eMedicine Specialties > Pulmonology > Infectious Lung Diseases

Upper Respiratory Tract Infection

Author: Anne Meneghetti, MD, Assistant Professor of Medicine, Tufts University School of Medicine; Medical Broadcaster, Life, Love and Health
Contributor Information and Disclosures

Updated: Aug 12, 2009

Introduction

Background

Upper respiratory tract infection (URI) represents the most common acute illness evaluated in the outpatient setting. URIs range from the common cold--typically a mild, self-limited, catarrhal syndrome of the nasopharynx--to life-threatening illnesses such as epiglottitis. Viruses account for most URIs. Bacterial primary infection or superinfection may require targeted therapy.

The upper respiratory tract includes the sinuses, nasal passages, pharynx, and larynx, which serve as gateways to the trachea, bronchi, and pulmonary alveolar spaces. Rhinitis, pharyngitis, sinusitis, epiglottitis, laryngitis, and tracheitis are specific manifestations of URIs. Further information can be found in the eMedicine articles Otitis Media; Bronchiolitis; Bronchitis; and Pediatrics, Bronchiolitis; and in articles about specific infectious agents.

Common URI terms are defined as follows:

• Rhinitis - Inflammation of the nasal mucosa
• Rhinosinusitis or sinusitis - Inflammation of the nares and paranasal sinuses, including frontal, ethmoid, maxillary, and sphenoid
• Nasopharyngitis (rhinopharyngitis or the common cold) - Inflammation of the nares, pharynx, hypopharynx, uvula, and tonsils
• Pharyngitis - Inflammation of the pharynx, hypopharynx, uvula, and tonsils
• Epiglottitis (supraglottitis) - Inflammation of the superior portion of the larynx and supraglottic area
• Laryngitis - Inflammation of the larynx
• Laryngotracheitis - Inflammation of the larynx, trachea, and subglottic area
• Tracheitis - Inflammation of the trachea and subglottic area

Pathophysiology

URIs involve direct invasion of the mucosa lining the upper airway. Person-to-person spread of viruses accounts for most URIs. Patients with bacterial infections may present in similar fashion, or they may present with a superinfection of a viral URI. Inoculation by bacteria or viruses begins when secretions are transferred by touching a hand exposed to pathogens to the nose or mouth or by directly inhaling respiratory droplets from an infected person who is coughing or sneezing.

After inoculation, viruses and bacteria encounter several barriers, including physical, mechanical, humoral, and cellular immune defenses. Hair lining the nose filters and traps some pathogens. Mucus coats much of the upper respiratory tract, trapping potential invaders. The angle resulting from the junction of the posterior nose to the pharynx causes large particles to impinge on the back of the throat. Ciliated cells lower in the respiratory tract trap and transport pathogens up to the pharynx, where they are then swallowed into the stomach.

Adenoids and tonsils contain immune cells that respond to pathogens. Humoral immunity (immunoglobulin A) and cellular immunity act to reduce infections throughout the entire respiratory tract. Resident and recruited macrophages, monocytes, neutrophils, and eosinophils coordinate to engulf and destroy invaders. A host of inflammatory cytokines mediates the immune response to invading pathogens. Normal nasopharyngeal flora, including various staphylococcal and streptococcal species, help defend against potential pathogens. Patients with suboptimal humoral and phagocytic immune function are at increased risk for contracting a URI, and they are at increased risk for a severe or prolonged course of disease.

Viral agents include a vast number of serotypes, which undergo frequent changes in antigenicity, posing challenges to immune defense. Pathogens resist destruction by a variety of mechanisms, including the production of toxins, proteases, and bacterial adherence factors, as well as the formation of capsules that resist phagocytosis.

Incubation times before the appearance of symptoms vary among pathogens. Rhinoviruses and group A streptococci may incubate for 1-5 days, influenza and parainfluenza may incubate for 1-4 days, and respiratory syncytial virus (RSV) may incubate for a week. Pertussis typically incubates for 7-10 days or even as long as 21 days before causing symptoms. Diphtheria incubates for 1-10 days. The incubation period of Epstein-Barr virus (EBV) is 4-6 weeks.

Most symptoms of URIs, including local swelling, erythema, edema, secretions, and fever, result from the inflammatory response of the immune system to invading pathogens and from toxins produced by pathogens. An initial nasopharyngeal infection may spread to adjacent structures, resulting in sinusitis, otitis media, epiglottitis, laryngitis, tracheobronchitis, and pneumonia. Inflammatory narrowing at the level of the epiglottis and larynx may result in a dangerous compromise of airflow, especially in children, in whom a small reduction in the luminal diameter of the subglottic larynx and trachea may be critical. Beyond childhood, laryngotracheal inflammation may also pose serious threats to individuals with congenital or acquired subglottic stenosis.

Frequency

United States

URIs are the most common infectious illness in the general population. URIs are the leading reasons for people missing work or school, and they represent the leading acute diagnosis in the office setting.¹

Nasopharyngitis

The incidence of the common cold varies by age. Rates are highest in children younger than 5 years. Children who attend school or daycare are a large reservoir for URIs, and they transfer infection to those who care for them. Children have about 3-8 viral respiratory illnesses per year. Adolescents and adults have approximately 2-4 colds a year, and people older than 60 years have fewer than 1 cold per year.

