Current Management of Bronchitis

Emerg Med 40(2):29, 2008

By Michael J. Bono, MD, FACEP

The author reviews clinical presentation and guidelines for one of the patient complaints you’re most likely to see at this time of year.

Acute bronchitis is a respiratory tract infection and one of the most common diagnoses in the fall and winter months. Most cases are caused by viruses and are self-limiting, but patients with bronchitis are uncomfortable and often seek symptomatic relief from their physician. In this article, I’ll discuss the pathophysiology of bronchitis, the hallmark cough and other signs and symptoms, and the appropriate use of antibiotics.

INFECTION OF THE AIRWAYS

Bronchitis (sometimes referred to as tracheobronchitis; in children, bronchiolitis) is usually associated with a generalized respiratory infection, upper respiratory infection (such as rhinosinusitis or pharyngitis), or the common cold. As a result of the infection, exudates form and bronchospasm often develops in the entire respiratory tree.

Both viruses and bacteria can cause acute bronchitis. Common viruses are influenza A and B, adenovirus, parainfluenza virus, rhinovirus, respiratory syncytial virus and Coxsackie virus A21. Other less common viruses include measles, rubella, herpesviruses, coronaviruses, and echovirus. Bacteria linked to acute bronchitis are Bordetella pertussis, Mycoplasma pneumoniae, Chlamydophila (formerly called Chlamydia pneumoniae), and Streptococcus pneumoniae (also called pneumococcus).

These pathogens invade at different times of the year. In the summer, for example, bronchitis may be caused by coxsackievirus and echovirus. In the wintertime, the influenza virus can be involved. Rhinovirus and <em>M. pneumoniae</em>, on the other hand, can cause acute bronchitis any time during the year. From fall to spring, all other viruses can come into play.

Severe cases of bronchitis are caused by herpes simplex and measles. Respiratory syncytial bronchitis in children can cause acute bronchitis in adults as well as acute pneumonia in adults.

Almost all causes of acute bronchitis are infectious. Viruses are far more common as causes of bronchitis overall (both acute and chronic) than bacteria.

AMONG THE TOP FIVE DIAGNOSES

Bronchitis is a very common disease and has remained in the top five diagnoses in the United States for the last 20 years. Acute bronchitis consistently ranks among the top 10 conditions accounting for most ambulatory visits to U.S. physicians.

Each year, approximately 5% of adults in the United States report an episode of bronchitis and seek medical care. Work absences from bronchitis cost businesses millions of dollars per year.

Bronchitis falls along a spectrum of disease ranging from the common cold to respiratory failure. There is a very strong association between asthma and bronchitis, and “asthmatic bronchitis” represents the middle range of this disease spectrum. Patients who are diagnosed with acute bronchitis are likely to have a previous history of asthma or atopic disease and are likely to have subsequent visits for asthma.

ANATOMY AND PATHOGENESIS

The trachea runs from the larynx to the fourth thoracic vertebra, with C-shaped cartilage plates throughout its length. Many mucous glands populate the entire respiratory tree in the pseudostratified respiratory epithelium. It is important to differentiate between bronchi and bronchioles. Bronchi are proximal to the last plate of cartilage in the airway, and there are approximately 15 generations of divisions. Bronchioles, which do not have cartilage, are distal to the last plate of cartilage in the airway. They are proximal to the alveolae and are the final three to five generations of divisions of the bronchi. Thus, the smallest airways, like the alveolae, collapse under pressure.

During an episode of acute bronchitis, the mucous membranes of the tracheobronchial tree become edematous and hyperemic. Bronchial secretions increase markedly. The role of these secretions is controversial; some researchers feel that they are helpful in moving pathogens up and out out of the respiratory tree, but others disagree. Their purulence and color are not important. Purulent secretions in bronchitis are as likely to be viral as bacterial in origin, so you can’t base a diagnosis on this finding. The same is true of color.

