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MidtermIIOct.26th MidtermIIOct.26th 40questions Multiplechoice Lectures815(ListeriatoPseudomonas) Onequestionfromlecture14 Twoquestionsfromlabmaterial Pseudomonas Lecture 14 Classification Classification Family Genera Species Pseudomonadaceae Pseudomonas/Pseudomonads P. aeruginosa GeneralCharacteristics GeneralCharacteristics gramnegative Straightrods,sometimesslightlycurved Arrangeinpairs Single,polarflagellum(Motile) Capsule Nonfermentative(obligateaerobes) althoughitcanuseNitrateaselectronacceptor underanaerobicconditions CatalaseandOxidasepositive Formbiofilms! Morphology Morphology Invitrogrowth SputumCFpatient OrganizationofFlagella OrganizationofFlagella specificstainingprocedurerequiredtovisualizeflagella StructureFlagellum StructureFlagellum (notexammaterial) E.ColiMovement E.ColiMovement http://www.rowland.harvard.edu/labs/bacteria/showmovie.php?mov=swimming_ecoli PeritrichousFlagellar PeritrichousFlagellar Slowmotion http://www.rowland.harvard.edu/labs/bacteria/showmovie.php?mov=fluo_bundle_500hz PeritrichousFlagellar http://www.rowland.harvard.edu/labs/bacteria/showmovie.php?mov=fluo_cell_near Ubiquitous(Soil,Water,Asymptomatic carriageonskin) 37OCoptimalgrowthtemperature butgrowthwellbetween4C42C Specialmedia(PseudomonasPorFagar)to produceblueorgreencolonies(pyocyaninvs. pyoverdinepigments) Coloniesafter12days P.aeruginosa Culture P.aeruginosagrownon: P.aeruginosa PseudomonasagarF PseudomonasagarP Pathogenesis Pathogenesis Extracellularpathogen(see,EPEC) Pathogenesis Pathogenesis Adhesins:Pilusandnonpilusadhesins,bind especiallywelltoBasementMembrane componentLamininwhichisonlyexposed afterdamageofepithelium Capsule:antiphagocytotic,anticomplement, antiantibiotic LPS:Proinflammatory,leadstosepticshock TTSS:transportofeffectormoleculesinto targetcells Pathogenesis Exotoxinsandsecretedenzymes Pyocyanin(Bluecolonycolor): secretedinsuchlargeamountsthatitcolors sputumblue thoughttoinhibitciliarymovementoflung epithelium ExotoxinA(Proteinsynthesisinhibitor):AB toxin;structurallyandfunctionallysimilarto diphtheriatoxinbuttargetsdifferentreceptor Pathogenesis Exotoxinsandsecretedenzymes ExoenzymeS+T: inhibitcytoskeletonpolymerization(cell rounding) inhibitwoundhealingviainhibitingcell division(importantforestablishing colonizationinepithelium) EffectofExoenzymeS EffectofExoenzymeS Epithelialcells Wildtypebacteria ExoSmutantbacteria Pathogenesis Exotoxinsandsecretedenzymes Elastases(LasAandLasB): degradeelastin(majorcomponentoflung tissue,giveselasticity) inducestissuedamageandthushelps establishandmaintaincolonization canalsodegradecomplement Pathogenesis Exotoxinsandsecretedenzymes PhospholipaseC: heatlabilehemolysine Rhamnolipid: heatstabilehemolysine Pseudomonascoloniesarebetahemolyticon bloodagar Pathogenesis Pathogenesis Biofilmformation increasesantibioticresistance helpsestablishandmaintainextracellularcolonization Epidemiology/Transmission P.aerigunosa Ubiquitousinenvironment!!! Haveminimalnutritionalrequirementsand growatwidevarietyoftemperatures Persistondrysurfaceformonths!! Ubiquitouswithinhospitalsonallsurfaces!!!! Epidemiology Epidemiology OpportunisticPathogen;uncommoninhealthy Mostcommoncauseofopportunistic individuals infectionsinCysticFibrosispatients(85%of patientsareinfected!) Importantcauseofnosocomialinfections (10%)(Catheter,prostheticdevicesand ventilators) 75%ofallintensivecareunitpatientsare colonized Infections Caused by P. aeruginosa Biofilms Biofilms Contact lens-associated corneal infection Catheter-associated infection Ventilator-associated pneumonia Chronic infection of cystic fibrosis patients ClinicalManifestation ClinicalManifestation UncompromisedIndividuals SwimmersEar: Externalotitis,treatmentwithtopicalantibiotics butsometimesmoreinvasiveform(Malignant ExternalOtitis),requiresmoreaggressive treatment(antimicrobialandsurgical) TubRash: Folliculitis,usuallybenignandselflimiting Botharecausedbyexposuretocontaminated water P.aeruginosa P.aeruginosa Skinlesions IntensiveCareUnitpatient TubRash Skinlesionappearasround(1cmdiameter)hardened,purpleareaswithulceratedcenter ClinicalManifestation OpportunisticInfections 1)Duetotissuedamage EyeInfections: initialtraumatothecornea,allows colonizationbybacteriaviacontaminated water CornealUlcersdevelop prompttreatmentnecessary ClinicalManifestation OpportunisticInfections 1)Duetotissuedamage PrimarySkinInfections: burnwoundsexposedeeper epithelialtissuewhichcan becolonizedbybacteria commoninpatientswith severburns leadstovasculardamage andtissuenecrosis andoftenalsotobacteremia BurnWoundInfection BurnWoundInfection ClinicalManifestation OpportunisticInfections 2)Duetomedicaldevices UrinaryTractInfections: mainlyinpatientswithlongtermcatheters patienthaveundergonemultipleroundsof antibiotictreatmentsforpreviousnosocomial infections,whichselectsforPseudomonas (Resistance) ClinicalManifestation OpportunisticInfections 2)Duetomedicaldevices Pneumonia: inimmunocompromisedpatients(AIDS, Cancertherapy)withrecentantibiotic treatmentandcurrentlyonventilator mortalityashighas70% Pneumonia: CysticFibrosis(defectinmucusexpulsion fromlung)orChronicGranulomatous Disease(defectinphagocyticcellstokill bacteria) canleadtosevernecrotizingpneumonia ClinicalManifestation OpportunisticInfections 3)Duetootherdisease Diagnosis Diagnosis Culture bhemolytic,pigmentation(P,Fagar),sweet grapelikeodor Biochemicaltests Nitratereduction(anaerobic) Oxidase/catalasepositive Drugresistance Drugresistance DrugResistance DrugResistance Antibiotic -Lactams Aminoglycosids Resistance Mechanisms -Lactamase hydrolysis; decreased permeability; altered binding proteins Enzymatic hydrolysis by acetylation, adenylation, or phosphorylation; decreased permeability; altered ribosomal target Enzymatic hydrolysis by acetyltransferase; decreased permeability Altered target (DNA gyrase); decreased permeability Chloramphenicol Fluoroquinolones AlloftheseresistancemechanismshavebeenfoundinP. aeruginosaisolates Treatment/Prevention Treatment/Prevention Treatment: Extremelydifficultduetoantibioticresistance Evensusceptiblestrainsmaybecomeresistantduring courseoftreatment Usuallycombinationoftwoantibioticwithdifferent targetsareused Prevention: Novaccineavailable Duetoubiquitousnatureofbacteriacannotbe completelyeliminated Maximalefforttoavoidcontaminationofmedical devices ... 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Lecture 15 Pseudomonas

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