Pharyngitis

Acute pharyngitis accounts for 1% of all ambulatory office visits.¹ The incidence of viral and bacterial pharyngitis peaks in children aged 4-7 years.

Rhinosinusitis

Sinusitis is common in persons with viral URIs. Transient changes in the paranasal sinuses are noted on CT scans in more than 80% of patients with uncomplicated viral URIs.² However, bacterial rhinosinusitis is a complication in only approximately 2% of persons with viral URIs.³

Epiglottitis

Epiglottitis occurs at a rate of 6-14 cases per 100,000 children, according to estimates from other countries.⁴ This condition typically occurs in children aged 2-7 years and has a peak incidence in those aged 3 years.⁵ Epiglottitis is estimated to occur at annual incidence of 9.7 cases per million adults.⁶ The occurrence of epiglottitis has decreased dramatically in the United States since the introduction of the Haemophilus influenzae type B (Hib) vaccine.

Laryngitis and laryngotracheitis

Croup, or laryngotracheobronchitis, may affect people of any age, but it usually occurs in children aged 6 months to 6 years. The peak incidence is in the second year of life.⁵ Thereafter, the enlarging caliber of the airway reduces the severity of the manifestations of subglottic inflammation. Vaccination has dramatically reduced rates of pertussis, including whooping cough. However, the incidence of whooping cough cases in the United States has increased in recent years, reaching 5.3 cases per 100,000 population in 2006.⁷ Adolescents and infants younger than 5 months account for many of these cases. In 2004, adults aged 19-64 years accounted for 7,008 (27%) of 25,827 reported cases of pertussis in the United States. Challenges in laboratory diagnosis and overreliance on polymerase chain reaction (PCR) tests have resulted in recent reports of respiratory illness outbreaks mistakenly attributed to pertussis.⁸

Frequency of selected pathogens

Group A streptococcal bacteria cause approximately 5-15% of all pharyngitis infections, accounting for several million cases of streptococcal pharyngitis each year. This infection is rarely diagnosed in children younger than 2 years.

Approximately 5-20% of Americans have the flu during each flu season.⁹ Early presentations include symptoms of URI.

EBV infection affects as many as 95% of American adults by age 35-40 years. Childhood EBV infection is indistinguishable from other transient childhood infections. Approximately 35-50% of adolescents and young adults who contract EBV infection have mononucleosis.¹⁰

After the advent of the diphtheria vaccine, case rates dramatically decreased in the United States. Since 1980, the prevalence has been approximately 0.001 case per 100,000 population.¹¹ Diphtheria remains endemic in developing countries. Sporadic cases have recently affected adults.

Seasonality

Although URIs may occur year round, in the United States, most colds occur during fall and winter. Beginning in late August or early September, rates of colds increase over several weeks and remain elevated until March or April.¹² Epidemics and miniepidemics are most common during cold months, with a peak incidence in late winter to early spring. Cold weather means more time spent indoors (eg, at work, home, school) and close exposure to others who may be infected. Humidity may also affect the prevalence of colds, because most viral URI agents thrive in the low humidity characteristic of winter months. Low indoor air moisture may increase friability of the nasal mucosa, increasing a person's susceptibility to infection. Laryngotracheobronchitis, or croup, occurs in fall and winter. Seasonality does not affect rates of epiglottitis.

Media File 1 illustrates the peak incidences of various agents by season. Rhinoviruses, which account for a substantial percentage of URIs, are most active in spring, summer, and early autumn. Coronaviral URIs manifest primarily in the winter and early spring. Enteroviral URIs are most noticeable in summer and early fall, when other URI pathogens are at a nadir. Adenoviral respiratory infections are most common in the late winter, spring, and early summer, yet they can occur throughout the year.

Mortality/Morbidity

URIs cause people to spend time away from their usual daily activities. Alone, URIs rarely cause permanent sequelae or death, although URIs may serve as a gateway to infection of adjacent structures, resulting in otitis media, bronchitis, bronchiolitis, pneumonia, sepsis, meningitis, intracranial abscess, and other infections. Serious complications may result in clinically significant morbidity and rare deaths.

