Actinomycetes

Question 1

Actinomycetes

Answer 1

Aerobic:

• Nocardia
• Streptomyces

Anaerobic:

• Actinomyces

Question 2

Genus actinomyces

Classification

Answer 2

Family: actinomycetaceae

Genus: Actinomyces

Most important species causing Actinomyces is:

• Actinomyces bovis
• Actinomyces naeslundi
• Actinomyces Israelii -> most important pathogen

> normal flora of mouth and female genital tract
opportunistic pathogen

Transmission:
~ dental extraction: poor dental hygiene
~ trauma (mouth or uterus)
~ organisms also aspirated into lungs > causing thoracic Actinomycosis

Question 3

A.Isrealii

Morphology

Answer 3

• Gram-positive

- Filamentous, branching rods

Question 4

Growth characteristics

Answer 4

• anaerobic
• slow growth on blood agar (4-7 days)
• 35 - 37 oC

Question 5

virulence factors

Answer 5

No toxins or virulence factors are known

Question 6

Disease

Answer 6

Actinomycosis (abscesses with draining fistulas -> pus usually contains yellow sulfur granules)

> cervical-facial type: lumpy jaw = 30%
thoracic type: 20% cases
abdominal type: most cases
Primary lesion is in cecum, appendix or pelvic organs -> developing multiple draining fistulae

Question 7

Microbiological diagnosis

Answer 7

• Gram-stained smear plus anaerobic culture on blood agar plate
• “sulfur granules” visible in the pus
• no serologic tests

Question 8

Treatment and prevention

Answer 8

• penicillin G and surgical drainage

- no vaccine available