Pneumonia Infections, Pulmonary Infections PDF

Pulmonary Infections pneumonia  Definition: any infection in the lung. the vulnerability of the lung to infection despite these defenses is not surprising because: 1. many microbes are airborne and readily inhaled into the lungs. 2. nasopharyngeal flora are regularly aspirated during sleep...

Pulmonary Infections pneumonia  Definition: any infection in the lung. the vulnerability of the lung to infection despite these defenses is not surprising because: 1. many microbes are airborne and readily inhaled into the lungs. 2. nasopharyngeal flora are regularly aspirated during sleep, even by healthy individuals. 3. lung diseases often lower local immune defenses.  Defense mechanisms and predisposing factors Nasal clearance: sneezing, blowing , cilia into nasopharynx. Tracheobronchial clearance: mucociliary action sweeping mucous to oropharynx. Alveolar clearance: by alveolar macrophages. Classification of acute pneumonia Anatomic: bronchopneumonia and lobar pneumonia. Cause: Bacterial, Viral, Fungal, Parasitic. Clinical presentation: Typical , Atypical. Source. Duration : acute, chronic.  Community-Acquired Bacterial Pneumonias bacterial pneumonias often follow a viral upper- respiratory tract infection. S. pneumoniae (i.e. the pneumococcus) is the most common cause of community-acquired acute pneumonia. Morphology bacterial pneumonia has two patterns of anatomic distribution: lobular bronchopneumonia and lobar pneumonia. bronchopneumonia characteristic by patchy consolidation in the lung lobar pneumonia characteristic by consolidation of a large portion of a lobe or of an entire lobe Lobar pneumonia: acute bacterial infection of a large portion or an entire lobe. usually affects young adults. effective antibiotics therapy. 90-95% are caused by pneumococci Bronchopneumonia usually arises as complication of bronchiolitis or an exacerbation of chronic bronchitis. affect commonly the two extreme of life. common in terminal disease of heart failure and disseminated cancer bronchopneumonia can spread to produce a lobar pattern. Etiology o Staph. o Strep. o Pneumococci o H influenza. o Coliform bacilli. Complications of pneumonia (1) abscess formation. (2) empyema. (3) bacteremic dissemination to the heart valves, pericardium, brain, kidneys, spleen, or joints, causing metastatic abscesses, endocarditis, meningitis, or suppurative arthritis. Clinical Features abrupt onset of high fever, shaking chills, and cough producing mucopurulent sputum; occasional patients have hemoptysis. when pleuritis is present, it is accompanied by pleuritic pain and pleural friction rub. the whole lobe is radiopaque in lobar pneumonia, whereas there are focal opacities in bronchopneumonia.  Community-Acquired Viral Pneumonias the most common causes of community-acquired viral pneumonias are influenza types A and B and respiratory syncytial viruses Clinical Features the clinical course of viral pneumonia is extremely varied. it may masquerade as a severe upper-respiratory tract infection or “chest cold” that goes undiagnosed, or manifest as a fulminant, life-threatening infection in immunocompromised patients. Cont. …. the initial presentation usually is that of an acute, nonspecific febrile illness characterized by fever, headache, and malaise and, later, cough with minimal sputum.  Hospital-Acquired Pneumonias it pulmonary infections acquired in the course of a hospital stay. it common in hospitalized individuals with severe underlying disease, those who are:  immunosuppressed on prolonged antibiotic regimens. Cont. …… patients on mechanical ventilation are a particularly high-risk group, and infections acquired in this setting are given the designation ventilator-associated pneumonia. Gram-negative rods (members of Enterobacteriaceae and Pseudomonas spp.) and S. aureus are the most common isolates organism.  Aspiration Pneumonia it occurs in debilitated patients or those who aspirate gastric contents while unconscious (e.g., after a stroke) or during repeated vomiting. typically, more than one organism is recovered on culture, aerobes being more common than anaerobes. abscess formation is a common complication.  Lung Abscess It a localized area of suppurative necrosis within the pulmonary parenchyma, resulting in the formation of one or more large cavities. Cont. …… Causative agents: S. aureus,  Streptococcus pyogenes, K. pneumoniae, Pseudomonas spp., Anaerobic bacteria Mycotic infections and bronchiectasis Clinical Features a prominent cough that usually yields copious amounts of foul-smelling, purulent, or sanguineous sputum; occasionally, hemoptysis occurs. spiking fever and malaise are common.  Chronic Pneumonias chronic pneumonia most often is a localized lesion in an immunocompetent individual, with or without regional lymph node involvement. there is typically granulomatous inflammation, which may be due to bacteria (e.g M. tuberculosis) or fungi.  