158: Actinomycosis, Nocardiosis, and Actinomycetoma Flashcards
What is the most likely diagnosis for a patient with a solid mass at the jaw angle and recurring abscesses?
The most likely diagnosis is cervicofacial actinomycosis, commonly caused by Actinomyces species originating from periapical abscesses or dental procedures.
What radiological findings are expected in a patient with thoracic actinomycosis?
Radiological findings may include a mass or pneumonia with pleural involvement, empyema necessitans, and parenchymal, pleural, and chest wall disease.
What is the most common source of infection in thoracic actinomycosis?
The most common source of infection is aspiration of microorganisms from the oropharynx.
What is the most common precipitating event for abdominal actinomycosis?
The most common precipitating event is appendicitis or diverticulitis.
What are the common clinical manifestations of actinomycosis?
The common clinical manifestations of actinomycosis include:
- Mass-like inflammatory infiltrate of the skin and subcutaneous tissue.
- Sinus formation with drainage.
- Relapsing or refractory clinical course after short-term therapy with antibiotics.
Additionally, actinomycotic granules may be seen macroscopically, which is always suggestive of the diagnosis.
What is the most frequent form of actinomycosis and its common locations?
The most frequent form of actinomycosis is cervicofacial actinomycosis, which accounts for approximately 55% of cases. The most common locations include:
Location | Percentage |
|———-|————|
| Jaw angle and high cervical area | 60% |
| Cheek | 16% |
| Chin | 13% |
What are the epidemiological characteristics of actinomycosis?
The epidemiological characteristics of actinomycosis include:
- Worldwide distribution.
- Relatively rare occurrence.
- Tendency to decline due to higher standards of oral care and the disease’s susceptibility to many antibiotics.
- More common in males than females (M>F).
- Affected age group is typically 20-60 years.
- Genitourinary actinomycosis is more common in females, especially associated with intrauterine devices (IUDs).
What is the definition of actinomycosis?
Actinomycosis is defined as a chronic, progressive, indolent infection caused by endogenous Actinomyces species, which are common inhabitants of the human mucosal surfaces such as the oral cavity, pharynx, distal esophagus, and genitourinary tract.
What is the primary cause of actinomycosis?
Endogenous Actinomyces species.
What is the typical presentation of thoracic actinomycosis?
Chest pain, fever, weight loss, cough, and may involve the lung, pleura, mediastinum, and chest wall.
What is the significance of actinomycotic granules in diagnosis?
They may be seen macroscopically and are always very suggestive of the diagnosis.
What is the age and gender distribution for actinomycosis?
More common in males (M>F) and typically occurs in individuals aged 20-60 years.
What are the common sources of infection for abdominal actinomycosis?
Spreading from the GI tract or from the female genital tract, often associated with appendicitis and diverticulitis.
What is the characteristic feature of the infection caused by Actinomyces?
The presence of sulfur granules or grains in infected tissue, although not always present and not specific.
What are the key distinguishing features of actinomycosis compared to actinomycetoma?
Actinomycosis is characterized by chronic, progressive, indolent infections caused by endogenous Actinomyces species, while actinomycetoma is caused by environmental actinomyces, indicating an exogenous source of infection.
What are the common clinical manifestations of cervicofacial actinomycosis?
Cervicofacial actinomycosis typically presents with:
- A mass-like inflammatory infiltrate of the skin and subcutaneous tissue.
- Sinus formation with drainage.
- A relapsing or refractory clinical course after short-term antibiotic therapy.
Additionally, actinomycotic granules may be observed macroscopically, which is suggestive of the diagnosis.
How does thoracic actinomycosis typically present and what are its potential complications?
Thoracic actinomycosis commonly presents with:
- Chest pain, fever, and weight loss.
- Cough, and less frequently, hemoptysis, which can mimic tuberculosis.
- Radiologically, it may appear as a mass or pneumonia with pleural involvement.
Complications can include empyema necessitans, cutaneous abscess formation, and sinus formation.
What are the potential routes of infection for abdominal actinomycosis?
Abdominal actinomycosis can arise from:
1. Spreading from the gastrointestinal tract or female genital tract.
2. Common precipitating events include appendicitis and diverticulitis.
3. Local extension may lead to inflammatory masses appearing in the abdominal wall or perineum.
What is the established risk factor for pelvic actinomycosis in women?
The established risk factor is IUD use for longer than 2 years, with an average usage duration of 8 years.
What special stains can be used to identify filamentous structures in actinomycosis?
Special stains include Brown-Brenn, Gram, Giemsa, and Gomori stains.
What is the Splendore-Hoeppli phenomenon?
This phenomenon is characterized by a rim of eosinophilic material surrounding granules in tissue cuts.
What imaging modalities can assist in diagnosing actinomycosis?
CT and MRI can assist in diagnosis by providing anatomical references and identifying abscesses or phlegmons.
What is the most common causative organism in actinomycosis?
The most common causative organism is Actinomyces israelii.
What is the most common origin of actinomycosis infections in humans?
Most often originates from ascending infection from the female genital tract.
What are the common clinical presentations of punch or fist actinomycosis?
Uncommon but interesting clinical presentation usually follows blunt trauma of a closed fist against a person’s mouth, with similar findings originating from a human bite.
What are the risk factors associated with actinomycosis?
