Human Diseases Human Diseases Caused Primarily by Gram-Positive Caused Primarily by Gram-Positive

and Gram-Negative Bacteria:  and Gram-Negative Bacteria:  

The Airborne Diseases – The Airborne Diseases – Part IPart I

Airborne DiseasesAirborne Diseases

DiphtheriaDiphtheria

Diphtheria - Diphtheria - Corynebacterium diphtheriaeCorynebacterium diphtheriae– General featuresGeneral features

Club shaped (coryne = “club” in Greek) – Club shaped (coryne = “club” in Greek) – pleomorphic V-shaped rodspleomorphic V-shaped rods

Gram positive, non-sporing, non-motileGram positive, non-sporing, non-motile

Refractile granules give rise to heterogeneous Refractile granules give rise to heterogeneous stainingstaining

– Accumulate in stationary phase – phosphate storageAccumulate in stationary phase – phosphate storage

Metachromatic granulesMetachromatic granules

VolutinVolutin

Babes-Ernst bodiesBabes-Ernst bodies

Only humans serve as a reservoir for this Only humans serve as a reservoir for this microorganismmicroorganism

– Acute, contagious diseaseAcute, contagious diseaseAffects mainly poor people living in crowded Affects mainly poor people living in crowded conditions – unvaccinatedconditions – unvaccinated

Acute infection of the respiratory tract Acute infection of the respiratory tract usually invading the tonsilar areausually invading the tonsilar area

Spread via respiratory route and contaminated Spread via respiratory route and contaminated milk (unpasteurized)milk (unpasteurized)

Virulence factors/pathogenicityVirulence factors/pathogenicity– Exotoxin = diphtheria toxin (AB exotoxin)Exotoxin = diphtheria toxin (AB exotoxin)

Tox gene encoded by bacteriophage that Tox gene encoded by bacteriophage that integrates into bacterium’s genome integrates into bacterium’s genome Prophage Prophage (lysogenic)(lysogenic)Protein synthesis inhibition (involving EF-2 and Protein synthesis inhibition (involving EF-2 and translocase)translocase)Can disseminate through bloodstream (toxemia) Can disseminate through bloodstream (toxemia) and affect nervous system, heart and kidneysand affect nervous system, heart and kidneys

– Cord factorCord factorGlycolipid containing trehaloseGlycolipid containing trehalose

Symptoms/PresentationSymptoms/Presentation– Dead tissue cells, WBC and RBC and bacterial Dead tissue cells, WBC and RBC and bacterial

cells form a dull gray exudate referred to as a cells form a dull gray exudate referred to as a pseudomembranepseudomembrane

Can block airway in trachea – suffocationCan block airway in trachea – suffocationTracheotomy may be requiredTracheotomy may be required

– Thick mucopurulant (mucous and pus) nasal Thick mucopurulant (mucous and pus) nasal dischargedischarge

– FeverFever– Cough, sore throatCough, sore throat– Malaise (vague feeling of physical discomfort)Malaise (vague feeling of physical discomfort)– Enlarged and tender cervical lymph nodesEnlarged and tender cervical lymph nodes

– Laboratory culture – swab the tonsilar areaLaboratory culture – swab the tonsilar areaTellurite added to medium (chocolate or blood Tellurite added to medium (chocolate or blood agar)agar)

– Enriches for C. diphtheriae and restricts growth of Enriches for C. diphtheriae and restricts growth of normal flora of the throatnormal flora of the throat

– Tellurite is reduced to tellurium metal precipitate Tellurite is reduced to tellurium metal precipitate (dark gray to black colonies)(dark gray to black colonies)

DiagnosisDiagnosis– Detection of toxinDetection of toxin

In vitro virulence test = ELEK testIn vitro virulence test = ELEK test– Streak bacteria out on agar in linesStreak bacteria out on agar in lines– Lay a paper strip containing anti-toxin antitoxin Lay a paper strip containing anti-toxin antitoxin

antibodiesantibodies– Include a positive control in parallel to patient’s Include a positive control in parallel to patient’s

samplesample– Incubate and look for line of identity (precipitate Incubate and look for line of identity (precipitate

caused by immune complexes)caused by immune complexes)

