Gram-Negative Anaerobic Rods

Question 1

A large group of bacteria that dominates the normal flora of the large intestine

Answer 1

Gram-negative anaerobic rods

Question 2

The most important members of the group fall into which closely-related genera?

Answer 2

Rod-shaped or coccobacillary

Question 3

Predominantly intestinal, tend to produce abdominal infections

Answer 3

Bacteroides

Question 4

The most important species of the entire bacteroides group

Answer 4

Bacteroides fragilis

Question 5

Predominantly oral; tend to produce infections of the head, neck, respiratory tract, bite wounds

Answer 5

Porphyromonas and Prevotella

Question 6

Makes black pigment; colonies fluoresce red under UV light

Answer 6

Porphyromonas

Question 7

Two less-important genera, not closely-related biologically to the first group or each other, but with similar biology are?

Answer 7

Fusobacterium and Veillonella

Question 8

Slender rods with tapered ends; mostly oral.

Answer 8

Fusobacterium

Question 9

Cocci, in oral flora

Answer 9

Veillonella

Question 10

Often contain multiple species of both anaerobic and facultative bacteria. The latter facilitate growth of anaerobes by using up ambient oxygen

-Often spread from endogenous sources

Answer 10

Infections with anaerobes

Question 11

Peridontal disease, abdominal abscesses, infections of the female reproductive tract, and pneumonia due to aspiration of oropharyngeal contents are examples of types of infections produced by

Answer 11

Gram-negative anaerobes

Question 12

Brain abscesses may form by spread of organisms from sites of infection in the

Answer 12

URT

Question 13

Occurs when the organisms spread to the bloodstream from the intestine or a focus of infection

Answer 13

Septicemia

Question 14

One of the organisms most commonly isolated from blood cultures

Answer 14

B. Fragilis

Question 15

Secretes an exotoxin which is a protease which cleaves E-cadherin, loosens epithelial zona adherens junctions between enterocytes, and causes cytoskeletal changes in them

Answer 15

B. Fragilis

Question 16

B. fragilis has recently been identified as a cause of

Answer 16

Diarrhea

Question 17

The frequency with which Bacteroides fragilis and Fusobacterium are isolated from infections is far out of proportion to their relative abundance in normal flora. This suggests that they must have

Answer 17

Virulence factors

Question 18

Has an anti-phagocytic capsule which is intensely inflammatory

Answer 18

B. Fragilis

Question 19

B. fragilis has an anti-phagocytic capsule which is intensely inflammatory - administration of purified capsular substance provokes formation of an

Answer 19

Abscess

Question 20

Their LPS lacks lipid A and has no endotoxic activity where as other Gram-negative anaerobes do have endotoxic LPS

Answer 20

Bacteroides

Question 21

Specimens are cultured on rich media; selective media contain either kanamycin/vancomycin or bile

Answer 21

Gram-negative anaerobes

Question 22

To treat infection by Gram (-) anaerobes, we create an

Answer 22

Oxygenated environment

Question 23

Not effective against anaerobes

Answer 23

Aminoglycosides