Pathogens invade the respiratory epithelium to varying degrees. Influenza is the worst invader; it destroys the entire epithelium, which takes weeks to regenerate fully. This is thought to be one of the reasons influenza is so deadly. At the other end of the spectrum, rhinovirus causes little damage to the epithelium.

The result of this invasion of the respiratory epithelium, in most cases, is impaired mucociliary function. With <em>M. pneumoniae</em>, however, there is a different result. Because <em>M. pneumoniae</em> is an organism that attaches to the respiratory epithelium, rather than invading it, the mucosal cells will eventually slough off, denuding the lining of the airway. Patients with <em>M. pneumoniae</em> will cough for weeks because of this denuded airway.

Air pollutants play a role in the severity of bronchitis. The severity and frequency of bronchitis episodes will increase with exposure to pollutants and cigarette smoke. The combination of exposures may lead to prolonged abnormalities in airway resistance and reactivity.

CLINICAL FEATURES

Cough is the hallmark of acute bronchitis, occurring in approximately 50% of all cases of common respiratory illness in people of all ages. Cough is one of the true respiratory tract symptoms, as opposed to fever, chest pain, shortness of breath, or dyspnea on exertion, which can be symptoms of many other diseases. Infection with any of the major respiratory viruses and bacteria will cause a cough.

Bronchitis is also frequently associated with fever and strongly associated with hoarseness. Other symptoms typically seen in bronchitis are rhinitis, myalgias, dyspnea or wheezing as a result of bronchospasm, and mucus production in the airways.

The influenza A and B viruses produce the most severe symptoms, with an abrupt onset of fever, chills, headache, and myalgias. These symptoms will subside over three or four days but are followed by a nonproductive cough lasting one to two weeks. One-quarter of patients may have rales or wheezes. Outbreaks of bronchitis caused by influenza A and B are common during the winter.

Rhinovirus is a much more common cause of acute bronchitis than the influenza viruses, but it causes less severe symptoms. Adenovirus causes acute bronchitis among patients in close contact, such as military recruits and college students living in dormitories. The measles virus causes a very severe cough and severe bronchitis. Respiratory syncytial virus is the usual cause of bronchiolitis in children.

Bordetella pertussis warrants special mention because its incidence has been increasing since 1981. Adults with a chronic cough that persists for several weeks may have B. pertussis infection. Childhood immunizations provide protection for 4 to 12 years and then lose immunogenicity. Adults may be reservoirs of the disease and may then transmit the infection to children. Patients will have low-grade fever, rhinorrhea, and conjunctivitis; adults do not have the “whoop” heard in children’s cough.

Mycoplasma pneumoniae is found in older children and young adults. There seem to be epidemics of bronchitis caused by this virus every four to seven years. An incubation period of 16 to 30 days is typical with this infection. Symptoms tend to resolve quickly.

Chlamydophila and closely associated organisms are also known as TWAR organisms (“TW” for Taiwan and “AR” for acute respiratory disease). This form of bronchitis is found mainly in the elderly and may cause wheezing. It has a 30-day incubation period, and patients may be afebrile and have minimal sputum production. Laryngitis is common, and symptoms may persist after antibiotic therapy. Chlamydophila is very difficult to detect and notoriously difficult to culture. Its incidence may actually be much higher than currently thought.

The causative organism in acute bronchitis is difficult to determine because of sampling techniques. The problem in getting a sample of tracheobronchial secretions by passing a bronchoscope through the nasopharynx is that the secretions are contaminated by the nasopharyngeal flora. The only way to do this without contamination is with transtracheal aspiration, which is extremely painful and has proved fatal in some cases. Some clues to determining the causative organism may lie in DNA markers for <em>M. pneumoniae</em> and Chlamydophila.

WHY PATIENTS SEEK MEDICAL ATTENTION

Patients seek medical attention because of acute discomfort or because their symptoms are getting worse or are persisting. The cough is usually the most troublesome symptom. It begins dry but later becomes productive of sputum, which starts out with a mucoid appearance and then becomes purulent.

