Chapter 10: Mechanisms of Disease

Question 1

Host

Answer 1

any organism capable of supporting the nutritional and physical growth requirements of another

Question 2

Infection

Answer 2

the presence and multiplication of microorganisms within a host, causing subsequent injury to the host

Question 3

Colonization

Answer 3

the act of microorganisms establishing a presence

Question 4

Normal Microflora

Answer 4

internal and external exposed surfaces of the human body that are normally and harmlessly inhabited by a multitude of bacteria

Question 5

Commensalism

Answer 5

microorganism receives benefit (i.e. nutrition)

host does not receive benefit or harm

Question 6

Mutualism

Answer 6

interaction in which both the microorganism and the host derive benefits
(Vitamin K and Vitamin B12)

Question 7

Parasitic Relationship

Answer 7

the infecting organism benefits from the relationship and the host either gains nothing or sustains injury

Question 8

Infectious Disease

Answer 8

when the host sustains injury or pathologic damage

Question 9

Pathogens

Answer 9

microorganisms capable of causing disease

Question 10

Opportunistic Pathogens

Answer 10

harmless microorgansims that are capable of causing infectious disease when the health and immunity of the host are weakened by illness, malnutrition, or medical therapy (antibiotics, chemotherapy)
Example: E. coli

Question 11

Prions

Answer 11

lack RNA or DNA
causes neurodegenerative diseases: Mad-Cow disease
occurs primarily from consuming infected meat

Question 12

Viruses

Answer 12

smallest obligate intracellular pathogens
surrounded by a capsid
live and replicate inside living cells
Examples: influenza, herpes, hepatitis

Question 13

Bacteria

Answer 13

reproduce outside of the host cells
vulnerable to antimicrobials
exotoxins and endotoxins cause damage to cells/tissues
flagella for motility
fimbriae helps adhere to surfaces
aerobes  and anaerobes

Question 14

Fungi

Answer 14

Yeasts (Candida) - colonies are smooth with a waxy or creamy texture
Molds (ringworm) - colonies produce a cottony or powdery appearance

Question 15

Penetration

Answer 15

invasion of microorganisms through disruption in skin or mucous membranes
Examples: abrasions/burns, wounds, surgery, catheterization, surface lesions (chick pox, impetigo)

Question 16

Direct Contact

Answer 16

transmission directly from infected tissue or secretions to exposed, intact mucous membranes
Examples: STIs (gonorrhea, syphilis, chlamydia, genital herpes)

Question 17

Vertical Transmission

Answer 17

passed from mother to child (across placenta or during birth)
Examples: TORCH infections

Question 18

Ingestion

Answer 18

entry of pathogenic microorganisms through the oral cavity and GI tract
contaminated food and water
Examples: food poisoning, traveller’s diarrhea, Hep A, dysentery, cholera/typhoid

Question 19

Inhalation

Answer 19

droplet and airborne
Examples: bacterial pneumonia, meningitis, tuberculosis
viruses: measles, mumps, chicken pox, influenza, the common cold

Question 20

Endogenous Source of Infection

Answer 20

acquired form the host’s own microbial flora

opportunistic infection

Question 21

Exogenous Source of Infection

Answer 21

acquired from sources in the external environment

water, food, soil, air

Question 22

Fomite

Answer 22

inanimate objects that carry an infectious agent

Question 23

Zoonoses

Answer 23

infectious diseases passed from another animal species to humans
Examples: rabies, cat-scratch disease, HIV, plague, influenza

Question 24

Vectors

Answer 24

biting arthropods such as mosquitoes, spiders, and ticks

Examples: Lyme disease, West Nile Virus

Question 25

Nosocomial (Healthcare-Associated) Infections

Answer 25

infections that develop in people while they are hospitalized (greater than 48 hours)

Question 26

Community-acquired Infections

Answer 26

infections that occur outside of healthcare facilities

Question 27

Incubation Period

Answer 27

pathogen begins replicating without producing symptoms | can be short (cholera) or prolonged (Hep B/HIV)

Question 28

Prodromal Stage

Answer 28

initial vague appearance of symptoms mild fever, myalgia, headache, fatigue duration varies host to host

Question 29

Insidious

Answer 29

extended prodromal stage

Question 30

Fulminant

Answer 30

abrupt onset of symptoms with little or no prodromal stage

Question 31

Acute Stage

Answer 31

period during which the host experiences the maximum impact of the infectious process immune response symptoms become more pronounced and specific

Question 32

Convalescent Period

Answer 32

beginning of resolution the containment of the infection, progressive elimination of the pathogen, and repair of damaged tissue may be days, weeks, or months

Question 33

Resolution

Answer 33

the total elimination of the pathogen from the body without residual signs and symptoms of disease

Question 34

-itis

Answer 34

inflammation of an anatomic location/involved tissue

Question 35

-emia

Answer 35

presence of a substance in the blood

Question 36

Septicemia/Sepsis

Answer 36

presence of microbial toxins in the blood causing systemic inflammation

Question 37

Localized Infection

Answer 37

microorganism is restricted to a certain body part/system Examples: influenza to respiratory tract gonorrhea to genitourinary tract H. pylori to GI tract

Question 38

Systemic Infections

Answer 38

disseminate from the primary site of infection through the circulatory system to involve other locations and organ systems Examples: staph aureus, meningitidis, Lyme disease

Question 39

Virulence Factors

Answer 39

substances or products generated by infectious agents that enhance their ability to cause disease

Question 40

Exotoxins

Answer 40

proteins released from the bacterial cell during growth that may damage host cells Examples: pertussis, anthrax, traveler's diarrhea, TSS, and food-borne illnesses

Question 41

Endotoxins

Answer 41

found in gram-negative bacteria - potent activators of the regulatory system Example: endotoxic shock: clotting, bleeding, inflammation, hypotension and fever

Question 42

Adhesion Factors

Answer 42

microbial attachment to host cell surfaces | slime or mucous layer (anchors and protects bacteria)

Question 43

Evasive Factors

Answer 43

factors produced by microorganisms to evade the host's immune system Examples: encapsulated organisms, H. pylori excretes urease

Question 44

Invasive Factors

Answer 44

products produced by infectious agents that facilitate the penetration of anatomic barriers and host tissue most are enzymes capable of destroying: cell membranes, connective tissue, intracellular matrices, structural protein complexes

Question 45

Culture

Answer 45

growth of a microorganism outside of the body, usually on or in artificial growth media (sugar plates, broth) microscopic appearance and gram stain for bacteria cell cultures for viruses obtain cultures prior to antibiotic administration

Question 46

Serology

Answer 46

an indirect means of identifying infectious agents by measuring serum anitbodies anitbody titers and antigen detection not as accurate as culture but useful in identifying diseases that are not able to be cultured (Hep B)