复旦大学：《医学微生物学 Medical Microbiology（MBBS）》课程讲义_讨论稿_03 Pyogenic Microorganisms

Pyogenic Microorganisms Roy, Nova, Jessie, Szechia, and Shangyoung

Pyogenic Microorganisms Roy, Nova, Jessie, Szechia, and Shangyoung

Contents Pyogenic Infections Virulence factors Pathogenesis Immuno-resistance

Contents • Pyogenic Infections – Virulence Factors – Pathogenesis • Immuno-resistance

Serious Pyogenic Infections Bacteremia- The presence of bacteria in blood Septicemia -a bacteremic condition that leads to Sepsis Pyemia-a Septicemic condition that leads to widespread abcesses of metastatic nature

Serious Pyogenic Infections • Bacteremia – The presence of bacteria in blood • Septicemia – a bacteremic condition that leads to Sepsis • Pyemia – a Septicemic condition that leads to widespread abcesses of metastatic nature

S. Aureus virulence Factors Enzymes: Coagulase, Hyaluronidase and dnase Protein A: binds to Fc-lgG to inhibit complemen fixation and phagocytosis Toxins 1. Superantigens: TSST-1 that produce toxic shock syndrome, enterotoxins that cause gastroenteritis 2. Exfoliative toxins: protease activity cases peeling of skin in staphylococcal scalded-skin syndrome 3. Other toxins: alpha, beta, and delta toxins act on cell membane and Panton -Valentine leukocidin (PVL) is associated with severe necrotizing pneumonia in children

S. Aureus Virulence Factors • Enzymes: Coagulase, Hyaluronidase, and DNAse • Protein A: binds to Fc-IgG to inhibit complement fixation and phagocytosis • Toxins: 1. Superantigens: TSST-1 that produce toxic shock syndrome, enterotoxins that cause gastroenteritis 2. Exfoliative toxins: protease activity cases peeling of skin in staphylococcal scalded-skin syndrome 3. Other toxins: alpha, beta, and delta toxins act on cell membanes, and Panton-Valentine leukocidin (PVL) is associated with severe necrotizing pneumonia in children

S. Aureus Pathogenesis Combined effect of extracellular factors and toxins together with invasive properties of the strain More dangerous strains of s Aureus causes focal abscess that can spread via lymphatics or blood Can result in meningitis, endocarditis and sepsis Can also causes disease through toxins: SSss and Tss

S. Aureus Pathogenesis • Combined effect of extracellular factors and toxins together with invasive properties of the strain • More dangerous strains of S.Aureus causes focal abscess that can spread via lymphatics or blood. • Can result in meningitis, endocarditis, and sepsis • Can also causes disease through toxins: SSSS and TSS

S Pyogenes Virulence Factors 1. Structural Components carbohydrate-based bacterial capsule composed of hyaluronic acid M protein inhibit opsonization poteichoic acid and protein F(Sfbl)allow attachment to various host cells 2. Toxins and Superantigens Streptolysin O is a exotoxin of beta hemolytic Group property Streptolysin S is a cardiotoxic exotoxin that is another beta hemolytic component EXotoxin A, B, and c are superantigens cause sTss and scarlet fever 3. Enzymes

S. Pyogenes Virulence Factors 1. Structural Components – carbohydrate-based bacterial capsule composed of hyaluronic acid – M protein inhibit opsonization – lipoteichoic acid and protein F (SfbI) allow attachment to various host cells 2. Toxins and Superantigens – Streptolysin O is a exotoxin of beta hemolytic Group property – Streptolysin S is a cardiotoxic exotoxin that is another beta￾hemolytic component – Exotoxin A, B, and C are superantigens cause STSS and scarlet fever 3. Enzymes

S Pyogenes Virulence Factors Streptokinase digest fibrin and other proteins Hyaluronidase breaks down hyaluronic acid in connective tissue allowing spread Streptodornase are DNAses C5a Peptidase are used to minimize influx of neutrophils early in infection

S. Pyogenes Virulence Factors – Streptokinase digest fibrin and other proteins – Hyaluronidase breaks down hyaluronic acid in connective tissue allowing spread – Streptodornase are DNAses – C5a Peptidase are used to minimize influx of neutrophils early in infection

Streptococcus Pyogenes Pathogenesis Serious infection of Beta-hemolytic group A s pyogenes can results in bacteremia with sepsis, which is rapidly fatal Usually involve rapidly spreading infection along lymphatics with little focal suppuration From lymphatics infection can spread via blood stream

Streptococcus Pyogenes Pathogenesis • Serious infection of Beta-hemolytic group A S.pyogenes can results in bacteremia with sepsis, which is rapidly fatal • Usually involve rapidly spreading infection along lymphatics with little focal suppuration. • From lymphatics infection can spread via blood stream

S. Agalactiae ·Viru| ence factor Capsule 阝 hemolysin GBS: The CaMP test is an important test for identification. It is characterized by the presence of group B Lancefield antigen and by its ability to hydrolyze sodium hippurate It is also sensitive to bile, and will lyse in its presence Causes Septicemia in newborns

S. Agalactiae • Virulence factor – Capsule – ß-hemolysin • GBS: The CAMP test is an important test for identification. It is characterized by the presence of group B Lancefield antigen and by its ability to hydrolyze sodium hippurate. • It is also sensitive to bile, and will lyse in its presence. • Causes Septicemia in newborns

Streptoccocus Agalactiae Pathogenesis Normal flora in gi tract, also can spread to the secondary site such as vagina in 10-30%women and large intestine Transferred to a neonate passing through the birth canal and can cause serious group B streptococcal infection S. Group B infection during the first month of life may present as fulminant sepsis, meningitis, or respiratory distress syndrome Neonatal pneumonia: S agalactiae invades via alveolar and pulmonary epithelial cells; newborns are especially susceptible to infection because they lack alveolar macrophages to prevent invasion

Streptoccocus Agalactiae Pathogenesis • Normal flora in GI tract, also can spread to the secondary site such as vagina in 10-30% women and large intestine • Transferred to a neonate passing through the birth canal and can cause serious group B streptococcal infection • S. Group B infection during the first month of life may present as fulminant sepsis, meningitis, or respiratory distress syndrome. • Neonatal pneumonia: S. agalactiae invades via alveolar and pulmonary epithelial cells; newborns are especially susceptible to infection because they lack alveolar macrophages to prevent invasion