Pathogenesis

Question 1

definition of PATHOGENS

Answer 1

microorganisms that PRODUCE DISEASE

Question 2

defnition of PATHOGENESIS

Answer 2

the BIOLOGICAL MECHANISM or MECHANISMS that LEAD TO DISEASE

Question 3

definition of PATHOGENICITY

Answer 3

the ABILITY OF AN ORGANISM to CAUSE DISEASE

Question 4

definition of VIRULENCE

Answer 4

the DEGREE OF PATHOGENICITY

Question 5

definition of PATHOGENIC DETERMINANTS

Answer 5

the ATTRIBUTES OF BACTERIA or VIRUSES that ENABLE THEM to ENHANCE their ability to cause disease

Question 6

definition of INFECTION

Answer 6

the INVASION of the HOST by DISEASE CAUSING ORGANISMS

Question 7

How does the MICROORGANISM CAUSE DISEASE?

Answer 7

• MUST GAIN ACCESS to the HOST
• ADHERE to HOST CELLS
• have to PENETRATE and EVADE IMMUNE RESPONSE
• have to DAMAGE THE HOST CELLS AND TISSUE
• EXIT

Question 8

what are the PORTALS OF ENTRY?

Answer 8

MUCOUS MEMBRANES:

• GI TRACT
• RESPIRATORY TRACT
• GENITOURINARY TRACT
• CONJUNCTIVA

SKIN:

• either its UNBROKEN or entering through other openings such as HAIR FOLLICLES

PARENTERAL ROUTE:

• a DIRECT DEPOSIT INTO TISSUE due to CUTS, INJECTIONS, BITES, and SURGERY

Question 9

definition of PREFERRED SITEs

Answer 9

specific BACTERIA have SPECIFIC SITES OF ENTRY in order to cause disease

ex. Salmonella typhi (Typhoid fever) has to be SWALLOWED

ex. Streptococci (Pneumonia) NO EFFECT WHEN SWALLOWED

ex. Yersinia pestis and Bacillus anthracis HAVE MORE THAN ONE PORTAL OF ENTRY

Question 10

definition of ID50

Answer 10

INFECTIOUS DISEASE 50:

• the DOSE that CAUSES DISEASE in 50% of the POPULATION
• used to compare the RELATIVE VIRULENCE under DEFINED CONDITIONS

Question 11

definition of LD 50

Answer 11

LETHAL DOSE 50:

the DOSE that KILLS 50% of the POPULATION within a CERTAIN TIME

• refers often to TOXIC AGENTS such as BOTULISM TOXIN or SHIGA TOXIN
• seen in DEFINED CONDITIONS

Question 12

definition of ADHERENCE/ADHESION

Answer 12

where PATHOGENS ATTACH THEMSELVES to HOST TISSUE

• necessary for PATHOGENICITY

Question 13

definition of ADHESINS

Answer 13

• GLYCOPROTEINS or LIPOPROTEINS–help to BIND SUGARS ON HOST CELL (MANNOSE)
• GREAT DIVERSITY–can be PILI, CAPSULES, CELL WALL COMPONENTS

Question 14

how do MICROORGANISMS PENETRATE the HOST CELL?

Answer 14

use of PRODUCE SURFACE PROTEINS known as INVASINS–helps to PROMOTE BACTERIA ENTERING THE HOST CELL

Question 15

what are some STRUCTURES microorganisms use to PENETRATE HOST DEFENSES (4)?

Answer 15

1. CAPSULES

• can ESCAPE PHAGOCYTOSIS
  (S. pneumoniae, K. pneumoniae)

2. M PROTEIN

• helps to MEDIATE ATTACHMENT and EVADE PHAGOCYTOSIS
  (S. pyogenes)

3. OPA PROTEIN

• gives ATTACHMENT and INTERNALIZATION by HOST CELLS
• INHIBITS T CELL PROLIFERATION and ACTIVATION
  (N. gonorrhoeae)

4. MYCOLIC ACID

• has a WAXY CELL WALL that can AVOID PHAGOCYTOSIS and MULTIPLY in PHAGOCYTES
  (Mycobacterium tuberculosis)

