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-Hemolytic Streptococci
Ali Somily MD,FRCPC,D(ABMM)
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Introduction Grouped by either A.phenotypic Or B.Genotypic
Hemolysis(,ß or ) Lancefield antigen Cell wall CHO A,B,C,D,Fand G ect Or B.Genotypic G+ve cocci in chains and/or pairs Colonize MM(Resp.,GIT& GUT) Catalase –ve Ferment CHOlactic acid
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&ß Hemolysis
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Lancefield Agglutination
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-Hemolytic Streptococci
Partial hemolysis of blood Green zoon around the colony Examples: S.Pneumoniae S.Viridans S.Bovis
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STREPTOCOCCUS PNEUMONIAE
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STREPTOCOCCUS PNEUMONIAE
VIRULANCE VACTORS Capsule Autolysin Pneumolysin CLINICAL PRESENTATION NF Resp.20-40%/pharynx Inhalation/droplets
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CLINICAL PRESENTATION
Primary infection CAPalveoli Blood Endocarditis Meningitis Localized Sinusitis O.M Secondary Infection Non-capsulated Opportunistic infection Lungs only Impair or poor ciliary activity Viral, Smoking, dust Risk factor Hyposplenism Splenectomy Asplenia Sickle Cell Diseases Liver disease Hypogammaglobinaemia Alcoholism Cigarette smoking Malnutrition
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Diagnosis Blood,CSF,Sputum& swab/aspirate DIRECT SMEAR G+ve diplococci
Lancet shape Capsulated halo (antiphagocytic)/pathogenic
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Diagnosis Quellung test(AB’s swelling of capsule)
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STREPTOCOCCUS PNEUMONIAE
CULTURE BAP; 5-10%CO2 -hemolytic Mucoid (capsule)SR Concave (punched out/collapse) IDENTIFICATION Bile solubility (NaDC) Optochin S (disk 5g&6mmzoon>=14 mm) 80 serotype(vaccine) capsular structure
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Treatment &Prevention
TTT Penicillin(↑R recently)PBP Ceftriaxon +/-Vancomycin or Rifampicin Vaccination Polsaccharide capsule Conjugate vaccine Indication Children SCD Splenectomised patient HIV Elderly Cardiopulmonary and renal diseases
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VIRIDANS STREPTOCOCCI
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Grouping of viridans streptococci
Mitis Mutans Salvarius Angionosis Mitis( hem.) 6 species Endocarditis S.gordonii S.sanguis Hard, adherent & smooth (dextran) 2.Mutans ( hem mostly) Dental caries 3.Salvarius( hem ) 3 species Hard ,large, mucoid colony (extracellular polsaccharide) 4.Angionosis (& ß hem.co2 or anaer.) i.e milleri Abscesses body cavity Butterscotch sweet odor (diacetyl) S.angionosis S.intermedius ,group F S.constellatus ß
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VIRIDANS STREPTOCOCCI
CLINCAL PRESENTATION NF (GIT,UGT&Oral cavity) Opportunistic organisms Dental caries Endocarditis
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Example of a biofilm Formation of dental plaque by Streptococcus mutans bacteria adhere to the tooth by a protein on the cell surface, grow and synthesize a dextran capsule binds the bacteria to the enamel and forms a biofilm cells of thickness bacteria can cleave sucrose to glucose + fructose glucose is polymerized into an extracellular dextran polymer that cements the bacteria to tooth enamel and becomes the matrix of plaque this dextran slime can be depolymerized to glucose for use as a carbon source, resulting in the production of lactic acid within the plaque that decalcifies the enamel and leads to dental caries
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Endocarditis Damage ,prosthetic valve SBE Predisposing factor
RHD CHD Mitral valve prolapse Degenerative H diseases PV Pathogenesis Dextran adhere to the damaged valve vegetation(fibrin,bacteria & platelets) Symptoms Fever Murmurs Immunological manifestations O,P,S SBE 2-5 Wks Diagnosis Blood culture ECHO
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Treatment VGS, NVS, sreptococcus Native valve prosthetic valve PenG
MIC <0.1 ug/mI PenG PenG 6wk +Gentamicin 2wk MIC >0.1 —0.5 ug/mI PenG 4wk +Gentamicin 2wk PenG 6wk + Gentamicin 4wk
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Microbiology DIRECT SMEAR CULTURE IDENTIFICATION G+ve cocci in chains
Can be OR rarely ß hemolytic Most lack distinct LA IDENTIFICATION Urea VP( acetoin production) Arginine hydrolysis Esculin hydrolysis CHO ferementation
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Enterococcus
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Introduction Fecal strep separated genus/by molecular
Harsh conditionAbiquitous/soil,water,plants, GIT, GU human 15 Spp/E.faecalis80-90% of clinical isolate Colonization/infection
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CLINICAL PRESENTATION
NC BACTEREMIA 1/3 NC UTI 16% WOUND ENDOCARDITIS CNS PNEUMONIA (rare) ELDERLY I’C TTT Vancomycin VRE (Van A,B&C ect) Plasmid/chromosomal High/low level VDE Direct smear Short chain/pairs/coccobaccilary
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CULTURE IDENTIFICATION Facultative anaerobs OR hemolysis
Catalase weak +ve Group D IDENTIFICATION Growth B/W Co 6.5% NaCl Esculin hydrolysis(40%)bile salt Pyrrolidonyl arylamidase(PYR)+ve Leucine arylamidase(LAP)+ve Motility ,Pigmentation,arabinose and methyl --D-glucopyranoside
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Bile esculin All Group D Enterococcus S.Bovis
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PYR/PYR-LAP
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Endocarditis Native valve Prosthetic valve MIC >0.5 ug/ul,
Enterococcus, Native valve Prosthetic valve MIC >0.5 ug/ul, PenG or Amp plus Gent for 4-6 wk total 6 wk
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BOVIS GROUP New Name Streptococcus gallolyticus (Group D Streptococci)
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BOVIS GROUP CLINICAL DIRECT SMEAR Human intestine and animals
Endocarditic Septicemia Link to colon cancer Stool isolation Two biotypes I&II Mannitol and glucan I DIRECT SMEAR G+ve cocci in chains
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Differed from viridans
CULTURE OR on BAP IDENTIFICATION LG group D Differed from viridans Growth in 40% bile salt Hydrolyze esculin IDENTIFICATION LG group D Differed from viridans Growth in 40% bile salt Hydrolyze esculin No sorbitol fermentation Mannitol and inulin & starch ferm.
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How you differentiate S. bovis from enterococcus?
Unable to grow in 45 Co 6.5% 37dC PYR –ve S to penicillin and cephalosporins R to vancomycin(rare) Enterococcus Able to grow in 45 Co 6.5% 37Co PYR +ve S to ampicillin
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Summary
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