Actinomyces israelii - Mycobacterium avium complex

Question 1

This bacterium is a Gram + anaerobe with filamentous branching. It is a non-acid fast rod. It is identified by presence of sulfur granules in infected tissues (orange). The culture shows molar tooth appearance after 1 week.

Answer 1

Actinomyces israelii

Question 2

How is Actinomyces israelii spread and where does it colonize?

Answer 2

spread world-wide from person to person

colonizes in mouth, colon, vagina (endogenous spread from mouth)

note: it is more common in men

Question 3

This type of actinomycosis results in soft tissue swelling, abscess, or mass lesions containing sulfur granules, and is often mistaken as neoplasm. It may spread to head, spine, or thorax

Answer 3

cervicofacial actinomycosis

Question 4

This type of actinomycosis is progressive, and located in the pulmonary parenchyma and/or pleural space. The chest X-ray shows mass lesion

Answer 4

Thoracic actinomycosis

Question 5

This type of actinomycosis takes months to years to develop following an event (appendicitis, diverticulitis, etc.). Any abdominal organ may be involved. It usually presents as an abscess or mass lesion

Answer 5

abdominal/pelvic actinomycosis

Question 6

In regards to virulence, actinomyces israelii infection can occur when the ____ barrier is harmed by trauma/surgery

Answer 6

mucosal

Question 7

This bacterium is a Gram + filamentous rod with branched hyphae and a short mycolic acid chain. It is a weak acid fast + bacterium.

Answer 7

Nocardia

Question 8

How is Nocardia identified?

Answer 8

look for branched filamentous Gram + rods in sputum or pus. BYCE agar shows aerial hyphae

Question 9

Where is Nocardia found and how does it spread?

Answer 9

found worldwide, saprophyte soil

it is seen mostly in Aids/IC people and after local trauma; acquired by inhalation

Question 10

This type of nocardiosis is most common. It is usually sub-acute and presents with nodules, abscesses, emphysema, prominent coughing with small amount of purulent sputum

Answer 10

bronchopulmonary nocardiosis

Question 11

This type of nocardiosis is painless and localized with S/C tissue swelling and suppuration (pus formation) with multiple sinus tracts

Answer 11

Cutaenous nocardiosis

Question 12

Nocardiosis forms an ____ with PMN infiltration. ___ factor prevents acidification of phagosome. ___ is needed to clear infection

Answer 12

abscess; cord; CMI

Question 13

This bacterium is aerobic, acid fast, rod with lipid coat linked to arabinogalactan and peptidoglycan. It can survive in latent infections for decades and is very very slow growing (24 hour doubling time)

Answer 13

M. tuberculosis

Question 14

How is M. tuberculosis Id’d?

Answer 14

Mantoux test; acid fast stain growth on Lowenstein-Jensen or Middlbrook 7H10/7H11 agar, PCR QuantiFERON-TB Gold test

Question 15

How is M. tuberculosis spread? How long does it take for infection to present?

Answer 15

resp. droplets must be inhaled
primary TB: after first exposure, lower transmission rate, only 10% get it, CMI can place it in granulomas and it can burst years later to cause second degree TB

Question 16

What are the symptoms of primary TB?

Answer 16

flu-like illness, CMI control of MTB -> calcified lung lesions (Ghon focus), fever, cough, night sweats, weight loss

Question 17

M. tuberculosis best grows in regions with high ___ (kidneys vertebral bodies)

Answer 17

O2

Question 18

This bacterium is a slow grower. It’s an acid fast intracellular parasite. It has a 5 yr incubation period (up to 20 yrs). it doesn’t do well at temps over 30 degrees celsius and impacts only the skin.

Answer 18

M. leprae

Question 19

How is M. leprae Id’d?

Answer 19

skin biopsy and acid fast staining

Question 20

How is M. leprae spread? Who is at risk?

Answer 20

due to CMI, not readily contagious; the early stages are most infectious; it is transmitted through skin/mucus lining of nose and throat

children are more susceptible

Question 21

Describe the progression of the M. leprae infection

Answer 21

very slow progression - begins as attack on dermis -> nerve sheath (may lead to loss of sensation)

Question 22

This type of leprosy is a limited disease with a few bacteria in the skin/nerves which have a few flat or slightly raised lesions of differing sizes that may be pale or reddish, dry, hairless, and numb to the touch

Answer 22

tuberculoid lepropsy

Question 23

This type of leprosy is a widespread disease with lots of bacteria and a diffuse involvement of skin and thickening of many peripheral nerves

Answer 23

Lepromatous leprosy

Question 24

M. marinum and M. ulcers cause skin infections, commonly known as ___ ____ granulomas

Answer 24

swimming pool

Question 25

The mycobacterium avium complex is composed of two species. What are they?

Answer 25

m. avium and m. intracellulare

Question 26

In what individuals is the mycobacterium avium complex commonly seen in?

Answer 26

AIDS and IC people

note: its the most common non-MTB infection. In AIDS, 50% of patients get this infeciton

Question 27

What are the symptoms of MAC infection?

Answer 27

disseminated infection; fever, swollen lymph nodes, diarrhea, fatigue, weight loss