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Streptococcus

Hugh B. FackrellHugh B. Fackrell

Filename:Filename:Strept.pptStrept.ppt

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Streptococcus Outline

StreptococcusStreptococcus Characteristics Characteristics Streptococcal DiseasesStreptococcal Diseases

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Streptococcus: characteristicsStreptococcus: characteristics

Genus definitionGenus definition Growth requirementsGrowth requirements CapsuleCapsule Colonial morphologyColonial morphology HemolysisHemolysis

Destruction of RBCsDestruction of RBCs Hemolysins Hemolysins

molecules that destroy RBCsmolecules that destroy RBCs

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StreptococcusGenus Definition

Gram +ve cocci, chains or pairsGram +ve cocci, chains or pairs Catalase -ve facultative Catalase -ve facultative

anaerobesanaerobes some strictly anaerobicsome strictly anaerobic some capnophilic (COsome capnophilic (CO22))

Ferment sugars to mixed acids Ferment sugars to mixed acids and ethanoland ethanol

Lancefield group D is motileLancefield group D is motile

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FastidiousFastidious

Most Streptococci are Most Streptococci are fastidious in their fastidious in their growth requirementsgrowth requirements

Grow poorly on Grow poorly on nutrient agarnutrient agar

Grow well on blood Grow well on blood agaragar

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Capsule

Made of hyaluronic acid: Made of hyaluronic acid: polymer of glucuronic acid & N-polymer of glucuronic acid & N-

acetylglucosamineacetylglucosamine Non immunogenicNon immunogenic

hyaluronic acid intercellular cementhyaluronic acid intercellular cement detected only in young(2-4 h) detected only in young(2-4 h)

broth culturesbroth cultures bacteria producebacteria produce hyaluronidasehyaluronidase

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Colonial Morphology

GLOSSY:GLOSSY: no capsule, no capsule, colonies smallcolonies small

MUCOID:MUCOID: capsule, capsule, colonies are large, colonies are large, glistening, viscousglistening, viscous

MATT:MATT:capsule, older capsule, older colonies are dried, colonies are dried, flatter rougher flatter rougher

Glossy

Mucoid

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Two Forms of HemolysisTwo Forms of Hemolysis

Beta HemolysisClearing

Alpha Hemolysis Greening “viridans”

(Gamma hemolysis = no lysis)

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Streptococcal Beta HemolysisStreptococcal Beta Hemolysis

Two hemolysinsTwo hemolysins Both cause clearingBoth cause clearing Both involved in diseaseBoth involved in disease

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Hemolysin S (stable in air)Hemolysin S (stable in air)

Beta hemolysis on blood agarBeta hemolysis on blood agar Do not develop antibodiesDo not develop antibodies Induces arthritisInduces arthritis Two partsTwo parts

CarrierCarrier hemolysin polypeptidehemolysin polypeptide

cell bound hemolysincell bound hemolysin lyses leukocytes and plateletslyses leukocytes and platelets stimulates release of lysosomal contentsstimulates release of lysosomal contents

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Hemolysin OHemolysin O

OxidizedOxidized in air in air oxygen labile (reversible)oxygen labile (reversible) ProteinProtein CardiotoxicCardiotoxic patients develop antibodiespatients develop antibodies ASOTASOT cholesterol labile (irreversible)cholesterol labile (irreversible)

Antistreptolysin O testAntistreptolysin O test

Subsurface colony of Streptococcus

producing Hemolysin 0

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Streptococcus pyogenes Suppurative DiseasesStreptococcus pyogenes Suppurative Diseases

PharyngitisPharyngitis Scarlet FeverScarlet Fever Erysipalas ( St. Antony’s Erysipalas ( St. Antony’s

fire)fire) CellulitisCellulitis Puerperal FeverPuerperal Fever SepsisSepsis MeningitisMeningitis PneumoniaPneumonia

Subacute Bacterial Subacute Bacterial EndocardititisEndocardititis

Otitis MediaOtitis Media

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Diseases of S. pyogenesDiseases of S. pyogenes

Pharyngitis:Pharyngitis: incubation period of 2 to incubation period of 2 to

4 days4 days sore throat, fever, sore throat, fever,

malaise, headachemalaise, headache Erythema of the pharynxErythema of the pharynx cervical cervical

lymphadenopathylymphadenopathy diagnosis -- differential diagnosis -- differential

-- viral pharyngitis-- viral pharyngitis

Scarlet fever:Scarlet fever: all of the above plus all of the above plus

red rash and red tonguered rash and red tongue

PyodermaPyoderma Non-suppurative, Non-suppurative,

inflammatory:inflammatory:

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Streptococcal SuppurationStreptococcal Suppuration

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Puerperal FeverPuerperal Fever

