abscessus

Abscessus (Mycobacterium abscessus) is a rapidly growing non-tuberculous mycobacterium that belongs to the Mycobacterium abscessus complex. It is environmental in origin, commonly found in water sources, soil, and biofilms, and can be acquired by inhalation or direct inoculation into tissue. In humans, it most often causes pulmonary disease, especially in individuals with preexisting lung conditions such as bronchiectasis or cystic fibrosis, but it can also cause skin and soft tissue infections after trauma or cosmetic procedures, as well as disseminated disease in immunocompromised hosts. Inhaled organisms can colonize the airways, leading to chronic infections that are difficult to eradicate.

Diagnosis relies on culture and molecular methods to distinguish M. abscessus from other mycobacteria and to separate subspecies within the complex (sensu stricto, massiliense, and bolletii). The organism grows rapidly on standard mycobacterial cultures, forming smooth, pigmented colonies within days. It is intrinsically resistant to many common antibiotics, and clinical management requires comprehensive susceptibility testing.

Treatment is challenging and typically involves a multi-drug regimen that includes a macrolide such as clarithromycin or azithromycin as a backbone therapy, often combined with an agent such as amikacin, cefoxitin, imipenem, tigecycline, or linezolid. The erm(41) gene can confer inducible macrolide resistance in some subspecies, complicating therapy. In pulmonary disease, treatment commonly extends for 12 months beyond culture conversion and may include surgical resection or localized therapies for focal disease. Outcomes vary and depend on disease site, baseline lung function, and antibiotic susceptibility.

Prevention focuses on reducing exposure to environmental reservoirs and meticulous infection control in healthcare settings. Abscessus remains an important cause of difficult-to-treat NTM infections worldwide.