Inject guinea pig Inject guinea pig morbid symptoms/mortality morbid symptoms/mortality

Susceptibility testSusceptibility test– SCHICK Test (rarely used anymore)SCHICK Test (rarely used anymore)

Diphtheria toxoid inject subcutaneouslyDiphtheria toxoid inject subcutaneously

Wait 48 hours and note formation of induration Wait 48 hours and note formation of induration in the absence of antibodies = susceptible in the absence of antibodies = susceptible immunity not presentimmunity not present

If antibodies are present (immune) then toxin is If antibodies are present (immune) then toxin is neutralized neutralized no induration no induration

DTH responseDTH response

TreatmentTreatment– Antitoxin administered to neutralize the Antitoxin administered to neutralize the

toxintoxin– Immediate administration based on Immediate administration based on

symptoms rather than waiting for symptoms rather than waiting for laboratory resultslaboratory results

– Also administer penicillin or erythromycinAlso administer penicillin or erythromycin

PreventionPrevention– Immunization (vaccination)Immunization (vaccination)

Has protected USA from this diseaseHas protected USA from this disease

Toxoid made from diphtheria toxinToxoid made from diphtheria toxin– Part of DPT vaccinePart of DPT vaccine

DiphtheriaDiphtheria

PertussisPertussis

TetanusTetanus

– Administered at 2, 4, 6, and 15-18 months, and again at 4-6 Administered at 2, 4, 6, and 15-18 months, and again at 4-6 years with boosters every 10 years recommended years with boosters every 10 years recommended (especially if traveling to areas where diphtheria is endemic (especially if traveling to areas where diphtheria is endemic – Asia, Africa, Central and South America and Russia)– Asia, Africa, Central and South America and Russia)

Legionnaires’ Disease Legionnaires’ Disease (Legionellosis)(Legionellosis)

General FeaturesGeneral Features– Caused by Caused by Legionella pneumophilaLegionella pneumophila

Gram negative rodsGram negative rods

This organism also causes Pontiac Fever (no pneumonia, This organism also causes Pontiac Fever (no pneumonia, self-limiting)self-limiting)

– 1976 – American Legion convention in 1976 – American Legion convention in Philadelphia in one of the city’s largest hotelsPhiladelphia in one of the city’s largest hotels

29 fatalities (182 participants)29 fatalities (182 participants)

– 1985 – Stafford, England1985 – Stafford, EnglandCooling systemCooling system

39 fatalities out of 163 people exposed39 fatalities out of 163 people exposed

– Not spread person-to-personNot spread person-to-person– Bacteria normally found in soil and aquatic Bacteria normally found in soil and aquatic

ecosystemsecosystems– Bacteria also found in air-conditioning Bacteria also found in air-conditioning

systems and shower stallssystems and shower stalls– Infection causes Infection causes cytotoxic damagecytotoxic damage to lung to lung

alveolialveoli

Virulence factors/pathogenicityVirulence factors/pathogenicity– Mist inhaled from poor water cooling Mist inhaled from poor water cooling

systems and mist machines in systems and mist machines in supermarketssupermarkets

– Soil Soil dust?? dust??– Whirlpool filters, shower heads, nebulizers Whirlpool filters, shower heads, nebulizers

and hot water systemsand hot water systems

– Endotoxin in cell wallEndotoxin in cell wall– Hemolysin generatedHemolysin generated– Cytotoxin producedCytotoxin produced– Bacteria divide within alveolar Bacteria divide within alveolar

macrophagesmacrophagesInhibition of fusion of phagosome with Inhibition of fusion of phagosome with lysosomelysosome

– Mediated by mip gene product (macrophage Mediated by mip gene product (macrophage infectivity potentiator)infectivity potentiator)

