Chapter 11 Flashcards
What are the differences between bacteria that reside in our bodies and those that cause disease?
Only normal in one part of your body
What is disease?
Any change from a general state of good health for an individual
Infection refers to:
An imbalance between the host and microbe
Mutualism
Both host and microbe benefit
Commensalism
The microbe benefits and the host is unaffected
What is a pathogen?
A microbe whose relationship with its host is parasitic and results in infection and disease
How does disease occur?
- An exogenous infection occurs if a pathogen enters sterile tissue
- An endogenous infection occurs if normal microbiota enter
- Primary infections occur in healthy bodies ex) flu
- Secondary infections occur in a body weakened by a primary infection ex) pneumonia
Portals of entry?
Mouth, GI, skin, urogenital
Disease progression as a microbe?
- Get in
- Attach
- Survive
- Damage
- Get out
What is it called when a microbe establishes itself in a host and causes damage?
Virulence
Disease progression in a human?
- Incubation - entry of microbe
- Prodromal - mild signs/symptoms
- Acute period -signs and symptoms are most intense
- Period of decline - signs and symptoms subside
- Period of convalescence - body back to normal
Acute diseases
Very short ex) flu
Chronic disease
Linger for long periods of time and slower to develop ex) hepatitis
What is invasiveness?
The ability of a pathogen to penetrate tissues and spread
What is virulence factors?
Any characteristic or structure of the microbe contributes to its ability to establish itself in the host and cause damage
Examples of virulence factors?
Streptokinase- dissolves fibrin clots and allows dissemination of the bacteria
Leukocidins-disintegrate neutrophils and macrophages (WBC)
Hemolysins-dissolves red blood cells
Biofilms- immune cells cannot reach bacterial cells covered in biofilm, protective structure
Two types of toxins:
- Exotoxins
2. Endotoxins
Exotoxins
Proteins that are secreted
Endotoxins
Released upon disintegration of bacteria
Chemical composition differential characteristics between exotoxins and endotoxins?
Exo: small particles
Endo: lipopolysaccaride of well wall
Denatured by heat differential characteristics of bacterial between exotoxins and endotoxins?
Exo: yes
Endo: no
Typical sources differential characteristics of bacteria between exotoxins and endotoxins?
Exo: a few gram + and gram -
Endo: all gram negative bacteria
Localized infection
Microbes enter the body, remain confined to a specific tissue
Ex) boils, warts, final skin infections
Systemic infection
Infection spreads to several sites and tissue fluids, usually the blood
Ex) mumps, rubella, chickenpox, aids, anthrax, typhoid, syphilis
Focal infection
Infectious agent spreads from a local site and is carried to other tissues
Ex) TB, streptococcal pharyngitis
Mixed infection
Several agents establish themselves simultaneously at the infection site
Ex) human bite infections, wound infections
Primary infection
The initial infection
Ex) can be any infection
Secondary infection
A second infection caused by a different microbe, which complicates a primary infection - often a result of lowered host immune defenses
Ex) flu complicated by pneumonia, common cold complicated by bacterial otitis media
Acute infection
Infection comes rapidly, with severe but short lived effects
Ex) flu
Chronic infection
Infection that progresses & persists over a long period of time
Ex) HIV
What is a sign?
Objective evidence of diseases as noted by an observer (what you can see)
Ex) edema, granulomas and abscesses, lymphadenyitis
What is a symptom?
Subjective evidence of disease as senses by the patient (what u feel)
Ex) fever, pain, soreness, swelling
What is a syndrome?
A disease identified by a certain complex of signs and symptoms
What is a reservoir?
Where pathogens live
- primary habitat in the natural world from which a pathogen originates
- often a human or animal carrier
- also soil, water, and plants
What is a transmitter?
Individual or object from which an infection is acquired
-syphilis: reservoir and transmitter are the same
- hepatitis: reservoir is a human, transmitter is food
Majority of animal reservoirs are….?
Arthropods - fleas, mosquitos, flies, ticks
Biological vector:
Actively participates in a pathogens life cycle, serving as a site in which it can multiply or complete its life cycle
Mechanical vector:
Carries the microbes more or less accidentally on its body parts
Ex) hands and spreading it
What’s Zoonosis?
Transfer of microbes b/t animals & humans
Transmission of infections:
Communicable, contagious, non communicable
What’s communicable?
A disease in which an infected host can transmit the infectious agent to another host and establish infection in that host
Contagious:
A disease that is highly communicable, especially they direct contact
Non-communicable
An infectious disease that does not arise thru transmission of the infectious agent from host to host
Nosocomial infection:
Infection acquired during hospital stay
-2-4 million cases a year resulting in 90,000 deaths
Epidemiology
The study of disease in populations
Prevalence:
the total number of existing cases with respect to the entire population
Incidence:
Measures the number of new cases over a certain time period
-also called the case or morbidity rate; indicates both the rate and risk of infection
Endemic:
Disease is always present at a low level in a certain geographic area
Epidemic:
Disease occurs in a region in excess of what is normally found in that population - not usually there
Outbreak:
Is a more contained epidemic
Pandemic:
Is a worldwide epidemic
