Streptococcus pneumoniae

BY DR HASAN ASKARI BDS MS PHD FDS DDS MJDS MFDS MD –PRESIDENT OF INTERNATIONAL DENTAL RESEARCH UNIT LONDON

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• MORHOLOGY

• Shape lancet shaped

• Arrangement diplococci sometime short chains

• Capsule encapsulated

• Motility non motile

• Spore non spore forming

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• Staining

• Gram staining

• Gram +ve staining

• Violet coloured

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• Culture media• Blood agar and chocolate agar• Colonies • Small rounded colconies at first dome shaped later

develop a central plateau with elevated rim• Alpha hemolysis on blood agar• Transformation• When uncapsulated pnemococci are cultured in the

presence of DNA extracted from a capsulated pneumococcus encapsulated puneumococci of later type are formed this is called transformation.

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• Lysis of colonies

• Pneumococcal colonies are sensitive to lysis by an autolytic enzymes L alanine muramylamidase that cleaves bond linking L alaninepeptide to muramic acid of peptidoglycanwall.

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• Growth characteristics

• Oxygen requirements: aerobic and facultative anaerobes.

• Peptostreptococci are obligate anaerobes

• Energy source is ferment sugar produces lactic acid but not gas. Lactic acid limits the growth.

• Temperature 37degree c

• 5-10% co2 promotes growth.

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• Antigen

• Capsular polysaccharide

• A distinct for each of more than 80 serologic types.

• B virulence is due to capsule which protect it from phagocytosis.

• B cells response which provide type specific immunity.

• M protein

• Characteristics for each type.

• C CHO

• It is group specific common to all pnemococci.

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• Enzymes

• IgA protease

• It enhances organism ability to colonizes mucosa of upper respiratory tract.

• Toxin

• Pnemolysin

• Binds to cholestrol in host cell membrane.

• Inhibit antimicrobial properties of neutrophilsand opsonic activity of serum.

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• Habitat and transmission

• Habitat

• Normal inhabitant of u.respiratory tract.

• Transmission

• Via respiratory droplets

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• Pathogenes and clinical finding• pnemococcal lobar pneumonia:• It is characterized by exudation of fibrinous edema fluid

into alveoli following by RBC and leukocytes many pnemococci are also present in alveoli. This causes consloidation of portion of lung.

• Clinical finding• A sudden onset of high fever with violent , shaking chills• B sharp pleutal pain and friction rub.• C cough at first dry or productive of thin watery sputum :

later bloody or rusty sputum.

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• Bacteremia with its complication• From alveolar exudates organism reach bloodstream

via lymphatics and causes bacteremia which have a traid of serious complication

• Meningitis• Endocarditis• Septic arthritis• Sinusitis• Pericardiditis• Empyema• Otitis media

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• Meningitis• Pneumococcus is the second common bacterial pathogen

that causes meningitis in adults.• Pathogenesis:• It may arises as a complication of pnemonia in which

pneumococci reach the meninges by way of blood stream.• It results from a skull fracture ,permitting pnemococci from

nasopharynx to enter the meninges.• Otitis media • Pnemococci is the etilogic agent of about 50% cases of

otitis media in chidren.

Pericardium

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• Diagnostic laboratory test

• Specimen blood pus sputum CSF

• Microscopy gram +ve diplococci

• Culture blood agar chocolate agar

• Capsule swelling test quelling test

• Omni antisera test

• opotochin disk test

• Animal inoculation test

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• Immunity

• Type specific immunity to reinfection with pnemococci develops. It is due to type specficanticapsular antibodies.

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• Treatment

• Penicillin

• Erythromycin

• Cephaothin

• Chloramphenical

• Prevention and control

• Immunization with polyvalent ( ploysaccharidevaccine)

• Vaccine provides protection for 5 years.

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• Difference b/w lobar pneumonia and bronchopneumonia

• Lobar pneumonia• Cased 90% by pneumococci few cases by klebsiella

pnemoniae, staph aureus.• Occurs in otherwise healthy individual b/w 30-50 years• Onset is sudden with high grade fever, shaking chills

and bloody or rust sputum• Conslidation of whole lobe.• Complication bacteremia, meningitis,endocarditis,

septic arthritis.

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• Bronchopneumonia• Caused by staphylococci streptococci, H

influenzae proteus and pseudomonas.• Occurs infants ,old and those suffering chronic

debiliating illness or immunosuppression.• Onset is insiduous with low grade fever and

cough productive of purulent sputum.• Patchy pneumonic consolidation.• Complications: fibrosis, bronchiectasis,lung

abscess.

Difference b/w lobar pneumonia and bronchopneumonia

Difference b/w lobar pneumonia and bronchopneumonia

Difference b/w lobar pneumonia and bronchopneumonia

Time out

Difference b/w lobar pneumonia and bronchopneumonia