Diseases of the upper respiratory tract are named according to the anatomic sites involved. Most of these infections are self-limiting, and the majority of infections are of viral origin.

Laryngitis

 Acute laryngitis is usually associated with the common cold or influenza syndromes. Characteristically, patients complain of hoarseness and lowering or deepening of the voice. Acute laryngitis is generally a benign illness.

Acute laryngitis is almost exclusively associated with viral infection. Although numerous viruses can cause laryngitis, influenza and parainfluenza viruses, rhinoviruses, adenoviruses, coronavirus, and human metapneumovirus are the most common etiologic agents. If examination of the larynx reveals an exudate or membrane on the pharyngeal or laryngeal mucosa, streptococcal infection, mononucleosis, or diphtheria should be suspected (see the discussion about miscellaneous infections caused by other agents, presented later in this chapter). Chronic laryngitis, although less frequently associated with infectious agents, may be caused by bacteria or fungal isolates. Infections have been identified that are associated with methicillin-resistant Staphylococcus aureus (MRSA) and Candida spp.

Laryngotracheobronchitis

Another clinical syndrome closely related to laryngitis is acute laryngotracheobronchitis, or croup. Croup is a relatively common illness in young children, primarily those younger than 3 years of age. Of significance, croup can represent a potentially more serious disease if the infection extends downward from the larynx to involve the trachea or even the bronchi. Illness is characterized by variable fever, inspiratory stridor (difficulty in moving enough air through the larynx), hoarseness, and a harsh, barking, nonproductive cough. These symptoms last for 3 to 4 days, although the cough may persist for a longer period. In young infants, severe respiratory distress and fever are common symptoms.

Similar to the etiologic agents of laryngitis, viruses are a primary cause of croup; parainfluenza viruses are the major etiologic agents. In addition to parainfluenza viruses, influenza viruses, respiratory syncytial virus, and adenoviruses can also cause croup.

Also capable of causing croup, though not as frequently, are Mycoplasma pneumoniae, rhinoviruses, and enteroviruses.

Epiglottitis

Epiglottitis is an infection of the epiglottis and other soft tissues above the vocal cords. Infection of the epiglottis can lead to significant edema (swelling) and inflammation. Most commonly, children between the ages of 2 and 6 years of age are infected. These children typically present with fever, difficulty in swallowing because of pain, drooling, and respiratory obstruction with inspiratory stridor. Epiglottitis is a potentially life-threatening disease because the patient’s airway can become completely obstructed (blocked) if not treated.

In contrast to laryngitis, epiglottitis is usually associated with bacterial infections. In the past, 2- to 4-year-old children were typically infected with Haemophilus influenzae type b as the primary cause of epiglottitis. However, due to the common use of Haemophilus influenzae type b conjugated vaccine, the typical patient is an adult with a sore throat. Other organisms occasionally implicated are streptococci and staphylococci. Diagnosis is established on clinical grounds, including the visualization of the epiglottis, which appears swollen and bright red in color. Bacteriologic culture of the epiglottis is contraindicated because swabbing of the epiglottis may lead to respiratory obstruction. Of importance, H. influenzae bacteremia usually occurs in children with epiglottitis caused by this organism.

Pharyngitis, Tonsillitis, and Peritonsillar Abscesses

 Pharyngitis and Tonsillitis. Pharyngitis (sore throat) and tonsillitis are common upper respiratory tract infections affecting both children and adults. Acute pharyngitis is an illness that frequently causes people to seek medical care.

Clinical Manifestations. Infection of the pharynx is associated with pharyngeal pain. Visualization of the pharynx reveals erythematous (red) and swollen tissue. Depending on the causative microorganism, either inflammatory exudate (fluid with protein, inflammatory cells, and cellular debris), vesicles (small blister-like sacs containing liquid) and mucosal ulceration, or nasopharyngeal lymphoid hyperplasia (swollen lymph nodes) may be observed.

Pathogenesis. Pathogenic mechanisms differ and depend on the organism causing the pharyngitis. For example, some organisms directly invade the pharyngeal mucosa (e.g., Arcanobacterium haemolyticum), others elaborate toxins and other virulence factors at the site (e.g., Corynebacterium diphtheriae), and still others invade the pharyngeal mucosa and elaborate toxins and other virulence factors (e.g., group A streptococci [Streptococcus pyogenes]). Pathogenic mechanisms are reviewed in Part III according to various organism groups.

