82 terms

microbiology - exam II (infectious disease and epidemiology

organisms that colonize the body's surfaces without normally causing disease
- normal flora
- indigenous microbiota
normal microbiota in hosts (synonyms)
- normal flora
- indigenous microbiota
remain part of normal microbiota of a person for life
resident microbiota
microbiota that remain in body for few hours, days, months before disappearing
transient microbiota
sites that are free of any microbes (microbiota) and in absence of disease, are never colonized by normal flora
axenic sites
examples of axenic areas of the body
- alveoli of lungs
- central nervous system
- circulatory system
- upper urogenital regions
- uterus
areas of normal microbiota
- upper respiratory tract
- upper and lower digestive tract
- female and male urinary and reproductive system
- eyes
- skin
when does microbiota begin to develop
during first month of life
- birthing process
- first breath
- handling by family
- mouth and nose through birth canal
normal microbiota that cause disease under certain circumstances
opportunistic pathogens
conditions that provide opportunities for pathogens
- introduction of normal microbiota into unusual site in body
- immune suppression
- changes in normal microbiota
sites where pathogens are maintained as a source of infection
reservoirs of infection
three types of reservoirs of infection
- animal reservoir
- human carriers
- nonliving reservoir
diseases that naturally spread from animal host to humans
ways in which zoonoses are acquired
- direct contact with animal or its waste
- eating animals
- bloodsucking arthropods
infected individuals who are asymptomatic but infective to others
carriers who develop illness
the mere presence of microbes in or on the body
when an organism evades the body's external defenses, multiplies, and becomes established in the body
sites through which pathogens enter the body
portals of entry
three major pathways of entry to the body
- skin
- mucus membrane
- placenta
line the body cavities that are open to the environment and provide a moist, warm environment hospitable to pathogens
mucus membranes
most common site of entry for pathogens
respiratory tract
table on page 17
pathogens that cross the placenta
means by which the portal of entry can be circumvented
parenteral route
what does inability of adhesion do to microorganisms
makes them avirulent
results if the invading pathogen alters normal body function
disease is also referred to as
group of symptoms and signs that characterize a disease or abnormal condition
gen-, -gen
give rise to
literally rotting; refers to presence of pathogens
haemophilus influenza B causes influenza
FALSE; meningitis in children
disease caused by infections of pathogenic microorganisms
germ theory of disease
statements to prove a particular pathogen causes a particular disease
Koch's postulates
exceptions to Koch's postulates
- some pathogens cannot be cultured in lab
- diseases caused by a combination of pathogens and other cofactors
- ethical considerations
difficulties in satisfying Koch's postulates
- disease can be caused by more than one pathogen
- some pathogens have been ignored as potential causes of disease
ability of a microorganism to cause disease
degree of pathogenicity
pathogenicity and virulence refer to severity of the disease
virulence factors
- adhesion
- biofilms
- extracellular enzymes
- toxins
- antiphagocytic factors
where are extracellular enzymes secreted from
function of extracellular enzymes
- dissolve structural chemicals in the body
- help the pathogen maintain infection, invade, and avoid body defenses
chemicals that harm tissues or trigger host immune responses that cause damage
toxins in the bloodstream that are carried beyond the site of infection
two types of toxins
- exotoxins
- endotoxins
lipid A is an example of
an endotoxin
protective molecules, antibodies, formed by the host
the ability of a chemical to trigger a specific immune response, particularly the formation of antibodies
factors that prevent phagocytosis by the host's phagocytic cells
antiphagocytic factors
a structure composed of chemicals not recognized as foreign that make it difficult for phagocytes to engulf bacteria
bacterial capsule
five stages of infectious disease in sequence
- incubation period
- prodromal period
- illness
- decline
- convalescence
period between infection and occurrence of first symptoms or signs
incubation period
short period of generalized, mild symptoms
prodromal period
most severe stage of infection where signs and symptoms are most evident
when the body gradually returns to normal as immune response/treatment vanquish pathogens
patient recovers from illness, tissues repaired and returned to normal
transport of pathogens from a reservoir or portal of exit to another host's portal of entry
five groups of transmission
- contact transmission
- vehicle transmission
- vector transmission
- airborne transmission
- perinatal transmission
ways in which disease can be classified
- the body system they affect
- taxonomic categories
- their longevity and severity
- how they are spread to their host
- the effects they have on populations
occurrence of disease is measured in two ways
- incidence
- prevalence
number of new cases of a disease in a given area during a given period of time
number of total cases of a disease in a given area during a given period of time
disease that normally occurs at regular intervals at a relatively stable incidence within a given population or geographical area
only a few scattered cases within an area or population
occurs at a greater frequency than is usual for an area or population
an epidemic that occurs simultaneously on more than one continent
careful tabulation of data concerning a disease
descriptive epidemiology
first case of a disease identified and reported
index case
observational studies and experimental studies
analytical epidemiology
infections acquired in health-care setting
nosocomial infections
percentage of americans that acquire nosocomial infection yearly
types of nosocomial infections
- exogenous
- endogenous
- iatrogenic
pathogen acquired from the health care environment
exogenous nosocomial infection
pathogen arises from normal microbiota due to factors within the health care setting
endogenous nosocomial infection
infection that results from modern medical procedures
iatrogenic nosocomial infection
the most effective way to reduce nosocomial infection
hand washing
disease acquired by inhaling aerosolized deer-mouse urine or feces stirred up by sweeping
Hantavirus pulmonary syndrome
table 14.12
classification of diseases