Lecture 7 - Gram positive rods

Question 1

Describe the gram stain appearance of Bacillus, and the disease suspected if it’s found in pregnant women?

Answer 1

Gram positive rod, brick shaped

Listeria

Question 2

Which two antibiotics do you use for Listeria?

Answer 2

Gentomycin and amoxicillin

Question 3

What is Listeria monocytogenes relationship with oxygen and temperature?

Answer 3

• Facultative anaerobe - prefers to grow with oxygen

- Broad range of growth temperature, can survive at 4 degrees aka in the fridge

Question 4

What are the clinical syndromes of Listeria?

Answer 4

Gastrointestinal illness
Bacteraemia: fever + myalgia
Slow growing meningitis

Question 5

Describe Clostridium difficile’s gram stain appearance, relationship with oxygen and virulence

Answer 5

Gram positive, regular shaped rod
Anaerobe
Spore forming
Virulence is determined by production of toxins A, B and binary toxin

Question 6

What disease does Clostridium difficile cause 2-30% of cases of?

Answer 6

Antibiotic resistant diarrhoea

Question 7

What disease does Bacillus anthracis cause?

Answer 7

Anthrax. Clinical forms are determined by route of acquisition - cutaneous, inhalation and gastrointestinal. Both Inhalation and GI have a 100% mortality if untreated

Question 8

What disease is Bacillus cereus associated with?

Answer 8

Food poisoning from poorly cooked, reheated rice. Endospores allow it to survive initial cooking

Question 9

What does Clostridium perfringens cause?

Answer 9

Gas gangrene if soil spores get into the wound
Food poisoning associated with pork/chicken or turkey
Necrotizing bowel disease, from poorly cooked pork in New Guinea feast

Question 10

Do Bacillus or Clostridium species produce endospores?

Answer 10

yes

Question 11

Where do you find lactobacillus?

Answer 11

In the vagina, GI tract and mouth. They are large, regular gram positive rods, most of which are facultative anaerobes

Question 12

Describe the appearance of Corynebacterium

Answer 12

Tiny, irregular gram-positive rods “coryneform morphology”

Question 13

Describe the disease caused by Coryneform diptheriae

Answer 13

Diphtheria, has a 30% mortality rate

Primarily infects pharynx, can cause thick white membrane which can extend down the trachea and case asphyxiation

Question 14

Describe Actinomycetes species

Answer 14

They are filamentous/branching bacteria, that may resemble fungi.
Typical lesion caused by aerobic actinomycetes is the Actinomycotic mycetoma