Mycobacterium abscessus is a rapidly growing mycobacterium

Mycobacterium

Mycobacterium is a genus of Actinobacteria, given its own family, the Mycobacteriaceae. The genus includes pathogens known to cause serious diseases in mammals, including tuberculosis and leprosy...

 that is a common water contaminant. It was until recently (1992) thought to be a subspecies of Mycobacterium chelonae

Mycobacterium chelonae

Mycobacterium chelonae is a rapidly growing mycobacterium, that is found all throughout the environment including sewage and tap water. It can occasionally cause opportunistic infections of humans.It is grouped in Runyon group IV....

. M. abscessus can cause chronic lung disease, post-traumatic wound infections, and disseminated cutaneous diseases, mostly in patients with suppressed immune systems.

It is classified as a rapid growing mycobacterium

Rapid growing mycobacterium

Rapid growing mycobacterium consists of organism of the Mycobacterium fortuitum group and Mycobacterium chelonae/Mycobacterium abscessus group and these usually cause subcutaneous abscesses or cellulitis following trauma in immunocompetent patients....

.

Description

Microscopy

• Gram-positive, nonmotile and acid-fast rods (1.0-2.5 µm x 0.5 µm).

Colony characteristics

• Colonies on Löwenstein-Jensen media may occur as smooth as well as rough, white or greyish and nonphotochromogenic.

Physiology

• Growth at 28°C and 37°C after 7 days but not at 43°C.
• On MacConkey agar at 28°C and even 37°C.
• Tolerance to 5% NaCl and 500 mg/l hydroxylamine (Ogawa egg medium) and 0.2% picrate (Sauton agar medium).
• Positive degradation of p-aminosalicylate.
• Production of arylsulfatase but not of nitrate reductase and Tween 80 hydrolase.
• Negative iron uptake test. No utilisation of fructose, glucose, oxalate and citrate as sole carbon sources.

Differential characteristics

• M. abscessus and M. chelonae can be distinguished from M. fortuitum or M. peregrinum by their failure to reduce nitrate and to take up iron.
• Tolerance to 5% NaCl in Löwenstein-Jensen media tolerance to 0.2% picrate in Sauton agar and non-utilisation of citrate as a sole carbon source are characteristics that distinguish M. abscessus from M. chelonae.
• M. abscessus and M. chelonae sequevar I share an identical sequence in the 54-510 region of 16S rRNA, However, both species can be differentiated by their hsp65, ITS or rpoB
  RpoB
  rpoB is a bacterial gene that codes for part of an enzyme which synthesises RNA. Specifically, rpoB is the β subunit of the bacterial RNA polymerase. It is the subunit which possesses the polymerase activity, that is, it catalyzes the synthesis of RNA...
  
   sequences

Pathogenesis

• Chronic lung disease, post-traumatic wound infections, post-tympanostomy tube otitis media, disseminated cutaneous diseases in patients of immune suppression.

It can be associated with otitis media

Otitis media

Otitis media is inflammation of the middle ear, or a middle ear infection.It occurs in the area between the tympanic membrane and the inner ear, including a duct known as the eustachian tube. It is one of the two categories of ear inflammation that can underlie what is commonly called an earache,...

.