Test 4 Chapter 15 Flashcards
Infection
Colonization of the host by a pathogen
Disease
Invading Pathogen alters normal body functions
Signs + Example
Objective manifestations of disease. Heart rate, respiratory rate, blood pressure.
Symptom + Example
Subjective manifestations of disease. I feel tired. My arm hurts.
Asymptomatic + Example
No signs or symptoms in host
Subclinical infection + Example
Very vague and non-specific. Flu like symptoms. fever.
Infectious Disease
Caused by direct effect of a pathogen
Communicable Disease
Capable of being spread from person to person. Direct or indirect contact.
Contagious Disease
A communicable disease that spreads very easily
Zoonotic Disease
Contracted from an animal
Iatrogenic Disease
Results of a medical procedure
Nosocomial Disease
Contracted in a hospital setting. Also called hosptial associated infection
Noncommunicable disease
Cannot be spread person to person
Noninfectious disease
Not caused by pathogens
Incubation Period
No signs or symptoms. Pathogen multiplication. Infectious.
Prodromal period
Non-Specific Symptoms. Know your sick. Pathogen number increasing
Period of illness
Highest concentration of pathogens. most severe symptoms and signs
Period of decline
Pathogen is dying. person getting better. decrease in severity of signs and symptoms
Period of convalescence
No signs or symptoms. some pathogens.
Acute
Pathologic changes occur over a short duration. It comes on quickly and resolves quickly.
Chronic
Pathologic changes occur over a long duration. Month or more. Tuberculosis
Latent
Causal pathogen remains dormant for an extended period of time with no active replication. Herpes viral infection.
Koch’s Posulates
- pathogen must be present in all cases of disease and not in healthy individuals.
- Must grow pathogen in pure culture
- infect healthy subject with pathogen, must get same signs and symptoms as original host.
- Pathogen must be re-isolated from new host and be identical to original pathogen
When don’t Koch’s Postulates apply
You can find pathogens in healthy individuals.
Not all healthy test subjects are equally susceptible to a disease
Not all pathogens can be grown in pure culture
Ethical issues
Molecular Koch’s Postulates
Identify a gene that may cause the organism to be pathogenic.
The sign or symptom should be associated with pathogenic strains of a species
Inactivation of the suspected gene associated with pathogenicity should result in a measurable loss of pathogenecity
Reversion of the inactive gene should restore disease pathogenicity.
Pathogenicity
The ability to cause a disease
Virulence
Measure of pathogenicity.
Severity or harmfulness of pathogen.
lD50
Dose required to infect 50% of a population.
Low lD50 the more virulent
LD50
Dose required to kill 50% of a population.
Refers to toxins. Botulinum most potent toxin
Primary Pathogens + Example
Can cause disease in a healthy individual.
Mycobacterium tuberculosis
Opportunistic pathogens + Example
Needs help/opportunity to cause disease.
Escherichia coli. Normal in gut but not bladder. will cause bladder infection
Major Portals of Entry
Sites through which pathogens enter the body:
Skin, Mucous Membrane, Placenta. Parenteral route circumvents usual portals
Major Portals of Exit
Sites through which pathogens exit the body:
Skin, Mucous Membrane, Placenta. Parenteral route circumvents usual portals
Adhesins
Proteins which help in adhesion
Biofilm Formation
Community of bacteria that produce a glycocalyx called extrapolymeric substance (EPS)
Biofilm Characteristics
EPS allows attachment to a surface.
Invasion
Dissemination of a pathogen through local tissues or the body
Local infection
Confined to a small area usually near portal of entry
Focal infection
Local infections spread to a secondary location.
Systemic infection
Disseminated throughout the body
Primary infection
Initial infection
Secondary infection
Primary infection allowed this infection to occur
Bacteremia
Presence of bacteria in the blood
Viremia
Presence of viruses in the blood
Toxemia
Presence of toxins in the blood
Septicemia
Presence of multiplying bacteria or toxin producing bacteria in the blood. Sepsis, Shock
Sepsis
Major body response to an infection, inflammation leads to damage.
Shock
Septic shock, multi organ failure, edema. Presence of many toxins in the blood.
Exoenzymes + Example
Secreted by the pathogen. Help pathogen maintain infection, invaid, and avoid body defenses. Dissolve structure chemical in the body.
Important to virulence of pathogen
Endotoxin
Lipopolysaccharide of outer membrane of gram-negative bacteria. Released during cell death or during binary fission. LD50 High
Endotoxin Producers
Gram-Negative Bacteria Only
Where endotoxins released from
Upon cell death or during binary fission.
Endotoxin Heat Tolerance
Heat Stable
Endotoxic Shock
An excessive inflammatory response leading to endotoxic shock. Low BP. Multi-Organ failure, death.
Exotoxins
released from the cell. Mostly produced by Gram-Positive bacteria, but also some pathogenetic Gram-Negative bacteria. Most heat labile. Cause specific damage to cells depending upon type of toxin. LD 50 low
AB toxins
Intracellular targeting toxins. B subunit binds to target cell and then toxin is internalized via endocytosis. A subunit enters cytoplasm and interferes with intercellular function
Membrane Disrupting Toxin
Form pores in or disrupt the plasma membrane of host cells.
Superantigens + Examples
Excessive, nonspecific stimulation of immune cells. Very large response. Cytokine storm, high fever, inflammation, shock.
Bacterial Capsule
Difficult for pahgocytosis
Antiphagocytic Chemicals
Prevent fusion of lysosome and phagosome
Coagulase
Break down blood clots and allow movement. Helps Bacteria avoid the immune system
Antigenic Variation
Bacteria (some protozoa. Trypanosoma bruceii African sleeping sickness) change their surface antigens 10-14 days.
Antigenic Drift (influenza virus)
Small mutations causing slight changes in Hemagglutinin (H) and neuramidase (N) spike proteins
Antigenic Shift (influenza virus)
Large changes in spike proteins due to gene reassortment of multiple strains.
Exoenzymes Examples
Glycohydrolases -> break down extracellular matrix
Hyaluronidase -> breaks down hyaluronan. Glue holding cells together.
Nucleases -> break down nucleic acids
Collagenase -> most common extracellular protein in the body.
Cholera toxin (A-B exotoxin)
Dysentery. causes fluid to move into the colon rather than out.
Tetanus Toxin (A-B exotoxin)
Clostridium tetani -> Rigid paralyze
Botulinum Toxin (A-B exotoxin)
Clostridium botulinum -> flaccid paralyze. Lowest LD50. Most potent toxin
Membrane Disrupting Toxins Most Common
Hemolysins and leukocidins. Target more than just red and white blood cells.
Bacterial Phospholipases (Membrane Disrupting Toxins)
Cause lysis of the phagosome. Bacteria can be phagocytized into an immune cell in a phagosome. Phospholipase allows the bacteria to escape the pahgosome
Toxic Shock Syndrome Toxin (superantigens)
Tampon misuse. TSST. amputations.
