Other Mycobacteria: Mycobacterium avium Complex, Mycobacterium kansasii, Mycobacterium scrofulaceum, Mycobacterium marinum and Mycobacterium ulcerans, Flashcards
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Mycobacterium avium complex (MAC): clinical findings
Mycobacterium avium complex (MAC) is a group of related mycobacterial species, including M. avium and M. intracellulare, which primarily cause infections in immunocompromised individuals, especially those with HIV/AIDS. Clinical manifestations include chronic pulmonary disease, lymphadenitis, and disseminated infections, with symptoms such as fever, weight loss, fatigue, and night sweats. It can also cause infections in the gastrointestinal tract and bones. Pulmonary disease often mimics tuberculosis with chronic cough, hemoptysis, and infiltrates on chest X-ray.
Mycobacterium avium complex (MAC): diagnosis and treatment
Diagnosis of MAC infection is based on culture of sputum, bronchial lavage, or biopsy from infected tissues. The diagnosis can be confirmed with PCR or acid-fast bacilli (AFB) staining. Treatment typically involves a combination of antibiotics, including macrolides (clarithromycin or azithromycin), rifabutin, and ethambutol. In severe cases, surgery may be required to remove infected tissue. Prophylaxis with macrolides is often used in immunocompromised patients, especially those with HIV/AIDS.
Mycobacterium kansasii: clinical findings
Mycobacterium kansasii is a nontuberculous mycobacterium (NTM) that causes pulmonary disease similar to tuberculosis. It is often found in the lungs of immunocompromised individuals and can also affect the lymph nodes and skin. Symptoms include chronic cough, hemoptysis, chest pain, and weight loss. It is more common in individuals with underlying lung disease or HIV infection.
Mycobacterium kansasii: diagnosis and treatment
Diagnosis of M. kansasii infection is made by culture, PCR, or AFB staining of sputum or other infected tissues. The organism grows slowly on standard mycobacterial media. Treatment typically involves a combination of drugs, including rifampin, isoniazid, and ethambutol, similar to the regimen used for tuberculosis. The duration of treatment can vary from 12 to 24 months depending on the severity of the infection.
Mycobacterium scrofulaceum: clinical findings
Mycobacterium scrofulaceum is a member of the nontuberculous mycobacteria (NTM) that primarily causes cervical lymphadenitis in children. The infection is usually localized to the lymph nodes and is often associated with a chronic, painless swelling, which may form a draining sinus. It can also cause skin infections and osteomyelitis, but it is less commonly associated with pulmonary disease.
Mycobacterium scrofulaceum: diagnosis and treatment
Diagnosis of M. scrofulaceum infection is based on culture from infected tissue or lymph node aspirates. Acid-fast bacilli can be seen on staining. Treatment typically involves a combination of macrolides (such as clarithromycin or azithromycin) and rifampin. Surgical drainage of infected lymph nodes may also be necessary in some cases.
Mycobacterium marinum: clinical findings
Mycobacterium marinum causes skin and soft tissue infections, usually following trauma with exposure to contaminated water, such as in swimming pools, fish tanks, or rivers. It often presents as localized granulomatous lesions, nodules, or ulcers. The infection may spread to the joints, tendons, or bones, causing a condition known as “fish tank granuloma.”
Mycobacterium marinum: diagnosis and treatment
Diagnosis of M. marinum infection is based on culture from skin lesions or aspirates. The organism grows on standard mycobacterial media. Treatment includes a combination of antibiotics such as doxycycline, clarithromycin, or rifampin. The infection typically responds well to antibiotics, but prolonged treatment may be necessary.
Mycobacterium ulcerans: clinical findings
Mycobacterium ulcerans causes Buruli ulcer, a chronic, necrotizing skin infection that often affects the limbs, particularly the lower extremities. It is characterized by large, painless ulcers with undermined edges and a necrotic center. The infection can lead to severe tissue damage and permanent deformities if left untreated.
Mycobacterium ulcerans: diagnosis and treatment
Diagnosis of M. ulcerans infection is made by PCR, culture, or biopsy of ulcer material. The presence of AFB in tissue samples or fluid from the ulcer is a hallmark of the infection. Treatment involves a combination of antibiotics, typically rifampin and clarithromycin, for 8 weeks. In severe cases, surgical debridement or grafting may be necessary to repair tissue damage.
Mycobacterium fortuitum complex: clinical findings
The M. fortuitum complex includes M. fortuitum and other related species, which are rapidly growing mycobacteria that can cause skin and soft tissue infections, often following trauma or surgery. They can also cause pulmonary disease in immunocompromised individuals. Common infections include abscesses, cellulitis, and surgical wound infections.
Mycobacterium fortuitum complex: diagnosis and treatment
Diagnosis of M. fortuitum complex infection is based on culture and AFB staining of the infected tissue or biopsy. The bacteria grow rapidly on standard media. Treatment typically involves a combination of antibiotics, such as amikacin, ciprofloxacin, or doxycycline. Surgery may also be necessary to remove infected tissue.
Mycobacterium chelonae-abscessus: clinical findings
Mycobacterium chelonae-abscessus is a rapidly growing mycobacterium that causes a variety of infections, including skin and soft tissue infections, post-surgical infections, and respiratory tract infections, particularly in immunocompromised patients. It can also cause chronic wounds, abscesses, and osteomyelitis. The infection can be persistent and difficult to treat.
Mycobacterium chelonae-abscessus: diagnosis and treatment
Diagnosis of M. chelonae-abscessus infection is based on culture, PCR, or AFB staining. It grows rapidly on standard media. Treatment typically involves a combination of antibiotics, including amikacin, imipenem, or clarithromycin, along with surgical debridement in some cases. Therapy may need to be prolonged due to the bacteria’s resistance to many antibiotics.
