Anaerobic Infections

Question 1

SOD?

Answer 1

Superoxide dismutase. It protects against oxygen free radicals. For the aerotolerant/facultative anaerobes.
They can survive in oxygen but can’t multiply.
There’s also strict anaerobes who cannot survive in oxygen.

Question 2

How do you culture anaerobes then?

Answer 2

Collect sterile fluids, pus, aspirate–> swabs.
Culture on selective media blood agar, anaerobic plain, glucose cooked meat. But takes 2-7 days which is slow and too long.

Question 3

After you have cultured it how do you identify it?

Answer 3

Biochemical and antibiotic testing
Gas-liquid chromatography (for volatile fatty acids)
Sequencing
MALDI-TOF

Question 4

How is antibiotic susceptibility testing for anaerobes performed?

Answer 4

• agar dilution conducted as annual surveys (agar diluted with different concentrations and culture anaerobes on them)
• E tests

Question 5

Why do anaerobes not matter in mixed infections?

Answer 5

• drainage is primary treatment
• empiric antibiotics covers anaerobes presumptively
• delays and difficulties in culture/identification/susceptibility testing
• anaerobic microbes colonise the same sites as aerobic microbes and are often present in mixed infections
• studies have shown better outcomes when anaerobes were treated.

Question 6

What is the basic antibiotic treatment (susceptibilities and resistance) for anaerobic infections?

Answer 6

Penicillin can treat all except gram negative

Metronidazole can treat all except gram positive bacilli

Question 7

Clostridium difficle toxin

Answer 7

Cytotoxins A and B

Question 8

Clostridium tetani toxin

Answer 8

Tetanospasmin