• Common cold: This is the leading cause of acute morbidity and missed days from school or work. The common cold is also the leading acute cause of office visits to a physician in the United States.
• Untreated group A streptococcal pharyngitis: This infection can result in acute rheumatic fever (ARF), acute glomerulonephritis, peritonsillar abscess, and toxic shock syndrome. Mortality from group A streptococcal pharyngitis is rare, but serious morbidity or death may result from one of its complications. Pharyngitis without complications rarely poses significant risk for morbidity. However, retropharyngeal, intraorbital, or intracranial abscesses may cause serious sequelae.
• Sinusitis: The condition itself is rarely life threatening, but sinusitis can lead to serious complications if the infection extends into surrounding deep tissue. Examples include orbital cellulitis, subperiosteal abscess, orbital abscess, frontal and maxillary osteomyelitis, subdural abscess, meningitis, and brain abscess.
• Epiglottitis: This infection poses a risk of death due to sudden airway obstruction and other complications, including septic arthritis, meningitis, empyema, and mediastinitis. In adults, epiglottitis has a fatality rate of approximately 1%.
• Selected pathogens
• Approximately 3-6% of cases of Hib disease are fatal.
• Each year, more than 200,000 people are hospitalized for influenza and approximately 36,000 people die from the flu and its complications.⁹
• Complications from whooping cough, or pertussis, reported from 2001-2003 included 56 pertussis-related deaths. Fifty-one (91%) of these deaths were among infants younger than 6 months, and 42 (75%) were among infants younger than 2 months.¹³
• Approximately 5-10% of patients with diphtheria die. Fatality rates up to 20% are reported in patients younger than 5 years or older than 40 years.¹³

Race

No notable racial difference is observed with URIs. However, Alaskan Natives have rates of Hib disease higher than those of other groups.¹⁴

Sex

• Rhinitis: Hormonal changes during the middle of the menstrual cycle and during pregnancy may produce hyperemia of the nasal and sinus mucosa and increase nasal secretions. URI may be superimposed over these baseline changes and may increase the intensity of symptoms in some women.
• Nasopharyngitis: The common cold occurs frequently in women, especially those aged 20-30 years.¹² This frequency may represent increased exposure to small children, who represent a large reservoir for URIs. However, hormonal effects on the nasal mucosa may also play a role.
• Epiglottitis: A male predominance is reported, with a male-to-female ratio of approximately 3:2.
• Laryngotracheobronchitis, or croup, is more common in boys than in girls, with male-to-female ratio of approximately 3:2.⁵

Age

• Nasopharyngitis: The incidence of the common cold varies by age. Rates are highest in children younger than 5 years. Children have approximately 3-8 viral respiratory illnesses per year. Adolescents and adults have approximately 2-4 colds a year, and people older than 60 years have fewer than 1 cold per year.
• Pharyngitis: The incidence of viral and bacterial pharyngitis peaks in children aged 4-7 years.
• Epiglottitis: This typically occurs in children aged 2-7 years and has a peak incidence in those aged 3 years.⁵
• Laryngitis and laryngotracheitis: Croup, or laryngotracheobronchitis, may affect people of any age, but it usually occurs in children aged 6 months to 6 years. The peak incidence is in the second year of life.⁵

Clinical

History

Details of the patient's history aid in differentiating a common cold from conditions that require targeted therapy, such as group A streptococcal pharyngitis, bacterial sinusitis, and lower respiratory tract infections. The table below contrasts symptoms of URI with symptoms of allergy and influenza (adapted from the National Institute of Allergy and Infectious Diseases).^9,12

Symptoms of Allergies, URIs, and Influenza

Open table in new window

Viral nasopharyngitis

Symptoms of the common cold usually begin 2-3 days after inoculation. Viral URIs typically last 6.6 days in children aged 1-2 years in home care and 8.9 days for children older than 1 year in daycare. Cold symptoms in adults can last from 3-14 days, yet most people recover or have symptomatic improvement within a week. If symptoms last longer than 2 weeks, consider alternative diagnoses, such as allergy, sinusitis, or pneumonia.

• Nasal symptoms: Rhinorrhea, congestion or obstruction of nasal breathing, and sneezing are common early in the course. Clinically significant rhinorrhea is more characteristic of a viral infection rather than a bacterial infection. In viral URI, secretions often evolve from clear to opaque white to green to yellow within 2-3 days of symptom onset. Thus, color and opacity do not reliably distinguish viral from bacterial illness.
• Pharyngeal symptoms: These include sore or scratchy throat, odynophagia, or dysphagia. Sore throat is typically present in the first days of illness, although it lasts only a few days. If the uvula or posterior pharynx is inflamed, the patient may have an uncomfortable sensation of a lump when swallowing. Nasal obstruction may cause mouth breathing, which may result in a dry mouth, especially after sleep.
• Cough: This may represent laryngeal involvement, or it may result from upper airway cough syndrome related to nasal secretions (postnasal drip). Cough typically develops on the fourth or fifth day, subsequent to nasal and pharyngeal symptoms.
• Other symptoms  
  • Foul breath: This occurs as resident flora process the products of the inflammatory process. Foul breath also occurs with allergic rhinitis.
  • Hyposmia: Also termed anosmia, it is secondary to nasal inflammation.
  • Headache: This symptom is common with many types of URI.
  • Sinus symptoms: These may include congestion or pressure and are common with viral URIs.
  • Photophobia or conjunctivitis: These may be seen with adenoviral and other viral infections. Influenza may evoke pain behind the eyes, pain with eye movement, or conjunctivitis. Itchy, watery eyes are common in patients with allergic conditions.
  • Fever: This is usually slight or absent, but temperatures can reach 39.4°C (103°F) in infants and young children. If present, fever typically lasts for only a few days. In influenza infection, fevers may result in temperatures as high as 40°C (104°F).
  • Gastrointestinal symptoms: Symptoms such as nausea, vomiting, and diarrhea may occur in persons with influenza, especially in children. Nausea and abdominal pain may be present in individuals with strep throat and viral syndromes.
  • Severe myalgia: This is typical of influenza infection, especially in the setting of sudden-onset sore throat, fever, chills, nonproductive cough, and headache.
  • Fatigue or malaise: Any type of URI can produce these symptoms. Extreme exhaustion is typical of influenza infection.

