-Hemolytic Streptococci

Ali Somily MD,FRCPC,D(ABMM)

Introduction

• G+ve cocci in chains and/or pairs

• Colonize MM(Resp.,GIT& GUT)

• Catalase –ve• Ferment CHOlactic

acid

• Grouped by either A.phenotypic

1. Hemolysis(,ß or )

2. Lancefield antigen– Cell wall CHO

– A,B,C,D,Fand G ect

Or B.Genotypic

&ß Hemolysis

Lancefield Agglutination

-Hemolytic Streptococci

• Partial hemolysis of bloodGreen zoon around the colony

• Examples:– S.Pneumoniae– S.Viridans– S.Bovis

STREPTOCOCCUS PNEUMONIAE

STREPTOCOCCUS PNEUMONIAE

• VIRULANCE VACTORS– Capsule

– Autolysin

– Pneumolysin

• CLINICAL PRESENTATION– NF

Resp.20-40%/pharynx

– Inhalation/droplets

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

Diagnosis

• Blood,CSF,Sputum& swab/aspirate

• DIRECT SMEAR– G+ve diplococci

– Lancet shape

– Capsulated halo (antiphagocytic)/pathogenic

Diagnosis

Quellung test(AB’s swelling of capsule)

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

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

VIRIDANS STREPTOCOCCI

Grouping of viridans streptococci

1. Mitis

2. Mutans

3. Salvarius

4. Angionosis

VIRIDANS STREPTOCOCCI

• CLINCAL PRESENTATION– NF (GIT,UGT&Oral

cavity)

– Opportunistic organisms

• Dental caries• Endocarditis

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 300-500 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

Endocarditis• Damage ,prosthetic valve

– 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

Treatment

VGS, NVS, sreptococcus

Native valve prosthetic valve

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

Microbiology

• DIRECT SMEAR– G+ve cocci in chains

• CULTURE– Can be OR rarely ß

hemolytic

– Most lack distinct LA

• IDENTIFICATION– Urea

– VP( acetoin production)

– Arginine hydrolysis

– Esculin hydrolysis

– CHO ferementation

Enterococcus

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

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

• CULTURE– Facultative anaerobs OR hemolysis

– Catalase weak +ve

– Group D

• IDENTIFICATION– Growth B/W 10-42 Co

– 6.5% NaCl

– Esculin hydrolysis(40%)bile salt

– Pyrrolidonyl arylamidase(PYR)+ve

– Leucine arylamidase(LAP)+ve

– Motility ,Pigmentation,arabinose and methyl --D-glucopyranoside

Bile esculin

• All Group D– Enterococcus

– S.Bovis

PYR/PYR-LAP

Endocarditis

Enterococcus, Native valve Prosthetic valve

MIC >0.5 ug/ul, PenG or Amp plus Gent for 4-6 wk

total 6 wk

BOVIS GROUPNew Name

Streptococcus gallolyticus

(Group D Streptococci)

BOVIS GROUP

• CLINICAL– 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

• CULTURE OR on BAP

• IDENTIFICATION– LG group D

• Differed from viridans– Growth in 40% bile salt

– Hydrolyze esculin

How you differentiate S. bovis from enterococcus?

• S.bovis– Unable to grow in

• 45 Co

• 6.5% salt @ 37dC

– PYR –ve

– S to penicillin and cephalosporins

– R to vancomycin(rare)

• Enterococcus– Able to grow in

• 45 Co

• 6.5% salt @ 37Co

– PYR +ve

– S to ampicillin

Summary