Nontuberculous mycobacteria
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Nima Nasiri, M.D.[2]
Overview
Historical Perspective
- [Disease name] was first discovered by [scientist name], a [nationality + occupation], in [year] during/following [event].
- In [year], [gene] mutations were first identified in the pathogenesis of [disease name].
- In [year], the first [discovery] was developed by [scientist] to treat/diagnose [disease name].
Classification
- [Disease name] may be classified according to [classification method] into [number] subtypes/groups:
- [group1]
- [group2]
- [group3]
- Other variants of [disease name] include [disease subtype 1], [disease subtype 2], and [disease subtype 3].
Pathophysiology
- The pathogenesis of [disease name] is characterized by [feature1], [feature2], and [feature3].
- The [gene name] gene/Mutation in [gene name] has been associated with the development of [disease name], involving the [molecular pathway] pathway.
- On gross pathology, [feature1], [feature2], and [feature3] are characteristic findings of [disease name].
- On microscopic histopathological analysis, [feature1], [feature2], and [feature3] are characteristic findings of [disease name].
Clinical Features
Differentiating [disease name] from other Diseases
- [Disease name] must be differentiated from other diseases that cause [clinical feature 1], [clinical feature 2], and [clinical feature 3], such as:
- [Differential dx1]
- [Differential dx2]
- [Differential dx3]
Epidemiology and Demographics
- The prevalence of [disease name] is approximately [number or range] per 100,000 individuals worldwide.
- In [year], the incidence of [disease name] was estimated to be [number or range] cases per 100,000 individuals in [location].
Age
- Patients of all age groups may develop [disease name].
- [Disease name] is more commonly observed among patients aged [age range] years old.
- [Disease name] is more commonly observed among [elderly patients/young patients/children].
Gender
- [Disease name] affects men and women equally.
- [Gender 1] are more commonly affected with [disease name] than [gender 2].
- The [gender 1] to [Gender 2] ratio is approximately [number > 1] to 1.
Race
- There is no racial predilection for [disease name].
- [Disease name] usually affects individuals of the [race 1] race.
- [Race 2] individuals are less likely to develop [disease name].
Risk Factors
- Common risk factors in the development of [disease name] are [risk factor 1], [risk factor 2], [risk factor 3], and [risk factor 4].
Natural History, Complications and Prognosis
- The majority of patients with [disease name] remain asymptomatic for [duration/years].
- Early clinical features include [manifestation 1], [manifestation 2], and [manifestation 3].
- If left untreated, [#%] of patients with [disease name] may progress to develop [manifestation 1], [manifestation 2], and [manifestation 3].
- Common complications of [disease name] include [complication 1], [complication 2], and [complication 3].
- Prognosis is generally [excellent/good/poor], and the [1/5/10year mortality/survival rate] of patients with [disease name] is approximately [#%].
Diagnosis
Diagnostic Criteria
- The diagnosis of [disease name] is made when at least [number] of the following [number] diagnostic criteria are met:
- [criterion 1]
- [criterion 2]
- [criterion 3]
- [criterion 4]
Symptoms
- [Disease name] is usually asymptomatic.
- Symptoms of [disease name] may include the following:
- [symptom 1]
- [symptom 2]
- [symptom 3]
- [symptom 4]
- [symptom 5]
- [symptom 6]
Physical Examination
- Patients with [disease name] usually appear [general appearance].
- Physical examination may be remarkable for:
- [finding 1]
- [finding 2]
- [finding 3]
- [finding 4]
- [finding 5]
- [finding 6]
Laboratory Findings
- There are no specific laboratory findings associated with [disease name].
- A [positive/negative] [test name] is diagnostic of [disease name].
- An [elevated/reduced] concentration of [serum/blood/urinary/CSF/other] [lab test] is diagnostic of [disease name].
- Other laboratory findings consistent with the diagnosis of [disease name] include [abnormal test 1], [abnormal test 2], and [abnormal test 3].
Imaging Findings
- There are no [imaging study] findings associated with [disease name].
- [Imaging study 1] is the imaging modality of choice for [disease name].
- On [imaging study 1], [disease name] is characterized by [finding 1], [finding 2], and [finding 3].
- [Imaging study 2] may demonstrate [finding 1], [finding 2], and [finding 3].
Other Diagnostic Studies
- [Disease name] may also be diagnosed using [diagnostic study name].
- Findings on [diagnostic study name] include [finding 1], [finding 2], and [finding 3].
Treatment
Medical Therapy
Prophylaxis and Treatment of NTM Disease
- For the treatment of MAC pulmonary disease in most patients with nodular/bronchiectatic disease, a three-times-weekly regimen of clarithromycin (1,000 mg) or azithromycin (500 mg), rifampin (600 mg), and ethambutol (25 mg/kg) are recommended. For patients with cavitary MAC lung disease or severe nodular/bronchiectatic disease, a daily regimen of clarithromycin (500–1,000 mg) or azithromycin (250 mg), rifampin (600 mg) or rifabutin (150–300 mg), and ethambutol (15 mg/kg) with consideration of three-times-weekly amikacin or streptomycin early in therapy is recommended. Patients should be treated until culture negative on therapy for 1 year.
- Treatment of disseminated MAC disease: Therapy should include clarithromycin (1,000 mg/d) or azithromycin (250 mg/d) and ethambutol (15 mg/kg/d) with or without rifabutin (150–350 mg/d). Therapy can be discontinued with resolution of symptoms and reconstitution of cell-mediated immune function.
- Prophylaxis of disseminated MAC disease: Prophylaxis should be given to adults with acquired immunodeficiency syndrome (AIDS) with CD4+ T-lymphocyte counts less than 50 cells/μl. Azithromycin 1,200 mg/week or clarithromycin 1,000 mg/day have proven efficacy. Rifabutin 300 mg/day is also effective but less well tolerated.
- Treatment of M.kansasii pulmonary disease. A regimen of daily isoniazid (300 mg/d), rifampin (600 mg/d), and ethambutol (15 mg/kg/d). Patients should be treated until culture negative on therapy for 1 year.
- Treatment of M.abscessus pulmonary disease. There are no drug regimens of proven or predictable efficacy for treatment of M.abscessus lung disease. Multidrug regimens that include clarithromycin 1,000 mg/day may cause symptomatic improvement and disease regression. Surgical resection of the localized disease combined with multidrug clarithromycin-based therapy offers the best chance for cure of this disease.
- Treatment of nonpulmonary disease caused by RGM (M.abscessus, M.chelonae, M.fortuitum). The treatment regimen for these organisms is based on in vitro susceptibilities. For M.abscessus disease, a macrolide-based regimen is frequently used. Surgical debridement may also be an important element of successful therapy.
- Treatment of NTM cervical lymphadenitis. NTM cervical lymphadenitis is due to MAC in the majority of cases and treated primarily by surgical excision, with a greater than 90% cure rate. A macrolide-based regimen should be considered for patients with extensive MAC lymphadenitis or poor response to surgical therapy.
Surgery
- Surgical resection in conjunction with multidrug clarithromycin-based therapy is the most common approach to the treatment of localized M.abscessus lung disease.
Prevention
- Effective measures for the primary prevention of NTM pulmonary disease include avoidance of exposure to NTM rich environments such as soil and water. Some experts believe that decreasing exposure to NTM organisms may be helpful preventive methods.