بسم الله الرحمن الرحيم Streptococcus pneumoniae Prof. Khalifa Sifaw Ghenghesh

n Diplococcus pneumoniae or Pneumococcus n Gram +ve Coccus, Encapsulated, Occur in Pairs with Broad Ends Opposed. n Requires Enriched Media for Growth. n Growth Enhanced by 0.1% Glucose and 5-10% CO 2.

Streptococcus pneumoniae

Colonies on Blood Agar n 1 mm in Diameter, Round, Domed and Surrounded by a Zone of  -Haemolysis. n On Prolonged Incubation: "Draughtsman" Colonies. n Some Strains > Mucoid Colonies. n In Broth > Short Chains or Isolated Cocci. n Soluble in Bile. n Sensitive to Optochin (Ethylhydrocuprein Hydrochloride).

VIRULENCE FACTORS n Capsular Polysacharide > Antiphagocytic. –Repeated Subculturing in the Presence of Specific Anticapsular Antibody Results in Non- Capsulated Strains. n Non-Capsulated Strains > Avirulent > "R" Colonies. n "S" Colonies >> Virulent. Capsule Can Be Demonstrated by: 1. "Quelling Reaction" or “Capsular Swelling Test”: 2. Addition of India Ink:

CLINICAL INFECTION n Pneumococcal Infections of the Respiratory Tract. n Causes Disease of the Middle Ear, Paranasal Sinuses, Mastoides and the Lung Paranchyma. n Meningitis, Endocarditis and Peritonitis. n Pneumococcal Bacteraemia.

Pneumococcal Meningitis

LABORATORY DIAGNOSIS 1. Specimens: n Sputum: i. Should Show a Predominance of Pus Cells Rather Than Squamous Epithelial Cells of Buccal Origin. ii. The Specimen is Then Homogenized by an Agent (e.g. N-Acetylcysteine). n CSF Deposit: From Cases of Meningitis. n Blood: Patients with Pneumococcal Pneumonia and Meningitis.

2. Isolation and Identification: Gram StainBA Incubate in 5-10% CO 2 / Overnight  - Haemolytic Colonies Susceptibility to Optochin Sensitive >> Strep. Pneumoniae Resistant >> Strep. viridans

TREATMENT n Penicillins, Cephalosporins, Erythromycin, Tetracycline, Clindamycin, Vancomycin and Ciprofloxacin. n Resistance:

Streptococcus viridans