23 - 158 - ACTINOMYCOSIS, NOCARDIOSIS AND ACTINOMYCETOMA Flashcards
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What is the difference of actinomycosis and actinomycetoma
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
Actinomycosis should be suspected when dealing with 1 of 3 features. Enumerate the 3 features
- mass-like inflammatory infiltrate of the skin and subcutaneous tissue,
- sinus formation with drainage, and a
- relapsing or refractory clinical course after short-term therapy with antibiotics
Most frequent form of actinomycosis
Cervicofacial actinomycosis
Most common location of actinomycosis
Jaw angle and high cervical area
followed by the cheek (16%), the chin (13%), and, less commonly, the temporomandibular joint and the retromandibular area
IUD use of longer than how many years predisposes a patient for actinomycosis from a primary pelvic disease?
2 years
Best material or specimen to culture in actinomycosis
purulent drainage, tissue, or microscopic granules
*avoid antibiotic treatment before culturing
* swabs are NOT appropriate
What is the characteristic morphology of colony of A. Israelii
“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.
What special stains are needed to demonstrate filamentous structures of sulfur granules?
Brown-Brenn, Gram, Giemsa, or Gomori
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?
Splendore-Hoeppli phenomena
Differentiate actinomyces and nocardia based on Fite-modified acid-fat stain
The lack of staining with Fite-modified acid-fast stain separates Actinomyces from Nocardia species, which is usually acid-fast positive.
Treatment of choice for actinomycosis
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.
If Nocardia is a consequence of hematogenous dissemination, the most likely microorganism is
Nocardia asteroides
Primary cutaneous nocardiosis is a disease of immunocompetent patients, whereas secondary hematogenous spreading is seen in the context of immunosuppression
most common presentation of nocardiosis
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.
nocardia speces most commonly associated with skin infection
N. brasiliensis
The most common cause of primary cutaneous nocardiosis is N. brasiliensis,
best tool and has become the gold standard for the identification of Nocardia species
RNA sequencing on 16S ribosomal RNA
cornerstone of therapy for Nocardia infections
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
T/F
AIDS patients receiving TMP-SMX for Pneumocystis organisms are already protected against Nocardia.
True
Differentiate actinomycetoma and eumycetoma
Actinomycetoma is caused by bacteria, as opposed to eumycetoma, which is caused by fungi.
mycetoma triad
- painless subcutaneous mass,
- sinus formation
- purulent or seropurulent discharge that contains grains
leading cause of actinomycetomas
N.brasiliensis
Granules of actinomycetoma are usually creamy in color except ______
A. pelletieri, in which the granules are red
Microorganisms reported to cause actinomycetomas include 3 genera:
Nocardia, Actinomadura, and Streptomyces
Sign on MRI that is considered very characteristic of mycetoma
“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)
treatment of choice in actinomycetoma caused by N. brasiliensis
- 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
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
What is the most common causative agent of actinomycosis?
Actinomyces israelii
usually as part of a polymicrobial infection, mixed with anaerobes and Gram-positive cocci.
its presence may be seen macroscopically and is always very suggestive of the diagnosis of actinomycosis
Actinomycotic granules
questions what should be asked in the history of patients with actinomycosis
- 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.
Grains are commonly seen in this particular form of actinomycosis
Punch or fist actinomycosis
common source of infection of thoracic actinomycosis
aspiration of a microorganism
although other routes are possible, such as propagation of cervicofacial disease to the mediastinum.
implies disease produced by endogenous, anaerobic, or microaerophile, Gram-positive, non–spore-forming bacteria, belonging to the families Actinomycetaceae, genus Actinomyces.
actinomycosis
the normal habitat of bacteria causing actinomycosis
human mucosal surfaces
with considerable host specificity, from the mouth to the upper respiratory, GI, and female genital tracts.
In orocervical and thoracic actinomycosis, what species commonly predominate?
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.
what history should you always ask in a patient suspected of having actinomycosis infection on the cervicofacial area?
history of dental procedures
Most cervical and facial cases originate from periapical abscesses or after dental procedures. Actinomyces bacteremia seems to occur quite often after dental procedures
what history should you always ask in a patient suspected of having perineal actinomycosis infection ?
presence of IUD
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.
risk factors for actinomycosis
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
The only exception to the endogenous origin of the actinomycosis infection
hand involvement that follows fist or bite trauma
the processing of culture for actinomyces should be done in what environment?
anaerobic conditions
- 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.
cutaneous manifestations of nocardia
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
Predisposing factors for primary cutaneous nocardiosis
soil or sand exposure while gardening or farming; or superficial injury from domestic shrubbery, outdoor falls, or accidents
The frequent history of thorn injury or gardening may suggest, incorrectly, a diagnosis of sporotrichosis.
most common pattern or presenation of cutaneous nocardiosis
lymphocutaneous nodules in a sporotrichoid pattern
gram stain findings of nocardiosis
- 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.
color of grains of causative agents of mycetoma
- A. madurae - white, yellow, or cream
- A. pelletieri - red
- f S. somaliensis - cream to brown color
T/F
Amputation may be indicated in severe manifestations of mycetoma involving the bone.
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.
