Chapter 13: Microbe-Human Interactions Flashcards
Infection
A condition in which pathogenic microbes penetrate host defenses, enter tissues, and multiply
Pathogen
Infectious agent
Infectious Disease
an infection that causes damage or disruption to tissues and organs
Transients
microbes that occupy the body for only short periods of time
Residents
microbes that become established
Probiotics
introducing known microbes back into the body
True pathogens
capable of causing disease in health persons with normal immune defenses
ex: influenza virus, plague bacillus, malarial protozoan
Opportunistic pathogens
cause disease when the host’s defenses are compromised or when they grow in part of the body that is not natural to them
Portals of entry
characteristic route a microbe follows to enter the tissues of the body
Exogenous agents
originate from source outside the body
Endogenous agents
already exist on or in the body (normal flora)
STORCH
Syphilis, Toxoplasmosis, Other diseases (hepatitis B, AIDS and chlamydia), Rubella, Cytomegalovirus and Herpes simplex virus
Adhesion
microbes gain a stable foothold at the portal of entry; dependent on binding between specific molecules on host and pathogen
Antiphagocytic factors
used to avoid phagocytics
Slime layer or capsule
makes phagocytosis difficult
Virulence factors
traits used to invade and establish themselves in the host, also determine the degree of tissue damage that occurs- severity of disease
Exoenzymes
dissolve extracellular barriers and penetrate through or between cells
Toxigenicity
capacity to produce toxins at the site of multiplication
Endotoxin
toxin that is NOT secreted but is released after the cell is damaged
composed of lipopolysaccharide (LPS), part of the outer membrane of gram-negative cell walls
Exotoxin
toxin molecule secreted by a living bacterial cell into the infected tissue with a strong specificity for a target cell
Hemolysins
A-B toxins (A-active, B-binding)
Incubation period (1st stage)
time from initial contact with the infectious agent to the appearance of first symptoms; agent is multiplying but damage is insufficient to cause symptoms; several hours to several years
Prodromal stage (2nd stage)
vague feelings of discomfort; nonspecific complaints
Period of invasion (3rd stage)
multiplies at high levels, becomes well-established; more specific signs and symptoms
Convalescent period (4th stage)
as person begins to respond to the infection, symptoms decline
Localized infection
microbes enter the body and remains confined to a specific tissue
Systemic infection
infection spreads to several site and tissue fluids usually in the bloodstream
Focal infection
when infectious agent breaks loose from a local infection and is carried to other tissues
Mixed infection
several microbes grow simultaneously (polymicrobial)
Primary infection
initial infection
Secondary infection
another infection by a different microbe
Acute infection
comes on rapidly, with severe but short-lived effects
Chronic infections
progress and persist over a long period of time
Signs of inflammation - Edema
accumulation of fluid
Signs of inflammation - Granulomas/abscesses
walled-off collections of inflammatory cells and microbes
Signs of inflammation - Lymphadenitis
swollen lymph nodes
Leuikocytosis
increase in white blood cells
Leukopenia
decrease in white blood cells
Septicemia
microorganisms are multiplying in the blood and present in large numbers
Septicemia - Bacteremia
small numbers of bacteria present in blood not necessarily multiplying
Septicemia - Viremia
small number of viruses present not necessarily multiplying
Asymptomatic (subclinical) infections
although infected, the host doesn’t show any signs of disease
Latency
after the initial symptoms in certain chronic diseases, the microbe can periodically become active and produce a recurrent disease; person may or may not shed it during the latent stage
Chronic carrier
person with a latent infection who sheds the infectious agent
Sequelae
long-term or permanent damage to tissues or organs
Reserovoir
primary habitat of pathogen in the natural world
ex: human or animal carrier, soil, water, plants
Source
individual or object from which an infection is actually acquired
Carrier
an individual who inconspicuously shelters a pathogen and spreads it to others; may or may not have experienced disease due to the microbe
Asymptomatic carrier
shows no symptoms
Passive carrier
contaminated healthcare provider picks up pathogens and transfers them to other patients
Asymptomatic carrier - Incubation carriers
spread the infectious agent during the incubation period
Asymptomatic carrier - Convalescent carriers
recuperating without symptoms
Asymptomatic carrier - Chronic carrier
individual who shelters the infectious agent for a long period
Communicable disease
when an infected host can transmit the infectious agent to another host and establish infection in that host (contagious)
Non-communicable disease
infectious disease that does NOT arise through transmission from host to host
occurs primarily when a compromised person is invaded by his or her own normal microflora
Contact with organism in natural, non-living reservoir
Direct contact
physical contact or fine aerosol droplets
Indirect contact
passes from infected host to intermediate conveyor and then to another host
Indirect contact - Vehicle
inanimate material, food, water, biological products, fomites
Prevalence
total number of existing cases with respect to the entire population usually represented by a percentage of the population
Incidence
measures the number of new cases over a certain time period, as compared with the general healthy population
Mortality rate
the total number of deaths in a population due to a certain disease
Morbidity rate
number of people afflicted with a certain disease
Endemic
disease that exhibits a relatively steady frequency over a long period of time in a particular geographic locale
Sporadic
when occasional cases are reported at irregular intervals
Epidemic
when prevalence of a disease is increasing beyond what is expected
Pandemic
epidemic across continents
