Microbio 4000: Exam #4 Study Guide
Questions Fully Solved.
remember that both normal microbiota and pathogens have adhesions to colonize our tissues.
pathogens have genetic differences (virulence factors) that lead to disease. what do we call the
type of relationship we have with good bacteria? pathogenic bacteria? - Answer -good
bacteria: mutualism
-pathogenic: parasitism
what is the scientifically accurate definition of a parasite? what is the difference between and
ectoparasite and endoparasite? - Answer -parasite: microbes that colonize and harm its host
-ectoparasite: live on the surface of the host
-endoparasite: live within the host
why isnt an infection by a pathogen always considered a disease? - Answer infection occurs
when a pathogen enters or begins to grow on a host, but disease only occurs when
sign/symptoms develop
**all pathogens are parasites, and nay growth of a pathogen in or on a host causes infection,
but not all infections will lead to disease**
know the differences between acute, chronic, latent, and opportunistic infections. - Answer -
acute: cause disease in which symptoms develop and resolve quickly (ex. ebola, strep throat)
-chronic: cause disease in which symptoms develop gradually and are slow to resolve (ex.
herpes, tuberculosis)
-latent: pathogen remains dormant in the host (ex. coldsores from herpes)
-opportunistic: cause disease only in an immunocompromised host
what two main factors determine pathogenicity? - Answer Infectivity - how easily an
organism causes disease
Virulence - how severe that disease is
be familiar with what ID50 and LD50 represent and how they are measured. be prepared to
interpret dose-response curves and compare virulence between them. - Answer -ID50
(infectious dose 50%): the number of microbial organisms required to cause disease symptoms
in 50% of experimental group of hosts; the lower the ID50 the more infectious that disease is
-LD50 (lethal dose 50%): the number of microbial organisms required to kill 50% of an
experimental group of hosts
, what three objectives must a pathogen accomplish to establish a successful infection? - Answer
- attachment: adhesions on microbes help them adhere to host cells by binding to host
receptors
- immune avoidance: all cellular organisms have antimicrobial mechanisms to resist infection,
and successful pathogens possess genes to avoid the host immune system
- stealing nutrients from the host: host cells hold onto their nutrients tightly; pathogens much
possess genes that enable them to take nutrients away from the host
how do we define disease? Infectious disease? - Answer -disease: a disruption of the normal
structure or function of any body part, organ, or system that can be recognized by a
characteristic set of symptoms and signs
-infectious disease:
know the difference between signs, symptoms, and sequelae - Answer -symptoms: aspects of
disease that are felt by the patient; often subjective and difficult to reliably measure; (ex. pain)
-signs: things that can be observed or measured by another person; often objective and have
standardized methods of measurement; (ex. temperature, blood values, vital signs)
-sequelae: signs and symptoms that can be aftereffects of an infectious disease that are not
necessarily the disease itself; (ex. long covid, lyme disease)
know the five general stages of an acute infectious disease - Answer 1. incubation phase:
microbe infects a person
2. prodromal phase: first vague symptoms appear
3. illness phase: typical signs and symptoms of the disease appear
4. decline phase: the symptoms begin to subside
5. convalescence: symptoms have completely disappeared
define bacteremia - Answer presence of bacteria in blood; usually transient, little, or no
replication
define septicemia - Answer presence and replication of bacteria in the blood ( blood
infection) ex. plague
define viremia - Answer presence of viruses in the blood ex HIV
define toxemia - Answer presence of toxin in the blood ex. diphtheria, toxic shock syndrome
define primary infection - Answer infection in a previously healthy individual ex. syphillis
Questions Fully Solved.
remember that both normal microbiota and pathogens have adhesions to colonize our tissues.
pathogens have genetic differences (virulence factors) that lead to disease. what do we call the
type of relationship we have with good bacteria? pathogenic bacteria? - Answer -good
bacteria: mutualism
-pathogenic: parasitism
what is the scientifically accurate definition of a parasite? what is the difference between and
ectoparasite and endoparasite? - Answer -parasite: microbes that colonize and harm its host
-ectoparasite: live on the surface of the host
-endoparasite: live within the host
why isnt an infection by a pathogen always considered a disease? - Answer infection occurs
when a pathogen enters or begins to grow on a host, but disease only occurs when
sign/symptoms develop
**all pathogens are parasites, and nay growth of a pathogen in or on a host causes infection,
but not all infections will lead to disease**
know the differences between acute, chronic, latent, and opportunistic infections. - Answer -
acute: cause disease in which symptoms develop and resolve quickly (ex. ebola, strep throat)
-chronic: cause disease in which symptoms develop gradually and are slow to resolve (ex.
herpes, tuberculosis)
-latent: pathogen remains dormant in the host (ex. coldsores from herpes)
-opportunistic: cause disease only in an immunocompromised host
what two main factors determine pathogenicity? - Answer Infectivity - how easily an
organism causes disease
Virulence - how severe that disease is
be familiar with what ID50 and LD50 represent and how they are measured. be prepared to
interpret dose-response curves and compare virulence between them. - Answer -ID50
(infectious dose 50%): the number of microbial organisms required to cause disease symptoms
in 50% of experimental group of hosts; the lower the ID50 the more infectious that disease is
-LD50 (lethal dose 50%): the number of microbial organisms required to kill 50% of an
experimental group of hosts
, what three objectives must a pathogen accomplish to establish a successful infection? - Answer
- attachment: adhesions on microbes help them adhere to host cells by binding to host
receptors
- immune avoidance: all cellular organisms have antimicrobial mechanisms to resist infection,
and successful pathogens possess genes to avoid the host immune system
- stealing nutrients from the host: host cells hold onto their nutrients tightly; pathogens much
possess genes that enable them to take nutrients away from the host
how do we define disease? Infectious disease? - Answer -disease: a disruption of the normal
structure or function of any body part, organ, or system that can be recognized by a
characteristic set of symptoms and signs
-infectious disease:
know the difference between signs, symptoms, and sequelae - Answer -symptoms: aspects of
disease that are felt by the patient; often subjective and difficult to reliably measure; (ex. pain)
-signs: things that can be observed or measured by another person; often objective and have
standardized methods of measurement; (ex. temperature, blood values, vital signs)
-sequelae: signs and symptoms that can be aftereffects of an infectious disease that are not
necessarily the disease itself; (ex. long covid, lyme disease)
know the five general stages of an acute infectious disease - Answer 1. incubation phase:
microbe infects a person
2. prodromal phase: first vague symptoms appear
3. illness phase: typical signs and symptoms of the disease appear
4. decline phase: the symptoms begin to subside
5. convalescence: symptoms have completely disappeared
define bacteremia - Answer presence of bacteria in blood; usually transient, little, or no
replication
define septicemia - Answer presence and replication of bacteria in the blood ( blood
infection) ex. plague
define viremia - Answer presence of viruses in the blood ex HIV
define toxemia - Answer presence of toxin in the blood ex. diphtheria, toxic shock syndrome
define primary infection - Answer infection in a previously healthy individual ex. syphillis
