Chapter 031. Pharyngitis, Sinusitis, Otitis, and Other Upper Respiratory Tract Infections (Part 1)

Harrisons Internal Medicine Chapter 31. Pharyngitis, Sinusitis, Otitis, and Other Upper Respiratory Tract InfectionsPharyngitis, Sinusitis, Otitis, and Other Upper Respiratory Tract Infections: IntroductionInfections of the upper respiratory tract (URIs) have a tremendous impact on public health. They are among the most common reasons for visits to primary care providers, and, although the illnesses are typically mild, their high incidence and transmission rates place them among the leading causes of time lost from work or school. Even though the minority (~25%) of cases are caused by bacteria, URIs are the leading diagnoses for which antibiotics are prescribed on an...
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Chapter 031. Pharyngitis, Sinusitis, Otitis, and Other Upper Respiratory Tract Infections (Part 1) Chapter 031. Pharyngitis, Sinusitis, Otitis, and Other Upper Respiratory Tract Infections (Part 1) Harrisons Internal Medicine > Chapter 31. Pharyngitis, Sinusitis, Otitis,and Other Upper Respiratory Tract Infections Pharyngitis, Sinusitis, Otitis, and Other Upper Respiratory TractInfections: Introduction Infections of the upper respiratory tract (URIs) have a tremendous impacton public health. They are among the most common reasons for visits to primarycare providers, and, although the illnesses are typically mild, their high incidenceand transmission rates place them among the leading causes of time lost fromwork or school. Even though the minority (~25%) of cases are caused by bacteria,URIs are the leading diagnoses for which antibiotics are prescribed on anoutpatient basis in the United States. The enormous consumption of antibiotics forthese illnesses has contributed to the rise in antibiotic resistance among commoncommunity-acquired pathogens such as Streptococcus pneumoniae—a trend thatin itself has had an enormous influence on public health. Although most URIs are caused by viruses, distinguishing patients withprimary viral infection from those with primary bacterial infection is difficult.Signs and symptoms of bacterial and viral URIs are, in fact, indistinguishable.Because routine, rapid testing is neither available nor practical for mostsyndromes, acute infections are diagnosed largely on clinical grounds. Thus thejudicious use of antibiotics in this setting is challenging. Nonspecific Infections of the Upper Respiratory Tract Nonspecific URIs are a broadly defined group of disorders that collectivelyconstitute the leading cause of ambulatory care visits in the United States. Bydefinition, nonspecific URIs have no prominent localizing features. They areidentified by a variety of descriptive names, including acute infective rhinitis,acute rhinopharyngitis/nasopharyngitis, acute coryza, and acute nasal catarrh, aswell as by the inclusive label common cold. Etiology The large assortment of URI classifications reflects the wide variety ofcausative infectious agents and the varied manifestations of common pathogens.Nearly all nonspecific URIs are caused by viruses spanning multiple virus familiesand many antigenic types. For instance, there are at least 100 immunotypes of rhinovirus (Chap. 179),the most common cause of URI (~30–40% of cases); other causes includeinfluenza virus (three immunotypes; Chap. 180) as well as parainfluenza virus(four immunotypes), coronavirus (at least three immunotypes), and adenovirus (47immunotypes) (Chap. 179). Respiratory syncytial virus (RSV) also accounts for a small percentage ofcases each year, as do some viruses not typically associated with URIs (e.g.,enteroviruses, rubella virus, and varicella-zoster virus). Even with sophisticateddiagnostic and culture techniques, a substantial proportion (25–30%) of cases haveno assigned pathogen. Clinical Manifestations The signs and symptoms of nonspecific URI are similar to those of otherURIs but lack a pronounced localization to one particular anatomic location, suchas the sinuses, pharynx, or lower airway. Nonspecific URI is commonly described as an acute, mild, and self-limitedcatarrhal syndrome, with a median duration of ~1 week. Signs and symptoms arediverse and frequently variable across patients. The principal signs and symptoms of nonspecific URI include rhinorrhea(with or without purulence), nasal congestion, cough, and sore throat. Othermanifestations, such as fever, malaise, sneezing, and hoarseness, are morevariable, with fever more common among infants and young children. Occasionally, clinical features reflect the underlying viral pathogen;myalgias and fatigue, for example, are sometimes seen with influenza andparainfluenza infections, while conjunctivitis may suggest infection withadenovirus or enterovirus. Findings on physical examination are frequently nonspecific andunimpressive. Between 0.5 and 2% of colds are complicated by secondarybacterial infections (e.g., rhinosinusitis, otitis media, and pneumonia), particularlyin high-risk populations such as infants, elderly persons, and chronically illpatients. Secondary bacterial infections are usually associated with a prolongedcourse of illness, increased severity of illness, and localization of signs andsymptoms. Purulent secretions from the nares or throat have often been used as anindication of sinusitis or pharyngitis. However, these secretions are also seen innonspecific URI and, in the absence of other clinical features, are poor predictorsof bacterial infection.