Important in establishing pneumoniaImportant in establishing pneumonia

SymptomsSymptoms– Chest pain, dry (non-productive) coughChest pain, dry (non-productive) cough– FeverFever– HeadacheHeadache– NeuralgiaNeuralgia– ““Atypical pneumonia” Atypical pneumonia”

(bronchopneumonia)(bronchopneumonia)– Abdominal cramping and gastrointestinal Abdominal cramping and gastrointestinal

symptoms may also occursymptoms may also occur

Laboratory cultureLaboratory culture– Mueller-Hinton agarMueller-Hinton agar

1% Hemoglobin + 1% Isovitalex (vitamins)1% Hemoglobin + 1% Isovitalex (vitamins)

5% CO5% CO22

– Cell cultureCell culture– Grown in animalsGrown in animals

Guinea pigsGuinea pigsChick embryosChick embryos

– Can survive in free-living amoebae Can survive in free-living amoebae (another potential source)(another potential source)

Increased susceptibilityIncreased susceptibility– SmokersSmokers– AlcoholismAlcoholism– Endotracheal intubationEndotracheal intubation– Chronic pulmonary diseasesChronic pulmonary diseases– Patients on immunosuppressive therapyPatients on immunosuppressive therapy

Transplant patientsTransplant patients

Autoimmune patientsAutoimmune patients

– AnesthesiaAnesthesia

Diagnosis and treatmentDiagnosis and treatment– Isolation and serological identification Isolation and serological identification

neededneededDirect immunofluorescence (organisms cultured Direct immunofluorescence (organisms cultured or obtained from sputum)or obtained from sputum)Indirect immunofluorescence (patient’s serum – Indirect immunofluorescence (patient’s serum – antibodies to organism)antibodies to organism)Agglutination testsAgglutination testsELISAELISARIA on urineRIA on urine

– Erythromycin and/or rifampinErythromycin and/or rifampin

MeningitisMeningitisNeisseria meningitidis*, Streptococcus Neisseria meningitidis*, Streptococcus pneumoniae, Haemophilus influenzae*, pneumoniae, Haemophilus influenzae*,

Salmonella choleraesuisSalmonella choleraesuis (invades from GI tracts), (invades from GI tracts), Listeria monocytogenes*Listeria monocytogenes*

MeningitisMeningitis - caused by a variety of - caused by a variety of organisms and conditionsorganisms and conditions– BacterialBacterial (septic) (septic) meningitismeningitis is diagnosed by the is diagnosed by the

presence of bacteria in the cerebrospinal fluidpresence of bacteria in the cerebrospinal fluid– Bacterial meningitis is treated with various Bacterial meningitis is treated with various

antibiotics, depending on the specific bacterium antibiotics, depending on the specific bacterium involvedinvolved

– Aseptic (nonbacterial) meningitis syndrome is Aseptic (nonbacterial) meningitis syndrome is more difficult to treat but the mortality is more difficult to treat but the mortality is generally lowgenerally low

Neisseria meningitidisNeisseria meningitidis(epidemic meningitis)(epidemic meningitis)

General featuresGeneral features– Gram negative dipolococci (meningococci)Gram negative dipolococci (meningococci)– Non-motileNon-motile– Oxidase positiveOxidase positive

Can oxidize dimethyl (and tetramethyl) para-phenylene diamine Can oxidize dimethyl (and tetramethyl) para-phenylene diamine hydrochloride)hydrochloride)

– Must be grown >30Must be grown >30ooCC– Require special media Require special media sensitive to trace metals and fatty sensitive to trace metals and fatty

acidsacidsChocolate agar (blood agar treated at 80Chocolate agar (blood agar treated at 80ooC for 10’)C for 10’)

– Decreases inhibitory effects of trace metals and fatty acidsDecreases inhibitory effects of trace metals and fatty acids

Incubated with 10% COIncubated with 10% CO22

– Causes 2000-3000 cases of meningitis annually in USACauses 2000-3000 cases of meningitis annually in USA

ClassificationClassification– Serotypes based on common antigensSerotypes based on common antigens

