1. Pulmonary infections (pneumonia) DR.AYSER HAMEED LEC.2

2. Pulmonary infections (pneumonia):
Could be Viral, bacterial (90% due to streptococcal pneumoniae), fungal and mycoplasma.
Bacterial pneumonia:
Bacterial invasion of the lung parenchyma will cause an exudative solidification (consolidation) of the lung tissue.
Predisposing factors:
Defect in immunity:
Defect in humoral immunity & neutrophils……… pyogenic infection.
Defect in cellular immunity …………. Intracellular infections (tuberculosis, viruses, pneumocystic carinii).

3. 2. Cigarette smoking …………
2. Cigarette smoking ………….. decrease in mucociliary clearance…………… affect pulmonary macrophages activity.
3. Alcohols …….. Decrease cough & epiglottis activity.……… increase aspiration.……… decrease neutrophils activity.
4. Head injury & surgery ……increase aspiration.
5. Lung cancers & cystic fibrosis ………. pulmonary obstruction………increases risk of pneumonia.

4. Classification of Pneumoniae:
I. classify according to anatomy & radiological features:
1. Bronchopneumonia: means initial infection in the bronchi & bronchioles with extension into adjacent alveoli.
Caused by staphylococcus, streptococcus, pneumococcus, hemophilus influenzae.
The consolidation is patchy that involve more than one lobe.
Occur in infancy and old age groups caused by low resistance.
Can complicate long term heart failure.

5. 2. Lobar pneumonia:
Means inflammation limited to part or all parts of one lobe (fill with exudate & consolidation).
90-95% are caused by pneumococci.
Others are klebsiella pneumonia , staphylococcus, strept., H. influenza.

7. Bronchopneumonia

8. Bronchopneumonia
At the left the alveoli are filled with a neutrophilic exudate that corresponds to the areas of consolidation seen grossly with the bronchopneumonia. This contrasts with the aerated lung on the right of this photomicrograph.

9. Bronchopneumonia
At high magnification, the alveolar exudate of mainly neutrophils is seen. The surrounding alveolar walls
have capillaries that are dilated and filled with RBC's. Such an exudative process is typical for bacterial
infection. This exudate gives rise to the productive cough of purulent yellow sputum seen with bacterial
pneumonias.

10. Lobar pneumonia

11. Note: points against this classification
organisms can cause both types of pneumonias.
Bronchpneumonia is difficult to detect by radiology.
II. Classify according to setting in which the pneumonia is occurred:

12. 1. Community acquired acute pneumonia: characterized by:-
This is the commonest type.
Due to bacterial pneumonia follows viral upper respiratory tract infection.
Most important causative agent is Pneumococci.
Increased risk in patients with congestive heart failure, chronic obstructive lung diseases, D.M, AIDS, absent spleen.
Site: lower lobes & right middle lobe.

13. Symptoms:
Abrupt onset of high fever with chills, pleuritic chest pain, mucopurulent (rusty) sputum.
Diagnostic tests:
1. Sputum examination: for Gram stain (numerous neutrophils contain diplococci). (non specific because organisms are normal flora).
2. Blood culture:
More specific, 20-30% is positive in early cases.

14. 2. Community acquired atypical pneumonias:
Differ from acute pneumonia by:
Sputum production was modest.
No signs of consolidation.
WBC count was only moderately increased.
Most important causative agent is Mycoplasma pneumoniae.
Diagnostic tests:
PCR (for detect DNA of Mycoplasma), Cold hemagglutination test.

15. 3. Nosocomial pneumonia (hospital acquired pneumonia):
Pneumonia acquired in the course of hospital stay.
More common in patients with immunosuppression, prolonged antibiotics treatment, intravascular catheters & those on mechanical ventilation.
Pseudomonas, enterobacteriaceae & staph. aureus are the important causative agents

16. Morphology of lobar pneumonia (community acquired acute pneumonia) :
There are four stages of evolvement of lobar pneumonia , these are:
1. Congestion stage
Grossly: the affected lobe is heavy, red, and boggy.
Mic.:
Alveolar vascular congestion.
Intra-alveolar proteinaceous fluid with neutrophils & many bacteria.