Risk factors include immunocompromised states such as prolonged administration of steroids, chemotherapy, HIV, lung and renal transplant receipt, alcoholism, and local tissue damage from trauma, recent surgery, or radiation.
What laboratory tests are useful for diagnosing actinomycosis?
Useful tests include direct examination of draining material for filamentous Actinomyces on Gram stain, culture from a sterile site, and biopsy.
What are the characteristics of sulfur granules in actinomycosis?
Sulfur granules are clusters of bacteria in filamentous aggregates, commonly surrounded by acute and chronic inflammation.
What imaging techniques are used in the diagnosis of actinomycosis?
Early stages show nonspecific and nondiagnostic findings. In advanced stages, CT and MRI may reveal nonspecific findings such as abscesses or phlegmon.
What is the first-line treatment for Actinomycosis and how long should it be administered?
The first-line treatment for Actinomycosis is penicillin G, administered at 18 to 24 million units IV for 2 to 6 weeks, followed by oral penicillin or amoxicillin for 6 to 12 months.
What are the risk factors for relapse or death in patients with Actinomycosis?
Risk factors for relapse or death in Actinomycosis include:
- Duration of disease > 2 months
- Lack of antibiotic therapy or surgical therapy
- Needle aspiration rather than open drainage or excision.
What are the clinical features of cutaneous nocardiosis?
Clinical features of cutaneous nocardiosis include:
- Abscesses
- Cellulitis
- Lymphocutaneous nodules in a sporotrichoid pattern.
What is the most common presentation of Nocardiosis?
The most common presentation of Nocardiosis is pulmonary disease, often associated with agricultural occupations.
What are the clinical features of cutaneous nocardiosis?
Clinical features of cutaneous nocardiosis include:
- Abscesses
- Cellulitis
- Lymphocutaneous nodules in a sporotrichoid pattern
- Disseminated disease from hematogenous spread, leading to hemorrhagic pustules and abscesses
What are the definitions of primary and secondary cutaneous nocardiosis?
Definitions:
- Primary cutaneous nocardiosis: Infection of skin by environmental Nocardia sp due to direct inoculation through trauma, occurring in immunocompetent patients.
- Secondary hematogenous spreading: Occurs in immunosuppressed individuals, often as a result of hematogenous seeding from a pulmonary source.
What is the first-line treatment for Actinomycosis?
Penicillin G, 18 to 24 million units IV for 2 to 6 weeks, followed by oral penicillin or amoxicillin for 6 to 12 months.
What are the alternative treatments for patients allergic to penicillin in Actinomycosis?
Tetracycline, doxycycline, erythromycin, clindamycin, imipenem, chloramphenicol, linezolid, and tigecycline.
What is cutaneous nocardiosis?
The infection of skin by environmental Nocardia sp, either as a result of direct inoculation through trauma or as a consequence of hematogenous seeding.
What are the common clinical features of cutaneous nocardiosis?
Common clinical features of cutaneous nocardiosis include:
- Abscess
- Cellulitis
- Lymphocutaneous nodules in a sporotrichoid pattern
- Disseminated disease from hemorrhagic pustules to ecthyma and abscesses
It is the second most frequent presentation after pulmonary involvement.
What factors increase the risk of primary cutaneous nocardiosis?
Soil or sand exposure while gardening or farming, superficial injury from domestic shrubbery, outdoor falls, or accidents.
What is the recommended duration of antibiotic therapy for cervicofacial disease in Actinomycosis?
30 days.
What is the significance of immunosuppression in nocardiosis?
At least 50% of patients with nocardiosis will have some sort of immunosuppression, increasing the risk of infection.
What surgical procedures are indicated for bulky disease in Actinomycosis?
Resection of necrotic tissue, excision of sinus tracts, draining of empyemas and abscesses, and curettage of bone.
What is the epidemiological trend of nocardiosis cases in the US?
Approximately 1000 cases annually, likely underestimated due to increasing numbers of immunosuppressed patients.
What is the treatment of choice for actinomycosis and how long should it be administered?
The treatment of choice for actinomycosis is penicillin G, administered at 18 to 24 million units IV for 2 to 6 weeks, followed by oral penicillin or amoxicillin for 6 to 12 months.
What are the risk factors for relapse or death in patients with actinomycosis?
Risk factors for relapse or death in actinomycosis include:
1. Duration of disease greater than 2 months
2. Lack of antibiotic therapy or surgical therapy
3. Needle aspiration rather than open drainage or excision
What are the predisposing factors for primary cutaneous nocardiosis?
Predisposing factors for primary cutaneous nocardiosis include:
- Soil or sand exposure while gardening or farming
- Superficial injury from domestic shrubbery, outdoor falls, or accidents
- Frequent history of thorn injury or gardening
- Insect bites, cat scratches, or minimal contact, especially in children
What are the risk factors for dissemination in nocardiosis?
Risk factors include immunosuppression (e.g., malignancy, transplantation, AIDS, corticosteroid use), chronic pulmonary diseases, and IV drug abuse.
What is the most commonly isolated species in disseminated nocardiosis with bacteremia?
The most commonly isolated species in disseminated nocardiosis with bacteremia is Nocardia asteroides.
What is the most likely causative organism in nocardiosis with cellulitis and abscesses on the lower extremities?
The most likely causative organism is Nocardia brasiliensis.
What is the most common location for lymphocutaneous nodules in nocardiosis?
