Related Subjects: Asthma
|Acute Severe Asthma
|Exacerbation of COPD
|Pulmonary Embolism
|Cardiogenic Pulmonary Oedema
|Pneumothorax
|Tension Pneumothorax
|Respiratory (Chest) infections Pneumonia
|Fat embolism
|Hyperventilation Syndrome
|ARDS
|Respiratory Failure
|Diabetic Ketoacidosis
About
- Cause of meningitis and pneumonia
- Resistance to Penicillin is increasing
Characteristics
- Alpha haemolytic Lanceolate Gram-positive diplococcus
- Heavily encapsulated with carbohydrate which increases pathogenicity
- Catalase negative Facultative anaerobe enhanced with 10% CO₂
- Colonies have raised edges resembling Draughtsmen on a board surrounded by greenish discolouration of alpha haemolysis
Virulence
- Capsulated resists phagocytosis
- Produce IgA1 protease which breaks down Immunoglobulin
- Exotoxin pneumolysis which affects neutrophil function
- Splenectomy or hyposplenism, sickle cells at risk
Source
- Commensal of the upper respiratory tract
Pathogenicity
- Community-acquired pneumonia (CAP),
- Osteomyelitis
- Peritonitis
- Endocarditis
- Exacerbation of COPD
- Conjunctivitis
- Bacterial Meningitis mainly in adults
- Sinusitis and otitis media
- Septicaemia with splenectomy
Investigations
- Gram staining and microscopy and culture
- Inhibited by optochin and lysed by bile
- Ferments inulin
- Testing for a capsular antigen of which there are 84 types
- Detection of pneumococcal antigen in CSF, sputum or urine
- Quellung reaction - capsule swells when mixed with specific antisera
Vaccination
- Vaccine containing 14 of the commonest serotype is available
- Consider in those at risk e.g. Splenectomy or hyposplenism, sickle cell, immunodeficiency at risk and those with chest, heart, renal, stroke disease etc.
Resistance
- Some increasing resistance to penicillin outside the UK
- Erythromycin and Tetracycline and Trimethoprim resistance commoner in the UK
Sensitivity
- Most strain sensitive to Penicillin
Treatment
- Amoxicillin and a macrolide e.g. clarithromycin
- Moderate to severe - Give oral therapy after 48 hours if improving
- Severe cases consider IV Co-amoxiclav and a macrolide e.g. clarithromycin