Mycobacteria

Abstract Mycobacteria are Gram-negative, rod-shaped bacilli comprising the Mycobacterium tuberculosis complex (TB) and non-tuberculous mycobacteria. Infection, usually via inhalation, is often asymptomatic but can lead to primary TB or to latent TB infection which can later develop into ‘reactivation’ or ‘post-primary’ active disease. Pulmonary TB is the commonest manifestation, but extrapulmonary disease can affect almost any organ. Definitive diagnosis is by culture. Standard chemotherapy involves the use of rifampicin, isoniazid, pyrazinamide, and ethambutol. Drug resistance is an increasing problem. Around 1.5 million people die from TB each year. Infection tends to present with a worsening of chronic respiratory symptoms in patients with underlying lung diseases. Diagnosis is difficult because these organisms are common in the environment. A long course of treatment with several drugs is required.