Infection with Mycobacterium avium complex in patients without predisposing conditions

Area of Science:

• Pulmonology
• Infectious Diseases
• Microbiology

Background:

• Mycobacterium avium complex (MAC) pulmonary disease typically affects immunocompromised individuals or those with chronic lung conditions.
• The prevalence of MAC pulmonary disease is increasing globally.
• Identifying MAC pulmonary disease in patients without traditional risk factors presents a diagnostic challenge.

Purpose of the Study:

• To describe the clinical characteristics of MAC pulmonary disease in patients lacking usual predisposing factors.
• To investigate the diagnostic delay and treatment outcomes in this patient cohort.
• To highlight the importance of considering MAC in atypical patient populations.

Main Methods:

• Retrospective case series analysis of 21 patients diagnosed with MAC pulmonary disease between 1978 and 1987.
• Review of patient demographics, clinical presentation, chest imaging, microbiological cultures, and histopathological findings.
• Assessment of treatment responses and long-term outcomes, including relapse and mortality.

Main Results:

• 18% of surveyed patients (21/119) had MAC pulmonary disease without typical risk factors; most were elderly women.
• Common symptoms included persistent cough and purulent sputum, with a mean diagnostic delay of 25 weeks.
• Nodular opacities on chest X-rays predominated (71%), with limited cavitary disease at presentation.
• All patients initially responded to therapy, but 8 relapsed after treatment cessation. Four patients died from progressive disease.

Conclusions:

• Pulmonary MAC can occur in individuals without predisposing conditions, especially elderly women.
• The indolent nature of the disease contributes to delayed diagnosis and potentially poorer outcomes.
• Increased awareness and diagnostic vigilance are crucial for timely management of MAC pulmonary disease in diverse patient groups.