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Rational Use of Antibiotics in Bronchitis
By David J. Karras, MD, FAAEM, FACEP
Unnecessary prescriptions for antibiotics are the most important factor in the development of antimicrobial resistance, needlessly exposing patients to the risk of adverse drug reactions and dramatically increasing health care costs. Although such costs are admittedly extremely difficult to calculate, it has been estimated that more than $100 million in excess health care costs are attributable annually to the consequences of inappropriate use of antimicrobial agents.1
Half of all antibiotic prescriptions in this country are provided for respiratory illnesses, the majority of which are not bacterial in etiology.2 Analyses of national hospital databases show that antibiotics are prescribed to 25% of all emergency department (ED) patients with colds and 42% of ED patients with uncomplicated bronchitis.3
Considering that there are about 2.7 million annual ED visits for those complaints, there are enormous numbers of patients receiving unnecessary antibiotic prescriptions from emergency physicians (EPs).
Why do so many patients receive antibiotics when they are not indicated? It does not appear to be a physician cognitive deficit—most doctors know the signs of bacterial respiratory illness and which patients are likely to benefit from antibiotics. Unfortunately, physicians do not make a causal link between development of drug resistance and the prescribing of antibiotics unnecessarily to their own patients. Drug resistance, in other words, is the result of everyone else’s inappropriate use of antibiotics. Many studies have shown that the single most important factor in inappropriate antibiotic prescription practices is the physician’s response to perceived patient expectations.4-6 The doctor thinks the patient wants an antibiotic and that he will be dissatisfied (and perhaps sue) if a prescription is not provided. Results from the same studies show that physicians do a very poor job of detecting which patients really expect to receive antibiotics, and patients don’t rank receipt of an antibiotic prescription as a major factor in their satisfaction with medical care.
Fortunately, it seems all the attention focused on appropriate use of antibiotics has been paying off. Recent data show that, although the number of prescriptions of broad-spectrum antibiotics in children continues to rise, the number of antimicrobial prescriptions for bronchitis and upper respiratory infections has started to decrease.7 The remainder of this article discusses specific recommendations for treating ED patients with bronchitis and sinusitis.
Acute Uncomplicated Bronchitis
Bronchitis is a term frequently misunderstood by physicians, and incorrect medical decision-making often arises from this confusion. Chronic bronchitis is overwhelmingly a disease of smokers and is not considered an infectious disease per se. Acute bronchitis can be broken down into two major categories: acute uncomplicated bronchitis and acute exacerbations of chronic bronchitis (AECB).
Acute uncomplicated bronchitis generally is defined as a respiratory tract infection of fewer than three weeks duration in which cough is the predominant feature; there is no evidence of pneumonia, and the patient has no serious underlying lung disease or co-morbidities. In 90% of cases, acute uncomplicated bronchitis is viral in origin, and there is no evidence that antibiotic therapy improves outcomes or shortens the course of illness in such cases. The remaining 10% of cases usually have infections with atypical organisms—chlamydia, mycoplasma, and Bordetella pertussis. More serious infections with Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis are very uncommon causes of bronchitis in healthy adults.8
Although antibiotic therapy is not a prerequisite for cure, it may shorten the course of acute uncomplicated bronchitis in patients who have atypical bacterial infections.9 Unfortunately, there are no signs or symptoms that distinguish patients with bacterial illnesses from patients with viral bronchitis, and it is obviously impractical to obtain sputum cultures in ED patients. Only duration of illness appears to distinguish patients with atypical bacterial bronchitis from those with viral infections. The literature supports the empiric antibiotic treatment of patients with prolonged bronchitis symptoms, generally considered more than 2-3 weeks in duration. Doxcycline or a second-generation macrolide (e.g., azithromycin or clarithromycin), would be appropriate for a patient with persistent symptoms. A respiratory fluoroquinone (e.g., levofloxacin and gatifloxacin, not ciprofloxacin) would be effective but might be reserved for more serious infections.
It is important to note that smokers can—and often do—have acute uncomplicated bronchitis. The majority of smokers do not have chronic obstructive pulmonary disease (COPD), and every respiratory illness in a smoker should not be assumed to be AECB. Absent a diagnosis of COPD, a history of smoking does not influence the etiology of acute bronchitis, and there is no benefit to routinely prescribing antibiotics to smokers with a cough.
Acute Exacerbations of Chronic Bronchitis
There is considerable controversy surrounding antibiotic therapy for patients with AECB. Unfortunately, the diagnosis of AECB is neither uniform nor objective. Most experts refer to what is known as the working definition of AECB: increased sputum purulence, increased sputum volume, or worsening dyspnea in a patient with COPD.10 The average patient with COPD will have one to four episodes of AECB annually. Like uncomplicated bronchitis, there is an increased incidence of AECB in winter months. Unlike uncomplicated bronchitis, however, AECB is associated with considerable morbidity and mortality.
A bacterial etiology of AECB is likely in about half of cases, most commonly H. influenzae, S. pneumoniae, and M. catarrhalis. Pseudomonas infections are seen in patients with more severe disease. Bacterial infection is suggested by more severe exacerbations, generally associated with the presence of green or gray purulent sputum and a significant drop in peak expiratory flow rate.11 It is important to recognize that patients with COPD may be colonized with bacteria, and recovery of a bacterial species in the sputum during an acute episode does not necessarily implicate the pathogen as the causative agent. Many experts, however, subscribe to the vicious circle hypothesis, which proposes that bacterial colonization leads to airway injury, which in turn enhances further bacterial colonization.12 By ridding the airways of colonizing bacteria during acute exacerbations, the theory goes, antibiotic therapy shortens the course of the exacerbation and slows the inexorable progression of disease.
There have been surprisingly few careful studies of the benefit of prescribing antibiotics in AECB, and most were performed in the era before respiratory fluoroquinolones and newer macrolides. A meta-analysis from 1995 found only nine placebo-controlled, randomized trials that examined clinically meaningful outcomes.13
The majority of studies found a small but statistically meaningful benefit to prescribing antibiotics to patients with moderate-to-severe episodes of AECB. An expert panel currently recommends prescribing antibiotics to patients with COPD who note acute exacerbations with purulent sputum or increased dypnea. Therapy in this group generally shortens the duration of illness by about two days and results in more rapid improvement in peak expiratory flow rate. 10
There are no definitive answers regarding appropriate selection of antibiotics in patients with moderate-to-severe AECB. For AECB in patients with mild COPD and not recently taking antibiotics, amoxicillin-clavulanic acid, first-generation cephalosporins, and second-generation macrolides usually are appropriate. Treatment with respiratory fluoroquinolones, second-generation macrolides, or second- or third- generation cephalo-sporins are appropriate in patients older than 55 years with frequent exacerbations, co-morbidities, or poor baseline airflow. Finally, patients with severe COPD and those with chronic production of purulent sputum may likely benefit from a fluoroquinolone with anti-pseudomonal properties (specifically ciprofloxacin and levofloxacin).10
Dr. Karras, Associate Professor of Emergency Medicine, Associate Chair for Academic Affairs, and Research Director, Department of Emergency Medicine, Temple University School of Medicine, Philadelphia, PA, is on the Editorial Board of Emergency Medicine Alert.
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