Bacterial pharyngitis

History alone is rarely a reliable differentiator between viral and bacterial pharyngitis. If symptoms persist beyond 10 days or progressively worsen after the first 5-7 days, a bacterial illness is suggested. Assessment for group A streptococci warrants special attention. A personal history of rheumatic fever (especially carditis or valvular disease) or a household contact with a history of rheumatic fever increases a person's risk. Fever increases the suspicion for infection with group A streptococci, as does the absence of cough, rhinorrhea, and conjunctivitis, because these are common in viral syndromes. Other factors include occurrence from November through May and a patient age of 5-15 years.

• Pharyngeal symptoms: Sore or scratchy throat, odynophagia, or dysphagia are noted. If the uvula or posterior pharynx is inflamed, the patient may have an uncomfortable feeling of a lump when swallowing. Nasal obstruction may cause mouth breathing, which may result in dry mouth, especially in the morning. Group A streptococci often produce a sudden sore throat.
• Secretions: These may be thick or yellow; however, these features do not differentiate a bacterial infection from a viral one.
• Cough: It may be due to laryngeal involvement or upper airway cough syndrome related to nasal secretions (postnasal drip).
• Other symptoms 
  • Foul breath: This symptom may occur because resident flora process the products of the inflammatory process. Foul breath may also occur with allergic rhinitis.
  • Headache: While common with group A streptococci and mycoplasmal infections, it also may reflect URI from other causes.
  • Fatigue or malaise: These may occur with any URI. Extreme exhaustion is typical of influenza infection.
  • Fever: While usually slight or absent, temperatures may reach 38.9°C (102°F) in infants and young children.
  • Rash: A rash may be seen with group A streptococcal infections, particularly in children or adolescents younger than 18 years.
  • Abdominal pain: This symptom may occur in streptococcal disease or with influenza and other viral conditions.
  • History of recent orogenital contact: This is relevant in cases of gonococcal pharyngitis.

Acute viral or bacterial rhinosinusitis

The presentation of rhinosinusitis is often similar to that of nasopharyngitis because many viral URIs directly involve the paranasal sinuses. Symptoms may have a biphasic pattern, wherein coldlike symptoms initially improve but then worsen. Acute bacterial rhinosinusitis is not common in patients whose symptoms have lasted fewer than 7 days. Unilateral and localizing symptoms raise the suspicion for sinus involvement.

• Nasal discharge: This may be persistent and purulent, and sneezing may occur. Mucopurulent secretions are seen with both viral and bacteria infections. Secretions may be yellow or green; however, the color does not differentiate a bacterial sinus infection from a viral one, because thick, opaque, yellow secretions may be seen with uncomplicated viral nasopharyngitis. Rhinorrhea is typically minimal or does not respond to decongestants or antihistamines. Congestion and nasal stuffiness predominate in some individuals.
• Hyposmia or anosmia: This may occur secondary to nasal inflammation.
• Facial or dental pressure or pain: In older children and adults, symptoms tend to localize to the affected sinus. Frontal, facial, or retroorbital pain or pressure is common. Maxillary sinus inflammation may manifest as pain in the upper teeth on the affected side. Pain radiating to the ear may represent otitis media or a peritonsillar abscess.
• Oropharyngeal symptoms: Sore throat may result from irritation from nasal secretions dripping on the posterior pharynx. Nasal obstruction may cause mouth breathing, which may result in dry mouth, especially in the morning. Mouth breathing may especially be noted in children. Dry mouth may be prominent, especially after sleep.
• Halitosis: Foul breath may be noted because resident florae process the products of the inflammatory process. This symptom may also occur with allergic rhinitis.
• Cough: Upper airway cough syndrome related to nasal secretions (postnasal drip) may result in frequent throat clearing or cough. Rhinosinusitis-related cough is usually present throughout the day. The cough may also be most prominent on awakening, occurring in response to the presence of secretions that have gathered in the posterior pharynx overnight. Daytime cough that lasts more than 10-14 days suggests sinus disease, asthma, or other conditions. Nighttime-only cough is common in numerous disorders, and many forms of cough are most noticeable at night. Upper airway cough syndrome related to nasal secretions occasionally precipitates posttussive emesis. Clinically significant amounts of purulent sputum may suggest bronchitis or pneumonia.
• Fever: This is more likely to occur in children than adults with rhinosinusitis. Fever may occur concomitantly with purulent nasal secretions in persons with sinus disease. In those with viral URI, fever, if present, typically precedes the development of purulent nasal secretions.
• Fatigue or malaise: These may be seen with any URI.

