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PNEUMONIA

PNEUMONIA. 2015. Objectives. Definition Defense mechanisms Pathogenesis Pathology. Objectives. Epidemiology Etiology Clinical manifestations , Dx Treatment , Prevention. Definition. Pneumonia is an infection of the pulmonary parenchyma. New Classification of P.

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PNEUMONIA

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  1. PNEUMONIA 2015

  2. Objectives • Definition • Defense mechanisms • Pathogenesis • Pathology

  3. Objectives • Epidemiology • Etiology • Clinical manifestations , Dx • Treatment , Prevention

  4. Definition • Pneumonia is an infection of the pulmonary parenchyma

  5. New Classification of P. • Community-acquired pneumonia (CAP) • Hospital-acquired pneumonia (HAP) • Ventilator-associated pneumonia (VAP) • Health care–associated pneumonia (HCAP)

  6. Clinical Conditions and Pathogens in HCAP

  7. Clinical Conditions and Pathogens in HCAP

  8. Pathophysiology • Proliferation of microbial pathogens at the alveolar level • The host's response to those pathogens

  9. Routes Of Infection • Microaspiration • Gross aspiration • Inhalation of aerosol ( Aerosolization ) • Hematogenous ( distant foci ) • Direct spread ( contiguous foci ) : infected pleural or mediastinal space

  10. Route Of Infection,Microaspiration • Microaspiration of oropharyngeal secretion is the most common route. • Most pulmonary pathogens originate in the oropharyngeal flora. • ~ 50% of healthy adults aspirate oropharyngeal secretions into LRT during sleep.

  11. Defense MechanismsMechanical factors • The hairs and turbinates of the nares • The branching architecture of the tracheobronchial tree : mucociliary clearance and local antibacterial factors

  12. Defense MechanismsMechanical factors • The gag reflex and the cough mechanism • The normal flora adhering to mucosal cells of the oropharynx

  13. Defense MechanismsMechanical factors • Resident alveolar macrophages • The host inflammatory response, rather than the proliferation of microorganisms, triggers the clinical syndrome of pneumonia

  14. The Host Inflammatory Response • IL1 , TNF : Fever • IL-8 , G- CSF: stimulate the release of neutrophils and their attraction to the lung: - Peripheral leukocytosis - Increased purulent secretions • The newly recruited neutrophils : (ARDS)

  15. The Host Inflammatory Response • Erythrocytes can cross the alveolar-capillary membrane : hemoptysis

  16. The Host Inflammatory Response • The capillary leak : * Radiographic infiltrate * Rales detectable on auscultation • Alveolar filling : hypoxemia • Increased SIRS : respiratory alkalosis

  17. The Host Inflammatory Response • ↓Compliance due to capillary leak • Hypoxemia • Increased respiratory drive • Increased secretions • Infection-related bronchospasm dyspnea

  18. Pathogenesis Colonization of ph. Air Nonpulmonary site Contiguous site Microaspiration Inhalation Bloodstream Disease Direct extension

  19. Pathology Edema (exudate and often of bacteria) Red hepatization(RBC+occasionally bacteria) Gray hepatization(no new RBC, PMN dominant, disappeared bacteria) Resolution(macrophage reappears)

  20. Pathology Pneumococcal Pneumonia • Lobar: Involvement an entire lunglobe, homogeneously Edema Red hepatization Gray hepatizationResolution Bacterial CAP

  21. Pathology • Bronchopneumonia: Patchy consolidation in 1 or more lobes, in lower & post of lung with poorlydemarcation. Bronchi Bronchioles Edema Exudate

  22. Pathology • Because of the microaspiration mechanism, abronchopneumonia pattern is most common in nosocomial pneumonias

  23. Pathology • Interstitial: Involvement of alveolar septa & connective tissue • Patchy or diffuse • Lymph, MQ & plasma cell in alveolar wall • No exudate in the alveoli

  24. Pathology • Viral and Pneumocystispneumonias Represent alveolar rather than interstitial processes

  25. Pathology • Abronchopneumonia pattern: most common in nosocomial pneumonias • Lobar pattern: more common in bacterial CAP • Alveolar rather than interstitial processes: Viral and Pneumocystis pneumonias

  26. Community-Acquired Pneumonia • Etiology: Streptococcus pneumoniae is most common

  27. Microbial Causes of CAP, by Site of Care Hospitalized Patients Pathogens are listed in descending order of frequency

  28. CAP : Etiology • “Typical" bacterial pathogens • “Atypical" organisms

  29. Typical" bacterial pathogens • S. pneumoniae • Haemophilusinfluenzae • In selected patients: * S. aureus * Gram-negative bacilli : - Klebsiellapneumoniae - Pseudomonas aeruginosa

  30. Atypical Bacterial Pathogens • Mycoplasmapneumoniae • Chlamydophilapneumoniae • Legionella spp. • Respiratory viruses : influenza viruses, adenoviruses, RSVs

  31. CAP, Etiology • The atypical organisms: cannot be cultured on standard media, nor can they be seen on Gram's stain

  32. CAP, Etiology • A virus in up to 18% of cases of CAP that require admission to the hospital • ~10–15% of CAP cases are polymicrobial

  33. Etiology, Anaerobes • An episode of aspiration days to weeks before presentation ► Unprotected airway (alcohol or drug overdose, seizure) +► Significantgingivitis

  34. Anaerobes • Often complicated by : - Abscess formation - Significant empyemas - Parapneumonic effusions

  35. S. aureusPneumonia • Complicates influenza infection • MRSA strains, primary causes of CAP, relatively uncommon • Necrotizing pneumonia

  36. CAP , Etiology • In more than half of cases, a specific etiology is never determined

  37. Epidemiologic Factors, Possible Causes of CAP

  38. Epidemiologic Factors, Possible Causes of CAP

  39. Epidemiologic Factors, Possible Causes of CAP

  40. Epidemiologic Factors, Possible Causes of CAP

  41. Epidemiology, CAP • In the U.S: 4 million CAP cases annually • ~80% are treated on an outpatient basis • ~20% are treated in the hospital

  42. CAP • >600,000 hospitalizations • 64 million days of restricted activity • 45,000 deaths annually • The overall yearly cost :$9–10 billion (U.S.) • The incidence rates are highest at the extremes of age

  43. Epidemiology, CAP • Risk factors: Alcoholism Asthma Immunosuppression Institutionalization ≥ 70 y.

  44. Epidemiology , R.F Pneumococcal pneumonia: • Dementia • Seizure disorders • Heart failure • cerebrovascular disease • Alcoholism • Tobacco smoking • COPD • HIV infection

  45. CA-MRSA Infection • Skin colonization with CA-MRSA • Skin infection with CA-MRSA

  46. The Enterobacteriaceae • Patients who have recently been hospitalized and/or received antibiotic therapy • Comorbidities : Alcoholism Heart failure Renal failure

  47. P. aeruginosa • Severe structural lung disease, such as: - Bronchiectasis - Cystic fibrosis - Severe COPD

  48. Legionella infection • Diabetes • Hematologic malignancy • Cancer • Severe renal disease • HIV infection • Smoking • Male gender • Recent hotel stay or ship cruise

  49. CAP, Clinical Manifestations • Fever • Tachycardic response • Chills and/or sweats • Cough :nonproductive or productive of mucoid, purulent, or blood-tinged sputum • shortness of breath

  50. CAP, Clinical Manifestations • If the pleura is involved: pleuritic chest pain • Up to 20%, GI symptoms : nausea, vomiting, and/or diarrhea • Other symptoms :fatigue, headache, myalgias, and arthralgias

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