出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2013/03/31 11:13:01」(JST)
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| Mycobacterium avium-intracellulare infection | |
|---|---|
| Classification and external resources | |
CT scan of patient with right middle lobe aspiration and Mycobacterium avium infection consistent with Lady Windermere syndrome |
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| ICD-10 | A31.0 |
| ICD-9 | 031.0 |
| DiseasesDB | 29182 |
| eMedicine | med/1532 |
| MeSH | D015270 |
Mycobacterium avium-intracellulare infection (MAI)[1] is an atypical mycobacterial infection which can occur in the later stages of AIDS. It can also affect people who do not have AIDS, and usually first presents as a persistent cough. Additionally, cases in elderly men have increased recently. It is typically treated with a series of three antibiotics for a period of at least six months.
Mycobacterium avium and M. intracellulare (the M. a. complex - MAC) are saprotrophic organisms present in soil and water; entry into hosts is usually via the gastrointestinal tract, but also can be via the lungs.
The MAC causes fevers, diarrhea, malabsorption and anorexia, and can disseminate to the bone marrow. Therapy for MAI is typically resistant to standard mycobacterial therapies.
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MAC bacteria are common in the environment and cause infection when inhaled or swallowed. Symptoms are reminiscent of tuberculosis (TB), and include fever, fatigue, and weight loss. Many patients will have anemia and neutropenia if bone marrow is involved. Pulmonary involvement is similar to TB, while diarrhea and abdominal pain are associated with gastrointestinal involvement. MAC bacteria should always be considered in a person with HIV infection presenting with diarrhea. Recently, M. avium has been found to deposit and grow in bathroom shower heads from which it may be easily aerosolized and inhaled.[2]
The various subspecies of M. avium are prevalent in different areas:
MAI is common in immunocompromised individuals, including senior citizens and those suffering from HIV or cystic fibrosis; however, these diseases, particularly Lady Windermere syndrome, do not require the individual to be immunocompromised.
M. avium and M. haemophilum infections in children form a distinct clinical entity, not associated with abnormalities of the immune system. M. avium typically causes unilateral swelling of one of the lymph nodes of the neck. This node is firm at the beginning, but a collarstud abscess is formed eventually, which is a characteristic blue-purple in colour with multiple discharging sinuses. The treatment of choice is surgical excision of the affected lymph nodes,[3] with antibiotic treatment (usually clarithromycin and rifabutin for 18 to 24 months) reserved for those patients who cannot have surgery.
MAC in patients with HIV disease is theorized to represent recent acquisition rather than latent infection reactivating (which is the case in many other opportunistic infections in immunocompromised patients).
The risk of MAC is inversely related to the patient's CD4 count, and increases significantly when the CD4 count decreases below 50 cells/mm³. Other risk factors for acquisition of MAC infection include using an indoor swimming pool, consumption of raw or partially cooked fish or shellfish, bronchoscopy and treatment with granulocyte stimulating factor.
Disseminated disease was previously the common presentation prior to the advent of highly active antiretroviral therapy (HAART). Today, in regions where HAART is the standard of care, localized disease presentation is more likely. This generally includes a focal lymphadenopathy/lymphadenitis.
AIDS patients are given macrolide antibiotics such as azithromycin for prophylactic treatment.
Diagnosis can be achieved through blood cultures, or cultures of other bodily fluids such as sputum. Bone marrow culture can often yield an earlier diagnosis, but is usually avoided as an initial diagnostic step because of its invasiveness.
Clarithromycin or azithromycin may be used for prophylaxis.[4]
Postinfection treatment involves a combination of antituberculosis antibiotics, including rifampicin, rifabutin, ciprofloxacin, amikacin, ethambutol, streptomycin, clarithromycin or azithromycin.
"Lady Windermere syndrome" describes infection in the lungs due to MAC.[5] It is named after a character in Oscar Wilde's play Lady Windermere's Fan.[6]
Lady Windermere syndrome is a type of mycobacterial lung infection.[7] Patients with this syndrome experience chronic cough, shortness of breath, fatigue and other less specific symptoms.
Mycobacterium avium complex is the most commonly found form of non-tuberculous mycobacteria.[8]
Immunodeficiency is not a requirement for MAI.[9]
Mycobacterium avium complex (MAC) usually affects patients with abnormal lungs or bronchi. However, Candace Baker, Jerome Reich and Richard Johnson describe a series of six patients with MAC infection of the right middle lobe or left lingula who did not have any predisposing lung disorders.[citation needed]
The right middle lobe and left lingula of the lungs are served by bronchi that are oriented downward when a person is in the upright position. As a result, these areas of the lung may be more dependent upon vigorous voluntary expectoration (cough) for clearance of bacteria and secretions.
Since the six patients in their retrospective case series were older females, Reich and Johnson and Baker propose that patients without a vigorous cough may develop right middle lobe or left lingular infection with MAC. They propose this syndrome be named Lady Windermere syndrome, after the character Lady Windermere in Oscar Wilde's play Lady Windermere's Fan.
The diagnosis requires consistent symptoms with two additional signs:
Lady Windermere syndrome is usually treated with a three-drug regimen of either clarithromycin or azithromycin, plus rifampicin and ethambutol. Treatment typically lasts at least 12 months.
The original Chest article proposing the existence and pathophysiology of the Lady Windermere syndrome suggested the character Lady Windermere in Oscar Wilde's Victorian-era play Lady Windermere's Fan is a good example of the fastidious behavior believed to cause the syndrome. The article states:
Victorian women presumably believed "Ladies don't spit," and consequently might have been predisposed to develop lung infection.
Shortly after the Lady Windermere syndrome was proposed, a librarian wrote a letter to the editor of Chest[10] challenging the use of Lady Windermere as the eponymous ancestor of the proposed syndrome. In the play, Lady Windermere is a vivacious young woman, married only two years, who never coughs or displays any other signs of illness. While her avoidance of shaking hands might be interpreted as "fastidiousness", two alternative explanations may be just as probable:
The scholars highlight the literary malapropism,[12] but some in the medical community have adopted the term regardless, and peer-reviewed medical journals still sometimes mention the Lady Windermere syndrome.[13]
In recent years, some have described the eponym as inappropriate,[14] and some have noted that it would have been unlikely that Lady Windermere had the condition to which her name was assigned.[15]
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| 関連記事 | 「Mycobacterium avium-intracellulare」「intracellular」「avium」「intracellulare」「Mycobacterium」 |