Polysaccharide capsulePolysaccharide capsule

Outermembrane proteinsOutermembrane proteins

A-D, X-Z, L, W135 and 29EA-D, X-Z, L, W135 and 29E

A,B an C are primarily responsible for A,B an C are primarily responsible for meningitis outbreaksmeningitis outbreaks

Virulence characteristicsVirulence characteristics– Obligate parasite of humansObligate parasite of humans– Often found in nasopharynx of Often found in nasopharynx of

asymptomatic carriersasymptomatic carriers– Spread via respiratory routeSpread via respiratory route– Pili enable attachment to host cellsPili enable attachment to host cells– Capsule resists phagocytosisCapsule resists phagocytosis– Release large amount of endotoxinRelease large amount of endotoxin– IgA1 protease producedIgA1 protease produced

Three stagesThree stages– First stage = nasopharyngeal infectionFirst stage = nasopharyngeal infection

Minor inflammation or asymptomaticMinor inflammation or asymptomaticLasts days to monthsLasts days to monthsProtective antibodies madeProtective antibodies made

– Second state = memingococcemiaSecond state = memingococcemiaMicrobes enter bloodstreamMicrobes enter bloodstreamCan be acute and rapid (death in 6-8 hours!)Can be acute and rapid (death in 6-8 hours!)May take longer to ensue with fever, malaise May take longer to ensue with fever, malaise and rashand rash

Sometimes lesion in joints, lungs, skin, internal Sometimes lesion in joints, lungs, skin, internal organs and adrenal glands developorgans and adrenal glands develop

– Endotoxin induced (TNF-alpha produced)Endotoxin induced (TNF-alpha produced)– Disseminated intravascular coagulation (DIC) may Disseminated intravascular coagulation (DIC) may

develop (Hageman factor)develop (Hageman factor)

Clots disrupt circulationClots disrupt circulation

Amputation may be necessaryAmputation may be necessary

– Third stage = meninges infected following Third stage = meninges infected following invasion of the blood brain barrier (BBB)invasion of the blood brain barrier (BBB)

Headache, stiff neck, vomiting, deleriumHeadache, stiff neck, vomiting, deleriumTNF-alpha found in CSFTNF-alpha found in CSF

– Concentration correlates with degree of BBB disruption Concentration correlates with degree of BBB disruption and severity of the diseaseand severity of the disease

Most severe form of meningococcemia is the Most severe form of meningococcemia is the life threatening life threatening Waterhouse-Friderichsen Waterhouse-Friderichsen syndromesyndrome– High fever, shock, widespread purpura, High fever, shock, widespread purpura,

disseminated intravascular coagulation and disseminated intravascular coagulation and adrenal insufficiency, seeding of multiple organs adrenal insufficiency, seeding of multiple organs including the meningesincluding the meninges

Bleeding into the skin (petechiae and purpura), and the tissue in these areas may die (become necrotic or gangrenous).

Diagnosis of Meningococcal infectionsDiagnosis of Meningococcal infections– Microscopy – smearsMicroscopy – smears– Culturing CSF, blood, skin lesion, Culturing CSF, blood, skin lesion,

nasopharyngeal secretionsnasopharyngeal secretionsChocolate agarChocolate agarBlood agarBlood agarThayer-Martin medium Thayer-Martin medium

– Nystatin, Polymyxin, Vancomycin – Antibioitics inhibit Nystatin, Polymyxin, Vancomycin – Antibioitics inhibit contaminants while favoring pathogenic Neisseriacontaminants while favoring pathogenic Neisseria

5-10% CO5-10% CO22 (candle jar or CO (candle jar or CO22 incubator) incubator)

– SerologySerologyGroup-specific antisera – agglutination of bacteriaGroup-specific antisera – agglutination of bacteria

– Sugar fermentation tests (Glucose+, Maltose+)Sugar fermentation tests (Glucose+, Maltose+)– CounterimmunoelectrophoresisCounterimmunoelectrophoresis