““Childbirth Fever”Childbirth Fever” SemmelweisSemmelweis

Membranes of genital Membranes of genital tract rupturedtract ruptured fulminating septicemiafulminating septicemia fatal 24-48 hrfatal 24-48 hr

S. pyogenesS. pyogenes 60-75% of 60-75% of casescases Anaerobic streptococci Anaerobic streptococci

20-25%20-25%

S. pyogenesS. pyogenes Not Not isolated from vagina isolated from vagina of healthy females of healthy females before birthbefore birth 50-60% from physician50-60% from physician rest from own nose & rest from own nose &

throatthroat

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Post vaccination Streptococcal InfectionPost vaccination Streptococcal Infection

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Streptococcal CellulitisStreptococcal Cellulitis

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Scarlet FeverScarlet Fever

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Scarlet Fever RashScarlet Fever Rash

Peticial Peticial hemorrhagehemorrhage Pin pointPin point SubcutaneousSubcutaneous

Erythrogenic toxinErythrogenic toxin Scarletina toxinScarletina toxin causes rashcauses rash associated with a associated with a

temperate phagetemperate phage

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Scarlet FeverScarlet Fever

Strawberry Tongue

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Schultz-Charlton testSchultz-Charlton test

Inject 0.1 ml antitoxin subcutaneouslyInject 0.1 ml antitoxin subcutaneously Rash fades after 6-8 hours (possible delay Rash fades after 6-8 hours (possible delay

14 h) 14 h) Differentiates from other similar rashesDifferentiates from other similar rashes

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Erysipalas Erysipalas

Secondary invasionSecondary invasion minor original lesion minor original lesion

Skin reddened thickenedSkin reddened thickened later purple later purple

Bacteria only in advancing Bacteria only in advancing edgeedge

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Erysipalas: butterfly rashErysipalas: butterfly rash

Butterfly rashButterfly rash common near nosecommon near nose spreads after 4-6 daysspreads after 4-6 days

Septicemia common Septicemia common complicationcomplication

No toxinNo toxin No immunityNo immunity

repeated attacks possiblerepeated attacks possible

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Rheumatic FeverRheumatic Fever

autoimmuneautoimmune acute glomerulonephritisacute glomerulonephritis Acute, non suppurativeAcute, non suppurative post streptococcal inflammationpost streptococcal inflammation

Joints, heart valves,myocardium,nervesJoints, heart valves,myocardium,nerves choreachorea- inflammation of nerves- inflammation of nerves

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Scarred heart valvesScarred heart valves

reduced cardiac outputreduced cardiac output heart failureheart failureMitral valve stenosis Mitral valve stenosis edema, hypertension, hematuria and edema, hypertension, hematuria and

proteinuriaproteinuria

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Scarred heart valvesScarred heart valves

Rheumatic EndocarditisRheumatic Endocarditis

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Rheumatic fever latent periodRheumatic fever latent period

Latent period 2-4 weeksLatent period 2-4 weeks same after repeated infectionssame after repeated infections

not immunologicalnot immunological Antibiotics taken during first week of Antibiotics taken during first week of

pharyngeal infectionpharyngeal infection Drop Steptococcal countDrop Steptococcal count Block rheumatic feverBlock rheumatic fever

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Aschoff BodiesAschoff Bodies

Inflammation of myocardiumInflammation of myocardium Mononuclear cell infiltrationMononuclear cell infiltration Granuloma-like nodulesGranuloma-like nodules Characteristc of rheumatic feverCharacteristc of rheumatic fever

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Streptococcal Antigens

Lancefield groupsLancefield groups M antigensM antigens T antigensT antigens R antigensR antigens

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StreptococcusLancefield GroupsStreptococcusLancefield Groups

Rebecca LancefieldRebecca Lancefield Grouped by presence of distinctive cell wall Grouped by presence of distinctive cell wall

antigensantigens Polysacchardies or glycero teichoic acidsPolysacchardies or glycero teichoic acids

Antigens labelled A-TAntigens labelled A-T exclude I & J exclude I & J

Group A Streptococci Clinically ImportantGroup A Streptococci Clinically Important

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Lancfield GroupsLancfield Groups

S. pneumoniae N/AS. pneumoniae N/A S.pyogenes -- Lancefield Group AS.pyogenes -- Lancefield Group A S.agalactiae -- Lancefield Group BS.agalactiae -- Lancefield Group B Enterococcus-Lancefield Group DEnterococcus-Lancefield Group D Viridans groupViridans group

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Group A StreptococciGroup A Streptococci

S. pyogenesS. pyogenes Group A Group A clinically importantclinically important

Lancefield grouping time Lancefield grouping time consumingconsuming

Group A correlated with Group A correlated with sensitivity to bacitracinsensitivity to bacitracin

Bacitracin sensitive Beta hemolytic Strept reported as Group A Strept

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Group D StreptococciGroup D Streptococci

glycerol teichoic acid glycerol teichoic acid -- associated with the -- associated with the cytoplasmic cytoplasmic membranemembrane Streptococcus bovis, Streptococcus bovis,

