Anaerobic Bacterial Infections of Soft Tissue

Question 1

Name the 4 main species of Clostridium.

Answer 1

C. tetani, C. botulinum, C. perfringens, and C. difficile

Question 2

Describe the morphology of the anaerobes Clostridium, Bacteroides/Prevotella, and Actinomyces in terms of Gram stain and general shape.

Answer 2

Clostridium and Actinomyces are Gram(+) rods, Bacteroides/Prevotella are Gram(-) rods

Question 3

State whether the following bacteria are found in the environment or as normal flora: C. tetani, C. botulinum, C. perfringens, C. difficile

Answer 3

C. tetani and C. botulinum are environmental, C. difficile is normal flora of the gut, C. perfringens is both

Question 4

State whether the following bacteria are found in the environment or as normal flora: B. fragilis, B. corroden, P. melaninogenica, A. israelii

Answer 4

Normal flora (B. fragilis is in the colon, the rest are in the mouth)

Question 5

What 2 bacterial exotoxins/proteases destroy the synaptobrevin/VAMP protein on synaptic vesicles? Release of which neurotransmitter is inhibited?

Answer 5

Tetanospasmin and botulinum toxin; ACh

Question 6

Contrast which nerves are affected by tetanus and botulism, and the resulting effects.

Answer 6

Tetanus acts on the CNS - muscle spasms

Botulism acts on peripheral nerves - flaccid paralysis

Question 7

Which 2 Clostridium species are commonly found in improperly canned or otherwise contaminated food? Does cooking inactivate the toxins?

Answer 7

C. botulinum and C. perfringens; yes - if cooked properly

Question 8

Which Clostridium species causes gas gangrene? What other anaerobes can cause gas gangrene?

Answer 8

C. perfringens; Bacteroides/Provotella can also cause it

Question 9

Which Clostridium species can present in neonatal, cephalic, local, or generalized forms?

Answer 9

C. tetani

Question 10

In which anaerobe infection will the patient exhibit an abnormal gag reflex (bite down rather than gag when the posterior pharyngeal wall is stimulated)?

Answer 10

C. tetani

Question 11

A and B toxins from what anaerobe are among the most toxic substances known?

Answer 11

C. botulinum

Question 12

Which anaerobic soft tissue bacteria form spores?

Answer 12

All the Clostridium: C. botulinum, C. tetani, C. perfringens, C. difficile

Question 13

Which anaerobic soft tissue bacteria are associated with wound infection?

Answer 13

C. botulinum, C. perfringens

Question 14

Which Clostridium species causes pseudomembrane colitis? How is it transmitted?

Answer 14

C. difficile; fecal-oral transmission

Question 15

Which anaerobe is associated with Exotoxin A, which disrupts tight junctions, causing intestinal swelling and inflammation; and Exotoxin B, which disrupts the cytoskeleton by depolymerizing actin?

Answer 15

C. difficile

Question 16

Which anaerobe can be detected by a sensitive but slow cytotoxicity test of stool filtrate? Untreated stool will kill human cells in culture, while antibody-treated stool will not.

Answer 16

C. difficile

Question 17

Which anaerobe has a polymicrobial nature of infection, where beta-lactamase from one organism can protect the whole colony from penicillins?

Answer 17

Bacteroides/Prevotella

Question 18

Which Bacteroides/Prevotella species is most commonly found below the diaphragm? Which one is found above the diaphragm?

Answer 18

Usually B. fragilis is below the diaphragm, P. melaninogenica is above

Question 19

Which anaerobe makes over 20 tissue degrading exotoxins such as alpha toxin, lecithinase, collagenase, hyaluronidase, sialidase, episilon and theta toxins (all form pores in cell membranes), and iota toxin (also depolymerizes actin)?

Answer 19

C. perfringens

Question 20

Infections of what anaerobe class are characterized by abscesses, peritonitis, necrotizing fasciitis, and bacteremia? How are the abscesses treated?

Answer 20

Bacteroides/Prevotella; abscesses have to be drained/debrided - just antibiotics are not enough

Question 21

Which anaerobic soft tissue infection forms distinctive black colonies in culture?

Answer 21

Prevotella melaninogenica

Question 22

Gram(+) filamentous rods that may present with hard, nontender “molar tooth” sulfur granules in the head and neck?

Answer 22

Actinomyces

Question 23

Which Bacteroides/Prevotella species has the most prominent antibiotic resistance?

Answer 23

B. fragilis

Question 24

How are C. tetani and C. botulinum treated? Are there vaccines available?

Answer 24

Treat with antitoxins; vaccine for tetanus only

Question 25

How is C. perfringens gas gangrene and C. perfringens food poisoning treated?

Answer 25

Gas gangrene: antibiotics and surgery (ASAP)

Food poisoning: treat symptoms

Question 26

How is C. difficile treated?

Answer 26

Change the patient’s antibiotic, surgery if needed

Question 27

How are Bacteroides and Prevotella treated?

Answer 27

Abscess removal and antibiotics (metronidazole/cefoxitin for anaerobes and aminoglycosides for facultatives living in the abscess)

Question 28

What is the prognosis for Actinomyces infection and how is it treated?

Answer 28

Good prognosis (slow growing); can usually treat with penicillin G + surgery if needed