At the pH used the anti-capsule antibodies have a At the pH used the anti-capsule antibodies have a positive charge and moves toward the anode while the positive charge and moves toward the anode while the capsular polysaccharides have a negative charge and capsular polysaccharides have a negative charge and moves toward the cathodemoves toward the cathode

– Electrophoresed for 30-60 minutesElectrophoresed for 30-60 minutes

– A precipitate line forms if positiveA precipitate line forms if positive

– Quellung reactionQuellung reactionAntibodies to capsular components – swelling Antibodies to capsular components – swelling of capsule occursof capsule occurs

– Latex bead agglutination (group-specific Latex bead agglutination (group-specific polysaccharide adsorbed to beads – polysaccharide adsorbed to beads – incubated with patient’s serum)incubated with patient’s serum)

TreatmentTreatment– Penicillin or erythromycinPenicillin or erythromycin

PreventionPrevention– Quadravalent vaccine – A, C, Y + W135 – Quadravalent vaccine – A, C, Y + W135 –

polysaccharide antigenspolysaccharide antigensUsed in epidemics and for military personnelUsed in epidemics and for military personnel

– Prophylactic rifampin used for those Prophylactic rifampin used for those exposedexposed

Haemophilus influenzae - Haemophilus influenzae - MeningitisMeningitis

General features and growth General features and growth requirementsrequirements– Small, Gram negative rod/coccobacillus Small, Gram negative rod/coccobacillus

(pleomorphic)(pleomorphic)– Non-motile, aerobicNon-motile, aerobic– Associated with bacterial meningitis in Associated with bacterial meningitis in

children and epiglottis infection (can block children and epiglottis infection (can block airway)airway)

Leading cause of invasive bacterial disease in Leading cause of invasive bacterial disease in childrenchildren

– Six capsular typesSix capsular typesType b = significant in human infectionsType b = significant in human infections

– Primary virulence factor - antiphagocyticPrimary virulence factor - antiphagocytic

Composed of PRPComposed of PRP– Polymer of ribose phosphate or ribulose phosphatePolymer of ribose phosphate or ribulose phosphate– Polysaccharide capsulePolysaccharide capsule

Non-encapsulated forms in majority of Non-encapsulated forms in majority of asymptomatic carriersasymptomatic carriers

– Can cause secondary bacterial pneumoni Can cause secondary bacterial pneumoni after viral infections (influenzae0after viral infections (influenzae0

– Require chocolate agar supplemented with Require chocolate agar supplemented with X and V factorsX and V factors

X factor = heat stable hematin (reguired for X factor = heat stable hematin (reguired for cytochromes and catalase)cytochromes and catalase)

V factor = heat labile, can be substituted with V factor = heat labile, can be substituted with NADNAD

Virulence factors/pathogenicityVirulence factors/pathogenicity– Respiratory route of infection/transmissionRespiratory route of infection/transmission– Menintigitis in childrenMenintigitis in children

1000-3000 cases annually in USA1000-3000 cases annually in USA

Mortality rate of 3-7%Mortality rate of 3-7%

Enters blood via nasopharynx, then meningesEnters blood via nasopharynx, then meninges

CSF resembles meningococcal infection:CSF resembles meningococcal infection:– PMNLs and elevated sugar concentrationPMNLs and elevated sugar concentration

Other diseases caused by HIBOther diseases caused by HIB– Epiglottitis in childrenEpiglottitis in children

Airway obstruction owing to inflmmation, edemaAirway obstruction owing to inflmmation, edema– Can lead to suffocation if not treatedCan lead to suffocation if not treated

– Otitis media with effusion (OME)Otitis media with effusion (OME)Within first 3 years of life, 60-70% of children are affected Within first 3 years of life, 60-70% of children are affected (40% more than once)(40% more than once)Usually the unencapsulated form is responsibleUsually the unencapsulated form is responsible

– Can also cause septic arthritis in children <2 years old (joint Can also cause septic arthritis in children <2 years old (joint inflammation)inflammation)