The most common location for these lesions is the upper extremity.
What are the common clinical manifestations of nocardiosis in AIDS patients?
In AIDS patients, the most common clinical manifestations of nocardiosis include:
- Cutaneous abscesses
- Suppurative adenitis
- Sporotrichoid or lymphocutaneous forms (24% of cases)
Most commonly affect the upper extremities, but can also involve the lower extremities and cervicofacial region.
What are the risk factors for pulmonary nocardiosis with subsequent dissemination in immunosuppressed patients?
The risk factors for pulmonary nocardiosis with subsequent dissemination in immunosuppressed patients include:
- Malignancy (solid organ or hematologic) on chemotherapy or corticosteroids
- Transplantation (most commonly renal and heart)
- AIDS
- IV drug abuse
- Systemic lupus
- Nephrotic syndrome
- Corticosteroids, either alone or in conjunction with other drugs.
What laboratory tests are useful for diagnosing nocardiosis?
Useful laboratory tests for diagnosing nocardiosis include:
1. Direct examination: Identification of granules, especially in disseminated cases and suppurative lesions.
2. Culture: Kept under observation for 2 to 3 weeks.
Grows satisfactorily on most nonselective media used for isolation of bacteria, mycobacterium, and fungi.
What is the most common cutaneous manifestation in AIDS patients?
Cutaneous abscesses and suppurative adenitis.
What is the most common form of clinical infection caused by Nocardia species?
Pulmonary disease.
Which Nocardia species is most commonly associated with lung and systemic disease?
N. asteroides.
What is a common risk factor for pulmonary nocardiosis?
AIDS, IV drug abuse, and malignancy.
What laboratory test is definitive for diagnosing nocardiosis?
Isolation of Nocardia species in culture.
What type of immune response is typically seen in Nocardia infections?
A neutrophilic response with branching, beading filamentous bacteria within abscesses.
What is a characteristic feature of Nocardia species in culture?
They grow satisfactorily on most nonselective media used for isolation of bacteria.
What is the typical appearance of Nocardia species under a microscope?
Gram-positive, branched, filamentous ‘hyphae’ that branch at right angles.
What is a common complication of immunosuppressive therapy related to Nocardia infections?
Ulcerative bullous, linear/keloid, and nodulopustular forms.
What are the common clinical manifestations of cutaneous nocardiosis in immunocompromised patients?
Common clinical manifestations include:
- Cutaneous abscesses and suppurative adenitis.
- Sporotrichoid or lymphocutaneous forms:
Most common on the upper extremity.
How does the presentation of nocardiosis differ in children compared to adults?
In children, nocardiosis typically presents as cellulitis, abscesses, and lymphadenitis affecting the lower extremities and trunk.
What are the risk factors associated with pulmonary nocardiosis and its dissemination?
Risk factors for pulmonary nocardiosis with subsequent dissemination include:
- Immunosuppression due to malignancy (solid organ or hematologic).
- Chemotherapy or corticosteroid use.
- Transplantation (especially renal and heart).
- AIDS and IV drug abuse.
What are the characteristics of Nocardia species that contribute to their virulence and resistance to treatment?
Characteristics contributing to the virulence and resistance of Nocardia species include:
- Complex cell wall glycolipids that enhance virulence.
- Certain strains, like N. farcinica, exhibit a high degree of resistance to various antibiotics.
What alternative treatments can be considered for a patient with nocardiosis treated with TMP-SMX who develops severe dermatologic reactions?
Alternative treatments include minocycline, amikacin, imipenem, ceftriaxone, or linezolid.
What is the gold standard diagnostic tool for suspected nocardiosis?
The gold standard diagnostic tool is sequencing of 16 ribosomal RNA.
What imaging modality is most useful for identifying cavitary lesions in pulmonary nocardiosis?
CT scans are most useful for identifying cavitary lesions in pulmonary nocardiosis.
What differential diagnoses should be considered for a patient with nocardiosis presenting with sporotrichoid lesions?
Differential diagnoses include sporotrichosis, tuberculosis, and atypical bacteria such as Mycobacterium marinum.
What is the recommended dose for primary cutaneous nocardiosis treated with TMP-SMX?
The recommended dose for primary cutaneous nocardiosis is 5 mg/kg of TMP.
What alternative drug can be used for a patient with nocardiosis who shows poor tolerance to sulfonamides?
Minocycline 100 to 200 mg twice a day can be used as an alternative.
What is the most likely causative organism in nocardiosis with a chalky appearance of colonies on culture?
The most likely causative organism is Nocardia asteroides.
What diagnostic tests should be performed for a patient with nocardiosis presenting with a history of thorn injury and cellulitis?
Diagnostic tests include bacterial, mycologic, and mycobacterial cultures, as well as direct examination and biopsy.
What are the key pathological features of nocardiosis?
- Monocytic infiltrates
- Fibrinopurulent exudates
- Granuloma formation
- Chronic granuloma formation
- Chronic nodular dermatitis
- Microabscess formation
- Coccobacillary organisms
- Granules in disseminated cases
What imaging patterns are associated with pulmonary nocardiosis?
- Irregular nodular
- Reticulonodular
- Diffuse pneumonitic patterns
CT scans help identify cavitary lesions.
What is the recommended treatment for primary cutaneous nocardiosis?
