LECTURE - Nocardia

Question 1

“Actinomycetes”

Answer 1

“ray fungus” in Greek

Question 2

Actinomycetes

Answer 2

• true gram pos

- can form branching filament which lead to mycelial colonies (mass of filaments) which make them look fuzzy like fungi

Question 3

“Ray” in actinomycetes refer to …

Answer 3

the radial arrangement of the often club-shaped structures in microcolonies isolated from infected tissue

Question 4

disease presentation of Actinomycetes

Answer 4

most can form chronic, granulomatous abscesses known as mycetomas that appear similar to those caused by fungi

Question 5

Nocardia spp

Answer 5

• aerobic
• gram +
• branching rod
• many new spp within the former Nocardiaasteroides
• somewhat acid-fast
• colonies (3-6 days) are chalky, matte, or velvety; can be dry and have a breadcrumb-like texture
• soil and plants worldwide

Question 6

Quantity of this correlates with Nocardia virulence, but no other clear virulence factors were identified

Answer 6

Superoxide dismutase; SOD

- negates hydrogen peroxide in phagolysosome to help it grow BUT not totally resistant to phagocytosis

Question 7

Popl’ns susceptible to Nocardia include:

Answer 7

• recipients of lung, heat, BM, and kidney transplants
• HIV-infected individuals
• chronic steroid users
• patients with underlying malignancy
• BUT 1/3 with nocardiosis have normal immunity (probably due to dose)

Question 8

Nocardia infection in lungs

Answer 8

• granulomatous and non-granulomatous lesions can be seen

- necrosis occurs and lesions coalesce, leading to dissemination throughout the body

Question 9

cutaneous infections by Nocardia

Answer 9

typically caused by trauma introducing organisms in the wound
- can show formation of burrowing sinuses to the surface where pus can drain

Question 10

Granular masses of filaments held together by calcium phosphate with yellowish colour (_____ ______) and can often be seen in __________ ____

Answer 10

sulfur granules; pigmented pus

Question 11

How to differentially diagnose Actinomycetes

Answer 11

fatty acid analysis by gas-liquid chromatography (GLC) and various biochemical tests

Question 12

Actinomyces israelii

Answer 12

• anaerobic
• gram + rods; typically branched (various lengths and shapes = pleomorphic)
• molar tooth colonies
• found in oral cavity, intestine, female genital tract

Question 13

Actinomyces israelii is most often associated with …

Answer 13

facial or oral trauma
- intrauterine contraception devices
= open it up, drain and treat with antimicrobials

Question 14

these are typically produced in vivo for Actinomyces israelii

Answer 14

sulfur granules

Question 15

Like other anaerobes, Actinomyces israelii is often associated in ___________ infections

Answer 15

polymicrobic = anaerobes bc they are introduced into the tissues through trauma, it’s not one organism that gets in there it’s whatever else is in there that gets introduced…

Question 16

Actinomyces israelii disease

Answer 16

• depending on where they are located/trauma occurring will determine clinical picture
• can also occur in thoracic and abdominal cavity = leak into body

Question 17

Treatment of Actinomyces israelii

Answer 17

penicillin or other derivatives + others if allergic

Question 18

Other anaerobic actinomycetes

Answer 18

• Bifidobacterium spp (higher numbers than E. coli in our body; not particularly pathogenic… but an opportunist!!)
• Eubacterium spp.
• Mobiluncus spp. (tend to be gram variable)
• Propionibacterium spp.

Question 19

Nocardia spp. two main disease presentations

Answer 19

• entry via inhalation (aerosol) = abscess in the lung
• cutaneous as well if either spread from lungs or tissues which is less likely and then spread to other areas and can cause abscesses

Question 20

Nocardia spp. treatment

Answer 20

trimethoprim-sulfamethoxazole combined with amikacin