Acute bronchitis is an inflammation of the bronchial tubes of the lungs. The bronchi are airway passages in the lungs that form a tree-like system, each getting narrower as they descend into the lungs. Acute bronchitis is usually caused by a viral infection that inflames these passages, causing them to narrow and secrete mucus. Common viruses that can cause acute bronchitis are the rhinovirus, respiratory syncytial virus, and influenza. Symptoms are often a loose productive cough, a runny nose, nasal congestion and a sore throat. Antibiotics are generally not effective …