Enterococcus faecalis, Enterococcus faecalis, Enterococcus faeciumEnterococcus faecium

resist bile and high resist bile and high concentrations of concentrations of sodium chloridesodium chloride

Disease:Disease: urinary tract infectionurinary tract infection intra-abdominal intra-abdominal

abcessesabcesses wound infectionwound infection EndocarditisEndocarditis

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M antigens

proteins of the pilusproteins of the pilus sensitive to Pepsin & Trypsinsensitive to Pepsin & Trypsin soluble at pH 2soluble at pH 2 50 types50 types

Involved in rheumatic feverInvolved in rheumatic fever 5-8 types5-8 types Antibodies neutralize streptococcal infectionsAntibodies neutralize streptococcal infections

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PathogenesisPathogenesis

capsule -- non-immunogeniccapsule -- non-immunogenic M Protein -- antiphagocytic, M Protein -- antiphagocytic,

anticomplementaryanticomplementary Lipoteichoic acid (LTA):Lipoteichoic acid (LTA):

mediates adherence to epithelial cells mediates adherence to epithelial cells LTA binding proteinLTA binding protein

Host cell membrane:Host cell membrane: Deacylated LTADeacylated LTA

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EnzymesEnzymes

Streptokinase A & B:Streptokinase A & B: lyse blood clotslyse blood clots

DNA ase:DNA ase: depolymerase DNA in pusdepolymerase DNA in pus

Hyaluronidase:Hyaluronidase: hyaluronic acidhyaluronic acid

DPN aseDPN ase

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Lab diagnosisLab diagnosis

Gram stain -- good in cases of pyodermaGram stain -- good in cases of pyoderma fluorescent antibodyfluorescent antibody

detection of antibodies to Streptolysin O ASO detection of antibodies to Streptolysin O ASO 3-4 weeks after exposure3-4 weeks after exposure

Culture:Culture: swab the lesion directlyswab the lesion directly blood agar plates - hemolysisblood agar plates - hemolysis

ElizaEliza

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S. pneumoniaeS. pneumoniae

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Streptococcus pneumoniaeStreptococcus pneumoniae

Gram positive cocci in pairs, singles, short Gram positive cocci in pairs, singles, short chainschains

alpha hemolysis -- aerobicalpha hemolysis -- aerobic beta hemolysis -- anaerobicbeta hemolysis -- anaerobic capsule -- immunogenic (84 serotypes)capsule -- immunogenic (84 serotypes)

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Diseases:Diseases:

Pneumonia -- inflammation of the lungs Pneumonia -- inflammation of the lungs with exudation and consolidation with exudation and consolidation (solidification)(solidification)

SinusitisSinusitis MeningitisMeningitis BacteremiaBacteremia

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PathogenesisPathogenesis

virulence factor, capsule -- prevents phagocytosis virulence factor, capsule -- prevents phagocytosis Pneumolysin is a temperate and oxygen labile Pneumolysin is a temperate and oxygen labile

hemolysinhemolysin Purpura-producing principalPurpura-producing principal is released during cell is released during cell

autolysisautolysis Neuraminidase -- glycoproteins and glycolipidsNeuraminidase -- glycoproteins and glycolipids Autolysins, amidases -- autolyse peptidoglycan layerAutolysins, amidases -- autolyse peptidoglycan layer

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Mechanisms of PathogenicityMechanisms of Pathogenicity

aspiration of S. pneumoniae, an endogenous aspiration of S. pneumoniae, an endogenous oral organismoral organism

organism colonizes the oropharynxorganism colonizes the oropharynx epiglottal reflex, coughing is inhibitedepiglottal reflex, coughing is inhibited

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Lobar PneumoniaeLobar Pneumoniae

multiplication in the alveolar spacesmultiplication in the alveolar spaces viral infection frequently precedes viral infection frequently precedes

bacterial infectionbacterial infection highly invasive due to capsulehighly invasive due to capsule bacteremia commonbacteremia common Meningitis -- most often in childrenMeningitis -- most often in children Treatment:Treatment:

Penicillin, ErythromycinPenicillin, Erythromycin

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Laboratory DiagnosisLaboratory Diagnosis

sputum -- gram+ cocci, lancet sputum -- gram+ cocci, lancet shaped,capsule, may appear over-shaped,capsule, may appear over-decolourizeddecolourized

alpha-hemolytic, optochin sensitivealpha-hemolytic, optochin sensitive Quellung reaction -- specific antiserum to Quellung reaction -- specific antiserum to

capsular polysaccharidecapsular polysaccharide capsular antigen can be detected by very capsular antigen can be detected by very

sensitive immunologic testssensitive immunologic tests

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The EndThe End