Other Pulmonary Infections
While pneumonia is most commonly due to bacteria or viruses, other more unusual organisms can also cause lung infections. Occasionally, organisms called fungi cause pneumonia. These organisms generally live in specific regions of the United States and cause disease in people who live in or travel to these areas. These infections usually resolve without therapy, but occasionally may be more serious and require treatment.
Tuberculosis (or TB) is another unusual infection that is much less common in the United States than half a century ago. Generally, people who have weakened immune systems or who live in countries where TB is common are at risk. TB is transmitted to close contacts by cough. Patients may acquire the TB organism at a young age. They frequently have no disease or symptoms in this phase only to activate the disease much later in life. The early asymptomatic stage (latent stage) can be detected with the help of skin testing (Tine test or PPD test). Certain patients with this early phase infection are candidates to receive antibiotic therapy to eradicate the infection thereby preventing potential active TB later in life.
The usual symptoms of active TB include many weeks of fevers, weight loss, sweats and tiredness. TB usually affects the lungs and can also cause cough productive of mucus sometimes mixed with blood. Abnormalities on chest x-rays frequently help raise the suspicion of TB and the diagnosis is made by testing the sputum. TB is very treatable but requires many months of a number of medications to cure it. It is critical that patients on therapy for TB take every dose of medication and complete the entire course of therapy.
Bronchitis is a very common infection that occurs in the main airways of the lungs (the bronchi) in contrast to pneumonia, which affects the air sacs (the alveoli) at the edges of the lungs. Bronchitis frequently causes cough (sometimes very severe and bothersome) that may be associated with production of mucus. Occasionally, bronchitis causes a slight fever and wheezing. These infections are frequently viral and for this reason, antibiotics may not be helpful. This illness will usually improve on its own but the cough may last for many days or even weeks.