Chapter 10: Mechanisms of Infectious Disease

Question 1

Host

Answer 1

organism capable of supporting growth of another organism

Question 2

Infectious disease

Answer 2

disease state due to interaction with another organism

Question 3

Colonization

Answer 3

presence of a living organism on or within the host

Question 4

Microflora

Answer 4

bacteria inhabiting exposed surfaces on the body

Question 5

Virulence

Answer 5

the disease-inducing potential

Question 6

Pathogens

Answer 6

virulent microorganisms that is rarely in absence of disease

Question 7

Saprophytes

Answer 7

organisms obtaining growth from dead material in environment

Question 8

Mutualism

Answer 8

interaction between microorganisms and the host both derive benefits from the interaction

Question 9

Commensalism

Answer 9

bacteria acquire nutrition and shelter from safe host

Question 10

Parasitic Relationship

Answer 10

infecting organism benefits from host

Question 11

Agents of Infectious Disease

Answer 11

prions
viruses 
bacteria
rickettsiaceae 
chlamydiaceae
fungi
parasites

Question 12

Viruses

Answer 12

• smallest pathogens
• have no organized cellular structure
• consist of a protein coat (capsid) surrounding a nucleic acid core of DNA or RNA
• are incapable of replication outside a living cell
• can penetrate host and remain dormant

Question 13

Two Types of Bacteria

1. Gram positive organisms
2. Gram negative organisms

Answer 13

gram positive:

• diplococci
• staphylococci
• streptococci

gram negative:

• bacilli
• sprilla (spirochete)

Question 14

Parasite definition
\+
Types of Parasites 
\+
Methods of Infecting

Answer 14

An agent that derives benefit from its biologic relationship with another organism
+
- protozoa
- helminths
- arthropods
+
- these are members of the animal kingdom infect and cause diseases in other animals
- these animals then transmit disease to humans

Question 15

Epidemiology

Answer 15

the study of factors, events and circumstances that influence the transmission of infectious diseases among humans

Question 16

Incidence

Answer 16

the number of new cases of an infectious disease that occur within a defined population

Question 17

Prevalence

Answer 17

the number of active cases at any given time

Question 18

Prevalence

Answer 18

the number of active cases at any given time

Question 19

Endemic Disease

Answer 19

• found in a particular geographic region

- the incidence and prevalence are expected and relatively stable

Question 20

Epidemic

Answer 20

abrupt and unexpected increase in the incidence of disease over endemic rates

Question 21

Pandemic

Answer 21

spread of disease beyond continental boundaries

Question 22

Symptomatology

Answer 22

• specific: reflex the site of infection (i.e. diarrhea, rash, convulsions hemorrhage, pneumonia
• non specific: can be share by a number of diverse infectious diseases (i.e. symptoms such as fever, myalgia, headache)
• obvious: predictable patterns (i.e. chickenpox, measles)
• covert: may require lab testing to detect (i.e. hepatitis, increase WBC count)

Question 23

Disease Course in Infection

Answer 23

1. incubation period: pathogens begins active replication but does not produce symptoms
2. prodromal stage: initial appearance of symptoms in host
3. acute stage: host experiences max s/s of pathogen, rapid proliferation and cell lysis, immune system respond, tissue damage + inflammation
4. convalescent stage: containment of infection, elimination of pathogen, repair of tissue
5. resolution stage: total elimination of pathogen from body without any s/s of disease

Question 24

Disease Course in Infection

Answer 24

1. incubation period: pathogens begins active replication but does not produce symptoms
2. prodromal stage: initial appearance of symptoms in host
3. acute stage: host experiences max s/s of pathogen, rapid proliferation and cell lysis, immune system respond, tissue damage + inflammation
4. convalescent stage: containment of infection, elimination of pathogen, repair of tissue
5. resolution stage: total elimination of pathogen from body without any s/s of disease

Question 25

Bactericidal

Answer 25

if it causes irreversible and lethal damage to the bacterial pathogen

Question 26

Bacteriostatic

Answer 26

if its inhibitory effects on bacterial growth are reversed when the agent is eliminated

Question 27

Bacteriostatic

Answer 27

if its inhibitory effects on bacterial growth are reversed when the agent is eliminated

Question 28

Antibiotic Mechanisms

Answer 28

• interference with a specific step in bacterial cell wall synthesis
• inhibition of bacterial protein synthesis
• interruption of bacterial nucleic acid synthesis
• interference with normal bacterial metabolism

Question 29

Antibiotic Target Site

Answer 29

penicillin: cell wall
cephalosporin: cell wall
monobactams: cell wall
aminoglycoside: ribosome
tetracyclines: ribosome
macrolides: ribosome
glycopeptide: ribosome
sulfonamides: folic acid synthesis
quinolones: DNA synthesis