Host-parasite Relationships

Question 0

Selective anatomical distribution

Answer 0

Micro organisms have specialized ecological niches in and on the body

Question 1

Describe two points of disease potential in normal flora

Answer 1

1. Displaced organisms can cause disease ( oral streptococci–> endocarditis, E. Coli –> UTIs)
2. Overgrowth of organisms at their normal site of colonization
   Broad spectrum antibiotics can cause overgrowth of Candida albicans–> vaginal candidiasis
   Or C. difficile in GI tract

Question 2

This works to specialize the location of organisms (dictates where the organism might be found)

Answer 2

Attachment ( adherence) of organisms to specific receptor sites

When normal flora occupy these sites, it renders these receptors unavailable to pathogens.

Question 3

If an individual becomes debilitated, the normal flora shifts from predominantly ___________ bacteria in the oropharynx and upper airways, to _________

Answer 3

gram + bacteria to gram -

Question 4

Upon hospitalization there is an increase in colonization of_________ (causes gangrene) on the skin, and gram __________bacteria

Answer 4

Clostridium perfrinigens

Negative

Question 5

Names 2 diseases associated w/ altered flora

Answer 5

Cystic fibrosis

Pneumonia <— Pseudomonas aeruginosa

Question 6

Describe 3 benefits of normal flora

Answer 6

1. Stimulation of immune response
   - -> can induce production of cross-reacting antibodies –> protective
2. Normal flora can prevent colonization by pathogenic oranisms
3. Normal flora synthesize nutrients–> ex vit B and vit K

Question 7

Give an example of cross- reacting Ab d/t normal flora

Answer 7

Antibodies induced by E.Coli protect against infection against haemophilus influenza epidemic, type b.

Question 8

List the 3 ways that Normal flora can prevent colonization of pathogenic oranisms

Answer 8

1. Occupying receptor sites
2. Completing for limited nutrients
3. Producing substances which are inhibitory or Cidal for pathogens

Question 9

The predominant flora of the skin are ________& __________

Answer 9

Coagulase-negative staphylococci (S. Edpidermidis) & propionibacteria (P. acnes)

Question 10

What is the predominant type of flora in the mouth?

Answer 10

Gram+ cocci especially alpha-hemolytic streptococci

–> potentially dangerous if displaces in Pt.s w/ heart valve defects–> endocarditis

Question 11

What anaerobes exist in the mouth?

Answer 11

Porphyryomonas & prevortella. (Bacteroides formerly)

Spirochetes and prevortella caus periodontal disease

Question 12

What bacteria predominate in the oro- & nasopharynx?

Answer 12

Gram + bacteria, esp alpha-hemolytic streptococci

Question 13

Gram - cocci is also present in the naso/oropharynx which resembles ______________

Answer 13

Neisseria meningitides ( a cause if meningitis)

Also,
Streptococcus pneumoniae, gram - rods (enterobacteriacea), and haemophilus influenzae can also be found and cause disease if misplaced

Question 14

If ______________ or _________________ are found in the naso/oropharynx, these individuals are immune carriers and must be treated to eradicated the carrier state.

Answer 14

Neisseria meningitides or Streptococcus pyogenes

Question 15

Bacteria in the GI tract

Answer 15

Predominantly anaerobes ( outnumber facultative 1000 to 1)

Bacteroides is the predominant genera

Coliforms
Enterococci. (Ex. Clostridium perfrinigens, C. Dif). –> can be fatal if misplaced ex. GI perforation

Question 16

Clostridium Perfrinigenes from gut can cause:

Answer 16

Food borne Dz or gangrene

Question 17

C. Difficile

Answer 17

Associated w/ pseudomembranous colitis

Question 18

Predominant flora of vagina:

Answer 18

Predominantly anaerobic.

Lactobacillus is predominant genera -> maintains health

Group B streptococci –> causes neonatal meningitis

Gardnerella vaginalis, staphylococcus aureus & Candida are opportunistic pathogens.

Question 19

Sterile sites in the body

Answer 19

Blood
Spinal 
Synovial fluid
Bladder (mehh)
Lower resp tract
Uterus
Internal tissues/organs