Bacterial Pathogenesis Flashcards
(32 cards)
What is the definition of disease?
A state of the body in which functions of a part or the whole body are disturbed. It may have infectious or non-infectious etiology.
What is infectivity?
The capacity of an organism to become established in the tissue of the host by colonizing, penetrating tissue, surviving host defenses, multiplying, and distributing. Infection doesn’t always lead to disease.
What is bacteraemia?
The presence of bacteria in the bloodstream.
What is a pathogen?
An organism with the potential to produce disease. Frank pathogens cause disease even in individuals with a healthy immune system.
What is pathogenicity?
The capacity of an organism to produce disease. Variability in this capacity is referred to as virulence.
What is an opportunistic pathogen?
Organisms normally harmless in their usual habitats that can cause disease in other tissues or in immunocompromised hosts.
What is septicaemia?
The presence of bacteria and their toxic products in the bloodstream.
What is septic shock?
A condition characterized by inadequate tissue perfusion following bacteraemia, especially due to gram-negative enteric bacilli.
What is toxaemia?
The presence of bacterial toxins in the bloodstream.
What is toxigenicity?
The capacity of organisms to produce toxins.
What is virulence?
A measure of the degree of pathogenicity.
Does infection always lead to disease?
No, infection does not always cause disease.
Why is it important to understand how bacteria infect and cause disease?
To diagnose, treat, and prevent bacterial diseases.
What can influence the outcome of infection and disease?
Host-pathogen balance and environmental factors.
What are common sources of pathogenic bacteria?
Carrier animals (active, passive, latent), environmental sources (e.g., water, feed), and the host’s own microbiota.
What is resident microbiota?
Normal microbial flora on animal body surfaces like skin and nasal cavities.
What are the roles of resident microbiota?
Mutualistic relationship in healthy animals, can cause disease if they access deeper tissue.
What are Koch’s postulates?
- Pathogen must be present in every case. 2. Isolated and grown in pure culture. 3. Cause disease when inoculated. 4. Must be recoverable from infected host.
What steps are involved in the pathogenesis of bacterial infection?
- Infectious source, 2. Transmission, 3. Colonization, 4. Tissue invasion, 5. Tissue damage, 6. Dissemination, 7. Exit/excretion.
What are the portals of entry for bacteria?
Respiratory tract, alimentary tract, skin/mucous membranes, genital tract, placenta, umbilicus, udder.
How do bacteria cause tissue damage?
- Direct invasion, 2. Inducing inflammation, 3. Producing toxins, 4. Secreting extracellular enzymes.
What are exotoxins?
Soluble proteins secreted mainly by Gram-positive bacteria with various toxic effects. Heat labile and highly antigenic.
What are the effects of enterotoxins?
Affect the small intestine, cause diarrhea by changing intestinal permeability.
What are systemic effects of exotoxins?
Include nerve toxins, toxins that lyse cells, block protein synthesis, or stimulate the immune system.
