Bacterial Pathogen Flashcards
Coagulase?
Essential virulence factor associated with formation fibrin capsule
- -> interfering phagocytosis
- -> fibrin clot –> abscess
Alpha-toxin?
major cytotoxic agent
member of pore forming beta-barrel toxin family
Superantigen toxins?
Class of antigen cause non-specific activation of T-cells, resulting
- polyclonal Tcell activation
- massive cytokine release
Mechanism of scalded skin syndrome?
The toxin (serine protease) cleaves the proteins (desmoglein I) attaching dermis and epidermis –> scalding off epidermis
Mechanism(s) of (localized focal abscess) cutaneous infections?
- Adherence : fibronectin binding protein
- Alpha-toxin : damage tissue & interfere with phagocytosis
- Coagulase, fibriogen-binding protein, Protein A interfere phagocytosis
Scalded skin syndrome in adult vs. newborn
Adult: localized infection
Newborn: systemic infection –> does NOT have previous antibodies against the bacteria
Symptoms of Toxic Shock Syndrome?
High fever Shock Vomiting Muscle pain Renal/hepatic injury or failure
Staphylococcal Food Poisoning?
Ingestion contaminated food with superantigen toxin
–> vomiting & diarrhea (1-5 hours)
Characteristic of enterotoxin
heat stable –> not destroyed by cooking
SSNA?
Staph species, not aureus
CNS?
Coagulase negative staphylococcus
Endocarditis?
Bacteria grows on damaged heart valve
Purpose of M-protein?
- Inhibit phagocytosis by binding factor H
- -> reduces C3b opsonization
- -> produce C5a peptidase - enhance adherence to epithelial cells
Cellulitis?
Spreading infection of the cutaneous & subcutaneous tissues
Glomerulonephritis
immune complex disease (following skin/pharyngeal infection)
Strep antigen-antibody complexes deposited in kidney
–> accumulate at the basement membrane
–> complement-mediated damage
Rheumatic fever
autoimmune inflammatory disease
- fever, inflammation of heart, joints
- NO bacteria on the heart tissue
- antibody-mediated damage
How to make pneumococcal vaccines effective in kids (get polysaccharide antigen to work)?
Conjugated vaccines: chemically couple polysaccharide antigen to protein immunogen –> the whole complex is immunogenic
Which bacteria frequently cause nosocomial infection (hospital acquired)?
Enterococcus faecalis & E. faecium
Why positive culture of clostridium difficile in stool not enough to diagnose pt with diarrhea and fever?
Unless toxin A & toxin B detected in the stool, presence of C. diff in stool does NOT mean it is the one causing the disease
Why patient on antibiotics treatment at risk for C. diff infection?
Depletion of intestinal flora by antibiotic, resulting overgrowth of C. diff
When should one use inactive toxoid vs. anti-toxin for tetanus?
- Inactive-toxoid is used to induce production of protective anti-toxin antibody
- Immunization with antitoxin (tetanus IgG) to treat non-immune individuals with clinical signs of tetanus.
Mechanism of E. coli GI disease
- Pili adherence to intestinal mucosa
* Toxin disrupts electrolyte balance in gut
Mechanism of E. coli UTI
- Adherence to bladder eipthelium
- Specific interactions with bladder epithelial cells
- beta-hemolytic
How to recover from the damage of tetanus?
The ONLY way is to grow that particular neuron
Difference between endotoxin, exotoxin and enterotoxin
Endotoxin = LPS from (-) gram cell wall Exotoxin = protein secreted that is insoluble Enterotoxin = exotoxin that acts on GI system
Mechanism of E. coli Abdominal infections
- Mixed infection
- Abscess (from anaerobic bacteria)
- Release/escape contents of colon to peritoneal cavity & adjacent tissues
