STREPTOCOCCUSSTREPTOCOCCUS

&&

ENTEROCOCCUSENTEROCOCCUS

Cocos Gram-PositivosStreptococcus

Gênero Streptococcus

Fisiologia e MetabolismoAnaeróbios facultativos

Exigentes nutricionalmente (fatores de crescimento)

Capnofilia

Catalase Negativa (2H2O2 ---> O2 + 2H2O)Beta, Alfa, ou Gama Hemolíticos em ágar sangue

Gênero StreptococcusSistemas de classificação

Quanto à hemóliseQuanto ao determinante antigênicoQuanto à apresentação clínicaQuanto às provas bioquímicas

Rebecca Lancefield Classificação de Streptococcus beta-hemolíticos pelo Carbohidrato da parede celular grupo-específico

Sorogrupos A a H e K a V

Grupos A, B, C, D, e G mais importantes

Classificação de Lancefield - Streptococcus Beta-Hemolíticos

Grupo A Streptococci:Streptococcus pyogenes

Um dos patógenos mais importantesDoenças Supurativas: Faringite; Escarlatina;

Infecções cutâneas & de tecidos moles; doenças sistêmicas

Não-Supurativas:FRA,GNDA

Grupo B Streptococci: Streptococcus agalactiae

Doenças sistêmicas, cutâneas, ITU Doenças NeonataisComplicações obstétricas REVIEW

Streptococcus pyogenes

(Contraste de fase)

Streptococcus Pyogenes – Grupo A

• Faringite eritemato-pultácea

• Erisipela

• Impetigo

• Escarlatina

• Síndrome do choque tóxico

• Fascite necrosante, mionecrose, septicemia

• Doenças não supurativas

Erisipelas

NOTE:

eritema

bolhas

Determinantes de PatogenicidadeFatores de Virulência Celulares

Cápsula

Antiphagocytic; Nonspecific adherenceHyaluronic acid (polysaccharide) mimics animal tissue

Ácido LipoteicoicoCytotoxic for wide variety of cellsAdherence: Complexes with M protein (LTA-M) and binds to fibronectin on epithelial cells

Proteína MLTA-M protein is adhesinAntiphagocyticInhibits alternate C’ pathway and opsonization

Proteínas M-like: bind IgM and IgG

Proteína F: mediates adherence

Fatores de Virulência ExtracelularesExotoxinas:

Estreptolisina O (SLO): Hemolytic and Cytolytic

Prototype of oxygen-labile and thiol-activated cytolytic exotoxins (e.g., Streptococcus, Bacillus, Clostridium, Listeria)

Lytic for variety of cells: bind to cholesterol-containing membranes and form arc- or ring- shaped oligomers that make cell leaky (RBC's, WBC’s, PMN's, platelets, etc.)

Causes sub-surface hemolysis on BAP

Stimulate release of lysosomal enzymes

SLO titer indicates recent infection (300-500 in pediatric populations)

Fatores de Virulência ExtracelularesExotoxinas:

Estreptolisina S (SLS): Hemolytic and Cytolytic

Oxygen stable, non-antigenic

Lytic for red and white blood cells and wall-less forms (protoplast, L- forms)

Causes surface hemolysis on BAP

Lisogenia: Lysogenized bacteriophages play key role in directing synthesis of various Group A streptococcal enzymes and toxins

• Pyrogenic Exotoxin (erythrogenic toxin)

• Phage-associated muralysins (lyse cell walls) produced by both Groups A and C

Fatores de Virulência ExtracelularesExotoxinas:Exotoxinas Pirogênicas (Eritrogênicas) (A, B &C)

Produced by more than 90% of Grp A strep Lysogeny: Structural gene is carried by temperate bacteriophage, as is the case with diphtheria toxin

Mediate pyrogenicity (fever)

Causes scarlet fever (scarletiniform) rash

Increase susceptibility to endotoxic shock Type C toxin increases permeability of blood-brain barrier

Enhance DTH

Mitogenic for T lymphocytes (cause cell division), myocardial and hepatic necrosis, decrease in antibody synthesis