Epidemiology/Etiologic Agents. Most cases of pharyngitis occur during the colder months and often accompany other infections, primarily those caused by viruses. Patients with respiratory tract infections caused by influenza types A and B, parainfluenza, coxsackie A, rhinoviruses, or coronaviruses frequently complain of a sore throat. Pharyngitis, often with ulceration, is also commonly found in patients with infectious mononucleosis caused by either Epstein-Barr virus or cytomegalovirus. Although less common, pharyngitis caused by adenovirus or herpes simplex virus is clinically severe. Finally, acute retroviral syndrome caused by human immunodeficiency virus 1 (HIV-1) is associated with acute pharyngitis.

Although different bacteria can cause pharyngitis or tonsillitis, the primary cause of bacterial pharyngitis is Streptococcus pyogenes (or group A beta-hemolytic streptococci). Viral pharyngitis or other causes of pharyngitis/ tonsillitis must be differentiated from that caused by S. pyogenes, because pharyngitis resulting from S. pyogenes is treatable with penicillin and a variety of other antimicrobials, whereas viral infections are not. In addition, treatment is of particular importance because infection with S. pyogenes can lead to complications such as acute rheumatic fever and glomerulonephritis. These complications are referred to as poststreptococcal sequelae (dis eases that follow a streptococcal infection) and are primarily immunologically mediated; these sequelae are discussed in greater detail in Chapter 15. S. pyogenes may also cause pyogenic infections (suppurations) of the tonsils, sinuses, and middle ear, or cellulitis as secondary pyogenic sequelae after an episode of pharyngitis. Accordingly, streptococcal pharyngitis is usually treated to prevent both the suppurative and nonsuppurative sequelae, as well as to decrease morbidity.

Although bacteria other than group A streptococci may cause pharyngitis, this occurs less often. Large colony isolates of groups C and G streptococci (classified as Streptococcus dysgalactiae subsp. equisimilis) are pyogenic streptococci with similar virulence traits as S. pyogenes; symptoms of pharyngitis caused by these agents are also similar to S. pyogenes. In contrast to S. pyogenes, these agents are rarely associated with poststreptococcal sequelae, namely glomerulonephritis and possibly rheumatic fever. Recent studies have demonstrated that these streptococci can exchange genetic information with S. pyogenes and thus potentially obtain virulence factors usually associated with S. pyogenes such as M proteins, streptolysin O, and superantigen genes. Arcanobacterium haemolyticum is also a cause of pharyngitis among adolescents. Examples of agents that can cause pharyngitis or tonsillitis are listed in Table 1.

Table1. Examples of Bacteria That Can Cause Acute  Pharyngitis and/or Tonsillitis

Although H. influenzae, S. aureus, and S. pneumoniae are frequently isolated from nasopharyngeal and throat cultures, they have not been shown to cause pharyngitis. Carriage of any of these organisms, as well as Neisseria meningitidis, may have clinical importance for some patients. Cultures of specimens obtained from the anterior nares often yield S. aureus. The carriage rate for this organism is especially high among health care workers, and 10%-30% of the general population can be colonized with this microbe, depending on the population characteristics.

Vincent’s angina, also called acute necrotizing ulcerative gingivitis, or trench mouth, is a mixed bacterial spirochetal infection of the gingival edge. The infection is relatively rare today, but it is considered a serious disease because it is often complicated by septic jugular thrombophlebitis, bacteremia, and widespread metastatic infection. Adults are more often affected than children; poor oral hygiene is a predisposing factor. Multiple anaerobes, especially Fusobacterium necrophorum, are implicated in this syndrome. Although Gram stain of a throat specimen is usually not predictive, in those patients with symptoms suggestive of Vincent’s angina, Gram stain reveals numerous fusiform, gram-negative bacilli, and spirochetes.

Peritonsillar Abscesses. Peritonsillar abscesses are generally considered a complication of tonsillitis. This infection is most common in children older than 5 years of age and in young adults. It is important to treat these infections because they can spread to adjacent tissues, as well as erode into the carotid artery to cause an acute hemorrhage. The predominant organisms isolated in peritonsillar abscesses include non–spore-forming anaerobes, such as Fusobacterium (especially F. necrophorum), Bacteroides (including the B. fragilis group), and anaerobic cocci. Streptococcus pyogenes and viridans streptococci may also be involved.

Rhinitis

 Rhinitis (common cold) is an inflammation of the nasal mucous membrane or lining. Depending on the host response and the etiologic agent, rhinitis is characterized by variable fever, increased mucous secretions, inflammatory edema of the nasal mucosa, sneezing, and watery eyes. With rare exceptions, rhinitis is typically associated with viral infections (20%-25%); some of these agents are listed in Box 1. Rhinitis is common because of the large number of different causative viruses, and reinfections may occur. Bacterial agents associated with rhinitis (10%-15%) include Chlamydia pneumoniae, Mycoplasma pneumoniae, and Group A streptococci.

Box1. Viral Agents That Can Cause Rhinitis

Miscellaneous Infections Caused by Other Agents.