– Elderly infections: pneumonia, meningitis, Elderly infections: pneumonia, meningitis, epiglottitis and female genital tractepiglottitis and female genital tract

Diagnosis, treatment and preventionDiagnosis, treatment and prevention– Centrifuge the CSFCentrifuge the CSF

Gram stain – pleomorphic Gram negative rodsGram stain – pleomorphic Gram negative rods

– Quellung reaction with type b antiserumQuellung reaction with type b antiserum– Fluorescent antibodiesFluorescent antibodies– Countercurrent electrophoresis of CSF Countercurrent electrophoresis of CSF

versus antiserumversus antiserum– ELISAELISA

– Latex bead agglutination (beads coated Latex bead agglutination (beads coated with antibodies to type b capsule)with antibodies to type b capsule)

– Culture CSF and blood Culture CSF and blood chocolate agar, chocolate agar, 353500C + COC + CO22 or TSA + X,V or XV discs or TSA + X,V or XV discs

Both X and V required for growthBoth X and V required for growth

– Treatment of meningitis must be immediate!Treatment of meningitis must be immediate!Relatively high mortality rate (3-7%)Relatively high mortality rate (3-7%)

High level of complications (in 30% of survivors)High level of complications (in 30% of survivors)– ConvulsionsConvulsions

– HydrocephalusHydrocephalus

– Mental retardationMental retardation

– BlindnessBlindness

Ampicillin or if ampicillin resistant then chloramphenicol Ampicillin or if ampicillin resistant then chloramphenicol or cephalosporinsor cephalosporins

Rifampin used as prophylactic for those exposedRifampin used as prophylactic for those exposed

– PreventionPreventionVaccine for type b capsular antigensVaccine for type b capsular antigensEarly vaccines were inefective in children <2 yearsEarly vaccines were inefective in children <2 yearsImproved vaccineImproved vaccine

– Conjugate vaccineConjugate vaccinePolysaccharide of type b conjugated to large proteins Polysaccharide of type b conjugated to large proteins which serve as carrierswhich serve as carriersTetanus toxoid = carrierTetanus toxoid = carrierDiphtheria toxoid = carrierDiphtheria toxoid = carrier

– Administered at 2 months of age, 3 doses, 2 months apart, Administered at 2 months of age, 3 doses, 2 months apart, then a booster at 12-15 monthsthen a booster at 12-15 months

– Tetramune: DPT + HbOCTetramune: DPT + HbOC

– Case StudyCase Study

Listeria monocytoenesListeria monocytoenes - - ListeriosisListeriosis

General featuresGeneral features– Small, Gram positive, motile, pleomorphic Small, Gram positive, motile, pleomorphic

rod (club shaped)rod (club shaped)– Facultative anaerobesFacultative anaerobes– Beta hemolytic on blood agar plates Beta hemolytic on blood agar plates

(narrow band)(narrow band)– 11 serotypes11 serotypes

Most prevalent forms include types 1a, 1b and Most prevalent forms include types 1a, 1b and 4b4b

PathogenicityPathogenicity– Transmitted by:Transmitted by:

AnimalsAnimals

Contaminated waterContaminated water

SoilSoil

Fecal-oral routeFecal-oral route

Poultry (major reservoir)Poultry (major reservoir)

Unpasteurized milkUnpasteurized milk

Coleslaw (raw vegetables not cleaned, Coleslaw (raw vegetables not cleaned, contaminated with manure)contaminated with manure)

Even pastueurized milk can be a potential source: Even pastueurized milk can be a potential source: intracellular microbes in leukocytes in milk are resistant intracellular microbes in leukocytes in milk are resistant to heatto heat

Meningitis occurs in >75% of infections (most common Meningitis occurs in >75% of infections (most common feature/manifestation in adults)feature/manifestation in adults)

Also causes endocarditis, urethritis, conjunctivitis and Also causes endocarditis, urethritis, conjunctivitis and abortions (miscarriage)abortions (miscarriage)