Immunomodulators (superantigens): stimulate T cells to release cytokines

Toxina Cardiohepática

Fatores de Virulência ExtracelularesEnzimas:

Nucleases: Four antigenic types (A,B,C,D) Facilitate liquefication of pus generating growth substratesNucleases A, C have DNase activityNucleases B, D also have RNase activity

Estreptoquinases: Two different formsLyse blood clots: catalyze conversion of plasminogen to plasmin, leading to digestion of fibrin

C5a Peptidase: destroys C’ chemotactic signals (C5a)

Hialuronidase: hydrolyzes hyaluronic acid

Others: Proteinase, NADase, ATPase, phosphatase, etc.

Nonsuppurative Sequelae of Acute Group A Streptococcal Infection

Acute Rheumatic Fever (ARF)

Inflammatory reaction characterized by arthritis, carditis, chorea (disorder of CNS with involuntary spastic movements), erythema marginatum (skin redness with defined margin), or subcutaneous nodules

Within 2-3 weeks following pharyngitis• Epidemic pharyngitis: ARF in as many as 3%• Sporadic pharyngitis: ARF in 1 per 1000

Morbidity & mortality linked to subsequent disease of heart valve (Rheumatic Heart Disease)

Poorly understood pathogenesis with several proposed theories including cross-reactivity of heart tissues & strep AGNs •?? (Type ?? hypersensitivity, exotoxins, direct invasion)II

REVIEW

Nonsuppurative Sequelae of Acute Group A Streptococcal Infection (cont.)

Acute Glomerulonephritis

Follows either respiratory (pharyngitis) or cutaneous (pyoderma) streptococcal infection

Associated with well-defined group of M-types

Incidence varies from <1% to 10-15%

Most often seen in children manifesting as dark, smoky urine with RBC's, RBC casts, white blood cells, depressed serum complement, decreased glomerular filtration rate

Latent period: 1-2 weeks after skin infection and 2-3 weeks after pharyngitis

Granular accumulations of immunoglobulin due to deposition of immune complexes within the kidney (Type ?? Hypersensitivity)III

REVIEW

Group B Streptococcus

Streptococcus agalactiae

Streptococcus agalactiae

Group B Streptococcal Infections

Grp B Streptococcal Infections (cont.)

Age-Specific Attack Rates of Group B Streptococcal Disease

Epidemiology of Neonatal Group B Streptococcal Disease

Group B Streptococcus S. agalactiae

Diagnostic Laboratory Tests

• CAMP factor positive

• Hippurase positive

CAMP Factor TestS. aureus

(Spingomyelinase C)Group B

Streptococcus

(CAMP Factor)

Group A Streptococcus

Enhanced Zone of

Hemolysis

Hippurase NEG

Hippurase POS

Grp B Streptococci

and

Campylobacter

Streptococcus pneumoniae

• Também chamado de pneumococcus

•

Streptococcus pneumoniae Infections

Epidemiology (cont.)Pneumococcal Infections (cont.)

S. pneumoniae

• Diplococcus

S. pneumoniae: lancet-shaped diplococcus

S. pneumoniae Virulence Factors

S. pneumoniae Seasonal Incidence

Comparison of Morbidity & Mortality

for Bacterial Meningitis

Genetic Variation (Mutation)

Beginning of Molecular Genetics

Transformation (In vivo) (Griffith)

Streptococcus pneumoniae

Diagnostic Laboratory Tests

• Optochin sensitivity (Taxo P disc)

Optochin Sensitivity

Taxo P

Streptococcus pneumoniae

Enterococcus faecalis Enterococcus faecium

• GI tract of humans and animals

• Group D carbohydrate cell wall antigen

• Formerly Streptococcus

Enterococcal Infections

Enterococcal Infections (cont.)

Important nosocomial pathogen

Vancomycin resistant Enterococcus (VRE)

Enterococcus

Diagnostic Laboratory Tests

• Resistant to bile

• Esculin hydrolysis

• BEA media

Bile Esculin Agar

POS

Enterococcus

Group D Streptococcus

Bile Esculin Agar

NEG

Esculin Bile

Assay