17. 2. Red hepatization
Grossly:
Lobe is red, firm, airless, look like a liver.
Mic.:
The inflammatory exudate composed of RBC, neutrophils & fibrin.
Fibrin of fibrinopurulent exudate on pleura.

18. Red hepatization

19. 3. Gray hepatization. Grossly: Grey –brownish, dry surface & firm. Mic
3. Gray hepatization. Grossly: Grey –brownish, dry surface & firm. Mic.: The exudate within alveoli is fibrino-suppurative (WBC,FIBRIN&LYSED RBC). 4. Resolution stage. The exudates undergo enzymatic digestion formation of granular debris that is either resorbed & ingested by the macrophages or expectorated and coughed up, leaving basic structures intact.

20. Gray hepatization

21. Advanced organizing pneumonia, featuring transformation of exudates to fibromyxoid masses richly infiltrated by macrophages and fibroblasts.

22. Stages of Streptococcus (Pneumococcal) pneumoniae
A, Acute pneumonia. The congested septal capillaries and extensive neutrophil exudation into alveoli corresponds to early red hepatization. Fibrin nets have not yet formed. B, Early organization of intra-alveolar exudates, seen in areas to be streaming through the pores of Kohn (arrow). C, Advanced organizing pneumonia, featuring transformation of exudates to fibromyxoid masses richly infiltrated by macrophages and fibroblasts.

23. Morphology of bronchopneumonia
Consolidation is patchy involve one or several lobes.
Most likely site (bilateral & basal).
Start as well defined lesions of (3 or 4cm) in diameter, slightly elevated , red/ yellow.
Then in several cases these lesions are confluence to form lobar lesion.

24. Complications :
90% of cases will end up with resolution, otherwise complication includes:
Abscess formation, specially if the m.o. is klebseilla and peumococcal infection.
Spread of infection to the pleural cavity empyema (pus inside the pleural cavity).
Organization of the exudate  part of the lobe will turn solid.
Bacteremic dissemination cause meningitis, infective endocarditis, arthritis.

25. Lung abscess: (sometime called necrotizing pneumonia).
Localized areas of suppurative necrosis within the pulmonary parenchyma, resulting in the formation of one or more of large cavities.
Pathogenesis:
These microorganisms reach lungs via the followings mechanisms:
Aspiration of infected material from carious teeth, infective sinuses or tonsils, this is occurring during oral surgery & anesthesia.
Aspiration of gastric contents usually associated with infective microorganisms from oropharynx.

26. 3. Complications of bronchopneumonia (staph. aureus, sterpto
3. Complications of bronchopneumonia (staph. aureus, sterpto. Pyogenes & pseudomonas).
4. Bronchial obstruction: particularly with bronchogenic cancers……. obstruct the bronchi……impaired drainage of secretion……… atelectasis & increase risk of abscess formation.
5. Septic embolism from infective endocarditis of right side of heart or from septic thrombophlebitis.
6. Hematogenous spread of bacteria (Staphylococcal bacteremia).

27. Causitive organisms:
1. Anaerobic bacteria, in two thirds of cases ( bacteroides).
2. Aerobic bacteria like staph. aureus, beta hemolytica streptococci & Nocardia.
3. Gram negative organisms.
Gross:
Various size cavities, filled with pus.
Those on right side are mostly due to aspiration (more vertical airway).
Those follow pneumonia & bronchiectasis are multiple, basal in locations .
Mic.:
Suppurative inflammation , necrosis & destruction of the lung parenchyma.

28. Clinically:
Cough, copious amount of foul smell sputum & fever.
Complications:
Pneumothorax (rupture into pleural cavity.
Empyema.
Bronchopulmonary fistula.
Meningitis & brain abscess (due to embolization).

29. Lung abscess/ necrotizing pneumonia

30. Abscesses complicating bronchopneumonia
Two lung abscesses, one in the upper lobe and one in the lower lobe of this left lung. An abscess is a complication of severe pneumonia, most typically
from virulent organisms such as S. aureus.

31. Lung Abscess complicating aspiration pneumonia
Bronchopneumonia (solid grey-yellow area) with abscess formation (cystic ragged area) in 2-year-old boy secondary to aspiration of foreign body.

32. Lung abscess