The duration and frequency of the cough are increased in smokers. All patients with bronchitis who are smokers should be advised of smoking cessation programs.

Another possible cause of patient discomfort is tracheal involvement, which may result in substernal chest pain with burning on deep inspiration. This symptom of acute bronchitis is sometimes difficult to distinguish from cardiac disease.

DIAGNOSTIC CRITERIA

Clinical diagnostic criteria for acute bronchitis include a cough of less than one week’s duration with no prior history of lung disease. The patient should have normal arterial oxygenation and no abnormalities on auscultation. Wheezing is also diagnostic, but it should be wheezing without a history of asthma or bronchospasm. Patients should not have significant dyspnea, cyanosis, or signs of consolidation on auscultation. A patient with any of these signs should have a chest x-ray performed to evaluate for pneumonia, which requires different treatment than acute bronchitis.

Fever may or may not be present. The organisms that cause fever are adenovirus, the influenza viruses, <em>M. pneumoniae</em>, and bacteria. Agents that typically do not cause fever are rhinovirus and coronaviruses.

The differential diagnosis should include foreign body aspiration, pulmonary embolus, heart failure, endobronchial tumor, and pulmonary fibrosis.

Obviously, it is mandatory to ask patients if they smoke cigarettes, and it is amazing how many patients will continue to smoke cigarettes even during a bout of acute bronchitis. But also ask about exposure to toxic substances—particularly if patients live in industrial areas—and immunizations, especially for influenza, S. pneumoniae, and Haemophilus influenzae.

Immunity to pertussis vaccination in early childhood wanes in adolescents and adults. Pertussis infection in adolescents and adults causes a severe prolonged cough and may have associated symptoms, such as rhinorrhea, conjunctival injection, lacrimation, and low-grade fever. The most serious problem with pertussis in older age groups is the potential for the disease to spread to children, particularly infants who have not developed immunity to pertussis. The Centers for Disease Control and Prevention (CDC) now recommend that the tetanus-diphtheria-acellular pertussis (Tdap) booster be given routinely to adolescents, adults, and health care workers.

LITTLE NEED FOR X-RAYS

Chest x-rays are not required for straightforward cases of acute bronchitis. The likelihood of infiltrates being present on a chest x-ray is less than 1% if there is no fever, no tachycardia, no tachypnea, and no auscultatory abnormalities. Chest x-rays would be appropriate if the patient appears sick or toxic, has a high fever (above 102.5°F), is a cigarette smoker, has chest pain or shortness of breath, or is a young African-American with a possible history of sarcoidosis.

Pulse oximetry is indicated if the patient has dyspnea or cyanosis. A peak flow meter may be helpful if the patient has dyspnea or wheezing. Blood tests are not necessary, and neither are sputum cultures except in immunocompromised patients.

TREATMENT OPTIONS

Since most cases of acute bronchitis are viral in origin, treatment is usually intended to alleviate bothersome symptoms such as myalgia and fever. Particular attention should be paid to controlling the cough. It should also be noted that antibiotics are markedly overutilized in treatment of acute bronchitis.

Guaifenesin is not effective in controlling cough. Dextromethorphan, which is a distant cousin of morphine, is effective with most coughs. Codeine compounds remain controversial. Other opiate analogs that are most effective in controlling cough include hydrocodone- and oxycodone-containing liquids. Analgesics can help with the myalgias, and hydration will prevent drying of bronchial secretions.