Most susceptibleMost susceptible– Immunocompromised and immunosuppressedImmunocompromised and immunosuppressed– NewbornsNewborns

Neonatal listeriosisNeonatal listeriosis

Neonatal listeriosisNeonatal listeriosis– Early and late onsetEarly and late onset

Early onset: Transplacental or transvaginal acquisitionEarly onset: Transplacental or transvaginal acquisition– Acutely ill at birth or shortly thereafterAcutely ill at birth or shortly thereafter– Pneumonia commonPneumonia common– Believed to be a result of decreased cell-mediated IRs in Believed to be a result of decreased cell-mediated IRs in

pregnancypregnancy– Growth of bacteria within placental cellsGrowth of bacteria within placental cells

Late onsetLate onset– 1-4 weeks after birth1-4 weeks after birth– Meningitis usuallyMeningitis usually– Probably acquired after birth as a result of person-to-person Probably acquired after birth as a result of person-to-person

contactcontact

Listerolysin O (LLO)Listerolysin O (LLO)– Hemolytic cytolysin responsible for Hemolytic cytolysin responsible for

intracellular growth in macrophages and intracellular growth in macrophages and epithelial cellsepithelial cells

– Permits escape of phagocytosed Permits escape of phagocytosed L. L. monocytogesmonocytoges from phagosome from phagosome into the into the cytosolcytosol

TreatmentTreatment– PenicillinPenicillin– Ampicillin Ampicillin – Or tetracycline (preferred)Or tetracycline (preferred)

Atypical MycobacteriaAtypical Mycobacteria

Mycobacterium avium - M. intracellulaireMycobacterium avium - M. intracellulaire pneumoniapneumonia– Organisms are normal soil and water Organisms are normal soil and water

inhabitants especially in Southern USAinhabitants especially in Southern USA– Both the respiratory and the gastrointestinal Both the respiratory and the gastrointestinal

tracts have been proposed as portals of entry tracts have been proposed as portals of entry – The gastrointestinal tract is thought to be the The gastrointestinal tract is thought to be the

most common site of colonization and most common site of colonization and disseminationdissemination

Pulmonary infectionPulmonary infection is similar to is similar to tuberculosis but usually mildertuberculosis but usually milder– Most often seen in elderly patients with Most often seen in elderly patients with

preexisting pulmonary diseasepreexisting pulmonary disease– Occurs in 15 to 40% of AIDS patients; is Occurs in 15 to 40% of AIDS patients; is

becoming a severe problembecoming a severe problem– Symptoms include fever, malaise, weight loss, Symptoms include fever, malaise, weight loss,

and diarrheaand diarrhea– Treatment is usually multiple drug therapyTreatment is usually multiple drug therapy

Bordetella pertussisBordetella pertussis – – Whooping CoughWhooping Cough

PertussisPertussis (whooping cough) - (whooping cough) - Bordetella Bordetella pertussispertussis– Highly contagiousHighly contagious disease that primarily affects disease that primarily affects

childrenchildren– Transmission is by Transmission is by droplet inhalationdroplet inhalation– Toxins are responsible for most of the Toxins are responsible for most of the

symptomssymptoms

General featuresGeneral features– Small, Gram negative cocco-bacillusSmall, Gram negative cocco-bacillus– Non-motileNon-motile– Non-spore formingNon-spore forming– Often encapsulatedOften encapsulated– SourceSource

Respiratory discharge (microdroplets)Respiratory discharge (microdroplets)

Direct or indirectDirect or indirect

Virulence characteristics (non-invasive)Virulence characteristics (non-invasive)– The disease progresses in stagesThe disease progresses in stages

Catarrhal stageCatarrhal stage– Inflamed mucous membranesInflamed mucous membranes– Resembles a cold (sneezing, coughing)Resembles a cold (sneezing, coughing)– Follows infection of ciliated epithelium of RTFollows infection of ciliated epithelium of RT– Lasts 7-10 daysLasts 7-10 days

