:Mycobacterium avium complex

File:Slant tubes of Löwenstein-Jensen medium with control, M tuberculosis, M avium and M gordonae.jpg. From left to right:
- Negative control
- M. tuberculosis: Dry-appearing colonies
- Mycobacterium avium complex: Wet-appearing colonies
- M. gordonae: Yellowish colonies]]

In the Runyon classification, both bacteria are nonchromogens. They can be differentiated from M. tuberculosis and each other by commercially available DNA probes.{{cite book|last1=Jones-Lopez|first1=Edward C.|last2=Ellner|first2=Jerrold J.|editor1-last=Guerrant|editor1-first=Richard L.|editor2-last=Walker|editor2-first=David H.|editor3-last=Weller|editor3-first=Peter F.|title=Tropical infectious diseases : principles, pathogens, & practice|date=2011|publisher=Saunders|location=Edinburgh|isbn=9780702039355|edition=3rd|chapter=Chapter 35: Tuberculosis and Atypical Mycobacterial Infections}}{{rp|245}}

They are characterized as Gram-positive, nonmotile, acid-fast, short to long rods.{{cn|date=December 2022}}

Colony characteristics

• Usually, colonies are smooth, rarely rough, and not pigmented colonies. Older colonies may become yellow.

Physiology

• Growth on Löwenstein-Jensen medium and Middlebrook 7H10 agar occurs at 37°C after seven or more days.
• The complex can be (but is not often) resistant to isoniazid, ethambutol, rifampin, and streptomycin.{{cite journal | vauthors = Haworth CS, Banks J, Capstick T, Fisher AJ, Gorsuch T, Laurenson IF, Leitch A, Loebinger MR, Milburn HJ, Nightingale M, Ormerod P, Shingadia D, Smith D, Whitehead N, Wilson R, Floto RA | title = British Thoracic Society guidelines for the management of non-tuberculous mycobacterial pulmonary disease (NTM-PD) | journal = Thorax | volume = 72 | issue = Suppl 2 | pages = ii1–ii64 | date = November 2017 | pmid = 29054853 | doi = 10.1136/thoraxjnl-2017-210927 | doi-access = free }}

Differential characteristics

• M. intracellulare and M. avium form the M. avium complex (MAC).
• Remarkable ITS heterogeneity is seen within different M. intracellulare isolates.

• Mycobacterium avium
• Mycobacterium avium subsp. paratuberculosis

• M. intracellulare type strains include ATCC 13950, CCUG 28005, CIP 104243, DSM 43223, JCM 6384, and NCTC 13025.[http://bacdive.dsmz.de/index.php?search=8403&submit=Search Type strain of Mycobacterium intracellulare at BacDive - the Bacterial Diversity Metadatabase]
• M. avium type strains include ATCC 25291, DSM 44156, and TMC 724.[http://bacdive.dsmz.de/index.php?site=search&rd=8419 Type strain of Mycobacterium avium at BacDive - the Bacterial Diversity Metadatabase]

MAC bacteria enter most people's body when inhaled into the lungs or swallowed, but only cause infection in those who are immunocompromised or who have severe lung disease such as those with cystic fibrosis or chronic obstructive lung disease (COPD). MAC infection can cause COPD and lymphadenitis, and can cause disseminated disease, especially in people with immunodeficiency.{{rp|245}}

During the last decade Mycobacterium chimaera (see below) infections following cardiothoracic surgery, especially open-heart surgery, have been increasingly reported worldwide.{{Cite journal |last1=Riccardi |first1=Niccolò |last2=Monticelli |first2=Jacopo |last3=Antonello |first3=Roberta Maria |last4=Luzzati |first4=Roberto |last5=Gabrielli |first5=Marco |last6=Ferrarese |first6=Maurizio |last7=Codecasa |first7=Luigi |last8=Di Bella |first8=Stefano |last9=Giacobbe |first9=Daniele Roberto |date=2020 |title=Mycobacterium chimaera infections: An update |url=https://linkinghub.elsevier.com/retrieve/pii/S1341321X19303459 |journal=Journal of Infection and Chemotherapy |language=en |volume=26 |issue=3 |pages=199–205 |doi=10.1016/j.jiac.2019.11.004|pmid=31843377 }} Infections usually involve the respiratory system. Mycobacterium chimaera is acquired during cardiopulmonary bypass via bioaerosols emitted from contaminated heater-cooler units water systems. Due to nonspecific symptoms and long latency, postoperative Mycobacterium chimaera infections may not be promptly diagnosed and treated, and may become life-threatening.

In 2004, Tortoli et al. proposed the name M. chimaera for strains that a reverse hybridization–based line probe assay suggested belonged to MAIS (M. avium–M. intracellulare–M. scrofulaceum group), but were different from M. avium, M. intracellulare, or M. scrofulaceum. The new species name comes from the Chimera, a mythological being made up of parts of three different animals.{{cite journal |last=Henry |first=Ronnie |date=March 2017 |title=Etymologia: Mycobacterium chimaera |journal= Emerg Infect Dis |volume=23 |issue=3 |pages=499 |doi=10.3201/eid2303.ET2303 |quote=Citing public domain text from the CDC.|pmc=5382748 }}{{cite journal|last1=Tortoli|first1=E|last2=Rindi|first2=L|last3=Garcia|first3=MJ|last4=Chiaradonna|first4=P|last5=Dei|first5=R|last6=Garzelli|first6=C|last7=Kroppenstedt|first7=RM|last8=Lari|first8=N|last9=Mattei|first9=R|last10=Mariottini|first10=A|last11=Mazzarelli|first11=G|last12=Murcia|first12=MI|last13=Nanetti|first13=A|last14=Piccoli|first14=P|last15=Scarparo|first15=C|title=Proposal to elevate the genetic variant MAC-A, included in the Mycobacterium avium complex, to species rank as Mycobacterium chimaera sp. nov.|journal=International Journal of Systematic and Evolutionary Microbiology|date=July 2004|volume=54|issue=Pt 4|pages=1277–85|pmid=15280303|doi=10.1099/ijs.0.02777-0}}

{{Reflist}}

• {{MeshName|Mycobacterium avium Complex}}

{{Gram-positive actinobacteria diseases}}

{{Mycobacteria}}

{{Taxonbar|from=Q3311330}}

{{DEFAULTSORT:Mycobacterium Intracellulare}}

Category:Acid-fast bacilli

avium complex

Category:Bacteria described in 1965

Category:Pathogenic bacteria