Sheet: Patho-Pulmonary infections Done by: Maen Faoury

Transcription

1 Sheet: Patho-Pulmonary infections Done by: Maen Faoury

2 Pneumonitis : might be an infection or not. Chemical Pneumonitis : not an infection.

3 Parenchyma : an infection.( تندرج تحت ال pneumonitis) Lung Parenchyma : alveoli and alveolar ducts (functional part) Community-Acquired Acute Pneumonia = lung infection in otherwise healthy individuals that is acquired from the normal environment (in contrast to hospital acquired pneumonia) May be bacterial or viral Clinical and radiologic features are usually insensitive in differentiating between them C-reactive protein and procalcitonin (acute phase reactant) significantly elevated in bacterial more than in viral infections Often, the bacterial infection follows an upper respiratory tract viral infection (influenza, common cold, destruction of mucociliary function of the epithelium ) because the viral infection weakens the immunity. The alveoli will be filled with an inflammatory exudate, thus causing consolidation ( solidification ) of the pulmonary tissue (fluid will replace the air in the alveoli, so the alveoli will look white on the X-RAY ) the black line in the image is an intact bronchus with air in it.

4 Consolidation Air bronchogram sign Viral acute pneumonia (mostly): Atypical (walking) Pneumonia,less symptoms (fever). Difficult to diagnose in routine culture studies, no need for Hospitalization. Bacterial acute Pneumonia (mostly) : typical, high temperature, chills,hospitalization needed. Some viral may cause typical pneumonia and some bacterial (mycoplasma, legionella and chlamydia ) may cause Atypical.

5 Streptococcus pneumonia ( pneumococcus) Unencapsulated Haemophilus Influenza : more common and less severe. C.psittaci : الببغاوات. Coxiella burnetti : from Sandfly (vector) Sandfly is responsible for sandfly fever, leishmania and q fever. Streptococcus pneumoniae (not common in hospital acquired) : Gram stain of sputum: numerous neutrophils containing the typical gram-positive, lancet-shaped diplococci but it is of the endogenous flora (normal flora) in 20% of adults, and therefore false-positive results may be obtained

6 Isolation of pneumococci from blood cultures is more specific but less sensitive (in the early phase of illness, only 20% to 30% of patients have positive blood cultures) Pneumococcal vaccines containing capsular polysaccharides from the common serotypes are used in individuals at high risk for pneumococcal sepsis Staphylococcus aureus an important cause of secondary bacterial pneumonia in children and healthy adults after viral respiratory illnesses (e.g., measles in children and influenza in both children and adults) associated with a high incidence of complications, such as lung abscess and empyema (exudate in the pleural cavity) in any pneumonia but especially high here.

7 Staphylococcal pneumonia occurring in association with right-sided staphylococcal endocarditis (in tricuspid) is a serious complication of intravenous drug abuse. It is also an important cause of nosocomial pneumonia. Everything in red is required :

8 Pseudomonas aeruginosa: after spreading it will cause : meningitis, endocarditis and sepsis. Alcoholics are at a higher risk of any pneumonia because of the disruption of ciliary function and phagocyte function. Mycoplasma pneumonia : no cell wall so penicillin resistant. It s an acute bacterial pneumonia but most of the time it causes Atypical pneumonia. age : less than 40 Morphology of community-acquired bacterial pneumonia: One of 2 patterns: Lobar ال) lobe)pneumoniaكل or bronchopneumonia(patchy) overlap is common

9 Morphology of lobar pneumonia, stages ( Pleuritis accompanies the process) 1-Congestion: The lung is heavy, boggy, and red. It is characterized by vascular engorgement, intraalveolar fluid with few neutrophils, and often the presence of numerous bacteria 2-Red hepatization: Massive confluent exudation, as neutrophils, red cells, and fibrin fill the alveolar spaces. On gross examination, the lobe is red, firm, and airless, with a liver-like consistency, hence the term hepatization 3-Gray hepatization: Disintegration of red cells and the persistence of a fibrinosuppurative exudate

10 4-Resolution: The exudate within the alveolar spaces is broken down by enzymatic digestion Clinical features of typical community-acquired acute bacterial pneumonia : Abrupt onset of high fever Shaking chills Cough producing mucopurulent sputum Occasional patients have hemoptysis When pleuritis is present, it is accompanied by pleuritic pain(pain with inspiration) and pleural friction rub( sound at the end of inspiration) The whole lobe is radiopaque in lobar pneumonia, whereas there are focal opacities in bronchopneumonia(air bronchogram sign) Complications of community-acquired bacterial pneumonia :

