Pathogenicity of Pneumococcus

Pathogenicity of Pneumococcus

Pneunococcus is pathogenic organism. Pathogenic intencity depend on some factor that lowers the natural resistance of respiratory mucosa.

These factors are- 

- Viral infection

- Bronchial congestion.

- Pulmonary congestion.

- Malnutrition.

Pathogenic lesions/diseases produced by S. pneumonia:

1. Lobar and broncho pneumonia
2. Bacteraemia.
3. Otitis media
4. Sinusitis
5. Meningitis.
6. Endocarditic.
7. Sepsis in splenectomized individuals.
8. Upper respiratory tract infection (URTI)

Laboratory diagnosis of Pneumococcal :

1. Specimen: Depends according to site of infection such as sputum, blood,CSF.
2. Microscopic examination: By gram staining.Findings: Gram  positive diplococcic, lancet-shaped.

3. Isolation  and identification from culture: Culture is done in blood agar mediaFindings: Alpha hemolytic colony on blood agar, culture also can be done in Mac Conkey’s agar media.

4. Biochemical tests:

-          Insulin fermentation test.

-          Optochin sensitivity test.

-          Bile solubility test.

5. Serological test:

    -            Capsular swelling test(Quelling reaction).