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STREPTOCOCCUS PNEUMONIAEMorphology and identification

►Gram positive cocci in pairs►Capsulated►Alpha hemolysis►Bile soluble ►Optochin Sensitive

Historical Information:► In 1881 S. pneumoniae discovered by Leo

Escolar and was isolated by Louis Pasteur and George Sternberg. 

► In 1884 Albert Fraenkle performed gram stain where it was found to be diplococcal. 

► In 1902 Neufeld discovered swelling of the capsular which lead to serotyping. 

►The type-specific antibody development in S. pneumoniae was shown by Lister in 1913. 

► In 1944 transformation experiments were performed by McCarty. 

► Lastly in 1997 Joseph Dillard and Janet Yother cloned common capsule DNA regions.

Staphylococcus gram positive cocci in clumps or grape like

clusters

Streptococcus gram positive cocci in chains

Gram positive diplococci or in pairs

Beta hemolytic Streptococcus

Also cause wound infections, sinusitis, etc.

The capsule of S pneumoniae renders it resistant to phagocytosis.

► S pneumoniae leading cause of bacterial pneumonia beyond the neonatal period.

► Pleural effusion is the most common and empyema (pus in the pleural space) one of the most serious complications of S pneumoniae.

► Most common cause of sinusitis, acute bacterial otitis media, and conjunctivitis beyond early childhood.

► Meningitis► Acute septic arthritis and bone

infections in patients with sickle cell disease

►Peritonitis (especially in patients with nephrotic syndrome) or endocarditis.

►- Streptococcus pneumoniae (previous names - Pneumococcus, Diplococcus)

►G+, catalase-, alpha hemolytic, URT resident.

► Possesses a large capsule to resist phagocytosis.

►Forms short chains. Mucoid colonies.

►>80 different serotypes based on capsule protein as Ag.

►Pathogenesis: - Predisposition is necessary. Considered endogenous infection. Transmission not an issue. Examples of predisposing factors:

1. Viral infection of respiratory tract-this causes damage to ciliated epithelial cells as mechanical defense factor.

2. Prolonged immobilization-causes fluid accumulation in alveoli, which stimulates growth of St. pneumoniae.

3. Malnutrition, alcoholism, diabetes, extreme prolonged fatigue.

►Pathology and Symptoms: 1. Short incubation period - Difficult to

determine, since organism is already present.

2. Organism proliferates causing

inflammation and extreme edema. Packed edematous fluid called consolidation.

3. Rapid onset of shaking, chills, fever, and chest pains. Sputum is purulent and rust-colored (from blood). Crisis in 5-10 days if untreated, followed by rapid recovery or death (30% fatality if untreated). Septicemia and meningitis are common complications.

►Diagnosis:1. Inflammation of lung tissue visible on

x-ray.

2. Direct microscopic examination of sputum (or CSF) shows heavily

encapsulated short chains of cocci.

3.Culture of sputum to yield mucoid colonies of cocci also may be

done.

4.Distinguished from  other Streptococcus species    by optochin-sensitivity test (S.p.is +).

5. Quellung Reaction – or capsular swelling test

oCertain antibodies against capsular material will cause a swelling of the capsules of  Streptococcus pneumoniae.

oPatient's serum is added to different serotypes of Streptococcus pneumoniae. If capsule swelling occurs, patient has that particular serotype. If no response to any of serotypes, patient does not have pneumococcal pneumonia.

Capsular swelling Test

6. Bile soluble

7. Inulin Fermentation

► Prevention:

Correct predisposing conditions

Vaccine - contains capsular material from 23 of most common serotypes.

Recommended for young children, elderly, when predisposed.

Treatment: 1. Penicillin (97% of isolates are susceptible).

2. Erythromycin, Klaracid, or other Macrolides antibiotics.

3. For chronic sinusitis CECLOR oral second generation cephalosporin

4. Quinolones etc. can be used.

Control►Antibiotic Treatment►Penicillin remains the drug of

choice for S pyogenes. It is safe, inexpensive, and of narrow spectrum, and there is no direct or indirect evidence of loss of efficacy.

►Prior to the 1990's, S pneumoniae was also uniformly sensitive to penicillin but a recent abrupt shift in the usefulness of penicillin has occurred.

►If penicillin allergy occurs, an alternative drug for treating pharyngitis is erythromycin, although sporadic erythromycin and tetracycline resistance has been reported, leaving clindamycin or the newer macrolides as possible treatments.

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