Pneumonia in the Immunocompromised Host the appearance of a pulmonary infiltrate and signs of infection (e.g., fever) are some of the most common and serious complications in individuals with immune systems that are suppressed by disease, immunosuppressive drugs, or therapeutic irradiation. Cont. …… the more common pulmonary pathogens include : (1) Bacteria (P. aeruginosa, Mycobacterium spp., L. pneumophila, and Listeria monocytogenes). (2) Viruses ( (cytomegalovirus and herpesvirus). (3) Fungi (P. jiroveci, Candida spp., Aspergillus spp.,and Cryptococcus neoformans). Chronic Obstructive Lung Disease Emphysema  characterized by permanent enlargement of the air spaces distal to the terminal bronchioles, accompanied by destruction of their walls without significant fibrosis. Cont. …. it is classified according to its anatomic distribution. there are four major types of emphysema: (1) Centriacinar. (2) Panacinar. (3) Distal acinar. (4) Irregular. Centriacinar (centrilobular) emphysema: it most common in cigarette smokers, often in association with chronic bronchitis. the lesions are more common and severe in the upper lobes, particularly in the apical segments.  Panacinar (panlobular) emphysema: the acini are uniformly enlarged, from the level of the respiratory bronchiole to the terminal blind alveoli. it occurs more commonly in the lower lung zones and is associated with α1-anti-trypsin deficiency.  Distal acinar (paraseptal) emphysema: in this type the distal part is primarily involved and the proximal portion of the acinus is normal. the emphysema is more striking adjacent to the pleura. Cont. …. the cause of this type of emphysema is unknown. it comes to attention most often in young adults who present with spontaneous pneumothorax.  Irregular Emphysema: it named because the acinus is irregularly involved, is almost invariably associated with scarring, such as that resulting from healed inflammatory diseases. although clinically asymptomatic, this may be the most common form of emphysema. Pathogenesis inhaled cigarette smoke and other noxious particles cause lung damage and inflammation, which, particularly in patients with a genetic predisposition, result in parenchymal destruction (emphysema) and airway disease (bronchiolitis and chronic bronchitis). Clinical Features dyspnea usually is the first symptom. in patients with underlying chronic bronchitis or chronic asthmatic bronchitis, cough and wheezing may be the initial complaints. Chronic Bronchitis Cont. …. it diagnosed on clinical grounds: it is defined by the presence of a persistent productive cough for at least 3 consecutive months in at least 2 consecutive years. Cont. …. it is common among cigarette smokers, some studies indicate that 20% to 25% of men in the 40- to 65- year-old age group have the disease. in early stages of the disease, the cough raises mucoid sputum, but airflow is not obstructed. Pathogenesis the characteristic feature : hypersecretion of mucus, beginning in the large airways. most important cause is cigarette smoking, other air pollutants, such as sulfur dioxide and nitrogen dioxide, may contribute. Cont. …. these environmental irritants induce hypertrophy of mucous glands in the trachea and bronchi as well as an increase in mucin-secreting goblet cells in the epithelial surfaces of smaller bronchi and bronchioles. these irritants also cause inflammation marked by the infiltration of macrophages, neutrophils, and lymphocytes. Clinical Features in some patients, cough and sputum production persist indefinitely without ventilatory dysfunction, while others develop COPD with significant outflow obstruction marked by hypercapnia, hypoxemia, and cyanosis. progressive disease is marked by the development of pulmonary hypertension, sometimes leading to cardiac failure ,recurrent infections; and ultimately respiratory failure. Asthma chronic inflammatory disorder of the airways that causes recurrent episodes of wheezing, breathlessness, chest tightness, and cough, particularly at night and/or early in the morning. Cont. …. the hallmarks of asthma are  intermittent, reversible airway obstruction;  chronic bronchial inflammation with eosinophils; bronchial smooth muscle cell hypertrophy and hyperreactivity; and increased mucus secretion. Asthma tends to “run” in families, but the role of genetics in asthma is complex Pathogenesis major factors contributing to the development of asthma include genetic predisposition to type I hypersensitivity (atopy), acute and chronic airway inflammation, and bronchial hyperresponsiveness to a variety of stimuli. Asthma may be subclassified as atopic (evidence of allergen sensitization) or nonatopic. Cont. …. in both types, episodes of bronchospasm may be triggered by diverse exposures, such as respiratory infections (especially viral), airborne irritants (e.g., smoke, fumes), cold air, stress, and exercise. Eosinophil is the most