23 - 158 - ACTINOMYCOSIS, NOCARDIOSIS AND ACTINOMYCETOMA

Question 1

f

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

followed by the cheek (16%), the chin (13%), and, less commonly, the temporomandibular joint and the retromandibular 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

• Appropriate culture media include thioglycolate with 0.5 sterile **rabbit serum **at 35°C (95°F) for 14 days.
• Colonies may appear within 5 to 7 days, but up to 2 weeks may be required.

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 and mycetoma, 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

• Some authors recommend the initial use of a β-lactam and a β-lactam inhibitor such as clavulanate or tazobactam, which provide additional cover against potential β-lactam producers such as Staphylococcus aureus and Gram-negative anaerobes.
• Alternative treatment for those allergic to penicillin includes tetracycline, doxycycline, erythromycin, and clindamycin. Imipenem has been used successfully as short-term therapy.

Question 13

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

Answer 13

Nocardia asteroides

Primary cutaneous nocardiosis is a disease of immunocompetent patients, whereas secondary hematogenous spreading is seen in the context of immunosuppression

Question 14

most common presentation of nocardiosis

Answer 14

Pulmonary disease

Agricultural occupation is common in pulmonary nocardiosis, but a history of environmental exposure on a farm or in the wilderness is also common in the primary cutaneous form.

Question 15

nocardia speces most commonly associated with skin infection

Answer 15

N. brasiliensis

The most common cause of primary cutaneous nocardiosis is 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.
• Minocycline 100 to 200 mg twice a day is considered the alternative treatment in cases of sulfonamide hypersensitivity or poor tolerance

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

1. painless subcutaneous mass,
2. sinus formation
3. purulent or 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. ## Footnote **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 Some resistant cases have been treated with: - amoxicillin, 500 mg, plus clavulanic acid, 125 mg/day for 5 months, especially in pregnancy - The use of clindamycin, ciprofloxacin, and moxifloxacin has been suggested in Nocardia infections Other treatment: - Amikacin +/- Imipenem - kanamycin, fosfomycin or streptomycin - linezolid

Question 26

What is the most common causative agent of actinomycosis?

Answer 26

Actinomyces israelii ## Footnote usually as part of a polymicrobial infection, mixed with anaerobes and Gram-positive cocci.

Question 27

its presence may be seen macroscopically and is always very suggestive of the diagnosis of actinomycosis

Answer 27

Actinomycotic granules

Question 28

questions what should be asked in the history of patients with actinomycosis

Answer 28

* Commonly, there is a history of **poor dental hygiene, dental or periodontal disease, dental procedure, surgery, or penetrating trauma through the oral mucosa.** * Most of the infections start as a periapical abscess. * The lesion starts as a solid mass in any of those locations, and initially may be confused with a neoplastic process * It may progress to form recurring abscesses and later will spread to adjacent structures, not respecting anatomic planes.

Question 29

Grains are commonly seen in this particular form of actinomycosis

Answer 29

Punch or fist actinomycosis

Question 29

common source of infection of thoracic actinomycosis

Answer 29

aspiration of a microorganism ## Footnote although other routes are possible, such as propagation of cervicofacial disease to the mediastinum.

Question 29

implies disease produced by **endogenous**, **anaerobic**, or **microaerophile**, Gram-positive, non–spore-forming bacteria, belonging to the families Actinomycetaceae, genus **Actinomyces**.

Answer 29

actinomycosis

Question 30

the normal habitat of bacteria causing actinomycosis

Answer 30

human mucosal surfaces ## Footnote with considerable host specificity, from the mouth to the upper respiratory, GI, and female genital tracts.

Question 31

In orocervical and thoracic actinomycosis, what species commonly predominate?

Answer 31

In **orocervical** disease, the predominant species include **A. israelii,** A. naeslundii, A. viscosus, and A. odontolyticus, whereas in **thoracic** disease, **Actinomyces graevenitzii**, seems to predominate.

Question 32

what history should you always ask in a patient suspected of having actinomycosis infection on the cervicofacial area?

Answer 32

history of dental procedures ## Footnote Most cervical and facial cases originate from periapical abscesses or after dental procedures. Actinomyces bacteremia seems to occur quite often after dental procedures

Question 33

what history should you always ask in a patient suspected of having perineal actinomycosis infection ?

Answer 33

presence of IUD ## Footnote Perineal disease occurs as a consequence of involvement of the internal organs of the pelvis, often secondary to use of an intravaginal device or IUD.

Question 34

risk factors for actinomycosis

Answer 34

conditions linked to immunosuppression, such as prolonged administration of steroids, bisphosphonates, leukemia with chemotherapy, HIV, lung and renal transplant receipt, alcoholism, and local tissue damage by trauma, recent surgery, or radiation, all are associated with the disease

Question 34

The only exception to the endogenous origin of the actinomycosis infection

Answer 34

hand involvement that follows fist or bite trauma

Question 35

the processing of culture for actinomyces should be done in what environment?

Answer 35

anaerobic conditions ## Footnote * The isolation of Actinomyces in culture should be considered diagnostic, if coming from a sterile site. * However, positive culture rates are as low as 35% in some series. * The processing should be done in anaerobic conditions, and the laboratory should be notified of the clinical suspicion of actinomycosis.

Question 36

cutaneous manifestations of nocardia

Answer 36

Cutaneous involvement by Nocardia can manifest either as an abscess, cellulitis, or more characteristically, as **lymphocutaneous nodules in a sporotrichoid pattern.** Disseminated disease also can be present in the skin as a consequence of hematogenous spread, from hemorrhagic pustules to ecthyma and abscesses

Question 36

Predisposing factors for primary cutaneous nocardiosis

Answer 36

soil or sand exposure while gardening or farming; or superficial injury from domestic shrubbery, outdoor falls, or accidents ## Footnote The frequent history of thorn injury or gardening may suggest, incorrectly, a diagnosis of sporotrichosis.

Question 37

most common pattern or presenation of cutaneous nocardiosis

Answer 37

lymphocutaneous nodules in a sporotrichoid pattern

Question 38

gram stain findings of nocardiosis

Answer 38

* Organisms are detected as Gram-positive, branched, **filamentous “hyphae”** (in reality, they are bacteria). * They characteristically **branch at right angles.** * **Acid-fast stains,** including Fite-Faraco and the modified Kinyoun technique, stain the filamentous bacteria.

Question 39

color of grains of causative agents of mycetoma

Answer 39

* A. madurae - white, yellow, or cream * A. pelletieri - red * f S. somaliensis - cream to brown color

Question 40

T/F Amputation may be indicated in severe manifestations of mycetoma involving the bone.

Answer 40

FALSE **Amputation is not indicated** in actinomycetoma because the high risk of lymphangitic or hematogenous dissemination. Functional impairment is common with osseous, pulmonary, or abdominal visceral involvement. The disease may be fatal.