- Sulfonamide (either sulfadiazine or sulfisoxazole) alone is considered adequate therapy.
- TMP-SMX is the treatment of choice, with a recommended dose of:
- 5 to 10 mg/kg TMP
- 25 to 50 mg/kg SMX in 2 to 4 divided doses
Clinical improvement is expected within 3 to 10 days and treatment may last 1 to 4 months for curative effects.
What factors should be considered when treating nocardiosis?
- Site and severity of infection
- Immune status of the host
- Potential for interactions
What is the cornerstone of therapy for nocardiosis?
Sulfonamides, alone or in combination with trimethoprim as TMP-SMX.
What is the recommended treatment for primary cutaneous nocardiosis of mild to moderate intensity?
Sulfonamide alone or TMP-SMX as the treatment of choice.
What is the recommended dosage for TMP-SMX in treating primary cutaneous nocardiosis?
5 to 10 mg/kg TMP and 25 to 50 mg/kg SMX in 2 to 4 divided doses.
What is the recommended treatment duration for clinical improvement in cutaneous nocardiosis?
3 to 10 days for clinical improvement, with 1 to 4 months of treatment for curative effects.
What factors should be considered when treating nocardiosis?
Site and severity of infection, immune status of the host, potential for interactions, and species of Nocardia.
What are the second-line drugs recommended for more severe cases of nocardiosis?
Amikacin, Imipenem, Ceftriaxone. Alternative second-line drugs include Amoxicillin-clavulanate and Linezolid.
What is the prognosis for primary cutaneous nocardiosis with appropriate antibiotic therapy?
Good prognosis when appropriate antibiotic therapy is given.
What is the prognosis for disseminated nocardiosis?
Less-favorable prognosis, especially with immunosuppression or extensive pulmonary involvement.
What is the best tool and gold standard for DNA hybridization in the context of Nocardiosis?
Sequencing of 16 ribosomal RNA.
What are the common imaging patterns in pulmonary nocardiosis?
Irregular nodular, reticulonodular, and diffuse pneumonitic patterns.
What surgical procedures may be indicated in the management of nocardiosis?
Drainage of abscesses and debridement of extensive necrosis.
Why is prophylactic use of antibiotics not justified in immuno-deficient states for Nocardia infections?
Due to the low incidence of Nocardia infections in these states.
What are the key pathological features observed in nocardiosis?
Key pathological features include monocytic infiltrates, fibrinopurulent exudates, granuloma formation, chronic granuloma formation, chronic nodular dermatitis, microabscess formation, coccobacillary organisms, and granules in disseminated cases.
What imaging patterns are associated with pulmonary nocardiosis on X-ray?
Imaging patterns associated with pulmonary nocardiosis include:
- Irregular nodular
- Reticulonodular
- Diffuse pneumonitic patterns
What imaging patterns are associated with pulmonary nocardiosis on CT scans?
CT scans help identify cavitary lesions.
What is the recommended treatment approach for primary cutaneous nocardiosis?
The recommended treatment approach for primary cutaneous nocardiosis includes:
1. Sulfonamide therapy (either sulfadiazine or sulfisoxazole) alone is considered adequate.
2. TMP-SMX is the treatment of choice, despite lack of controlled trials, based on in vitro synergistic activity.
- Recommended dose: 5 to 10 mg/kg TMP and 25 to 50 mg/kg SMX in 2 to 4 divided doses.
- Clinical improvement typically observed within 3 to 10 days.
- Prolonged therapy is necessary for immunosuppressed patients.
What factors should be considered when managing nocardiosis in immunosuppressed patients?
Factors to consider when managing nocardiosis in immunosuppressed patients include:
- Site and severity of infection
- Immune status of the host
- Potential for drug interactions
- Species of Nocardia
What is the prognosis for disseminated nocardiosis associated with immunosuppression?
The prognosis for disseminated nocardiosis associated with immunosuppression is generally less favorable, especially in cases with extensive pulmonary involvement or bacteremia. In contrast, primary cutaneous nocardiosis has a good prognosis when appropriate antibiotic therapy is administered.
What is the most likely diagnosis for a patient with a painless subcutaneous mass, sinus formation, and purulent discharge containing grains?
The most likely diagnosis is actinomycetoma.
The pathognomonic triad includes: 1) a painless subcutaneous mass, 2) sinus formation, and 3) purulent or seropurulent discharge containing grains.
What is the most likely causative organism in Mexico for a patient with chronic, localized, painless swelling of the foot with sinus tracts and grains?
The most likely causative organism in Mexico is Nocardia brasiliensis.
What are the primary causes of actinomycetoma?
The primary causes of actinomycetoma are: 1. Nocardia brasiliensis 2. Actinomyces madurae 3. Actinomyces pelletieri 4. Streptomyces somaliensis.
What are the clinical features of actinomycetoma?
The clinical features of actinomycetoma include:
- Chronic, localized, slowly progressive, painless disease of the skin and subcutaneous tissue.
- Begins with a minor traumatic injury.
- Most common site is the lower limbs (71%).
- Characteristic triad: 1. A painless subcutaneous mass 2. Sinus formation 3. Purulent or seropurulent discharge containing grains.
- Granules may be seen with the naked eye, creamy in color except for A. pelletieri which is red.
What are the risk factors associated with actinomycetoma?
The risk factors associated with actinomycetoma include:
- Walking barefoot in areas of high prevalence.
