Which conditions are associated with a cough productive of foul-smelling sputum?

A cough that produces foul-smelling sputum is typically associated with certain pulmonary conditions that involve necrotic or infected lung tissue. Bronchiectasis and lung abscess both fit this profile well.

In bronchiectasis, chronic inflammation leads to the destruction of the bronchial walls, and it often results in chronic infection. This impaired clearance of mucus allows pathogens to thrive, leading to sputum that can be foul-smelling due to the presence of bacteria and necrotic tissue.

Similarly, a lung abscess, which is a localized collection of pus within the lung, can also produce foul-smelling sputum. The anaerobic bacteria typically responsible for these infections—often due to aspiration—contribute to the unpleasant odor of the sputum.

In contrast, the other conditions listed do not typically produce foul-smelling sputum. Asthma and bronchitis usually present with clear to yellow sputum, while pneumonia and tuberculosis can cause purulent sputum but generally not the distinctly foul odor that is characteristic of bronchiectasis and lung abscess. Chronic obstructive pulmonary disease and emphysema may lead to increased sputum production but again do not typically present with a foul smell.