Normal Microbial Flora

Question 1

aspiration pneumonia

Answer 1

case in which chronic aspiration leads to polymicrobial disease (note gram positive cocci clusters, and types of gram negative rods shown in histology), anaerobes predominantly

Question 2

two most common etiologic agents for extra-intestinal infections

Answer 2

E Coli (present in all humans) and bacteroides fragilis (minor group)

Question 3

Name three areas of the body normally colonized with bacterial flora

Answer 3

Mouth, GI tract and skin

Question 4

Name six factors affecting normal flora

Answer 4

Age
Diet
Hormonal State
Sanitary Conditions
Personal Hygiene
General Health

Question 5

Give the order of body areas of colonization by normal flora in a newborn

Answer 5

skin, oropharynx, GI tract, other mucosal membranes

Question 6

Name the three possible outcomes when humans are exposed to microorganisms

Answer 6

transient colonization
permanent colonization
disease

Question 7

What are the three ways in which disease from microbial factors can result?

Answer 7

1. Proliferation of organisms damages organs
2. Toxins are produced by microorganisms
3. The host immune system does not respond (appropriately) to microorganisms

Question 8

What is the difference between strict and opportunistic pathogens? Give two examples of each.

Answer 8

Strict are almost always associated with disease, produce relatively few infections. Examples: Mycobacterium tuberculosis, Bacillus anthracis

Opportunistic pathogens are part of the normal flora, and produce most infections, either when numbers increase or when introduced into a normally sterile site (blood stream, tissue, CNS). Examples: E coli, Candida albicans

Question 9

Name three common bacterial causes of gastroenteritis

Answer 9

Salmonella
Campylobacter
Vibrio cholerae

Question 10

The most numerous normal flora microorganism for post-puberty females in the anterior urethra

Answer 10

Lactobacillus

Question 11

Name the two areas of the body in which anaerobes are in notable excess of aerobes

Answer 11

Upper respiratory tract (10 to 1)
Large intestine (at least 1000 fold)

Question 12

What sites of the genitourinary system are permanently colonized with normal flora?

Answer 12

Anterior urethra and vagina

Question 13

Three most important pathogens of cervix

Answer 13

(Contains no NF)

1. Neisseria gonorrhoeae
2. Chlamydia trachomatis
3. Actinomyces spp (Assoc with IUDs)

Question 14

Clostridium difficile

Answer 14

Bacteria that causes disease when normal flora is absent, associated with antibiotic use that eliminates NF of oropharynx and GI tracts

Question 15

What organisms are typically implicated in infective endocarditis?

Answer 15

Alpha hemolytic streptococci (viridians strep)