 Corynebacterium diphtheriae. Pharyngitis caused by Corynebacterium diphtheriae is less common than streptococcal pharyngitis. After an incubation period of 2 to 4 days, diphtheria usually presents as pharyngitis or tonsillitis. Patients are often febrile and complain of sore throat and malaise (body discomfort). The hallmark for diphtheria is the presence of an exudate or membrane that is usually on the tonsils or pharyngeal wall. The gray white membrane is a result of the action of diphtheria toxin on the epithelium at the site of infection. Complications occur frequently with diphtheria and are usually seen during the last stage of the disease (paroxysmal stage). The most feared complications are those involving the central nervous system such as seizures, coma, or blindness. Information as to how this organism causes disease is discussed in Chapter 69. Additional specifics regarding this organism are provided in Chapter 17.

Bordetella pertussis. Although mass immunization programs have greatly reduced the incidence of pertussis, enough cases (because of outbreaks and regional epidemics) still occur. In 2010, the CDC reported 27,500 cases of pertussis. This increased number of identifiable cases may be due to improved awareness and improved diagnostic methods, such as nucleic acid-based testing. It is important that laboratories are capable of detecting, isolating, and identifying the organism, or the specimen should be referred to a reference laboratory.

Characteristically, pertussis, or whooping cough, is a prolonged disease (lasting as long as 6 to 8 weeks) marked by paroxysmal (sudden or intense) coughing.

Following an incubation period of 7 to 13 days, the patient with symptomatic infection develops upper respiratory symptoms, including a dry cough, fever, runny nose, and sneezing. After about 2 weeks, this may progress to spells of paroxysmal coughing. As these episodes worsen, the characteristic whoop, caused by attempted inspiration through an epiglottis undergoing spasm, begins. Vomiting may occur, and usually a lymphocytosis is present. This phase of the illness may last as long as 6 weeks. Bacterial culture for B. pertussis is effective using nasopharyngeal specimens during the first 2 weeks when symptoms are evident. Amplification and polymerase chain reaction may demonstrate positive results within 0-4 weeks of the onset of symptoms. However, positive results should be interpreted with caution and in correlation with patient signs and symptoms. More information regarding B. pertussis is provided in Chapter 37.

Klebsiella spp. Rhinoscleroma is a rare form of chronic, granulomatous infection of the nasal passages, including the sinuses and occasionally the pharynx and larynx. Associated with Klebsiella rhinoscleromatis and Klebsiella ozaenae, the disease is characterized by nasal obstruction appearing over a long period, caused by tumor-like growth with local extension. K. ozaenae may contribute to another infrequent condition called ozena, characterized by a chronic, mucopurulent nasal discharge that is often foul smelling. It is caused by secondary, low-grade anaerobic infection.

اخر الاخبار

اخبار العتبة العباسية المقدسة

معهد القرآن الكريم النسوي ينهي استعداداته لإقامة مهرجان السقاء القرآني الخامس

قسم الشؤون الفكرية يقيم ورشة تطويرية عن مهارات الإلقاء والخطابة في ذي قار

قسم العلاقات العامة يختتم تحضيراته لإقامة مهرجان (الأقمار المحمدية) في واسط

معهد القرآن الكريم النسوي يعلن استقباله 50 بحثًا للمشاركة في مهرجان السقّاء القرآني الخامس

المزيد

الآخبار الصحية

اللحظات الأخيرة قبل الموت.. هذا هو تسلسل "فقدان الحواس"

وخز الأطراف وضعف الذاكرة.. علامات على نقص فيتامين هام

عادة صباحية بسيطة.. تأثيرها قد يحسن ضغط الدم

عادات يومية تدمر قلبك بصمت.. خبراء يطلقون التحذير

المزيد

الآخبار التكنلوجية

الذكاء الاصطناعي يفك لغز آثار أقدام الديناصورات

القمر أولا.."سبيس إكس" تؤجل خططها الخاصة بالرحلات إلى المريخ

الذكور أم الإناث؟ دراسة "تنسف الشائع" بشأن التوحد

خبير يكشف عن اقتراب العلماء من فك شفرات "لغات الحيوانات" !

المزيد

مواضيع ذات صلة

Introduction and History of Paroxysmal Nocturnal Hemoglobinuria

Diseases of The Central Nervous System

Diseases of The Oral Cavity

Hyperthyroidism: Etiology and Treatment

Clinical Features of Hyper- and Hypothyroidism

Clinical Associations of Aplastic Anemia

Typical and Atypical Presentations of Aplastic Anemia

Pathophysiologic Pathways Leading to Aplastic anemia

Epidemiology of Aplastic anemia

Pneumonia

Bronchitis

Pathogenesis of the respiratory tract: Microorganism Factors