- Occupational activities such as firewood collection, especially in endemic regions.
What laboratory tests are used for diagnosing actinomycetoma?
Laboratory tests for diagnosing actinomycetoma include:
-
Direct examination of granules:
- Nocardia granules: microscopic with a yellowish color.
- A. madurae: white, yellow, or cream.
- A. pelleterii: red.
- S. somalienesis: cream to brown color.
- Gram stain.
- Culture.
- Fine-needle aspiration cytology for diagnostic purposes.
- Cell block technique for cytodiagnosis.
What are the noncutaneous findings and complications of actinomycetoma?
Noncutaneous findings and complications of actinomycetoma include:
- Chronic and progressive nature of the disease.
- Potential involvement of bones, lung, and abdominal viscera.
- In women, lesions may increase in size during pregnancy and improve spontaneously after delivery.
- Advanced cases may lead to functional disability.
- Atypical clinical forms include:
- Cryptic mycetoma (without sinus tracts).
- Minimycetoma (single or multiple small lesions, mainly in children and adolescents).
- Inguinal “metastatic” lesions from a primary mycetoma of the foot.
What are actinomycetomas caused by?
Chronic infections caused by bacteria (actinomycetomas) or fungi (eumycetomas).
What is the leading cause of actinomycetoma in Mexico?
Nocardia brasiliensis.
What is a common risk factor for developing actinomycetoma?
Walking barefoot in areas of high prevalence.
What are the clinical features of actinomycetoma?
Chronic, localized, slowly progressive, painless disease of the skin and subcutaneous tissue.
What is the pathognomonic triad of actinomycetoma?
The pathognomonic triad includes: (Information not provided in the text)
What is the pathognomonic triad of actinomycosis?
1) A painless subcutaneous mass, 2) sinus formation, 3) purulent or seropurulent discharge that contains grains.
What are the most frequent causes of actinomycosis?
N. brasiliensis, A. maduriae, A. pelletieri, and S. somaliensis.
What laboratory tests are used for diagnosing actinomycosis?
Direct examination, Gram stain, culture, and fine-needle aspiration cytology.
What is the typical appearance of Nocardia granules under microscopic examination?
Microscopic with a yellowish color.
What is a common noncutaneous complication of actinomycosis?
Potential involvement of bones, lung, and abdominal viscera.
What is the typical age range for patients with actinomycosis?
21-40 years old.
What are the clinical features of actinomycosis, and how do they differ based on the causative agents?
Actinomycosis presents as a chronic, localized, slowly progressive, painless disease of the skin and subcutaneous tissue, typically starting from a minor traumatic injury. The clinical features include:
-
Nocardia species:
- Very inflammatory process
- Tumefaction, tumor-like or nodular soft-tissue swelling
- Discharging sinus tracts with pus (97% of cases)
- Pathognomonic triad: painless subcutaneous mass, sinus formation, purulent or seropurulent discharge containing grains.
-
A. madurae, A. pelletieri, and S. somaliensis:
- Less inflammatory with smaller sinus tracts
- Granules may be visible; creamy in color (except A. pelletieri, which is red).
Ulceration, crusting, and scarring may also be observed, with the foot being the most common site of involvement.
What are the epidemiological characteristics of actinomycoma?
Actinomycoma is included in the ‘top 17’ neglected tropical diseases and has a worldwide distribution, particularly in the endemic ‘mycetoma belt’ around the Tropic of Cancer, affecting countries in Africa, Asia, and Latin America, especially India, Sudan, Somalia, Mexico, and Venezuela.
What is the leading cause of actinomycoma?
N. brasiliensis (97% in Mexico, also prevalent in South America and Australia).
What are other causative agents of actinomycoma?
Streptomyces somaliensis, Actinomyces durae pelletieri, and Actinomyces durae madurae.
What are the demographics of actinomycoma?
More common in males (M:F ratio 3:1), primarily affecting individuals aged 21-40 years.
What are the risk factors for actinomycoma?
Agricultural rural workers in tropical/subtropical zones, outdoor activities, and walking barefoot or wearing sandals increases risk, particularly in lower limbs (71% of cases).
What are the potential complications associated with actinomycoma?
Complications can be chronic and progressive, potentially involving bones, lungs, and abdominal viscera.
What are specific manifestations of actinomycoma?
- Increased size during pregnancy: In women, actinomycoma may increase in size during pregnancy and improve spontaneously after delivery.
- Functional disability: Advanced cases can lead to significant functional impairment.
- Atypical clinical forms: Cryptic mycetoma (without sinus tracts), Minimycetoma (small lesions, mainly in children/adolescents), Inguinal ‘metastases’.
What are the main genera responsible for actinomycosis and their associated pathogens?
The main genera responsible for actinomycosis include:
Genus | Common Pathogens | Frequency of Occurrence |
|—————-|—————————————————-|————————-|
| Nocardia | N. brasiliensis, N. asteroides, N. caviae | Most frequent |
| Actinomyces | A. madurae, A. pelletieri | Common |
| Streptomyces | S. somaliensis | Common |
What are less frequent causes of actinomycosis?
Less frequent causes include Nocardiosis dassevilliei and Nocardia transvalensis. New agents such as N. pseudobrasiliensis and N. veteran have also been identified in human actinomycosis cases.
