Chapter 15 UTA Microbiology
Tholen Exam|75 Accurate Q’s and
A’s
Disease - -a condition where normal structure and/or function are damaged
or impaired
- Infection - -invasion of pathogen or parasite that lead to disease
- Signs - -things that can be directly measured by clinician (e.g. body
temperature)
- Symptoms - -things felt by patient that cannot be clinically measured (e.g.
nausea)
- Syndrome - -groups of signs and symptoms that help indicate a particular
disease
- Signs and symptoms help direct towards: - -Diagnosis
- Asymptomatic/subclinical - -only signs can be observed through correct
testing
- WHO's International Classification of Diseases (ICD) is used globally to: - -
classify and monitor diseases
- Infectious - -disease is directly affected by pathogens
- Communicable - -capable of spreading person-to-person
- Iatrogenic - -acquired as result of medical procedure
- Nosocomial - -acquired from hospital setting
- Zoonotic - -acquired from animal
- Non-communicable - -obtained from non-living thing such as soil or
contaminated object
- Non-infectious - -not caused by pathogen
- Periods of Disease - -1) Incubation
2) Prodromal
, 3) Illness
4) Decline
5) Convalescence
- Incubation - -intial entry of pathogen; replication begins
- Prodromal - -Replication continues; host shows signs and symptoms
- Illness - -signs and symptoms are most severe in host
- Decline - -pathogen number starts to decrease; host's immune system is
weak and vulnerable to secondary infection
- Convalescence - -host starts to recover
- Acute disease - -relatively short (hours, days, weeks); ex. influenza
- Chronic disease - -longer time (months, years, lifetime); ex. cancer, HIV
- Latent disease - -comes in episodes; pathogen replicates when disease is
active; Ex. herpes virus
- Koch's Postulates - -set of standards that must be met to demonstrate that
X pathogen causes X disease; Developed in 1884 and is still used today
- Koch's Postulates list - -1) The suspected pathogen must be found in every
case of disease and not be found in healthy individuals
2) The suspected pathogen can be isolated and grown in pure culture
3) A healthy test subject infected with the suspected pathogen must develop
the same signs and symptoms of disease as seen in postulate 1
4) The pathogen must be re-isolated from the new host and must be
identical to the pathogen from postulate 2
- Koch's (wrong) assumptions - -1) Pathogens are found only in disease
individuals
2) All subjects are equally susceptible to infection
3) All pathogens can be grown in culture
- Molecular Koch's Postulates - -1) The phenotype (sign or symptom of
disease) should be associated only with pathogenic strains of a species
2) Inactivation of the suspected gene(s) associated with pathogenicity should
result in a measurable loss of pathogenicity
3) Reversion of the inactive gene should restore the disease phenotype
- Pathogenicity - -ability of pathogen to cause disease
Tholen Exam|75 Accurate Q’s and
A’s
Disease - -a condition where normal structure and/or function are damaged
or impaired
- Infection - -invasion of pathogen or parasite that lead to disease
- Signs - -things that can be directly measured by clinician (e.g. body
temperature)
- Symptoms - -things felt by patient that cannot be clinically measured (e.g.
nausea)
- Syndrome - -groups of signs and symptoms that help indicate a particular
disease
- Signs and symptoms help direct towards: - -Diagnosis
- Asymptomatic/subclinical - -only signs can be observed through correct
testing
- WHO's International Classification of Diseases (ICD) is used globally to: - -
classify and monitor diseases
- Infectious - -disease is directly affected by pathogens
- Communicable - -capable of spreading person-to-person
- Iatrogenic - -acquired as result of medical procedure
- Nosocomial - -acquired from hospital setting
- Zoonotic - -acquired from animal
- Non-communicable - -obtained from non-living thing such as soil or
contaminated object
- Non-infectious - -not caused by pathogen
- Periods of Disease - -1) Incubation
2) Prodromal
, 3) Illness
4) Decline
5) Convalescence
- Incubation - -intial entry of pathogen; replication begins
- Prodromal - -Replication continues; host shows signs and symptoms
- Illness - -signs and symptoms are most severe in host
- Decline - -pathogen number starts to decrease; host's immune system is
weak and vulnerable to secondary infection
- Convalescence - -host starts to recover
- Acute disease - -relatively short (hours, days, weeks); ex. influenza
- Chronic disease - -longer time (months, years, lifetime); ex. cancer, HIV
- Latent disease - -comes in episodes; pathogen replicates when disease is
active; Ex. herpes virus
- Koch's Postulates - -set of standards that must be met to demonstrate that
X pathogen causes X disease; Developed in 1884 and is still used today
- Koch's Postulates list - -1) The suspected pathogen must be found in every
case of disease and not be found in healthy individuals
2) The suspected pathogen can be isolated and grown in pure culture
3) A healthy test subject infected with the suspected pathogen must develop
the same signs and symptoms of disease as seen in postulate 1
4) The pathogen must be re-isolated from the new host and must be
identical to the pathogen from postulate 2
- Koch's (wrong) assumptions - -1) Pathogens are found only in disease
individuals
2) All subjects are equally susceptible to infection
3) All pathogens can be grown in culture
- Molecular Koch's Postulates - -1) The phenotype (sign or symptom of
disease) should be associated only with pathogenic strains of a species
2) Inactivation of the suspected gene(s) associated with pathogenicity should
result in a measurable loss of pathogenicity
3) Reversion of the inactive gene should restore the disease phenotype
- Pathogenicity - -ability of pathogen to cause disease