common leukocytes. Types of Asthma this is the most common type of asthma and is a classic example of i. type I IgE–mediated hypersensitivity Atopic reaction. Asthma: it usually begins in childhood. Positive family history Positive Skin test. Cont. …. patients with nonatopic forms of asthma do not have evidence of ii. Non- allergen sensitization, and skin test Atopic results usually are negative. Asthma: positive family history of asthma is less common. Cont. …. common triggers: respiratory infections due to viruses (e.g rhinovirus, parainfluenza virus) inhaled air pollutants (e.g sulfur dioxide, ozone, nitrogen dioxide) Cont. …. several pharmacologic agents iii. provoke asthma, Aspirin being the Drug- most striking example. Induced the precise pathogenesis is Asthma: unknown. Cont. …. may be triggered by fumes (epoxy resins, plastics), iv. organic and chemical Occupational dusts (wood, cotton, Asthma: platinum), gases (toluene), and other chemicals. Asthma attacks usually develop after repeated exposure to the inciting antigen(s). Clinical Features an attack of asthma is characterized by severe dyspnea and wheezing due to bronchoconstriction and mucus plugging, which leads to trapping of air in distal airspaces and progressive hyperinflation of the lungs. the usual case, attacks last from 1 to several hours and subside either spontaneously or with therapy. Bronchiectasis  is the permanent dilation of bronchi and bronchioles caused by destruction of smooth muscle and the supporting elastic tissue, it typically results from or is associated with chronic necrotizing infections. it is not a primary disorder, as it always occurs secondary to persistent infection or obstruction caused by a variety of conditions. Cont. …. Bronchiectasis gives rise to a characteristic symptom complex dominated by cough and expectoration of copious amounts of purulent sputum. Diagnosis: depends on an appropriate history and radiographic demonstration of bronchial dilation. Clinical Features Bronchiectasis is characterized by severe, persistent cough associated with expectoration of mucopurulent, sometimes fetid, sputum. other common symptoms include dyspnea, rhinosinusitis, and hemoptysis. symptoms often are episodic and are precipitated by upper respiratory tract infections or the introduction of new pathogenic agents.  Chronic Interstitial (Restrictive, Infiltrative) Lung Diseases  Chronic interstitial diseases a heterogeneous group of disorders characterized by bilateral, often patchy, pulmonary fibrosis mainly affecting the walls of the alveoli. many of the entities in this group are of unknown cause and pathogenesis; some have an intraalveolar and an interstitial component. Cont. ….. Chronic interstitial lung diseases are categorized based on clinicopathologic features and characteristic histology. the hallmark of these disorders is reduced compliance (stiff lungs), which in turn necessitates increased effort to breathe (dyspnea). Fibrosing Diseases  Pneumoconioses it include diseases induced by organic and inorganic particulates, and some experts also regard chemical fume- and vapor-induced lung diseases as pneumoconioses. the mineral dust pneumoconioses—the three most common of which are caused by inhalation of coal dust, silica, and asbestos—usually stem from exposure in the workplace. Pathogenesis the reaction of the lung to mineral dusts depends on many variables, including the size, shape, solubility, and reactivity of the particles. most inhaled dust is entrapped in the mucus blanket and rapidly removed from the lung by ciliary movement. Cont. ….. some of the particles become impacted at alveolar duct bifurcations, where macrophages accumulate and engulf the trapped particulates. tobacco smoking worsens the effects of all inhaled mineral dusts, more so with asbestos than other particles. Coal Worker’s Pneumoconiosis the spectrum of lung findings in coal workers are: Asymptomatic anthracosis, in which pigment deposits without a perceptible cellular reaction. Simple coal worker’s pneumoconiosis (CWP), in which macrophages accumulate with little to no pulmonary dysfunction. Cont. ….. Complicated CWP or progressive massive fibrosis (PMF), in which fibrosis is extensive and lung function is compromised. although coal is mainly carbon, coal mine dust contains a variety of trace metals, inorganic minerals, and crystalline silica. Clinical Features CWP usually is a benign disease that produces little decrement in lung function. in those in whom PMF develops, there is increasing pulmonary dysfunction, pulmonary hypertension, and cor pulmonale.  