What laboratory testing methods are utilized for the diagnosis of actinomycosis?
Diagnosis of actinomycosis is limited to expert hands and involves several laboratory testing methods:
- Direct examination: Microscopic examination of Nocardia granules (yellowish color).
- Gram stain: Useful for identifying bacterial presence.
- Culture: To isolate the causative organism.
- Fine-needle aspiration cytology: A good diagnostic tool for obtaining samples.
- Cell block technique: Used for cytodiagnosis, showing findings similar to histopathologic sections.
What does a patient with actinomycosis caused by Nocardia brasiliensis typically require?
A patient with actinomycosis caused by Nocardia brasiliensis is treated with appropriate antimicrobial therapy.
What is the treatment for actinomycetoma caused by Nocardia brasiliensis?
The treatment includes dapson and TMP-SMX.
What additional drugs can be combined for resistant cases of actinomycetoma?
Additional drugs include streptomycin, clofazimine, rifampin, tetracycline, and isoniazid.
What is the most likely causative organism for actinomycetoma with firm, red grains that are 200-500 µm in diameter?
The most likely causative organism is Actinomyces pelleteri.
What is the treatment for actinomycetoma caused by Nocardia brasiliensis with imipenem?
The treatment includes imipenem and amikacin.
What is the recommended dosing schedule for imipenem?
The recommended dosing schedule for imipenem is 500 mg three times daily, often in combination with intravenous amikacin.
What is the most likely causative organism for actinomycetoma with soft, purple grains that are 1-3 mm in diameter?
The most likely causative organism is Actinomyces madurae.
What is the most likely causative organism for actinomycetoma with rounded, hard, pale grains that are 1.5-10 mm in diameter?
The most likely causative organism is Streptomyces somaliensis.
What is the most likely causative organism for actinomycetoma with grains that are 30-200 µm in diameter and show the Splendore-Hoeppli phenomenon?
The most likely causative organism is Nocardia species.
What is the most likely causative organism for actinomycetoma with red and firm grains?
The most likely causative organism is Actinomyces pelleteri.
What is the most likely causative organism for actinomycetoma with creamy colored grains?
The most likely causative organism is Actinomyces species.
What is the most likely causative organism?
The most likely causative organism is Actinomadura madurae.
What are the common radiographic abnormalities associated with actinomycetoma?
The most common radiographic abnormalities include:
- Soft-tissue swelling
- Extrinsic pressure
- Bony periosteal reaction
- Erosion
- Sclerosis
- Joint involvement
- Bone cavities (referred to as ‘geoda’)
What is the significance of the ‘dot-in-circle’ sign observed in MRI for mycetoma?
The ‘dot-in-circle’ sign is a very characteristic feature of mycetoma observed on MRI. It appears as multiple small, round-shaped hyperintense lesions surrounded by a low-signal intensity rim (the circle) and a central low-signal focus (the dot). This sign helps in differentiating mycetoma from other conditions.
What are the treatment options for actinomycetoma caused by N. brasiliensis?
The treatment of choice for actinomycetoma caused by N. brasiliensis includes:
- Diaminodiphenylsulfone (Dapsone): 100 to 200 mg/day (3 to 5 mg/kg) plus TMP-SMX 160/800 mg twice a day for several months, continuing for up to 2 years.
-
Combination therapy with:
- Streptomycin: 1 g/day
- Clofazimine: 100 mg/day
- Rifampin: 300 mg twice/day
- Tetracycline: 1 g/day
- Isoniazid: 300 to 600 mg/day
- Alternative treatments for severe or multiresistant mycetomas may include amikacin and imipenem.
What factors influence the management of actinomycetoma?
Management of actinomycetoma should be individualized based on:
- Economic considerations that may influence the choice of therapy.
- Molecular identification of the causal agents.
What is molecular identification?
The identification of causal agents and development of genetic markers for disease.
What is clinical activity in relation to cure rates?
Clinical activity and the absence of grains and negative cultures define cure rates, which range from 60% to 90%.
What are prolonged treatment periods?
Prolonged treatment periods, especially in cases with bone and visceral involvement where the prognosis is poor.
What are the differential diagnoses for actinomycosis?
The differential diagnoses for actinomycosis include:
What is eumycetoma?
A differential diagnosis for actinomycosis.
What is botryomycosis?
Mimics actinomycosis and eumycetoma, caused by various organisms such as S. aureus, E. coli, and Pseudomonas aeruginosa.
What is tuberculosis in relation to actinomycosis?
May rarely present as pseudomycetoma.
What is the significance of the ‘dot-in-circle’ sign observed in MRI for mycetoma?
It is a very characteristic feature of mycetoma observed on MRI, appearing as multiple small, round-shaped hyperintense lesions surrounded by a low-signal intensity rim (the circle) and a central low-signal focus (the dot). This sign helps in differentiating mycetoma from other conditions.
What are the common staining methods used for identifying Nocardia and actinomycosis?
Gomori methenamine silver, periodic acid-Schiff, and Brown-Brenn modification of the Gram stain.
What imaging techniques are used to identify the limits of lesions in actinomycosis?
Conventional radiographs, ultrasonography, MRI, and CT.
What does the term ‘mycetoma’ refer to?
Mycetoma is a chronic granulomatous disease characterized by the presence of multiple lesions.
What are the characteristics of the lesions in mycetoma?
