Atypical mycobacteria

Atypical mycobacteria, also known as nontuberculous mycobacteria (NTM), are types of mycobacteria that do not cause tuberculosis or leprosy. They are found in a variety of environmental sources including water, soil, and animals. Atypical mycobacteria can cause a range of diseases in humans, particularly in those with weakened immune systems.

Classification

Atypical mycobacteria are classified into four groups (I-IV) based on their growth rate and pigment production. Group I includes slow-growing, photochromogenic species such as Mycobacterium kansasii. Group II includes slow-growing, scotochromogenic species such as Mycobacterium scrofulaceum. Group III includes slow-growing, nonchromogenic species such as Mycobacterium avium and Mycobacterium intracellulare. Group IV includes rapid-growing species such as Mycobacterium fortuitum and Mycobacterium chelonae.

Diseases caused

Atypical mycobacteria can cause a variety of diseases in humans, including pulmonary disease, skin disease, lymphadenitis, and disseminated disease. The type of disease often depends on the species of mycobacteria and the individual's immune status. For example, Mycobacterium avium complex (MAC) is a common cause of pulmonary disease in individuals with chronic obstructive pulmonary disease (COPD) and disseminated disease in individuals with AIDS.

Diagnosis

Diagnosis of atypical mycobacterial infection typically involves microbiological culture of body fluids or tissues, followed by identification of the mycobacterial species using molecular techniques such as polymerase chain reaction (PCR). Imaging studies such as chest X-ray or CT scan may also be used to assess the extent of disease.

Treatment

Treatment of atypical mycobacterial infections typically involves a combination of antibiotics over a prolonged period, often several months to years. The choice of antibiotics depends on the species of mycobacteria and the site of infection. In some cases, surgical intervention may be required.

See also

• Mycobacterium
• Tuberculosis
• Leprosy
• Pulmonary disease
• Skin disease
• Lymphadenitis
• Disseminated disease