CONCERNS WITH ANTIBIOTICS

Microbial resistance to antibiotics is a major concern, and there is undoubtedly emerging resistance throughout the United States. Before the mid-1980s, all strains of Pneumococcus were sensitive to penicillin, but in the past 15 years, the CDC reports a 60-fold rise in high-level resistance to the drug. Some areas of the United States showed 30% of strains with intermediate or high-level resistance to penicillin, and these strains are often resistant to other antibiotics, such as macrolides, trimethoprim-sulfamethoxazole, and second- and third-generation cephalosporins. Pneumococcus is a virulent organism and is responsible for common lethal infections, such as meningitis, pneumonia, bacteremia, and cellulitis.

Antibiotic resistance is growing with other pathogens, such as Streptococcus pyogenes, H. influenzae, Enterococcus faecalis (formerly known as Streptococcus faecalis), Neisseria gonorrhoeae, Salmonella, Escherichia coli, and other urinary pathogens, as well as staphylococci.

How often do physicians prescribe antibiotics for upper respiratory illness? For patients with colds, 51% of the time; for patients with upper respiratory infection, 52%; for patients with bronchitis, 66%.

Do antibiotics help the patient with acute bronchitis? In the Cochrane library, there are eight studies of 750 patients with acute bronchitis, and those who received an antibiotic versus placebo had slightly better outcomes and returned to work 0.7 days earlier. However, another study in 1998 also compared patients who received an antibiotic versus placebo and found that the antibiotic did not affect resolution of the cough and did not alter the course of the illness.

The latest recommendations regarding the use of antibiotics in bronchitis are summarized in the box below.

Bronchodilators such as albuterol have been shown to decrease cough by 50%. Anticholinergic bronchodilators have not been studied, and neither have inhaled corticosteroids. The combination of inhaled corticosteroids and bronchodilators, such as fluticasone and salmeterol, may be of some benefit.

Another reason for limiting antibiotic use is cost. A seven-day course of levofloxacin costs approximately $75; a five-day course of azithromycin is about $40. Side effects, such as Stevens-Johnson syndrome and gastrointestinal disturbances with macrolides, are a constant concern.

WHICH PATIENTS SHOULD BE TREATED?

Patients with a history of severe asthma that required intubations or multiple hospitalizations and those with a very low initial peak-expiratory flow rate may benefit from treatment with antibiotics, depending on duration of their illness. Certainly, the patient with HIV/AIDS or any other immune-compromising condition should be treated. Dialysis and transplantation are additional indications. Patients with sarcoidosis, cancer, or diabetes should be viewed with caution since they are likely to develop bacterial infection that may progress to pneumonia.

When the criteria for antibiotic treatment are met, consider coverage for <em>M. pneumoniae</em>, which is provided by erythromycin, tetracycline, or doxycycline. During an outbreak of B. pertussis, erythromycin is the drug of choice. A very effective treatment is oral erythromycin 250 mg four times daily for 10 days, along with a codeine-containing cough suppressant. If the patient is wheezing, an albuterol metered-dose inhaler with spacer (two puffs every two hours while awake for three days) is effective. It is not unreasonable to excuse the patient from work for two days with strict orders for bed rest and plenty of fluids.

ACUTE EXACERBATION OF CHRONIC BRONCHITIS

Acute bronchitis is different from acute exacerbation of chronic bronchitis (AECB). Approximately two-thirds of cases of AECB are bacterial in origin. The bacteria involved are H. influenzae, S. pneumoniae, and Moraxella catarrhalis. High-risk patients include the elderly, patients with a history of chronic obstructive pulmonary disease, and patients with poor lung function, structural lung disease, or comorbid diseases. Also, patients with any two of the following should be treated with antibiotics: increased dyspnea, increased sputum volume, or increased sputum purulence.

Antibiotic treatment choices on an outpatient basis for AECB are doxycycline 100 mg twice daily or an extended-spectrum cephalosporin, such as cefaclor 500 mg every eight hours, cefixime 400 mg daily, cefpodoxime 200 mg twice daily, or cefprozil 500 mg twice daily. Other options include an advanced macrolide such as azithromycin (500 mg in the office and then 250 mg daily for four days) or amoxicillin-clavulanate (175/125 mg twice daily or 500/125 mg three times daily). Fluoroquinolones, such as levofloxacin 500 mg daily or moxifloxacin 400 mg daily, are effective. Duration of treatment is controversial, but 7 to 14 days is reasonable for all antibiotics with the exception of azithromycin, which is prescribed for 5 days.