The lesions are multiple, small, and round-shaped, surrounded by a low-signal intensity rim.
What is the appearance of the lesions in imaging studies?
The lesions appear as hyperintense on imaging studies.
What is the treatment of choice for actinomycosis caused by Nocardia brasiliensis?
Diaminodiphenylsulfone (Dapsone) combined with TMP-SMX for several months, continuing for up to 2 years.
What factors influence the choice of therapy in managing actinomycosis?
Economic considerations, molecular identification of causal agents, and the severity of the disease.
What are the common medications used in the treatment of actinomycosis?
Antibiotics such as Dapsone, streptomycin, clofazimine, rifampin, tetracycline, and amikacin.
What is the prognosis for actinomycosis with bone and visceral involvement?
The prognosis is poor, and treatment periods should be prolonged in such cases.
What is the differential diagnosis for actinomycosis?
Botryomycosis and eumycetoma, both clinically and histologically.
What are the common predisposing factors for botryomycosis?
Local trauma, foreign body, diabetes, or HIV.
What is the cure rate for actinomycosis with appropriate treatment?
Cure rates range from 60% to 90%.
What imaging techniques are most accurate for determining the extent of mycetoma disease, and what specific features do they reveal?
MRI and CT are the most accurate diagnostic tools for determining the extent of mycetoma disease. They provide evidence about:
- Degree of visceral, muscular, and vascular invasion
- Size of the involvement
- Characteristic ‘dot-in-circle’ sign on MRI, which appears as multiple small, round-shaped hyperintense lesions surrounded by a low-signal intensity rim and a central low-signal focus.
How do the ultrasound findings differ between actinomycosis and eumycetoma?
Ultrasound findings can help differentiate between actinomycosis and eumycetoma.
What are the ultrasound findings for eumycetoma?
Numerous sharp bright hyperreflective echoes due to grain cement.
What are the ultrasound findings for actinomycetoma?
Less distinct findings, likely due to smaller size and consistency of grains.
How do hyperreflective echoes help in differentiating mycetoma types?
Hyperreflective echoes help differentiate mycetoma from nonmycetoma, but sinus tracts can obscure clarity.
What are the key differential diagnoses for actinomycetoma and eumycetoma?
Key differential diagnoses include:
1. Botryomycosis
- Caused by organisms such as: Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Proteus vulgaris, Actinobacillus species, Streptococcus species, Propionibacterium acnes.
- Commonly presents with localized infiltration and draining sinuses.
2. Tuberculosis
- May present as pseudomycetoma, though this is rare.
What are the recommended treatment strategies for actinomycetoma?
Recommended treatment strategies include:
1. Individualized therapy based on disease localization and severity.
2. Combined antibiotic therapy to prevent drug resistance and eradicate residual infection:
- Dapsone (100-200 mg/day) plus TMP-SMX (160/800 mg twice a day).
- Additional options include streptomycin, clofazimine, rifampin, tetracycline, and isoniazid.
What are the four key medications mentioned?
Lofazimine, rifampin, tetracycline, and isoniazid.
What is the significance of prolonged treatment periods?
Especially for cases with bone and visceral involvement, where prognosis is poor.
What does monitoring for cure include?
Defined by lack of clinical activity, absence of grains, and negative cultures, with cure rates ranging from 60%-90%.
What are the characteristics of granules associated with different types of mycetoma?
Characteristics include size and appearance description.
What is the size range for Nocardia granules?
30-200 µm.
What is the appearance description for Nocardia granules?
Partially basophilic to amphophilic with amorphous eosinophilic material on the periphery (Splendore-Hoeppli phenomenon).
What is the size range for A. madurae granules?
1-3 µm.
What is the appearance description for A. madurae granules?
Soft, purple, cartographic shape with eosinophilic fringe.
What is the size range for A. pelleterii granules?
200-500 µm.
What is the appearance description for A. pelleterii granules?
Firm, red.
What is the size range for S. somalienesis granules?
1.5-10 µm.
What is the appearance description for S. somalienesis granules?
Rounded, hard, pale.
Why are these characteristics important?
They help in the identification and differentiation of mycetoma types.
What treatment is given to a patient with nocardiosis?
Amikacin.
What monitoring is required during treatment for nocardiosis?
Monitoring includes audiometry for auditory toxicity and renal function tests for nephrotoxicity every 3 to 5 weeks.
What treatment is given to a patient with nocardiosis using linezolid?
The most important adverse effect to monitor is myelosuppression.
What treatment is given to a patient with actinomycetoma caused by Nocardia brasiliensis?
Dapsone.
What enzyme determination is obligatory before using dapsone?
Determination of 6-glucose phosphate dehydrogenase enzyme is obligatory.
What is the role of glucose phosphate dehydrogenase enzyme?
It is obligatory before using dapsone.
What is the typical immune status of most patients with actinomycosis?
Most patients are immunocompetent or immunosuppressed.
In which patients does primary cutaneous nocardiosis occur?
In immunocompetent or immunosuppressed patients.
Why is amputation not indicated in actinomycosis?
Because of the high risk of lymphangitic or hematogenous dissemination.
What is the treatment regimen used by Ramam and colleagues for nocardiosis?
A 2-step regimen consisting of an intensive phase with intravenous penicillin (1,000,000 IU every 6 hours) plus intravenous gentamicin.