Question 16

what ENYZMES do bacteria produce to aid in virulence? (4)

Answer 16

1. COAGULASE

• helps to CLOT FIBRINOGEN IN BLOOD–protection from PHAGOCYTOSIS

2. KINASE

• breaks CLOTS and allows to EXTEND INFECTION

3. IgA protease
4. COLLAGENASES

• break down CONNECTIVE TISSUE OF MUSCLES–leads to GREATER SPREAD OF BACTERIA

Question 17

definition of ANTIGENIC VARIATION

Answer 17

where pathogens can alter their SURFACE PROTEINS

• even after the BODY MOUNTS AN IMMUNE RESPONSE–already has altered its ANTIGEN

ex. Influenza virus and N. gonorrhoeae

Question 18

How do BACTERIAL PATHOGENS DAMAGE HOST CELLS (4)?

Answer 18

1. using the HOST NUTRIENTS
2. CAUSING DIRECT DAMAGE in INFECTION AREA
3. INDUCING HYPERSENSITIVITY
4. PRODUCTION OF TOXINS

Question 19

how do pathogens use HOST NUTRIENTS?

Answer 19

use of SIDEROPHORES–can SEQUESTER IRON away from HEMOGLOBIN (significant for oxygen transport in blood)

Question 20

how do pathogens DIRECTLY DAMAGE AREAS of INFECTION?

Answer 20

use the host cell as its SOURCE OF NUTRIENTS and production of waste products

Question 21

definition of EXOTOXINS

Answer 21

proteins that are PRODUCED INSIDE A PATHOGEN and is SECRETED INTO SURROUNDING or RELEASED BY LYSIS

• use of ENZYMES that are repetitive in use
• GENES carried in PLASMIDS or PHAGES
• work by affecting the HOST CELL and METABOLIC PATHWAY

Question 22

definition of ENDOTOXINS

Answer 22

specific LIPID PORTIONS (LIPID A) seen in LIPOPOLYSACCHARIDES of OUTER MEMBRANE OF GRAM - BACTERIA–released when the BACTERIA DIES or CELL LYSES

Question 23

are diseases directly caused by EXOTOXINS? does the body have defenses against EXOTOXINS?

Answer 23

most often diseases that have BACTERIA THAT PRODUCE EXOTOXINS are caused by the ACTUAL EXOTOCXIN rather than the BACTERIA

• we do have ANTIBODIES AGAINST THEM KNOWN AS; ANTITOXINS
• INACTIVATION OF HEAT or CHEMICALS to create VACCINE; known as TOXOIDS

Question 24

what are the FOUR TYPES OF EXOTOXINS?

Answer 24

1. A-B TOXINS

• the MOST COMMON EXOTOXINS
• (A) part of TOXIN and (B) the BINDING PART
  ex. diphtheria toxin, cholera toxin

2. MEMBRANE DISRUPTING TOXINS

• causes LYSIS OF HOST CELL–disruption of plasma membrane
• aids BACTERIA ESCAPE FROM SACS within phagocytes
  ex. hemolysins, leukocidins

3. SUPERANTIGENS

• VERY INTENSE IMMUNE RESPONSE
• stimulates PROLIFERATION OF T CELLS
• releases ENORMOUS AMOUNTS OF CYTOKINES
  ex. S. aureus

4. GENOTOXINS

• DAMAGES DNA
• causes MUTATION and MAY LEAD TO CANCER

Question 25

what are the PORTALS OF EXIT (4)?

Answer 25

1. RESPIRATORY TRACT - cough or sneeze 2. GI TRACT - feces, saliva 3. GENITOURINARY TRACT - urine, vaginal secretions 4. SKIN 5. BLOOD - bites of arthropods, needles, syringes

Question 26

definition of TRIAD

Answer 26

the TRIAD: - DISEASE HOST - SUSCEPTIBLE HOST - ENVIRONMENT that brings hosts together DISEASE results from INTERACTION between DISEASE and SUSCEPTIBLE HOST within an ENVIRONMENT that SUPPORTS SAID TRANSMISSION of AGENT FROM SOURCE TO THAT HOST