Anaerobic Bacteria (lecture)

Question 1

Strict anaerobic (lack catalase and superoxide dismutase), G +, spore forming rod - what is the genus?

Answer 1

Clostridia

Bacteroides has both cat and superoxide dismutase

Question 2

Actinomyces is Gram ______ (+/-) ________ (aerobic/anaerobic), ________ (non-sporeforming/spore forming), ________ (cocci, rod).

Answer 2

G +, anaerobic, non-sporeforming, rod

Question 3

Propionibacterium is ________ (aerobic/anaerobic), ________ (non-sporeforming/spore forming), ________ (cocci, rod), Gram (+/-).

Answer 3

anaerobic, non-sporeforming, rod, G +

Question 4

Baceroides and Fusobacterium are ________ (aerobic/anaerobic), ________ (non-sporeforming/spore forming), ________ (cocci, rod), Gram (+/-).

Answer 4

anaerobic, non-sporeforming, rod, G -

Question 5

What is the only anaerobe bacteria mentioned in class that is catalase and superoxide dismutase positive (is not a strict anaerobe)?

Answer 5

Bacteroides

Question 6

What is the virulence factor of Clostridia?

Answer 6

Toxin formation

Remember that botulism must be preformed

Question 7

What is the most common source of anaerobic infections?

Answer 7

One’s own flora

Question 8

How is polymicrobial infection of both anaerobic and aerobic infection of a wound beneficial to anaerobes?

Answer 8

Aerobes may use up all of the O2, resulting in an ideal environment for anaerobes

Question 9

What is the most common source of anaerobic infections above the waist?

Answer 9

Dental carries

Question 10

What is the most common source of anaerobic infections below the waist?

Answer 10

GI/GU flora

Question 11

What are the three most commonly used antibiotics used for above the waist anaerobic infections?

Answer 11

Metronidazole (interferes with nucleic acid production)
Augmentin (amox/clav acid)
Clindamycin (target 50s subunit)

Question 12

What bacteria genus is most associated with gas gangrene?

Answer 12

Clostridia

Question 13

Clostridia is confirmed. On gram stain, it is found to have a polar clearing (looks like a tennis racket). What is the likely species? What if it were to have a central clearing (as in a propeller)?

Answer 13

tetani is tennis racket like

botulinum is propeller like

Question 14

What characteristic of Clostridium contributes most to its ability to cause gas gangrene?

Answer 14

The high metabolic rate causes gas formation.

Question 15

Diabetic with severe gas gangrene and blue and black discoloration of his foot. What is the most significant virulence factor of the likely causal organism?

Answer 15

Lecithinase kills cells and lyses RBCs.

Question 16

What is the term used when a bacteria goes from a spore to its active form?

Answer 16

germination

Question 17

Man with poor dentition presents with significant submandibular swelling and purulent discharge that has grainy contents coming out of the swollen area. What is expected on gram stain?

Answer 17

Actinomyces: Long, G + rods that form chains

Question 18

What is the most common causal organism of acne and its staining pattern?

Answer 18

Propionibacterium: Anaerobic, G + rods (does NOT grow in BILE vs. bacteroides)
Note: also common in PROSTHETIC related infections

Question 19

Woman with poor dentition present with abdominal pain. One of the organisms identified on staining show G - rods that are very long and skinny (looks like strings). What is the likely organism identified?

Answer 19

Fusobacterium nucleatum

Question 20

Abdominal abscess is found to have G - rods that are aerotolerant and catalase +. What is the main virulence factor of the likely causative organism? What consideration must be made with regard to Abx prescription?

Answer 20

Bacteroides: Its polysaccharide capsule helps it avoid phagocytosis. It makes B-lactamase (no PCNs)