Introduction - Interaction b/n Microbe & Host Koch’s Postulates
● Disease-causing microorganisms = pathogens ● Koch’s postulates are criteria for establishing that specific microbes
● Pathogenic microorganisms have special properties that allow them cause specific diseases
to invade the human body or produce toxins ● Koch’s postulates have the following requirements: (1) the same
● When a microorganism overcomes the body’s defenses, a state of pathogen must be present in every case of the disease; (2) the
disease results pathogen must be isolated in pure culture; (3) the pathogen isolated
Pathology, Infection, & Disease from pure culture must cause the same disease in a healthy,
● Pathology = scientific study of disease susceptible laboratory animal; and (4) the pathogen must be
● Pathology = concerned w/ etiology (cause), pathogenesis reisolated from the inoculated laboratory animal.
(development), & effects of disease Exceptions to Koch’s Postulates
● Infection = invasion & growth of pathogens in the body ● Koch’s postulates are modified to establish etiologies of diseases
● Host = organism that shelters & supports growth of pathogens caused by viruses and some bacteria, which cannot be grown on
● Disease = abnormal state in which part or all of the body is not artificial media
properly adjusted or is incapable of performing normal functions. ● Some diseases, such as tetanus, have unequivocal signs and
Human Microbiome symptoms
● Microorganisms begin colonization in and on the surface of the body ● Some diseases, such as pneumonia and nephritis, may be caused by
soon after birth a variety of microbes
● Microorganisms that establish permanent colonies inside or on the ● Some pathogens, such as S. pyogenes, cause several different
body w/out producing disease make up the normal microbiota diseases
Transient microbiota are microbes that are present for various ● Certain pathogens, such as HIV, cause disease in humans only.
periods and then disappear. Classifying Infectious Diseases
Relationships b/n the Normal Microbiota & Host ● A patient may exhibit symptoms (subjective changes in body
● The normal microbiota can prevent pathogens from causing an functions) and signs (measurable changes), which a physician uses
infection; this phenomenon is known as microbial antagonism to make a diagnosis (identification of the disease)
● Normal microbiota and the host exist in symbiosis (living together) ● A specific group of symptoms or signs that always accompanies a
● The three types of symbiosis are commensalism (one organism a specific disease is called a syndrome.
benefits, and the other is unaffected), mutualism (both organisms ● Communicable diseases are transmitted directly or indirectly from
benefit), and parasitism (one organism benefits, and one is harmed) one host to another
Opportunistic Microorganisms ● A contagious disease is a very communicable disease that is capable
● Opportunistic pathogens do not cause disease under normal of spreading easily and rapidly from one person to another
conditions but cause disease under special conditions ● Noncommunicable diseases are caused by microorganisms that
Cooperation among Microorganisms normally grow outside the human body and are not transmitted
, ● In some situations, one microorganism makes it possible for another from one host to another
to cause a disease or produce more severe symptoms Occurrence of a Disease
The Etiology of Infectious Diseases ● Disease occurrence is reported by incidence (number of people
● Disease-causing microorganisms = pathogens ● Koch’s postulates are criteria for establishing that specific microbes
● Pathogenic microorganisms have special properties that allow them cause specific diseases
to invade the human body or produce toxins ● Koch’s postulates have the following requirements: (1) the same
● When a microorganism overcomes the body’s defenses, a state of pathogen must be present in every case of the disease; (2) the
disease results pathogen must be isolated in pure culture; (3) the pathogen isolated
Pathology, Infection, & Disease from pure culture must cause the same disease in a healthy,
● Pathology = scientific study of disease susceptible laboratory animal; and (4) the pathogen must be
● Pathology = concerned w/ etiology (cause), pathogenesis reisolated from the inoculated laboratory animal.
(development), & effects of disease Exceptions to Koch’s Postulates
● Infection = invasion & growth of pathogens in the body ● Koch’s postulates are modified to establish etiologies of diseases
● Host = organism that shelters & supports growth of pathogens caused by viruses and some bacteria, which cannot be grown on
● Disease = abnormal state in which part or all of the body is not artificial media
properly adjusted or is incapable of performing normal functions. ● Some diseases, such as tetanus, have unequivocal signs and
Human Microbiome symptoms
● Microorganisms begin colonization in and on the surface of the body ● Some diseases, such as pneumonia and nephritis, may be caused by
soon after birth a variety of microbes
● Microorganisms that establish permanent colonies inside or on the ● Some pathogens, such as S. pyogenes, cause several different
body w/out producing disease make up the normal microbiota diseases
Transient microbiota are microbes that are present for various ● Certain pathogens, such as HIV, cause disease in humans only.
periods and then disappear. Classifying Infectious Diseases
Relationships b/n the Normal Microbiota & Host ● A patient may exhibit symptoms (subjective changes in body
● The normal microbiota can prevent pathogens from causing an functions) and signs (measurable changes), which a physician uses
infection; this phenomenon is known as microbial antagonism to make a diagnosis (identification of the disease)
● Normal microbiota and the host exist in symbiosis (living together) ● A specific group of symptoms or signs that always accompanies a
● The three types of symbiosis are commensalism (one organism a specific disease is called a syndrome.
benefits, and the other is unaffected), mutualism (both organisms ● Communicable diseases are transmitted directly or indirectly from
benefit), and parasitism (one organism benefits, and one is harmed) one host to another
Opportunistic Microorganisms ● A contagious disease is a very communicable disease that is capable
● Opportunistic pathogens do not cause disease under normal of spreading easily and rapidly from one person to another
conditions but cause disease under special conditions ● Noncommunicable diseases are caused by microorganisms that
Cooperation among Microorganisms normally grow outside the human body and are not transmitted
, ● In some situations, one microorganism makes it possible for another from one host to another
to cause a disease or produce more severe symptoms Occurrence of a Disease
The Etiology of Infectious Diseases ● Disease occurrence is reported by incidence (number of people
