Acute bronchitis is an inflammation of the tracheobronchial tree, usually in association with a generalized respiratory infection affecting 40/1000 adults each year in the United Kingdom.1 It is the fifth most common diagnosis in patients presenting with cough.2 It occurs most commonly during the winter months and is associated with respiratory viruses, including rhinovirus, coronavirus, influenza viruses, and adenovirus. Mycoplasma pneumoniae, Chlamydia pneumoniae, and Bordetella pertussis may also cause bronchitis. Secondary invasion with bacteria such as Haemophilus influenzae and Streptococcus pneumoniae may also play a role in acute bronchitis. However in only 50% of persons with acute bronchitis have a pathogen identified.1
Cough is the most prominent manifestation of acute bronchitis. Initially, the cough is nonproductive, but later mucoid sputum is produced. Still later in the course of the illness, purulent sputum is present. Many patients with acute bronchitis also have tracheitis. Symptoms of tracheal involvement include burning substernal pain associated with respiration and a very painful substernal sensation with coughing. Rhonchi and coarse crackles may be heard on examination of the chest; however, there are no signs of consolidation and the chest radiograph shows no opacity. Cough persists on average 11.4 days.1,2
Most cases of acute bronchitis require measures directed only at relieving cough. There are very few good clinical trials comparing various symptomatic relief measures to placebo so we do not know whether or not they are better than placebo.1 Such measures include analgesics, antihistamines, antitussives, inhaled or oral beta2-agonists, expectorants and mucolytics. For patients with fever or a predominant tracheitis component and purulent sputum, the sputum should be gram stained and cultured. If there is a predominant microorganism seen in the presence of more than 25 polymorphonuclear neutrophils and fewer than 10 squamous epithelial cells per low-power field, antibiotic therapy directed against S. pneumoniae and H. influenzae should be instituted. Most patients, however, do not require antibiotic therapy for acute bronchitis; it is a self-limited disease. Indeed, overuse of antibiotics in this setting is a driver of antimicrobial resistance.
Community-Acquired Pneumonia: Epidemiology, Clinical Assessment, and Diagnostic Work-Up
Pneumonia is defined as inflammation and consolidation of lung tissue due to an infectious agent (see also Chapter 122). Pneumonia that develops outside the hospital is considered community-acquired pneumonia (CAP). A clinical definition of pneumonia is two or more of the following symptoms/physical findings: productive cough, purulent sputum, dyspnea or tachypnea (respiratory rate >20 breaths per minute), rigors or chills, pleuritic chest pain in conjunction with a new opacity on chest radiograph.3 Pneumonia developing 72 hours or more after admission to hospital is nosocomial, or hospital acquired. There is still some debate as to whether nursing home–acquired pneumonia (NHAP) should be considered community-acquired or nosocomial pneumonia. In recent years, the concept of healthcare-associated pneumonia (HCAP) has arisen. This term was introduced in 2005 ...