Epiglottitis

This condition is more often found in children aged 1-5 years who present with a sudden onset of symptoms:

• Sore throat
• Drooling, odynophagia or dysphagia, difficulty or pain during swallowing, globus sensation of a lump in the throat
• Muffled dysphonia or loss of voice
• Dry cough or no cough, dyspnea
• Fever, fatigue or malaise (may be seen with any URI)

Laryngotracheitis

• Nasopharyngeal symptoms: Nasopharyngitis often precedes laryngitis and tracheitis by several days. Odynophagia or dysphagia may be reported. Swallowing may be difficult or painful. Patients may experience a globus sensation of a lump in the throat.
• Hoarseness or loss of voice: This is a key manifestation of laryngeal involvement.
• Cough  
  • Dry cough: In adolescents and adults, laryngotracheal infection may manifest as severe dry cough following a typical URI prodrome. Mild hemoptysis may be present.
  • Barking cough: Children with laryngotracheitis or croup may have the characteristic brassy, seal-like barking cough. Symptoms may be worse at night. Diphtheria also produces a barking cough.
  • Whooping cough: The classic whoop sound is an inspiratory gasping squeak that rises in pitch, typically interspersed between hacking coughs. The whoop is more common in children. Coughing often comes in paroxysms of a dozen coughs or more at a time and is often worst at night. The cough may persist for several weeks.
• Posttussive symptoms: Posttussive gagging or emesis may be present after paroxysms of whooping cough. Subconjunctival hemorrhage may result from severe cough. Rib pain, with pinpoint tenderness worsening with respiration, may result from rib fracture associated with severe cough.
• Dyspnea and increased work of breathing: Symptoms may be worse at night because of changes in airway mechanics while the patient is recumbent. Apnea may be a chief feature in infants with pertussis, or whooping cough. Apnea may also result from upper airway obstruction due to other causes.
• Other symptoms: Myalgias are characteristic in influenza infection, especially in the setting of hoarseness with sudden sore throat, fever, chills, nonproductive cough, and headache. Fever may be present, but it is not typical in persons with croup. Fatigue or malaise may occur with any URI.

Physical

Viral nasopharyngitis

Patients with the common cold may have a paucity of clinical findings despite notable subjective discomfort. 

• Nasal mucosal erythema and edema: These are common.
• Nasal discharge: Profuse discharge is more characteristic of viral infections than bacterial infections. Initially clear secretions typically become cloudy white, yellow, or green over several days.
• Foul breath: Halitosis may be noted because resident florae process the products of the inflammatory process.
• Fever: This is unusual in adults with the common cold, but it may be present in children with rhinoviral infections.

Viral pharyngitis  

This condition may be associated with the following clinical findings:

• Pharyngeal erythema: Marked erythema typically occurs with adenoviral infection. In contrast, rhinoviral and coronaviral infections are not likely to manifest as severe erythema.
• Exudates: These may occur in half the patients with adenovirus infections. Exudative pharyngitis and tonsillitis may be seen with mononucleosis caused by EBV. Exudates are uncommon in rhinoviral, coxsackievirus, and herpes simplex virus (HSV) pharyngitis. Yellow or green secretions do not differentiate a bacterial pharyngitis from a viral one. Thick, yellow secretions are commonly seen with uncomplicated viral nasopharyngeal infections.
• Mucosal ulcers, erosions, vesicles: The presence of palatal vesicles or shallow ulcers is characteristic of primary infection with HSV. Ulcerative stomatitis may also occur in coxsackievirus or other enteroviral infection. Mucosal erosions may also be seen in primary HIV infection. Small vesicles on the soft palate, uvula, and anterior tonsillar pillars suggest infection by coxsackievirus, known as herpangina.
• Tonsillar hypertrophy: This may be noted.
• Foul breath: Halitosis may be noted because resident florae process the products of the inflammatory process.
• Anterior cervical lymphadenopathy: This is seen with viral and bacterial infections. Approximately half of EBV mononucleosis cases involve generalized adenopathy or splenomegaly. An enlarged liver may also be palpable. Primary HIV infection may also include lymphadenopathy.
• Conjunctivitis: This symptom may be seen with adenoviral pharyngoconjunctival fever and is present in one half to one third of all adenoviral URIs. Watery, injected conjunctiva may also be seen with allergic conditions.
• Cough: This is more suggestive of a viral than a bacterial etiology.
• Diarrhea: If associated with a URI, it suggests a viral etiology.
• Fever: EBV infections and influenza cause fever.

Bacterial pharyngitis

This may be difficult to distinguish from viral pharyngitis. Assessment for group A streptococci warrants special attention. Physical findings that suggest a high risk for group A streptococcal disease are erythema, swelling, or exudates of the tonsils or pharynx; temperature of 38.3°C (100.9°F) or higher; tender anterior cervical nodes (>1 cm); and an absence of conjunctivitis, cough, or rhinorrhea, which are suggestive of viral illness.¹⁵ (Also see the guideline summary, Pharyngitis.)