Silicosis Silicosis is currently the most prevalent chronic occupational disease in the world. it is caused by inhalation of crystalline silica, mostly in occupational settings. Clinical Features asymptomatic workers on routine chest radiographs, which typically show a fine nodularity in the upper zones of the lung. many patients with PMF develop pulmonary hypertension and cor pulmonale as a result of chronic hypoxia–induced vasoconstriction and parenchymal destruction. Cont. ….. associated with an increased susceptibility to tuberculosis. nodules of silicotuberculosis often contain a central zone of caseation. Silica exposure is associated with some increase in risk of lung cancer.  Asbestosis and Asbestos-Related Diseases Asbestos is a family of crystalline hydrated silicates with a fibrous geometry. on the basis of epidemiologic studies, occupational exposure to asbestos is linked to:. Cont. ….. (1) Parenchymal interstitial fibrosis (asbestosis). (2) Localized fibrous plaques, or, rarely, diffuse fibrosis in the pleura. (3) Pleural effusions. (4) Lung carcinoma. (5) Malignant pleural and peritoneal mesothelioma. (6) Laryngeal carcinoma Pathogenesis as with silica crystals, once phagocytosed by macrophages, asbestos fibers activate the inflammasome and damage phagolysosomal membranes, stimulating the release of proinflammatory factors and fibrogenic mediators. asbestos probably also functions as both a tumor initiator and a promoter. Clinical Features progressively worsening dyspnea appears 10 to 20 years after exposure. it is usually accompanied by a cough and production of sputum. the disease may remain static or progress to congestive heart failure, cor pulmonale, and death. Cont. ….. Pleural plaques are usually asymptomatic and are detected on radiographs as circumscribed densities. both lung carcinoma and malignant mesothelioma develop in workers exposed to asbestos. Lung Tumors  about 95% of primary lung tumors are carcinomas; the remaining 5% span a miscellaneous group that includes carcinoids, mesenchymal malignancies. the most common benign tumor is a spherical, small (1 to 4 cm), discrete “hamartoma” that often shows up as a so-called “Coin lesion” on chest imaging.  Carcinomas the four major histologic types of carcinomas of the lung are adenocarcinoma, squamous cell carcinoma, small cell carcinoma (a subtype of neuroendocrine carcinoma), and large cell carcinoma. Cont. …. Squamous cell and small cell carcinomas have the strongest association with smoking. Adenocarcinomas also are by far the most common primary tumors arising in women, in never-smokers, and in individuals younger than 45 years of age. Etiology and Pathogenesis like other cancers, smoking-related carcinomas of the lung arise by a stepwise accumulation of driver mutations that result in transformation of benign progenitor cells in the lung into neoplastic cells possessing all of the hallmarks of cancer. Cont. …. passive smoking (proximity to cigarette smokers) also increases the risk for developing lung cancer, as does smoking of pipes and cigars, albeit only modestly. Morphology Carcinomas of the lung begin as small lesions that typically are arise as intraluminal masses, invade the bronchial mucosa or form large bulky masses pushing into adjacent lung parenchyma. Adenocarcinomas usually peripherally located, but also may occur closer to the hilum. it grow slowly and form smaller masses than do the other subtypes, but they tend to metastasize widely at an early stage. Squamous cell carcinomas more common in men and are closely correlated with a smoking history they tend to arise centrally in major bronchi and eventually spread to local hilar nodes, but they disseminate outside the thorax later than do other histologic types. large lesions may undergo central necrosis, giving rise to cavitation. Cont. …. squamous cell carcinomas often are preceded by the development, over years. squamous metaplasia or dysplasia in the bronchial epithelium, which then transforms to carcinoma in situ, a phase that may last for several years. Cont. …. Histologic examination. the tumors range from well differentiated squamous cell neoplasms showing keratin pearls and intercellular bridges to poorly differentiated neoplasms exhibiting only minimal squamous cell features Large cell carcinomas Large cell carcinomas are undifferentiated malignant epithelial tumors that lack the cytologic features of neuroendocrine carcinoma and show no evidence of glandular or squamous differentiation. the cells typically have large nuclei, prominent nucleoli and moderate amounts of cytoplasm. Small cell lung carcinomas (SCLCs) generally appear as pale gray, centrally located masses that extend into the lung parenchyma. these cancers are composed of relatively small tumor cells with a round to fusiform shape, scant cytoplasm and finely granular chromatin with a salt and pepper appearance. numerous mitotic figures are present. Cont. …. each of these lung cancer subtypes tends to spread to lymph nodes in the carina, the mediastinum, and the neck (scalene nodes) and clavicular regions. involvement of the left supraclavicular node (Virchow node) is particularly characteristic and sometimes calls attention to an occult primary tumor. Thanks for attention