Mycobacterium avium-complex (MAC, Mycobacterium avium intracellulare, MAI)
Jump to navigation
Jump to search
Etiology
- immunodeficiency (most commonly AIDS)
- HIV1 infection with CD4 count < 50/uL[3]
- underlying pulmonary disease
Epidemiology
- organism is ubiquitous in the environment
- respiratory tract & GI tract are portals of entry
- 18-44% of patients with AIDS will develop MAC without prophylaxis; 2% with effective antiviral therapy
- white, middle-aged/elderly male smokers/COPD
- non-smoking women over age 50 without underlying lung disease (Lady Windermere Syndrome)
- most common nontuberculous mycobacterial infection[3]
- most common cause of chronic lung infection worldwide[3]
Pathology
- disseminated multiorgan infection
- occurs in patients with HIV1 with CD4 counts < 50/uL & not received prophylaxis for MAC (see management)[3]
- sustained bacteremia
- generally late-stage HIV complication with CD4 < 50/mm3
- localized disease syndrome (uncommon)
- hypersensitivity pneumonitis 'hot-tub lung'
- tuberculosis-like infection in elderly male smokers
- chronic right middle lobe syndrome, lingula infection & cough in elderly women (Lady Windermere syndrome)
- enteritis
- pericarditis
- osteomyelitis
- skin lesions
- soft tissue abscesses
- central nervous system lesions
- lymphadenitis[3]
Clinical manifestations
- fever
- night sweats
- chronic cough
- weight loss
- fatigue
- wasting
- diarrhea
- abdominal pain
- hepatosplenomegaly
- intra-abdominal lymphadenopathy
- resembles tuberculosis symptomatically
Laboratory
- complete blood count
- anemia (Hct < 30%)
- neutropenia
- liver function tests
- elevated alkaline phosphatase
- sputum for acid-fast bacteria
- sputum culture for Mycobacterium
- repeat sputum culture if positive before treating
- supposedly this will help distinguish infection for colonization (common)[3]
- repeat sputum culture if positive before treating
- blood cultures
- bone marrow biopsy & culture
- antimicrobial sensitivities
- Mycobacterium avium complex DNA
- Mycobacterium avium complex rRNA
- IFN-gamma release test is negative[3]
Diagnostic procedures
Radiology
- resembles tuberculosis radiographically
- nodular opacities with bronchiectasis in the right middle lobe on chest imaging (Lady Windermere syndrome)
Complications
- immune reconstitution inflammatory syndrome occurs in AIDS patients with disseminated Mycobacterium avium complex[3]
Management
- pulmonary disease or disseminated infection with patients with CD4 count < 50/uL sufficient to warrant therapy[3]
- organisms usually resistant to most conventional anti- mycobacterial agents*
- combination of 2 or 3 drugs
- macrolide[3]
- clarithromycin 500 mg BID
- azithromycin 500 mg QD
- ethambutol 25 mg/kg/day x 2 months, then 15 mg/kg/day +
- with or without rifabutin 300 mg/day or rifampin
- dosage 3 times weekly as effective as daily with fewer adverse effects[6]
- macrolide[3]
- alternative agents
- fluoroquinolone
- levofloxacin
- ciprofloxacin 500-750 mg BID
- streptomycin
- amikacin 10-15 mg/kg/day IV
- fluoroquinolone
- response may be expected after 2-8 weeks of therapy
- discontinue treatment after 12 months of successful treatment[4]
- consider surgery for local or unresponsive disease
- prophylaxis when CD4 count < 50/uL
- azithromycin 1200 mg weekly (prophylaxis of choice)
- clarithromycin 500 mg BID
- discontinue prophylaxis when CD4 count > 100/mm3 for 3 months[4]
- empiric antibiotic therapy for Mycobacterial infection in a patients with advanced HIV infection
* Mycobacterium avium is frequently/generally resistant to isoniazid & rifampin.
More general terms
More specific terms
Additional terms
References
- ↑ Mayo Internal Medicine Board Review, 1998-99, Prakash UBS (ed) Lippincott-Raven, Philadelphia, 1998, pg 579
- ↑ Harrison's Principles of Internal Medicine, 13th ed. Isselbacher et al (eds), McGraw-Hill Inc. NY, 1994, pg 723
- ↑ 3.00 3.01 3.02 3.03 3.04 3.05 3.06 3.07 3.08 3.09 3.10 Medical Knowledge Self Assessment Program (MKSAP) 11, 16, 17, 18, 19. American College of Physicians, Philadelphia 1998, 2012, 2015, 2018, 2021.
- ↑ 4.0 4.1 4.2 Journal Watch 22(20):150, 2002 Yeni PG et al, JAMA 288:222, 2002 Dybul M et al, Ann Intern Med 137:381, 2002 MMWR Recomm Rep 51:1-64, 2002 http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5107a1.htm Masur H et al, Ann Intern Med 137:435, 2002 http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5108a1.htm
- ↑ Kasperbauer SH, Daley CL. Diagnosis and treatment of infections due to Mycobacterium avium complex. Semin Respir Crit Care Med. 2008 Oct;29(5):569-76 PMID: https://www.ncbi.nlm.nih.gov/pubmed/18810690
- ↑ 6.0 6.1 Jeong B-H et al. Intermittent antibiotic therapy for nodular bronchiectatic Mycobacterium avium complex lung disease. Am J Respir Crit Care Med 2015 Jan 1; 191:96. PMID: https://www.ncbi.nlm.nih.gov/pubmed/25393520
Bag R and Griffith DE. Therapy for Mycobacteriium avium complex lung disease. It ain't perfect, but it's progress. Am J Respir Crit Care Med 2015 Jan 1; 191:14 PMID: https://www.ncbi.nlm.nih.gov/pubmed/25551346 - ↑ NEJM JWatch Question of the Week. March 27, 2018 https://knowledgeplus.nejm.org/question-of-week/562/
- ↑ Ebihara T, Sasaki H. Bronchiectasis with Mycobacterium avium Complex Infection. N Engl J Med 2002; 346:1372 <PubMed> PMID: https://www.ncbi.nlm.nih.gov/pubmed/11986411 Free full text <Internet> http://www.nejm.org/doi/full/10.1056/NEJMicm010899
- ↑ Kasperbauer SH, Daley CL. Diagnosis and treatment of infections due to Mycobacterium avium complex. Semin Respir Crit Care Med 2008 Sep 24; 29:569 PMID: https://www.ncbi.nlm.nih.gov/pubmed/18810690