• Erythema: This may be especially prominent in persons with group A streptococcal pharyngitis. Palatal petechiae may be seen.
• Exudates of the pharynx: These are common with bacterial pharyngitis, manifesting as white or yellow patches. A whitish coating may appear on the tongue, causing the normal bumps to appear more prominent. Yellow or green coloration does not differentiate bacterial pharyngitis from a viral disease because thick, yellow secretions may be seen with uncomplicated viral nasopharyngitis. A whitish adherent membrane forming on the nasal septum, along with a mucopurulent blood-tinged discharge, should prompt a consideration of diphtheria. Pharyngeal and tonsillar diphtheria may manifest as an adherent blue-white or gray-green membrane over the tonsils or soft palate; if bleeding has occurred, the membrane may appear blackish.
• Tonsillar hypertrophy: Peritonsillar abscess may manifest as unilateral palatal and tonsillar pillar swelling, with downward and medial tonsil displacement; the uvula may tilt to the opposite side. Bulging of the posterior pharyngeal wall may signal a retropharyngeal abscess.
• Tender anterior cervical adenopathy: This may be present with streptococcal infection or with viral infections. In persons with diphtheria, submandibular and anterior cervical edema may be present along with adenopathy.
• Foul breath: This may be noted because resident florae process the products of the inflammatory process.
• Fever: Compared with other URIs, group A streptococcal infections are more likely cause fever, with temperatures around 38.3°C (101°F).
• Exanthem: This rash may be seen with group A streptococcal infections, particularly in patients younger than 18 years. This scarlet fever rash appears as tiny papules over the chest and abdomen, creating roughness similar to sandpaper and a sunburned appearance. The rash spreads, causing erythema in the groin and armpits. The face may be flushed, with pallor around the lips. Approximately 2-5 days later, the rash begins to resolve. Peeling is often noted on the tips of toes and fingers. Cutaneous diphtheria may appear as a scaling rash or as well-demarcated ulcers with membranes. Neisseria gonorrhoeae infection may also cause a rash.
• Uncommon findings: Drooling may be noted in cases of peritonsillar abscess, or it may denote epiglottitis. Lower respiratory tract findings (eg, rales) with concomitant URI are suggestive of infection with pathogens such as Mycoplasma pneumoniae and Chlamydia pneumoniae, as well as viruses. Conjunctivitis, cough, and diarrhea are more common with viral than with bacterial URIs. Rhinorrhea is not a common feature of pharyngitis caused by bacteria such as group A streptococci. Finally, in the setting of acute pharyngitis, the presence or absence of preexisting murmurs should be documented for comparative purposes in case rheumatic fever later develops.

Acute rhinosinusitis

This is most often viral; it may be challenging to differentiate common viral illnesses from uncommon bacterial cases on clinical grounds alone. Suspicion for acute bacterial rhinosinusitis is raised when symptoms last more than 7 days, when the patient has maxillary pain or tenderness in the face or teeth (especially unilateral), and when purulent nasal secretions are present. Occasional patients with acute bacterial sinusitis present with severe symptoms, especially unilateral face pain, even when symptoms have not lasted for 7 days or longer.¹⁶ The paranasal sinuses develop and enlarge after birth; ethmoid and sphenoid sinuses may not be of significant size until age 3-7 years. The frontal sinuses are the last to develop and may not be of significant size until adolescence.

Both viral and bacterial sinusitis may be associated with the following findings:

• Unilateral signs: This suggests sinus involvement, as opposed to uncomplicated rhinitis.
• Mucopurulent secretions: These may be present in the nares with both viral and bacterial sinusitis. A lighted nasal speculum directed posteriorly allows the clinician to view secretions emanating from the area of the middle meatus. Secretions may be thick or yellow; however, color does not differentiate a bacterial sinus infection from a viral one. Thick, yellow secretions may be seen several days into the course of uncomplicated viral nasopharyngitis.
• Mucosal edema and erythema: When rhinitis is present, the nasal mucosa may be inflamed. Typical findings include swelling and redness of the turbinates. In many cases of sinusitis, the nares serve only as a conduit for purulent secretions, and the nasal mucosa may not be inflamed. Pallor and edema may be associated with underlying allergic rhinitis.
• Nasal obstruction due to preexisting polyps or septal deviation: This may contribute to sinusitis, and it is best appreciated upon direct inspection with nasal endoscopy.
• Periorbital swelling: This may be present in ethmoid sinusitis.
• Facial tenderness to palpation or percussion: It may be present and most easily appreciated over the frontal or maxillary sinuses. Percuss and apply digital pressure to the forehead above the brow to evaluate frontal sinus area tenderness. The floor of the frontal sinuses may be approached by pressing upward on the supraorbital area of the skull beneath the eyebrows. Maxillary sinuses are posterior to the cheekbones; use digital pressure and percussion on the cheeks to elicit tenderness. Tapping on the upper teeth with a tongue depressor may evoke pain in the corresponding maxillary sinus. The floor of the maxillary sinuses may be approached by pressing upward on the palate. Ethmoid sinuses are between the eyes and behind the nasal bridge. Palpate the area around the middle canthus to assess the ethmoids. The sphenoid sinuses are deep to the ethmoids and behind the eyes. Evaluating the ethmoid and sphenoid sinuses during routine physical examination is challenging.
• Sinus cavity opacification on transillumination: Opacity is best appreciated in a completely darkened room. Place the illuminator directly on the skin at the level of the infraorbital rim to evaluate the maxillary sinuses and at the medial aspect of the supraorbital rim to evaluate the frontal sinuses. The maxillary sinuses may also be transilluminated by placing a light beam inside the patient's mouth against the palate directed upward. Bright transmission of light suggests a normal air-filled sinus; absent light transmission suggests the presence of fluid. This approach depends on the examiner's skill and experience, and results are best interpreted along with other findings. Transillumination findings may be unreliable in children. The frontal sinuses may not begin to develop until age 5-8 years.
• Halitosis: Foul breath may be noted because resident florae process the products of the inflammatory process.
• Fever: Less than 2% of individuals with sinusitis have fever.
• Suppuration: Suspect an intracranial suppurative complication (eg, abscess) when the examination reveals signs such as proptosis, impaired extraocular movements, decreased vision, papilledema, changes in mental status, or other neurologic findings.