Spasmodic/Paroxysmal stageSpasmodic/Paroxysmal stage– After 1-2 weeksAfter 1-2 weeks– Prolonged coughing sieges with inspiratory whoopProlonged coughing sieges with inspiratory whoop

ExhaustiveExhaustive

VomitingVomiting

ConovulsionsConovulsions– Lasts ~2 weeksLasts ~2 weeks

Convalescent stageConvalescent stage– Lasts a further 2 weeks or sometimes longerLasts a further 2 weeks or sometimes longer

– Some fatalitiesSome fatalities

Virulence factorsVirulence factors– Pertussis toxin (AB exotoxin)Pertussis toxin (AB exotoxin)

Increased cAMPIncreased cAMP– Activated protein kinases in cellActivated protein kinases in cell

Anaphylaxis sensitivity (histemine-sensitizing effect)Anaphylaxis sensitivity (histemine-sensitizing effect)Increased insulin – hypoglycemiaIncreased insulin – hypoglycemiaIncreased lymphocytes n bloodIncreased lymphocytes n blood

Aids in adherence to host cellsAids in adherence to host cells

– Extracytoplasmic adenylate cyclase (bacterial Extracytoplasmic adenylate cyclase (bacterial enzyme)enzyme)

Increased cAMPIncreased cAMPInhibition of neutrophils, macrophages and NK cellsInhibition of neutrophils, macrophages and NK cells

– Filamentous HemagglutininFilamentous HemagglutininBinding to epitheliumBinding to epithelium

– PertactinPertactinBinding to epitheliumBinding to epithelium

– Tracheal cytotoxinTracheal cytotoxinCauses mucous and inflammatory debris to Causes mucous and inflammatory debris to build up in the lungsbuild up in the lungs

= PTG degradation product= PTG degradation product– Induces IL-1 peroductionInduces IL-1 peroduction

Ciliated epithelial cells are killedCiliated epithelial cells are killed

– Spontaneous mutations in lab cultures of Spontaneous mutations in lab cultures of virulence factors virulence factors can lead to phase can lead to phase changes (phase 1,2,3,4)changes (phase 1,2,3,4)

Phase 1 = most virulentPhase 1 = most virulent

Phase 4 = avirulentPhase 4 = avirulent

Reversible processReversible process

Colony morphology may changeColony morphology may change

Loss of virulence factorsLoss of virulence factors

Treatment and preventionTreatment and prevention– CultureCulture

Push swab in back of nose to posterior nares Push swab in back of nose to posterior nares and ask patient to coughand ask patient to cough

– Swab (not cotton) coated with penicillinSwab (not cotton) coated with penicillin

Cultured on Bordet-Gengou mediumCultured on Bordet-Gengou medium– Potato blood glycerol agar (high % blood, 20-30%)Potato blood glycerol agar (high % blood, 20-30%)– 3-4 days3-4 days

– DetectionDetectionAgglutination testsAgglutination tests

Fluorescent antibodiesFluorescent antibodies

– AntibioticsAntibioticsErythromycin or tetracyclines or Erythromycin or tetracyclines or chloramphenicolchloramphenicol

Not always helpful, but important in limiting Not always helpful, but important in limiting secondary infections (bronchitis and secondary infections (bronchitis and pneumonia caused by other organisms)pneumonia caused by other organisms)

VaccinationVaccination– Effective but there are complicationsEffective but there are complications– 5-20 deaths; 50 cases of brain damage in USA per 5-20 deaths; 50 cases of brain damage in USA per

year over last 10 yearsyear over last 10 yearsPost vaccine encephalopathyPost vaccine encephalopathy

– DPT vaccineDPT vaccine2,4,6 and 12-15 mos2,4,6 and 12-15 mos

Killed Bordetella pertussisKilled Bordetella pertussis

Results of vaccination:Results of vaccination:– 1934 – 265,000 cases 1934 – 265,000 cases 7500 deaths 7500 deaths

– 1998 – 6000 cases 1998 – 6000 cases 3-5 deaths 3-5 deaths