23 - 158 - ACTINOMYCOSIS, NOCARDIOSIS AND ACTINOMYCETOMA

Question 1

What is the difference of actinomycosis and actinomycetoma

Answer 1

Actinomycosis - chronic, progressive, indolent infection by endogenous Actinomyces species, which are common inhabitants of the human mucosal surfaces, including the oral cavity, pharynx, distal esophagus, and genitourinary tract

Actinomycetoma - infection agent is an environmental actinomyces, making the bacteria responsible for the infection of exogenous origin

Question 2

Question 3

Actinomycosis should be suspected when dealing with 1 of 3 features. Enumerate the 3 features

Answer 3

1. mass-like inflammatory infiltrate of the skin and subcutaneous tissue,
2. sinus formation with drainage, and a
3. relapsing or refractory clinical course after short-term therapy with antibiotics

Question 4

Most frequent form of actinomycosis

Answer 4

Cervicofacial actinomycosis

Question 5

Most common location of actinomycosis

Answer 5

Jaw angle and high cervical area

Question 6

IUD use of longer than how many years predisposes a patient for actinomycosis from a primary pelvic disease?

Answer 6

2 years

Question 7

Best material or specimen to culture in actinomycosis

Answer 7

purulent drainage, tissue, or microscopic granules

*avoid antibiotic treatment before culturing
* swabs are NOT appropriate

Question 8

What is the characteristic morphology of colony of A. Israelii

Answer 8

“Molar tooth” colony

Question 9

What special stains are needed to demonstrate filamentous structures of sulfur granules?

Answer 9

Brown-Brenn, Gram, Giemsa, or Gomori

Question 10

In actiomycosis, the microscopic examination of the granules may reveal a rim of eosinophilic material surrounding the granules in tissue cuts. what do you call this phenomena?

Answer 10

Splendore-Hoeppli phenomena

Question 11

Differentiate actinomyces and nocardia based on Fite-modified acid-fat stain

Answer 11

The lack of staining with Fite-modified acid-fast stain separates Actinomyces from Nocardia species, which is usually acid-fast positive.

Question 12

Treatment of choice for actinomycosis

Answer 12

penicillin G, 18 to 24 million units IV for 2 to 6 weeks, followed by oral penicillin or amoxicillin, to be given for 6 to 12 months

However, this prolonged therapy may not be needed in all patients. Cervicofacial disease or any limited disease can receive a shorter course of therapy. A good rule to follow is to give therapy until full resolution of clinically evident disease

Question 13

If Nocardia is a consequence of hematogenous dissemination, the most likely microorganism is

Answer 13

Nocardia asteroides

Question 14

most common presentation of nocardiosis

Answer 14

Pulmonary disease

Question 15

nocardia speces most commonly associated with skin infection

Answer 15

N. brasiliensis

Question 16

best tool and has become the gold standard for the identification of Nocardia species

Answer 16

RNA sequencing on 16S ribosomal RNA

Question 17

cornerstone of therapy for Nocardia infections

Answer 17

Sulfonamides, alone or in combination with trimethoprim, as trimethoprim-sulfamethoxazole (TMP-SMX)

• ineffective against N. otitidiscaviarum
• The commercially available preparation has a fixed ratio of 1:5, and the dose currently recommended is 5 to 10 mg/kg TMP and 25 to 50 mg/kg SMX in 2 to 4 divided doses. For primary cutaneous nocardiosis, 5 mg/kg of TMP should be sufficient.

Question 18

T/F

AIDS patients receiving TMP-SMX for Pneumocystis organisms are already protected against Nocardia.

Answer 18

True

Question 19

Differentiate actinomycetoma and eumycetoma

Answer 19

Actinomycetoma is caused by bacteria, as opposed to eumycetoma, which is caused by fungi.

Question 20

mycetoma triad

Answer 20

painless subcutaneous mass, with sinus formation and seropurulent discharge that contains grains

Question 21

leading cause of actinomycetomas

Answer 21

N.brasiliensis

Question 22

Granules of actinomycetoma are usually creamy in color except ______

Answer 22

A. pelletieri, in which the granules are red

Question 23

Microorganisms reported to cause actinomycetomas include 3 genera:

Answer 23

Nocardia, Actinomadura, and Streptomyces

Question 24

Sign on MRI that is considered very characteristic of mycetoma

Answer 24

“dot-in-circle” sign

observed as multiple, small, round-shaped hyperintense lesions surrounded by a low-signal intensity rim (the circle), and a central, low-signal focus (the dot)

Question 25

treatment of choice in actinomycetoma caused by N. brasiliensis

Answer 25

diaminodiphenylsulfone (Dapsone) 100 to 200 mg/day (3 to 5 mg/kg) plus TMP-SMX 160/800 mg twice a day for several months in initial cases; the treatment should continue for up to 2 years.

Dapsone also can be combined with streptomycin, 1 g/day; clofazimine, 100 mg/day; rifampin, 300 mg twice/day; tetracycline, 1 g/day; or isoniazid, 300 to 600 mg/day