Epiglottitis

Direct visualization is the best way to confirm the diagnosis of epiglottitis. However, such examination may compromise the airway. Therefore, in suspected epiglottitis, limit the examination to observation and an assessment of the vital signs. Oropharyngeal examination performed by using a tongue depressor or speculum can provoke laryngospasm. Direct visualization of the upper airway should be performed only when emergency endotracheal intubation or cricothyroidotomy can be safely performed if necessary.

Physical findings associated with epiglottitis include the following:

• Drooling
• Muffled dysphonia or loss of voice
• Stridor: Inspiratory stridor may be notable and best appreciated with auscultation over the anterior trachea. Wheezing heard on only expiration is most consistent with bronchial disease.
• Mild cough
• Tenderness to gentle palpation over the larynx
• Cervical adenopathy
• Respiratory distress: This may manifest as tachypnea, tachycardia, and the use of accessory muscles of respiration. Observe the patient for rib retractions, use of strap muscles, and perioral cyanosis. The classic tripod position describes a patient sitting upright supported by his or her hands with the tongue out and head forward.
• Fever

Laryngitis and laryngotracheitis

Many patients with croup or laryngotracheitis are less ill than they sound. However, in severe cases, children may have respiratory fatigue that leads to respiratory failure. Physical findings associated with laryngitis and tracheitis include those described below.

• Hoarseness: Hoarseness is a hallmark of laryngeal involvement. Lowered vocal pitch and loss of voice may occur.
• Cough  
  • Dry cough may be present with laryngeal involvement. Mild hemoptysis may be present. Clinically significant amounts of purulent sputum may suggest bronchitis or pneumonia.
  • Barking cough: Children with laryngotracheitis or croup may have the characteristic brassy, seal-like barking cough. A barking cough may also be present in diphtheria laryngitis.
  • Whooping cough: The classic whoop sound in whooping cough is an inspiratory gasping squeak that rises in pitch, typically interspersed between hacking coughs. The whoop is more common in children than in adults.
  • Inspiratory stridor may be audible with croup or whooping cough. It is often best heard with the stethoscope placed on the anterior aspect of the trachea during inspiration.
• Respiratory compromise: This manifests as tachypnea, tachycardia, and the use of accessory muscles of respiration. Diminished breath sounds in association with pallor and cyanosis may indicate impending respiratory failure.
• Posttussive effects: Conjunctival hemorrhages may result from paroxysms of coughing. Petechial hemorrhages may be noted in the upper body, resulting from severe paroxysms of coughing, such as those associated with whooping cough. Rib fracture, with pinpoint tenderness worsening with respiration, may result from severe coughing.
• Lymphadenopathy: This may be present in the anterior cervical nodes.
• Fever: While fever may be present, it is not typical in persons with croup. Fever may be seen with influenza laryngitis.

Causes

Most URIs are viral in origin. More than 200 different viruses are known to cause the common cold. Typical viral agents that cause URIs are rhinoviruses, coronaviruses, adenoviruses, or coxsackieviruses. With a few exceptions, similar agents cause URI in adults and children.

Nasopharyngitis  

More than 200 viruses are known to cause the symptoms of the common cold.

• Rhinoviruses: These cause approximately 30-50% of colds in adults. They grow optimally at temperatures near 32.8°C (91°F), which is the temperature inside the human nares.
• Coronaviruses: While they are a significant cause of colds, exact case numbers are difficult to determine because, unlike rhinoviruses, coronaviruses are difficult to culture in the laboratory.
• Enteroviruses, including coxsackieviruses, echoviruses, and others: These are also leading causes of the common cold.
• Other viruses: Adenoviruses, orthomyxoviruses (including influenza A and B viruses), paramyxoviruses (eg, PIV), RSV, EBV, and hMPV account for many URIs. Varicella, rubella, and rubeola infections may manifest as a nasopharyngitis before other classic signs and symptoms develop. The remainder of URI pathogens are not identified but are presumed to be viral. This group represents greater than 30% of common colds in adults.

