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Microbiology Chapter 14 Troy University

Terms in this set (93)

pathology
the study of disease
what are the three objectives of pathology
1. etiology
2. pathogenesis
3. structural and functional changes
etiology
the cause of a disease
pathogenesis
the development of disease
structural and functional changes
brought about by disease and their effects on the body
infection
invasion or colonization of the body by pathogens
presence of a microbe in a part of the body where it is not normally found
pathogens
disease causing microbes
disease
an abnormal state in which the body is not performing normal functions
microbiomes
microbial communities established inside and on the human body
transient microbiota
may be present for days, weeks, months
normal microbiota
permanently colonize the host and do not cause disease under normal conditions
human microbiome project
analyzes relationships between microbial communities on the body and human health
Goal: to understand the relationship between changes in the microbiome and human health and disease
what are the regions of the body in which microbes are localized
mouth/eyes
stomach
intestines
respiratory
skin
urogenital
What are distribution and composition of normal micro-bacteria determined by?
-nutrients
-physical and chemical factors (pH, temperature, oxygen levels, CO2, salinity, sunlight)
-host defenses (molecules and activated cells that kill microbes, inhibit their growth, prevent adhesion to host cell, neutralize toxins)
-mechanical factors
microbial antagonism
competition between microbes
how do normal microbiota protect their host
-competing for nutrients
-producing substances harmful to invading microbes
-affecting pH and available oxygen
when balance between normal microbiota and pathogens is disturbed, disease can occur
symbiosis
relationship between normal microbiota and the host
commensalism
one organism benefits, and the other is unaffected
mutualism
both organisms benefit
parasitism
one organism benefits at the expense of the other
opportunistic pathogens
a microbe that does not ordinarily cause a disease but can become pathogenic under certain circumstances
robert koch
proved that bacteria can cause disease (germ theory of disease)
what are the 4 parts of Koch's Postulates
1. the same pathogen must be present in every case of the disease
2. the pathogen must be isolated from the diseased host and grow in pure culture
3. the pathogen from the pure culture must cause the disease when its inoculated into a healthy, susceptible laboratory animal
4. the pathogen must be isolated from the inoculated animal and must be shown to be the original organism
what are Koch's Postulates used for?
to prove the cause of an infectious disease
what are the exceptions to Koch's Postulates?
1. some pathogens can cause several disease conditions, symptoms and signs
2. some pathogens cause disease only in humans- ethical issues with human experiments
3. human experiments with untreatable diseases are not allowed today
4. some microbes have never been cultured
symptoms
changes in body function that are felt by a patient as a result of disease, such as pain or malaise - not apparent to the observer
signs
changes in a body that can be measured or observed as a result of disease
syndrome
specific group of signs and symptoms that accompany a disease
how are diseases classed
how they behave within a host and a given population
communicable disease
disease that is spread from 1 host to another
contagious disease
disease that is easily and rapidly spread from one host to another
noncommunicable disease
a disease that is not spread from one host to another
incidence
fraction of a population that contracts a disease during a particular time period
an indicator of the spread or the odds of people contracting the disease
prevalence
fraction of a population having a specific disease at a given time, regardless of when it first appeared

indicates how widespread the disease is
sporadic disease
disease that occurs only occasionally
endemic disease
disease constantly present in a population
epidemic disease
disease acquired by many people in a given area in a short time
pandemic disease
worldwide epidemic
acute disease
symptoms develop rapidly but the disease lasts only a short time
chronic disease
symptoms develop slowly and likely to continue to recur for long periods of time
subacute disease
intermediate between acute and chronic
latent disease
causation agent is inactive for a time but then activates and produces symptoms
herd immunity
immunity in most of a population
local infection
pathogens are limited to a small area of the body
systemic (generalized) infection
an infection throughout the body
focal infection
systemic infection that begins as a local infection
sepsis
toxic inflammatory condition arising from the spread of microbes, especially bacteria or their toxins, from a focus of infection
bacteremia
bacteria in the blood
septicemia
also known as blood poisoning, growth of bacteria in the blood
toxemia
toxins in the blood
viremia
viruses in the blood
primary infection
acute infection that causes the initial illness
secondary infection
opportunistic infection after a primary infection
subclinical infection
no noticeable signs or symptoms (inapparent infection)
what does the occurrence of disease depends on...
the resistance of the host to the activities of the pathogen
what are some factors that make the body susceptible to disease
-gender
-inherited traits
-climate and weather
-fatigue
-age
-lifestyle
-nutrition
-chemotherapy
incubation period
interval between initial infection and first signs and symptoms
depends on the pathogen
prodromal period
short period after incubation; early, mild symptoms
period of illness
disease is most severe
if patients immune system and other defenses do not overcome at this point the patient will die
period of decline
signs and symptoms subside
24 hrs- several days, patient is susceptible to secondary infections
period of convalescence
body returns to its prediseased state
what is a reservoirs of infection
-continual source of infection for a disease to exist
-provides pathogen adequate conditions for survival and multiplication and opportunity for transmission
what are the 3 kinds of reservoirs
-human
-animal
-nonliving
human reservoirs
people with disease
carriers may have inapparent infections or latent diseases
zoonoses
diseases transmitted from animals to humans
nonliving reservoirs
soil and water
direct contact transmission
requires close association between the infected and susceptible host
indirect contact transmission
spreads to a host by a nonliving object called a fomite
droplet transmission
transmission via airborne droplets less than a meter
vehicle transmission (3 types)
waterborne
foodborne
airborne
also includes blood, other body fluids, drugs, intravenous fluids
waterborne
-water is untreated or poorly treated sewage
foodborne
-food is undercooked, refrigerated poorly, or prepared under unsanitary conditions
airborne
-infection by droplet nuclei in dust that travels more than 1 meter
vectors are...
arthropods
-fleas
-ticks
-mosquitos
mechanical transmission
arthropod carriers pathogen on its feet
biological transmission
pathogen reproduces in the vector, transmitted via bites or feces
HIA/ nosocomial infections
infections patients acquire while receiving treatment in a health care facility
-8th leading cause of death in the US
-2 million per year
-20,000 deaths each year
what do HIA's result from
-microbes in hospital environment
-weakened status of the host
-chain of transmission in a hospital
compromised host
an individual whose resistance to infection is impaired by disease, therapy, or burns
what 2 conditions can compromise a host
-broken skin or mucous membrane
-suppressed immune system
what are the routes of transmission for HAI's
-direct contact transmission
-indirect contact transmission
emerging infectious disease
diseases that are new, increasing in incidence, or showing potential to increase in the near future
most are zoonotic, of viral origin, and likely vector borne
what are some contributing factors to emerging infectious diseases
-genetic recombination
-evolution of new strains
-widespread use of antibiotics and pesticides
-changes in weather patterns
-modern transportation
-ecological disaster, war, expanding human settlement
-animal control measures
-public health failure
epidemiology
the study of where and when diseases occur and how they are transmitted
what do epidemiologists do
-determine etiology of a disease
-identify important factors concerning the spread of disease
-develop methods for controlling a disease
-assemble graphs and data to outline incidence of disease
descriptive epidemiology
collection and analysis of data that describe the occurrence of disease
analytical epidemiology
analyzes a particular disease to determine its probable cause
experimental epidemiology
involves hypothesis and controlled experiments
morbidity
incidence of a specific notifiable disease
mortality
deaths from notifiable disease
notifiable infectious disease
disease in which physicians are required to report occurence
morbidity rate
number of people affected in relation to the total population in a given time period
mortality rate
number of deaths from a disease in relation to the population in a given time
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