAB O introduced into the eye by trauma or following autoinducer by Lasl. The molecule is detected by LasR. + PqsH PQS corneal injury caused by contact lenses. molecule OH PqsR u N -butanoyl-l-homoserine lactone (C4-HSL) is produced by RhlI and detected N Airway H Ear infections by RhlR , Biofilm formation Fluoroquinolones Cephalosporin ‘Swimmer’s ear’ is an infection of the outer , Virulence factor u 2-heptyl-3-hydroxy-4-quinolone (PQS) is synthesized by the products of the production (e.g. elastase, Supplement to Nature Publishing Group Carbapenem ear canal that develops when water remains in the pqsABCDE and phnAB operons along with PqsH. PQS is detected by PqsR. exotoxin A and pyocyanin) Aminoglycoside ear after swimming. Malignant otitis externa is a Cephalosporin severe infection that occurs when bacteria in the ear Penicillin OprD Carbapenem canal invade through the surrounding cartilage to Fluoroquinolone Low [O2], [nutrients] and metabolic activity High deeper structures, including the middle ear, mastoid CupA CupB Centre Surface air cells and temporal bone. CupC RND Pel polysaccharide LecB Chronic respiratory infections Rhamnolipid Neutrophil MFP P. a e r u g i n o s a is commonly isolated from Psl polysaccharide Antibiotic resistance the respiratory tracts of individuals with eDNA AmpC -lactams cystic fibrosis and is associated with an OMF Treatment of P. a e r u g i n o s a infections accelerated decline in lung function in Alginate is made increasingly difficult by the rising Autolysis MexA– Efflux pump levels of drug resistance; isolates resistant to these patients. Chronic lung colonization MexB– Colistin all conventional antibiotics are increasingly and infection also occur in bronchiectasis, OprM a disease characterized by irreversible common. The mechanisms of drug resistance can be specific for a particular -lactams drug class or general, affecting many different types of antibiotics. Specific dilation of the bronchial tree, and in PelA–PelG Aminoglycosides mechanisms include alteration of antibiotic targets (such as topoisomerase IV chronic obstructive pulmonary disease, and gyrase, which are targeted by fluoroquinolones; and LPS, which is a disease characterized by narrowing ‘Planktonic’ targeted by colistin), uptake channels (such as OprD, which mediates influx of the airways and abnormalities in of carbapenems) or regulatory systems (such as AmpD, which indirectly air flow. represses the gene encoding AmpC β-lactamase). General mechanisms Attachment Hospital-acquired pneumonia to surface ‘Sessile’ include drug efflux pumps, which remove a variety of antibiotics from the P. a e r u g i n o s a is one of the most bacterium (see below). Efflux pumps consist of outer membrane channel- common causes of hospital- forming proteins (OMFs), a cytoplasmic membrane-associated antiporter acquired pneumonia, especially Surface-associated Microcolony Biofilm formation Dispersal motility formation (RND) and a periplasmic membrane fusion protein (MFP). Plasmids, in mechanically ventilated Biofilms transposons and integrons can encode additional antibiotic resistance patients; it is associated 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 factors, including metallo-β-lactamases, which are active against nearly with a particularly high 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 all β-lactams, and enzymes that inactivate aminoglycosides. mortality rate. 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 1 Complicated intra-abdominal infections Antibiotic efflux pumps 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. P. a e r u g i n o s a is identified in some cases of RND efflux pump Substrates 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 hospital-acquired complicated intra-abdominal MexA–MexB–OprM FQ, B-lactams (except IMI), tetracyclines, chloramphenicol, 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. macrolides, trimethoprim, sulphonamides infections. MexC–MexD–OprJ FQ, Anti-PA PCN, CPM, MERO, tetracycline, Urinary tract infections chloramphenicol, macrolides, trimethoprim Pyoverdin MexE–MexF–OprN FQ, carbapenems, chloramphenicol, trimethoprim P. a e r u g i n o s a accounts for a substantial proportion Pathogenesis P. aeruginosa of nosocomial urinary tract infections. These Fe3+ + Fe2+ MexX–MexY FQ, Anti-PA PCN, CPM, MERO, tetracyline, AG, Pathogenesis in FpvA infections are usually associated with a foreign Pyocyanin Inner membrane macrolides, chloramphenicol P. aeruginosa is MexJ–MexK Tetracycline, erythromycin body or surgery of the urinary
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