Treatment of AECB leads to modest improvement in clinical outcome, fewer therapeutic failures, and more rapid recovery of lung function.

INFLUENZA IMMUNIZATION

Encourage influenza immunization for high-risk patients and their household contacts, health care workers, and children under 9 years of age who would be immunized for the first time. Four antiviral agents are approved for the treatment of influenza: amantadine, oseltamivir, rimantadine, and zanamivir. Influenza A can rapidly develop resistance to amantadine and rimantadine; the CDC recommends against prescribing these two agents for outbreaks of influenza A.

Oseltamivir is available as a capsule or oral suspension, while zanamivir is a dry powder that is inhaled through a plastic device. The recommended duration of treatment with either drug is five days.

Initiation of antiviral treatment is most likely to be helpful if symptoms are present for less than 48 hours.

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Suggested Reading Centers for Disease Control and Prevention Web site. Clinical guidelines. Available at www.cdc.gov/drugresistance/clinical.htm. Accessed January 9, 2008. Chodosh S, et al.: Comparison of ciprofloxacin with ampicillin in acute infectious exacerbations of chronic bronchitis. A double-blind crossover study. Am J Med 87(5a):107S, 1989. Fahey T, et al.: Quantitative systematic review of randomized controlled trials comparing antibiotic with placebo for acute cough in adults. BMJ 316(7135):906, 1998. Gernsheimer J, et al.: Antibiotics in the ED: how to avoid the common mistake of treating not wisely, but too well. Emerg Med Practice 7(4), 2005. Gilbert VE: Detection of pneumonia by auscultation of the lungs in the lateral decubitus positions. Am Rev Respir Dis 140(4):1012, 1989. Gonzales R, et al.: Principles of appropriate antibiotic use for treatment of acute respiratory tract infections in adults: background, specific aims, and methods. Ann Emerg Med 37(6):690, 2001. Gonzales R, et al.: Principles of appropriate antibiotic use for treatment of nonspecific upper respiratory tract infections in adults: background. Ann Emerg Med 37(6):698, 2001. Gonzales R, et al.: Principles of appropriate antibiotic use for treatment of uncomplicated acute bronchitis: background. Ann Emerg Med 37(6):720, 2001. Influenza prevention 2002-2003. Med Lett Drugs Ther 44(1138):75, 2002. Lipsky BA, et al.: Ofloxacin treatment of Chlamydia pneumoniae (strain TWAR) lower respiratory tract infections. Am J Med 89(6):722, 1990. Moffa DA, Emerman CL: Bronchitis, pneumonia, and pleural empyema. In Tintinalli JE, Kelen GA (Eds): Emergency Medicine: A Comprehensive Study Guide, 6th ed, 2004. Pages 445-453. Rodnick JE and Gude JK: The use of antibiotics in acute bronchitis and acute exacerbations of chronic bronchitis. West J Med 149(3):347, 1988. Sherman S, et al.: Routine chest radiographs in exacerbations of chronic obstructive pulmonary disease. Diagnostic value. Arch Intern Med 149(11):2493, 1989. Stocks JM, et al.: Ofloxacin in community-acquired lower respiratory infections. A comparison with amoxicillin or erythromycin. Am J Med 87(6C):52s, 1989. Stone S, et al.: Antibiotic prescribing for patients with colds, upper respiratory tract infections, and bronchitis: A national study of hospital-based emergency departments. Ann Emerg Med 36(4):320, 2000. Talan DA and Moran GJ: Why did the chicken cross the road?…to get the antibiotics. Ann Emerg Med 36(4):353, 2000.

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