Pφ

Viruses responsible for the majority of common colds include rhinoviruses (most common), coronavirus, influenza virus, respiratory syncytial virus, parainfluenza virus, and adenovirus. These viruses are thought to be spread mainly by direct contact with secretions on skin and environmental surfaces; dissemination by infectious secretions in the form of droplet nuclei or larger particles can also occur. The pathogenesis of the common cold is actually poorly understood. Biopsy samples of nasal mucosa from individuals with experimentally induced rhinovirus colds do not reveal evidence of viral cytopathic effect. It is believed that cytokines (interleukins 1, 6, and 8) and other inflammatory mediators play an important role in pathogenesis.

TP

The incubation period of the common cold is short (<3 days). Patients present with sneezing, nasal discharge, and symptoms of nasal obstruction, along with sore or scratchy throat. Mild systemic symptoms, such as low-grade fever, myalgias, and malaise, may be present. Cough may develop during the first few days of illness. Influenza is characterized by the abrupt onset of fever, chills, headache, and myalgia, with the systemic symptoms predominating over the respiratory symptoms.

Dx

A diagnosis of the common cold (often referred to as nonspecific URI) is made on clinical grounds. Influenza may be confirmed by RADTs, but (as discussed above) when influenza is known to be circulating in the community, clinical diagnosis is both sensitive and specific. Weekly reports of influenza activity in the United States can be found at http://www.cdc.gov/flu/weekly/index.htm. Many state health departments also post weekly reports of regional influenza activity on their websites.

Pφ

The nasopharynx of healthy individuals may be colonized with bacteria that cause ACABS (e.g., S. pneumoniae); besides S. pneumoniae, Haemophilus influenzae (mainly untypable) and Moraxella catarrhalis are most commonly implicated. Obstruction of the sinus ostia, which may occur as a result of an antecedent VRS, plays an important role in the pathogenesis of ACABS. It is believed that blowing the nose creates a sudden increase in intranasal pressure that forces fluid that may contain these bacteria from the nasal cavity into the sinuses.

TP

Patients present with nasal congestion, purulent nasal discharge, and facial pain/pressure, which may be worsened by leaning forward. There may be maxillary tooth pain in maxillary sinusitis and retro-orbital headache in ethmoid and sphenoid sinusitis; unilateral symptoms are especially suggestive of bacterial sinusitis. Patients may have fever. There is often a history of antecedent symptoms suggestive of VRS, which either fail to improve or begin to improve and then worsen again after 7–10 days of illness.

Dx

The diagnosis of ACABS is mainly clinical. Patients with severe symptoms of sinusitis may need antibiotic therapy early in the course of disease; those with mild to moderate symptoms who are not improving by the second week of illness should also be assumed to have a bacterial infection and receive antibiotics. Studies utilizing sinus puncture have been performed to define the microbiology of ACABS; in clinical practice this invasive procedure can be utilized in severely ill patients (especially those with nosocomially acquired sinusitis), but it is not routinely performed. Antibiotics are chosen empirically based on knowledge of the microbiology of bacterial infection of the sinuses. Culture of purulent nasal secretions is not recommended. As discussed above, sinus radiographs cannot distinguish bacterial from viral infections and are not routinely recommended.

Pφ

Infection of the tracheobronchial epithelium leads to acute inflammation and the release of cytokines. The same viruses implicated in the common cold can cause acute bronchitis. The one bacterial pathogen that may be considered in certain patients is Bordetella pertussis (discussed in the Zebra Zone section). Inflammation of the tracheobronchial epithelium leads to airway hyperresponsiveness that manifests as persistent cough and wheezing. The production of purulent sputum reflects inflammation and does not indicate a bacterial infection.

TP

Patients present with cough and may have mild systemic symptoms and wheezing; an antecedent history of symptoms suggestive of the common cold may be present. Auscultation of the chest may reveal diffuse coarse rhonchi and wheezing.

Dx

The diagnosis of acute bronchitis is made clinically; some patients with acute cough may require a chest radiograph to exclude the diagnosis of pneumonia, as discussed above under Tests for Consideration.

Pφ

The pathogenesis of viral pharyngitis is similar to that of the common cold. The inflammatory mediator bradykinin is thought to play a key role in the pathogenesis of sore throat. The pathogenesis of streptococcal pharyngitis is not well understood. The organism is often found colonizing the pharynx in asymptomatic individuals. The factors that lead from colonization to infection are not well elucidated, although a number of extracellular factors produced by S. pyogenes, including hemolysins, hyaluronidase, and pyrogenic exotoxins, are probably important in the pathogenesis of disease. The common cold viruses are also implicated as causes of pharyngitis; in addition, patients with Epstein-Barr virus (EBV), cytomegalovirus (CMV), and acute HIV infection can present with pharyngitis accompanied by a mononucleosis-like syndrome. Bacteria are responsible for only 5% to 10% of cases of pharyngitis in adults; the most common is S. pyogenes (group A β-hemolytic streptococcus [GABHS]).

TP

Patients with viral pharyngitis may present with complaints of sore throat along with other symptoms suggestive of URI. In patients with pharyngitis due to GABHS, sore throat and pain in the throat when swallowing are the presenting complaints. Patients may have quite impressive systemic complaints (including fever and chills, abdominal pain, and headache) or may be only mildly ill. On examination, the posterior pharynx will be markedly erythematous with patches of yellow exudates on the tonsils. There may be redness of the tongue with prominence of the papillae (strawberry tongue) and tender enlargement of the cervical lymph nodes.

Dx

The presence of the Centor criteria (fever, exudates, tender cervical adenopathy, and absence of cough) can increase the pre-test probability of GABHS pharyngitis; however, the diagnosis should be confirmed by a RADT or a throat culture. Because the prevalence of GABHS infection in adults is lower than in the pediatric population, the diagnosis can be excluded based on a negative RADT.

Pφ

The middle ear communicates with the eustachian tube and mastoid air cells, the nasopharynx, and the nares. Any process that interferes with eustachian tube function, such as edema of the mucosa from a viral infection, can predispose to fluid accumulation in the middle ear, and if this fluid contains bacteria (e.g., S. pneumoniae) that can normally be found colonizing the nasopharynx, infection of the middle ear (OM) can ensue. Viruses associated with the common cold may also cause OM; bacterial infections are most frequently caused by S. pneumoniae, followed by H. influenzae and M. catarrhalis.

TP

Adults with OM typically present with pain in the ear, which may be accompanied by decreased hearing, drainage from the ear, and fever. Tinnitus and vertigo may also occur. There may be an antecedent history of URI symptoms.

Dx

The tympanic membrane (TM) can be erythematous in any infection of the upper respiratory tract, and this finding alone is insufficient to make a diagnosis of OM. In acute OM, the TM is opaque and may be bulging or retracted. Decreased mobility of the TM with pneumatic otoscopy is consistent with fluid in the middle ear.