Branching (Partially Acid-Fast), Gram-Positive Bacilli

Question 1

partially acid-fast aerobic actinomycetes

Answer 1

Nocardia
Rhodococcus
Gordonia
Tsukamurella

Question 2

characterized by beaded appearance in Grams stain

Answer 2

Nocardia spp

Question 3

components of the peptidoglycan of the cell wall of Nocardia spp.

Answer 3

mesodiaminopimelic acid (DAP)
sugars: arabinose
galactose

Question 4

the partially acid-fast actinomycetes that is commonly associated with human disease

Answer 4

Rhodococcus equi

• • found in patients infected with HIV
• • capable of replicating inside macrophages

Question 5

three types of skin infections that are caused by Nocardia spp

Answer 5

• mycetoma
• lymphocutaneous infections
• skin abcess/cellulities

— Nocardia brasiliensis is the most common cause of these skin infections

Question 6

infection caused by Nocardia spp in compromised patients

Answer 6

invasive pulmonary infections
disseminated infections

– often spread hematogenously

Question 7

infections caused by NON-ACID FAST, AEROBIC actinomycetes

Answer 7

mycetomas – often called ACTINOMYCETOMA

• • chronic granulomatous lesions in the skin
• • traumatic inoculation of the organism into the skin

Question 8

type of acid fast stains used

Answer 8

modified acid fast stain

– 1% sulfuric acid as decolorizer; NOT 3% hydrochloric acid

Question 9

stain that can be used on biopsies that are suspected of Actinomycetes

Answer 9

Gomori’s methanamine-silver stain

Question 10

media that can be used to isolate Nocardia spp.

Answer 10

Martin-Lewis, CNA

Sabouraud Dextrose Agar
fungal media containing cyclohexamides (Mycosel)