11 Necrosis : liquefactive Community-Acquired Viral Pneumonia : Most common are: (they all cause common cold) -Influenza types A and B ( B only in humans) -The respiratory syncytial viruses -Human metapneumovirus -Adenovirus -Rhinoviruses -Rubeola virus (measles) -Varicella virus(chicken pox) Community-Acquired Viral Pneumonia, pathogenesis : Nearly all of these agents also cause upper-respiratory tract infections ( common cold ) There is usually interstitial inflammation, but some outpouring of fluid into alveolar spaces may also occur, so that on chest films the changes may mimic those of bacterial pneumonia (which results in a consolidation so it will be difficult to differentiate it from the bacterial) Damage leading to necrosis of the respiratory epithelium inhibits mucociliary clearance and predisposes to secondary bacterial infections. Such serious complications of viral infection are more

12 likely in infants, older adults, malnourished patients, alcoholics, and immunosuppressed individuals Viral : mainly lymphocytic(mononuclear) infiltration. Community-Acquired Viral Pneumonia, morphology : Patchy or involving whole lobes bilaterally or unilaterally On histologic examination, the inflammatory reaction (mainly mononuclear) is largely confined to the walls of the alveoli Less intraalveolar infiltrate but outpouring into alveoli by inflammatory cells occurs Diffuse alveolar damage may occur(acute respiratory distress syndrome because the inflammation is in the walls of alveoli) ( diffuse alveolar damage ) : fibrin will be deposited in the alveolar spaces forming hyaline membranes. Community-Acquired Viral Pneumonia, cont d The localization of the inflammatory exudate to the alveolar walls, prevents oxygenation of blood flowing through the affected air spaces which in turn causes mismatch of ventilation and perfusion as a result, the degree of respiratory distress often seems out of proportion to the physical and radiographic findings

13 the viral pneumonia is Atypical which means less fever and symptoms, but at the same time the respiratory distress is more than that of bacterial pneumonia,why? Because the inflammation is in the site of gas exchange ( Alveolar walls ) Respiratory distress : ( cyanosis, flaring of the nose, increased effort in breathing ) Hospital-Acquired (Nosocomial) Pneumonias Defined as pulmonary infections acquired in the course of a hospital stay Of them: ventilator-associated pneumonia Gram-negative rods (members of Enterobacteriaceae and Pseudomonas spp.) and S. aureus are the most common isolates unlike community-acquired pneumonias, S. pneumoniae is not a common pathogen in the hospital setting. Health Care-Associated Pneumonia

14 Not a patient but a worker at a clinical place. Instead of going to the GI tract it enters the respiratory tract It contains organisms from the mouth (dental caries) Aspiration pneumonia in debilitated patients or those who aspirate gastric contents while (البلع unconscious (e.g., after a stroke)(they have a problem in reflexes or during repeated vomiting the resultant pneumonia is partly chemical, due to the extremely irritating effects of the gastric acid, and partly bacterial more than one organism is recovered on culture, aerobes being more common than anaerobes often necrotizing and fulminant ) septicemia) in those who survive, abscess formation is a common complication (on the right side, in the posterior segment of the upper lobe and in the بسسب الجاذبية النو المصابين غالبا بكونو lobe) apical segments of the lower نايمين ) Instead of going to the GI tract, particles enter the respiratory tract. they contain organisms from the mouth (dental caries) Lung abscess: a localized area of suppurative necrosis within the pulmonary parenchyma, resulting in the formation of one or more large cavities

15 Sources: -from sinuses, tonsils or carious teeth during oral surgery, anesthesia, coma, or alcoholic intoxication, and in debilitated patients with depressed cough reflexes -after necrotizing bacterial pneumonias (esp. S. aureus, Streptococcus pyogenes, K. pneumoniae, Pseudomonas spp.) or mycotic infections -Bronchiectasis -Bronchial obstruction, esp. tumors -Septic embolism, from right-sided endocarditis -Hematogenous, esp. Staphylococcal multiple lung abscesses NOT REQUIRED :Anaerobic bacteria are present in almost all lung abscesses, especially oral commensals (Prevotella, Fusobacterium, Bacteroides, Peptostreptococcus, and microaerophilic streptococci) Lung abscess : disruption of the structure of alveoli (locally) Pneumonia : the structure is preserved but contains exudate. Lung abscess, cont d Complications: -Abscesses may rupture into the pleural cavity and produce bronchopleural fistulas, the consequence of which is pneumothorax )Air in the pleura)or empyema

16 -Embolization of septic material to the brain, giving rise to meningitis or brain abscess -Amyloidosis (any chronic inflammation might be followed by Amyloidosis) Symptoms: similar to bronchiectasis also: clubbing of the fingers, weight loss, and anemia may all occur Chronic pneumonias Most often: 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 In immunocompromised patients: widespread disease Among the fungal causes: Histoplasmosis-Blastomycosis- Coccidioidomycosis The disease is mainly localized in immune competent patients. (Every day, every hour, turn that pain into power)