📖 General Pathology
Str. Pneumoniae
General PathologyStr. Pneumoniae
Probably the most important streptococci. Primary cause of pneumonia. Usually are diplococci. Ste. pneumoniae are α-hemolytic and nutritionally fastidious. Often are normal flora.
Key virulence factor is the capsule polysaccharide which prevents phagocytosis. Other virulence factors include pneumococcal surface protein and α-hemolysin.
Major disease is pneumonia, usually following a viral respiratory infection. Characterized by fever, cough, purulent sputum. Bacteria infiltrates alveoli. PMN’s fill alveoli, but don’t cause necrosis. Also can cause meningitis, otitis, sinusitis.
There are vaccines against the capsule polysaccharide. Resistance to penicillin, cephalosporins, erythromycins, and fluoroquinalones is increasing.
Neutrophilia
General PathologyNeutrophilia
Causes
-Pyogenic infections.
-Haemorrhage and trauma.
-Malignancies.
-Infarction.
-Myelo proliferative disorders.
Cryptococcosis
General PathologyCryptococcosis
An infection acquired by inhalation of soil contaminated with the encapsulated yeast Cryptococcus neoformans, which may cause a self-limited pulmonary infection or disseminate, especially to the meninges, but sometimes to the skin, bones, viscera, or other sites.
Cryptococcosis is a defining opportunistic infection for AIDS, although patients with Hodgkin's or other lymphomas or sarcoidosis or those receiving long-term corticosteroid therapy are also at increased risk.
AIDS-associated cryptococcal infection may present with severe, progressive pneumonia with acute dyspnea and an x-ray pattern suggestive of Pneumocystis infection.
Primary lesions in the lungs are usually asymptomatic and self-limited
Pneumonia usually causes cough and other nonspecific respiratory symptoms. Rarely, pyelonephritis occurs with renal papillary necrosis development.
Most symptoms of cryptococcal meningitis are attributable to brain swelling and are usually nonspecific, including headache, blurred vision, confusion, depression, agitation, or other behavioral changes. Except for ocular or facial palsies, focal signs are rare until relatively late in the course of infections. Blindness may develop due to brain swelling or direct involvement of the optic tracts. Fever is usually low-grade and frequently absent.
Respiratory Pathology
General PathologyRespiratory Pathology
A. Pulmonary infections
1. Bacterial pneumonia
a. Is an inflammatory process of infectious origin affecting the pulmonary parenchyma.
2. Bacterial infections include:
a. Streptococcus pneumoniae (most common).
b. Staphylococcus aureus.
c. Haemophilus influenzae.
d. Klebsiella pneumoniae.
e. Anaerobic bacteria from the mouth
(aspiration of oral secretions).
3. Viral infections include:
a. Influenza.
b. Parainfluenza.
c. Adenoviruses.
d. Respiratory syncytial virus.
Note: viruses can also cause pneumonia. Infection of the interstitial tissues, or interstitial pneumonia, is commonly associated with these types of infections.
Common symptoms include fever, dyspnea, and a productive cough
Two types:
(1) Lobar pneumonia
(a) Infection may spread through entire lobe(s) of lung. Intraalveolar exudates result in dense consolidations.
(b) Typical of S. pneumoniae infections.
(2) Bronchopneumonia
(a) Infection and inflammation spread through distal airways, extending from the bronchioles and alveoli. A patch distribution involving one or more lobes is observed.
(b) Typical of S. aureus, H. influenzae,and K.pneumoniae infection
Diseases that Produce a Productive Cough
Pneumonia
Lung abscess
Tuberculosis
Chronic bronchitis
Bronchiectasis
Bronchogenic carcinoma
Classification
Diseases of the respiratory system can be classified into four general areas:
- Obstructive Diseases (e.g., Emphysema, Bronchitis, Asthma)
- Restrictive Diseases (e.g., Fibrosis, Sarcoidosis, Alveolar Damage, Pleural Effusion)
- Vascular Diseases (e.g., Pulmonary Edema, Pulmonary Embolism, Pulmonary Hypertension)
- Infectious, Environmental and Other Diseases (e.g., Pneumonia, Tuberculosis, Asbestosis, Particulate Pollutants)