What is the dosing regimen for cilastatin?
Cilastatin is administered at a dose of 1,000,000 IU every 6 hours.
What is the dosing regimen for intravenous gentamicin?
Intravenous gentamicin is given at a dose of 80 mg twice a day.
What is the dosing regimen for oral TMP-SMX?
Oral TMP-SMX is administered at a dose of 80 to 400 mg twice a day for 5 to 7 weeks.
What are the main disadvantages of using linezolid for nocardiosis treatment?
The main disadvantage of linezolid is its cost, despite its demonstrated efficacy against N. brasiliensis.
What laboratory tests should be monitored to assess improvement in patients undergoing treatment for nocardiosis?
Clinical assessment should be monitored alongside laboratory tests including hemoglobin level, white cell count, C-reactive protein, erythrocyte sedimentation rate, enzyme-linked immunosorbent assay (when available), biopsy, and culture.
What are the potential adverse effects of linezolid treatment?
Adverse effects of linezolid include diarrhea, headache, nausea, and myelosuppression, which is the most important adverse effect.
Why should carbapenems be avoided in certain patients?
Carbapenems should not be prescribed in patients who are allergic to penicillin and other beta-lactam antibiotics.
What is the significance of monitoring renal function and auditory toxicity during amikacin treatment?
Close clinical observation is required every 3 to 5 weeks during amikacin treatment to adjust the dose and monitor for potential nephrotoxicity (renal function tests) and auditory toxicity (audiometry).
What is the cornerstone of therapy in nocardiosis?
The cornerstone of therapy in nocardiosis is the use of appropriate antibiotics, typically starting with intravenous therapy followed by oral maintenance therapy.
What is the most common form of clinical infection of nocardiosis?
The most common form of clinical infection of nocardiosis is pulmonary nocardiosis.
What is nocardiosis?
The most common form of clinical infection of nocardiosis is pulmonary nocardiosis caused by the organism Nocardia species.
What is the pathognomonic triad in mycetoma?
The triad pathognomonic in mycetoma includes: tumor-like swelling, sinus tracts, and discharge of grains that can be seen microscopically or with the naked eye.
What is a significant risk factor for actinomycosis?
A significant risk factor for actinomycosis is the presence of an intrauterine device (IUD) used longer than a specified duration, with an average usage of time being a contributing factor.
What are the clinical patterns associated with Actinomycosis, Nocardiosis, Actinomycetoma, Eumycetoma, and Botryomycosis?
Disease | Clinical Pattern |
|———|—————–|
| Actinomycosis | Lump with draining sinuses |
| Nocardiosis | Sporotrichoid, cellulitis, abscesses |
| Actinomycetoma | Lump with draining sinuses |
| Eumycetoma | Lump with draining sinuses |
| Botryomycosis | Lump with draining sinuses |
What is the most common agent for each of the diseases listed in the diagnostic approach to diseases that produce grains?
Disease | Most Common Agent |
|———|——————|
| Actinomycosis | Actinomyces israelii |
| Nocardiosis | Nocardia brasiliensis, Nocardia asteroides |
| Actinomycetoma | Nocardia brasiliensis, Actinomyces madurae, Actinomyces pelletieri, Streptomyces somaliensis |
| Eumycetoma | |
What is Madurella pelletrieri?
A species of fungus associated with the disease caused by Streptomyces somaliensis.
What are some species associated with Eumycetoma?
Madurella mycetomatis, Madurella grisea, Pseudallescheria boydii.
What are the causative agents of Botryomycosis?
Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa.
How do the grain contents differ among Actinomycosis, Nocardiosis, Actinomycetoma, Eumycetoma, and Botryomycosis?
Different diseases have varying grain contents.
What type of bacteria is associated with Actinomycosis?
Filamentous bacteria.
What type of bacteria is associated with Nocardiosis?
Filamentous bacteria.
What type of bacteria is associated with Actinomycetoma?
Filamentous bacteria.
What type of fungi is associated with Eumycetoma?
Hyphae.
What is the most common agent for Botryomycosis?
Cocci.
What staining characteristics are associated with Actinomycosis?
Gram positive.
What staining characteristics are associated with Nocardiosis?
Gram positive, weak acid-fast bacillus.
What staining characteristics are associated with Actinomycetoma?
Gram positive, weak acid-fast bacillus (only if Nocardia).
What staining characteristics are associated with Eumycetoma?
Periodic acid-Schiff, Grocott.
What staining characteristics are associated with Botryomycosis?
Gram positive.
What is the most common agent for Actinomycosis?
Actinomyces israelii.
What type of bacteria is commonly found in Actinomycosis?
Filamentous bacteria.
What is the staining characteristic of Nocardiosis?
Gram positive and weak acid-fast bacillus.
What is the clinical pattern associated with Nocardiosis?
Specific clinical patterns related to the disease.
What is the clinical pattern associated with Nocardiosis?
Sporotrichoid, cellulitis, abscesses
What type of grains are found in Actinomycosis?
Common
What is the source of infection for Actinomycosis?
Endogenous flora
What is the most common agent for Botryomycosis?
Staphylococcus aureus
What type of grains are always present in Actinomycetoma?
Always present
What is the staining characteristic of Actinomycetoma?
Gram positive and weak acid-fast bacillus
What is the clinical pattern associated with Actinomycetoma?
Lump with draining sinuses
