Anaerobes T03

Question 1

Name the 2 genus that are Gram+ anaerobes.

What are the main difference between them?

Answer 1

1. Clostridium
2. Actinomyces

Clostridium are spore-forming while actinomyces are non-spore-forming

Question 2

Clostridium botulinum can either cause disease in the form of botulinum toxin that blocks Ach at NMJ, it can also be ____________.

Answer 2

Foodborne in canned food in the form of preformed toxin

Question 3

What are the clinical manifestations of Clostridium botulinum?

Answer 3

Botulism:

• constant descending flaccid paralysis
• Vomiting
• Diplopia
• Respiratory failure > death
• Floppy baby syndrome (hypotonia)

Question 4

Which of the following concerning the C. botulinum is false?
A. It is treated by antitoxin (anti-A-B-E)
B. Respiratory support should be given in treatment
C. It can be prevented by heating all canned food
D. Children <1y/o should not be given honey to prevent infection by C. botulinum
E. C. botulinum is toxin heat-liable as well as their spores

Answer 4

All except E

Their spores are heat-resistant

Question 5

On an agar plate, a G+ bacilli with a drumstick appearance can be observed. What microorganism is that?

Answer 5

Clostridium tetani.

Question 6

Which of the following about Clostidium tetani is false?
Explain.

A. They are present in a dirty puncture wound
B. They work by blocking Ach release at NMJ
C. It can cause trismus (lockjaw)
D. It should be treated by antitoxin (Tetanus IG) and penicillin
E. It can be prevented by DTaP vaccine

Answer 6

B should be C. Botulinum

It contains tetanospasmin that cut SNARE proteins, blocking the release of inhibitory NTs like GABA and glycine.

Question 7

Tetanus can be caused by C. tetani. It means constant spastic paralysis.
Other than trismus, which means lockjaw, what are the other 2 clinical manifestations can be seen?

Answer 7

1. Risus sardonicus
   ~grin, facial muscle paralysis
2. Opisthotonos = hyperextension, arched back

“opi-stho-to-nous”

Question 8

A microorganism showed double zone of hemolysis on blood agar and opacity in Nalger test. 
Stormy fermentation (clot+gas) can also be seen in milk media. What is the likely bacilli? 

Why do they cause opacity in Nalger test and a double zone hemolysis in BA?

Answer 8

Clostridium perfringens;

it’s because they contain alpha toxin: lecthinase

Question 9

Other than lecithinase, the alpha toxin, what toxin does C.perfringens contain? What is its effects?

Answer 9

Enterotoxin that increases cAMP, increases Cl- secretion and cause profuse diarrhea.

Question 10

Which of the following about Clostridium perfringens are correct?
A. Its mode of transmission is either foodborne or by traumatic implants.
B. Enterotoxin is the cause of the gas gangrene with necrosis
C. Gas gangrene causes acute and increasing pain, crepitus and foul-smelling discharge and may even cause tachycardia and death
D. Food poisoning due to C. perfringens is self-limiting
E. It can be treated by debridement, antitoxin and penicillin.

Answer 10

B

Alpha toxin should be the cause for the gangrene.

Question 11

What toxins are released by Clostridium difficile and how can it be diagnosed/detected?

Answer 11

1. Toxin A (enterotoxin)
2. Toxin B (cytotoxin)
   Diagnosed by detecting toxin in stool

Question 12

What is the clinical manisfestation in a patient infected with Clostridium difficile?

Answer 12

Pseudomembranous colitis - diarrhea

Question 13

How is infections by Clostridium difficile treated?

Answer 13

Vancomycin PO

Metronidazole PO

Question 14

Which of the following about Actinomyces israelii are correct?

A. Sulphur granule can be seen on agar plate.
B. They have acid fast branching rods that are fungi-like, similar to Nocardia.
C. They are present in the normal flora of oral cavity and the vagina.
D. They are assoicated with poor dental hygiene
E. They causes solitary brain abscess rather than multiple.

Answer 14

All except B

B: they are non-acid fast but with branching rods that are fungi-like; acid-fast is Nocardia!

E: yes, compared to Nocardia, which causes multiple brain abscesses

Question 15

Which of the following about Actinomyces israelii are correct?

A. Sulphur granule can be seen on agar plate.
B. They have acid fast branching rods that are fungi-like, similar to Nocardia.
C. They are present in the normal flora of oral cavity and the vagina.
D. They are assoicated with poor dental hygiene
E. They causes solitary brain abscess rather than multiple.

Answer 15

All except B

B: they are non-acid fast but with branching rods that are fungi-like; acid-fast is Nocardia!

E: yes, compared to Nocardia, which causes multiple brain abscesses

Question 16

A patient with IUD has experienced a lumpy jaw. Which microorganism is likely to be involved?

Answer 16

Actinomyces israelii

Lumpy jaw is due to the infection of the jaw, poor dental hygiene

Other clinical manisfestaions:
- abscesses: Thorax, abdomen, pelvis
CNS: brain solitary abscess

Question 17

How to treat the abscesses formed by infection by Actinomyces israelii?

Answer 17

Debridement and penicillin.

Question 18

Which of the following about collection of transport of anaerobes are correct?
A. They should be protected from air
B. Refrigeration is needed
C. Aspirate is more down than swab for pus specimen
D. AN-ID ring is for identification
E. Gas liquid chromatography can be done to detect short-chain fatty acids produced by anaerobes

Answer 18

All except B

- do not refrigerate.

Question 19

What is the only G- bacilli anaerobe that you have learnt?

- it is non-spore forming like Actinomyces.

Answer 19

Bacteroidaceae

Question 20

Bacteriodes fragilis is:
A. Non-motile
B. Moderataly pleomorphic 
C. Gram- rod
D. gives hemolytic colonies on blood agar
E. Saccharolytic

Answer 20

All except D
Should be non-hemolytic

E is correct! , but not proteolytic

Question 21

Prevotella melaninogenica:
A. Non-motile
B. develop black pigment on blood agar from haem
C. Gram- bacillus/ diplobacillis
D. Proteolytic
E. Asaccharolytic
F. shows brick-red fluorescene under UV light in pus containint it

Answer 21

All except E

Both proteolytic and saccharolytic

Question 22

Potphyromonas are saccharolytic/asaccharolytic?

Answer 22

Assacharolytic

Question 23

_____________ is a fairly large non-motile Gram- anaerobe that often occurs as a long rod with a central unstianed bar, but is highly pleomorphic.

Is it proteolyic and saccharolytic?

Answer 23

Fusobacterium necrophorum

Assachrolytic and non-proteolytic

Question 24

Most used identification methods for anaerobes? (2)

Answer 24

1. Antibiotic-containing diagnostic discs (AN-ID ring)

2. Gas liquid chromatography (GLC) to detect short-chain volatile fatty acids produced by some anaerobic bacteria

Question 25

Among all Bacteroidaceae, which of them are normal colon flora, and cause infection in intra-abdominal and soft tissue below waist?

Answer 25

Bacteroides fragillis

Question 26

Both Prevotella melaninogenica and Porphyromonas gingivalis causes?

Answer 26

periodontal infection (teeth)

Question 27

How can infections caused by Bacteroidaceae me treated? (2)

How can their infection be prevented in surgeries?

Answer 27

Metronidazole
Abscess drainage

• Prophylatic abx for GI surgery