medical microbiology: infections in immunocompromised Flashcards
(34 cards)
What is the first line of defense
Physical barrier & chemical protection
What is six examples of the first line of defence
- pH: saliva, stomach, skin & vagina
- Flushing mechanisms: tears, urine & cilia
- Mucus protection: traps organisms
- Secreted substances: lysozyme that damage walls of bacteria
- Peristalsis: gut
- Skin: sweat, shedding of upper layer
What is the normal/indigenous flora
Ecological niche that helps maintain environment & prevent infection with organisms
What does the normal flora secrete against bacteria
Bactericidins that inhibit or kill pathogens
What is the innate response
Second line of defence that is rapid non specific response to a pathogen
What are the two components of the innate immunity
- Cells: phagocytes (neutrophils & macrophages) & extracellular killers (NK cells & eosinophils)
- Soluble factors: APP & complement
What is neutropenia
Reduced WBC count
What is the consequences of neutropenia
Increased risk of infections, dissemination, severe sepsis & death
What factors worsens immunosuppression in neutropenic patients
Chemotherapy & antibiotics
What is a treatment option for neutropenia
Stem cell transplant where malignant & normal cells are removed
What is the adaptive immunity
Third line of defence delayed specific response to a particular pathogen
What is the two component of adaptive immunity
- Humoral immunity
- Cellular immunity
What is the component of the humoral adaptive immunity & what organisms does it kill
Antibody production by B cells killing extra cellular pathogens
What is the component of the cellular adaptive immunity & what organisms does it kill
Cellular activities that is T cell mediated killing intracellular pathogens
What population is at risk for immunosuppression
Very young/elderly
Pregnant women
Patient with long term therapy
Haematological malignancies
HIV/AIDS
Diabetes
What is the effects of HIV/AIDS on the immune system & why
Decrease in CD4+ T cells that increase risk for opportunistic infections
B cell mediated immunity is also impaired
Over activity & dysregulation of immune system
What is the effects of diabetes on the immune system & why
Hyperglycaemia causing impaired immune response & colonisation of organisms due to increased adhesions to glucose
Ischemia due to vasular insufficiency
What three infections are common in diabetes
- Candida
- Mucormycosis
- TB, UTI & diabetic foot
What is the effects of immunosuppression on infections
Less able to prevent/respond to infection causing severe infection that develops more rapidly by low virulence organisms
Re-activation/primary infection
What is virulence of an organism
The ability of a microorganism to cause disease
What is a primary infection
Organisms that can cause disease in host regard of host’s resident microbiota or immune system
What is opportunistic pathogens
Organism that can only cause disease when host defence is compromised
What is latent infection
Infection does it asymptomatic & activated under certain circumstances (herpes viruses & TB)
What is the three factors that determine infection in immunocompromised host
- Type of immune deficit
- Severity of immune defect
- Duration of immune defect
