Harrison's Internal Medicine Chapter 31. Pharyngitis, Sinusitis, Otitis, and Other Upper Respiratory Tract Infections
Pharyngitis, Sinusitis, Otitis, and Other Upper Respiratory Tract Infections: Introduction
Infections 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.
Infections of the Ear and Mastoid Infections of the ear and associated structures can involve both the middle and external ear, including the skin, cartilage, periosteum, ear canal, and tympanic and mastoid cavities. Both viruses and bacteria are known causes of these infections, some of which result in significant morbidity if not treated appropriately.
Infections of the External Ear Structures
Infections involving the structures of the external ear are often difficult to differentiate from noninfectious inflammatory conditions with similar clinical manifestations.
Infections of the Larynx and Epiglottis
Laryngitis is defined as any inflammatory process involving the larynx and can be caused by a variety of infectious and noninfectious processes. The vast majority of laryngitis cases seen in clinical practice in developed countries are acute. Acute laryngitis is a common syndrome caused predominantly by the same viruses responsible for many other URIs. In fact, most cases of acute laryngitis occur in the setting of a viral URI.
Infection of the submandibular and/or sublingual space typically originates from an infected or recently extracted lower tooth. The result is the severe, lifethreatening infection referred to as Ludwig's angina (see "Oral Infections," above). Infection of the lateral pharyngeal (or parapharyngeal) space is most often a complication of common infections of the oral cavity and upper respiratory tract, including tonsillitis, peritonsillar abscess, pharyngitis, mastoiditis, or periodontal infection.
Sexually transmitted infections (STIs) are defined as infections that spread primarily through person-to-person sexual contact. However, several of these infections, in particular HIV, syphilis and hepatitis B, can also be transmitted via mother-to-child-transmission during pregnancy and childbirth, blood products or tissue transfer.
Upper Respiratory Infections: Treatment Antibiotics have no role in the treatment of uncomplicated nonspecific URI. In the absence of clinical evidence of bacterial infection, treatment remains entirely symptom-based, with use of decongestants and nonsteroidal antiinflammatory drugs. Other therapies directed at specific symptoms are often useful, including dextromethorphan for cough and lozenges with topical anesthetic for sore throat. Clinical trials of zinc, vitamin C, echinacea, and other alternative remedies have revealed no consistent benefit for the treatment of nonspecific URI.
Clinical Manifestations Most cases of acute sinusitis present after or in conjunction with a viral URI, and it can be difficult to discriminate the clinical features of one from the other. A large proportion of patients with colds have sinus inflammation, although bacterial sinusitis complicates only 0.2–2% of these viral infections. Common presenting symptoms of sinusitis include nasal drainage and congestion, facial pain or pressure, and headache.
Chronic otitis externa is caused primarily by repeated local irritation, most commonly arising from persistent drainage from a chronic middle-ear infection. Other causes of repeated irritation, such as insertion of cotton swabs or other foreign objects into the ear canal, can lead to this condition, as can rare chronic infections such as syphilis, tuberculosis, or leprosy.
Serous Otitis Media In serous otitis media (otitis media with effusion), fluid is present in the middle ear for an extended period and in the absence of signs and symptoms of infection. In general, acute effusions are self-limited; most resolve in 2–4 weeks. In some cases, however (in particular after an episode of acute otitis media), effusions can persist for months. These chronic effusions are often associated with a significant hearing loss in the affected ear.
Acute mastoiditis. Axial CT image shows an acute fluid collection within the mastoid air cells on the left.
Purulent fluid should be cultured whenever possible to help guide antimicrobial therapy. Initial empirical therapy is usually directed against the typical organisms associated with acute otitis media, such as S. pneumoniae, H. influenzae, and M. catarrhalis. Some patients with more severe or prolonged courses of illness should be treated for infection with S. aureus and gram-negative bacilli (including Pseudomonas).
Diagnosis The primary goal of diagnostic testing is to separate acute streptococcal pharyngitis from pharyngitis of other etiologies (particularly viral) so that antibiotics can be prescribed more efficiently for patients to whom they may be beneficial. The most appropriate standard for the diagnosis of streptococcal pharyngitis, however, has not been definitively established. Throat swab culture is generally regarded as such.
NHIỄM TRÙNG ĐƯỜNG TIỂU (Urinary Tract Infection)
Nhiễm trùng đường tiểu rất hay làm phiền phái nữ. Ở Mỹ, tính chung, mỗi năm phụ nữ đi khám bác sĩ khoảng 8 triệu lần vì nhiễm trùng đường tiểu, và ít nhất, có 100.000 trường hợp phải vào bệnh viện để chữa trị. Nhiễm trùng đường tiểu bắt đầu đến thăm phụ nữ ở tuổi học trò (schoolgirl), rồi xảy ra nhiều nhất trong khoảng tuổi 20 đến 50, khi đời sống tình dục người phụ nữ ở mức độ phong phú nhất.
Hib strains cause systemic disease by invasion and hematogenous spread from the respiratory tract to distant sites such as the meninges, bones, and joints. The type b polysaccharide capsule is an important virulence factor affecting the bacterium's ability to avoid opsonization and cause systemic disease.
Nontypable strains cause disease by local invasion of mucosal surfaces. Otitis media results when bacteria reach the middle ear by way of the eustachian tube. Adults with chronic bronchitis experience recurrent lower respiratory tract infection due to nontypable strains.
Urinary Tract Infections Urinary tract infections (UTIs) account for as many as 40–45% of nosocomial infections; up to 3% of bacteriuric patients develop bacteremia. Although UTIs contribute only 10–15% to prolongation of hospital stay and to extra costs, these infections are important reservoirs and sources for spread of antibiotic-resistant bacteria in hospitals. Almost all nosocomial UTIs are associated with preceding instrumentation or indwelling bladder catheters, which create a 3–10% risk of infection each day.
Tuyển tập các báo cáo nghiên cứu về y học được đăng trên tạp chí y học Critical Care giúp cho các bạn có thêm kiến thức về ngành y học đề tài: Procalcitonin testing has the potential to reduce unnecessary antibiotic use in patients with suspected lower respiratory tract infections...
Acute Sinusitis: Treatment
Most patients with a diagnosis of acute rhinosinusitis based on clinical grounds improve without antibiotic therapy. The preferred initial approach in patients with mild to moderate symptoms of short duration is therapy aimed at facilitating sinus drainage, such as oral and topical decongestants, nasal saline lavage, and—in patients with a history of chronic sinusitis or allergies—nasal glucocorticoids.
Etiology Acute otitis media typically follows a viral URI. The causative viruses (most commonly RSV, influenza virus, rhinovirus, and enterovirus) can themselves cause subsequent acute otitis media; more often, they predispose the patient to bacterial otitis media. Studies using tympanocentesis have consistently found S. pneumoniae to be the most important bacterial cause, isolated in up to 35% of cases. H. influenzae (nontypable strains) and M.
Pharyngitis: Treatment Antibiotic treatment of pharyngitis due to S. pyogenes confers numerous benefits, including a decrease in the risk of rheumatic fever. The magnitude of this benefit is fairly small, however, since rheumatic fever is now a rare disease, even among untreated patients. When therapy is started within 48 h of illness onset, however, symptom duration is also decreased. An additional benefit of therapy is the potential to reduce the spread of streptococcal pharyngitis, particularly in areas of overcrowding or close contact.