Infection, Infectious Disease, and Epidemiology Flashcards
Define pathology
Pathology is the study of the causes and effects of disease or injury.
Define etiology
study of the cause of disease
Define infection
an invasion of the body by an infectious microorganism or virus
Define disease
a condition where health is affected
Define normal microbiota
Acquired from our environment, colonize the skin and large intestine.
define microbial antagonism
good bacteria outcompete bad bacteria
define mutualism
both organisms benefit
define commensalism
one organism benefits and the other is neutral
define parasitism
one organism benefits and other is harmed
How does an infection become oppurtunistic?
normal microbiota that moves to a new area and becomes pathogenic or on an immunocompromised host
Examples of portal of entry
mucous membranes, parenteral (nonintact skin, puncture), inhalation or ingestion, through skin (hair follicle, sweat gland), and placenta (congenital).
define signs vs symptoms
symptoms: subjective changes felt by a patient (headache, pain, dizziness)
signs: objective changes that acn be observed or measured (temp, BP, labs)
define epidimieology
study of when and where diseases occur and how they are transmitted
define endemic
always present
define epidemic
large # of people affected in a short period of time in one area
define pandemic
epidemic occurring on one or more continents
define mortality
number of individuals killed by a disease
define morbidity
Number of individuals affected by a disease
define incubation period
time between the entrance of the infectious agent and the onset of illness
define latent period
period of time when an infectious agent is not causing signs and symptoms but can show up later
list the exceptions of koch’s postulates
-can’t always grow in pure culture
-the same agent can cause different diseases
-some people are immune/carriers and won’t get the disease
-not always possible to inoculate the same animal
-different strains with different virulence factors are possible
describe virulence
how pathogenic an infectious agent is, how transmissible or how easily it causes disease
Describe the relationship between adhesins/ligands and receptors on the surface of the host cell.
adhesions/ligands bind to receptors on the surface of the cell and help the pathogen stick to the cell. Receptors and ligands must match.
What is the target of leukocidins?
break down WBC
What is the target of hemolysins?
break down RBC
What is the target of coagulases?
convert fibrinogen to fibrin, and cause blood clots
What is the target of kinases?
anticlotting
What is the target of hyaluronidase?
breaks down hyaluronic acid in connective tissue
What is the target of collagenese?
breaks down collagen in connective tissue
How do invasions affect the host cell?
rearrange the cytoskeleton of the host cell and converts it into a shield for itself
Examples of exotoxin infections
gangrene, tetanus, botulism, diptheria, scarlet fever
Examples of endotoxin infections
typhoid fever, UTI, and mengi meningitis
Which produces a fever, exo or endo toxins?
endo
Which is more toxic, exo or endo toxin?
exo
Describe some antiphagocytic factors that exist
-capsule
-M protein (strep pyrogenes)
- invasins
prodromal period
not all diseases have this, illness has not started yet but host does not feel normal, mild symptoms
illness
full blow signs and symptoms
decline
severity of symptoms lessen
convalescence
patient recovering
acute vs chronic disease
acute: symptoms come on fast and last a short time
chronic: symptoms are slow to develop and last longer
reservoir of infection and examples
a living or non-living habitat that can harbor an infectious agent until a new host is encountered
human reservoirs-
host with signs and symptoms
healthy chronic carrier
asymptomatic carrier (incubation/latent)
non human reservoirs-
animals, soil, water
Types of contact transmission
direct, indirect, and droplet
direct: person to person, skin to skin
indirect: transmission via fomite
droplet: aerosol produced by coughing, and sneezing, travels less than 1 m.
Describe vehicle transmission via food, water and air.
Something containing infectious agent that is ingested or inhaled
water
food
air
Describe vector transmission, distinguish between mechanical and biological vectors.
mechanical is passively transportation on body
biological has the agent in the body and spreads through bite
Distinguish between communicable and noncommunicable disease.
communicable- can be spread from host to host
noncommunicable- not spread from person to person. can live outside host for a long time or is caused by normal microbiota (acne/tooth decay)
How are healthcare-associated (nosocomial) infections acquired?
from interaction with hospital fomites and from staff-patient interaction
Why are healthcare-associated (nosocomial) infections acquired?
patients are often immunocompromised and have broken skin
differences between exogenous and endogenous infections in nosocomial
exogenous-directly from environment of hospital
endogenous- result of normal microbiota becoming pathogenic due to medical procedures
How can nosocomial infections be controlled?
infection control committees, wash hands, change gloves, no ties
what are iatrogenic infections in nosocomial infections?
physician induced
How would you describe transient microbes?
microorganisms that are only temporarily found in the human body, and these may include pathogenic microorganisms
How would you define a fomite?
inanimate object that that can spread disease
What is the most common procedural cause of nosocomial infections?
catherterization
name some locations where we lack normal microbiota.
blood, lower respiratory system, and CSF
define amensalism
one organism is harmed the other is neutral
