Mechanisms of Bacterial Pathogenesis

I.Entry into the body

routes

ingestion

inhalation

trauma

needlestick

arthropod bite

sexual transmission

Salmonella

Shigella

enterotoxigen E.coli

Vibrio

Clostridium botulinum

Mycobacterium

Mycoplasma pneumoniae

Clostridium tetani

Staphylococcus aureus

Pseudomonas

Rickettsia

Yersinia pestis

Neisseria gonorrhoeae

Chlamydia trachomatis

II.Adhesion,colonization and invasion

adherance

pili (fimbriae)

afimbrial adhesins

G(-)

Enterobacteriaceae

Vibrio cholerae

P fimbriae

G(+)

Streptococcus pyogenes

M protein

Biofilm

polysaccharide slime

Staphylococcus

IgA protease

colonize mucosa

III. Mechanisms of bacterial pathogenesis

Byproducts of growth

Endotoxin

Other cell wall components

Exotoxin

G(-)

G(+)

A-B toxins

Superantigen

Bacteremia

Antibiotic resistant

Immunopathogenesis

Streptococcus mutants

Mycobacteria tuberculosis

Helicobacter pylori

teeth

macrophage

stomatch

urease

LPS(lipid A)

發燒+低血壓+休克

Structure

Gene location

Simple A toxin

Simple A-B toxin

Compound A-5B toxin

Plasmid

Chromosome

Phage gene

function

enzymatic lysis

pore formation

inhibition of protein synthesis

hyperactivation

Clostridium perfringens 產氣莢膜梭菌

Staphylococcus aureus 金黃色葡萄球菌

Corynebacterium diphtheriae 白喉

Vibrio cholerae 霍亂

interfere nerve-muscle transmission

Clostridium tetani 破傷風

Clostridium botulinum 肉毒桿菌毒素

作用於肌肉

作用於神經

Apoptosis of immune cells

Over-immune response

lung

granuloma

Mycobacterium tuberculosis

heart

rheumatic fever

Streptococcus pyogenes

kidney

poststreptococcal glomerulonephritis

skin

rash

sepesis

IV.Escaping host defense

Immune Defense to Bacteria

First lines

Second lines

Prevention of epidermis

phagocytic cell responses

Complement

Cytokines and Chemokines

Antibody

Cytotoxic cells

Defense of skin

Defense of mucosal surfaces

secretory IgA

第二次感染時中和細菌

opsonization

IgG

most common antibody type

IgM

earliest appearing antibody

IgE

allergy-associated antibody

sIgA

defense of mucosal surfaces

Natural killer (NK) cells

Cytotoxic T cells

ADCC=Antibody-depedent cell-mediated cytotoxicity cells

Escaping host defense

Capsule

Resistance to antibody and complement

Evasion of phagocytic clearance

Enzymes

Formation of granuloma

Poor immunogen

Slimy

survive in phagolysosome

extent the time to spread

例子

Streptococcus pneumoniae

Neisseria miningitidis

Intracellular growth

Antigen variation

Production of IgA proteases

Production of IgG-binding protein

long O Ag of LPS

Mycobacteria

Chlamydia

Rickettsiae

Neisseria gonorrhoeae

Staphylococcus aureus

catalase

V. Pathogenic microbial flora

Strict pathogens

Opportunistic pathogens