Pharyngitis  

This is most often viral in origin. Importantly, group A streptococcal pharyngitis must be recognized because serious complications may follow untreated disease.

• Causes of viral pharyngitis  
  • Adenovirus, which may also cause laryngitis and conjunctivitis
  • Influenza viruses
  • Coxsackievirus
  • HSV
  • EBV (infectious mononucleosis)
  • Cytomegalovirus
• Causes of bacterial pharyngitis 
  • Group A streptococci (approximately 15% of all cases of pharyngitis)
  • Group C and G streptococci
  • N gonorrhoeae
  • Arcanobacterium (Corynebacterium) hemolyticum
  • Corynebacterium diphtheriae
  • Atypical bacteria (eg, M pneumoniae, C pneumoniae): Absent lower respiratory tract disease, the clinical significance of these pathogens is uncertain.
  • Anaerobic bacteria

Rhinosinusitis

If this is present in an immunocompetent individual, it is typically related to an uncomplicated viral URI.

• Viral causes:  These are similar to agents that cause viral nasopharyngitis and include rhinovirus, enterovirus, coronavirus, influenza A and B virus, PIV, RSV, and adenovirus.
• Bacterial causes: These are similar to the agents that cause otitis media. Bacterial pathogens isolated from maxillary sinus aspirates in children include Streptococcus pneumoniae (30-66%), H influenzae (20%, usually nontypeable), and Moraxella catarrhalis (20%).¹⁶  Other important pathogens include group A streptococci and other streptococcal species. Uncommon causes include C pneumonia, Neisseria species, anaerobes, and gram-negative rods.
• Nosocomial sinusitis: This often involves pathogens that colonize the upper respiratory tract and migrate into the sinuses. Prolonged endotracheal intubation places patients at increased risk for nosocomial sinusitis. Methicillin-resistant Staphylococcus aureus is a significant cause. Gram-negative bacilli (eg, Escherichia coli, Pseudomonas aeruginosa) are other causes. Aspergillus species are the leading causes of noninvasive fungal sinusitis. Although fungi are part of the normal flora of the upper airways, they may cause acute sinusitis in patients with immunocompromise or diabetes mellitus.

Epiglottitis

This is a bacterial infection. In the vast majority of children, Hib is isolated from blood or epiglottal cultures. Since the routine use of the Hib conjugate vaccine began in 1990, case rates in children younger than 5 years have declined by more than 95%. The prevalence of invasive Hib disease is approximately 1.3 cases per 100,000 children.¹⁴  Rates in adults have remained low and stable; Alaskan Natives have the highest rates of disease.

Other bacteria, found more commonly in adults than in children, include group A streptococci, S pneumoniae, and M catarrhalis. In adults, cultures are most likely to be negative.

Laryngotracheitis 

This is typically caused by viruses, with a few exceptions.

• Croup, or laryngotracheobronchitis: This is typically caused by PIV type 1, 2, or 3. PIVs account for up to 80% of croup infections. PIV type 1 is the leading cause of croup in children. Other viruses include influenza viruses and RSV. Uncommon causes include hMPV, adenovirus, rhinovirus, enterovirus (including coxsackievirus and enteric cytopathic human orphan [ECHO] viruses), and measles virus.
• Whooping cough: Approximately 95% of all cases are caused by the gram-negative rod Bordetella pertussis. The remaining cases result from Bordetella parapertussis.
• Other forms of laryngitis and laryngotracheitis: These are typically caused by viruses similar to those that cause nasopharyngitis, including rhinovirus, coronavirus, adenovirus, influenza virus, parainfluenza virus, and RSV. Candida species may cause laryngitis in immunocompromised hosts. Bacterial causes of laryngitis are far less common than these and include the following:  
  • Group A streptococci
  • C diphtheriae, an aerobic gram-positive rod that may infect only the larynx or may represent an extension of nasopharyngeal infection
  • C pneumonia
  • M pneumoniae
  • M catarrhalis
  • H influenzae

Other risk factors for URIs

• Contact: Close contact with small children who frequent group settings, such as school or daycare, increases the risk of URI.
• Travel: The incidence of contracting a URI is increased because of exposure to large numbers of individuals in closed settings.
• Smoking and exposure to second-hand smoke: These may alter mucosal resistance to URI.
• Immunocompromise that affects cellular or humoral immunity: This increases the likelihood of contracting a URI. Weakened immune function may result from splenectomy, HIV infection, use of corticosteroids, immunosuppressive treatment after stem cell or organ transplantation, multiple medical problems, or common stress. Cilia dyskinesia syndrome and cystic fibrosis also predispose individuals to URIs.
• Anatomic changes due to facial dysmorphisms, previous upper airway trauma, and nasal polyposis: These conditions may predispose individuals to URIs.
• Carrier state: Some people are carriers for group A streptococci. Such individuals may have repeated URIs.

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