Download 05-Hemolytic Streptococci

-Hemolytic Streptococci
Ali Somily MD,FRCPC,D(ABMM)
Introduction
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Grouped either by :
• A.phenotypic
1.
2.
Hemolysis(,ß or )
Lancefield antigen
– Cell wall CHO
– A,B,C,D,Fand G ect
Or B.Genotypic
&ß Hemolysis
Lancefield Agglutination
-Hemolytic Streptococci
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Partial hemolysis of blood
Green zoon around the colony
Examples:
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S.Pneumoniae
S.Viridans
Enterococcus
S.Bovis
STREPTOCOCCUS PNEUMONIAE
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Aerobic extracellular
Feature :
• Gram Positive cocci in pairs or short chains(Lancet
shape)
• Colony :Gray –white variable on BAP
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Non motile
Capsule : Polysaccharidemore than 80 types
Note : No Glycocalyx , No Exotoxin
Virulence Factors
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Capsule: Polysaccharide (resist phagocytosis
IgA Protease:Prevent Opsonization by IgA at
Mucous Membrane
Adhesion: Mediates attachement of
S.pneumoniae to Epithelial Cell
Autolysin/Pneumolysin
Quellung Test
(AB’s swelling of capsule
CULTURE
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BAP; 5-10%CO2
-hemolytic Mucoid
(capsule) SR
Concave (punched
out/collapse)
Laboratory Tests
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Catalase : -ve
Hemolysis : Alpha
6.5% Nacl : No growth
CAMP Test : -ve
Bile Esculin: -ve
Bile Solubility : +ve
Optochin :Sensitive
Lancefiield : None (CHO C)
IDENTIFICATION
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Bile solubility (NaDC)
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Optochin S (disk
5g&6mmzoon>=14
mm)
Source and Transmission
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Normal Flora of Upper Respiratory Tract in
20-40% of people
Horizontal Transmission via Droplet and
Inhalation
Pulmonary infection due failure of
Muccocilliary action AlveoliLobe
Meningitis after Sinusitis , Otitis Media or
Bacteremia through Choroid Plexus
Clinical
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Primary infection
• Community Acquired
Pneumonia
• Bacteremia
• Endocarditis
• Meningitis
• Localized
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Sinusitis
O.M
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Secondary Infection
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Non-capsulated
Opportunistic infection
Lungs only
Impair or poor ciliary
activity
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Viral, Smoking, dust
Lober Pneumonia
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Adult and Sickle Cell
Disease
Fever , cough(sputum),
Dull on Percussion
Can be fatal, Abscesses
Diagnosis: Sputum GS
and Culture
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Risk factor
• Hyposplenism
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Splenectomy
Asplenia
Sickle Cell Diseases
Liver disease
Hypogammaglobinaemia
Alcoholism
Cigarette smoking
Viral Infection
Malnutrition
Meningitis
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Adult and Elderly
Symptoms: fever, neck
Pain,Neck rigidity
Medical Emergency
Lumbar Puncture
PMNs , Protein,
Glucose and Cloudy
Direct Extension :
Sinises,OM or Through
Blood
Sinusitis and O.M
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Sinusitis : S.pneumoniae most common cause,
follow allergy or viral infection
O.M : S.pneumoniae most common cause,
follow allergy or viral infection which prevent
eustachian tube drainage.
Host Defense and Immunity
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IgG Antibodies :
Type specific immunity
Classical Pathway Immunity:
C1 activated by capsule: Antibody -dependent
Opsonization
Alternative Pathway Complement Antibody
-independent Opsonization
C5a complement : chemotaxis attract PMNs
Vaccine :Immunity for few years
Treatment and Prevention
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Treatment
• PenicillinG ↑ resistant recently due to PBP alternation
• Ceftriaxone for meningitis
• Ceftriaxone +/-Vancomycin and or Rifampicin
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Vaccination
• Polsaccharide capsule
• Conjugate vaccine
• Indication
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Children
SCD
Splenectomised patient
HIV
Elderly
Cardiopulmonary and renal diseases
VIRIDANS STREPTOCOCCI
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Streptococcus Viridans Group
1.
2.
3.
4.
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Mitis
Mutans
Salvarius
Angionosis
Extracellular aerobic Gram positive cocci in
chains and pairs
Gray-white variable colony on BAP
No exotoxin
Virulence Factors
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Dextran exopolysaccharide glycocalx:
• Provides means of adherence to defective hearts valves
• May block the action of antibiotics
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Lipoteichoic Acid (LTA): mediates adhesion to
fibronectin in clots on defective heart valves
Glucan: Polysaccharides made by S.mutans from
sucrose in the mouth , they provide a mean of
attachement to teeth enamel.
Other Acids: Made by S.mutans from fermentation of
sugars in the mouth contributed to tooth decay
Example of A biofilm
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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
Laboratory tests
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Catalase : -ve
Hemolysis: Alpha
6.5% NaCl : No growth
Bile Esculin : -ve
Bile Solubility : -ve
Optochin : Resistant
CAMP Test : -ve
Lancefield ; Non (CHO C)
Clinical
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Normal Flora in the Oropharynx ,GIT and GUT, enters blood
after dental work or due to poor oral hygiene
Bacteremia : S.mutan .
Sub-acute Endocarditis: most common cause , after bacteremia
due to dental work and infect maily abnormal valve or
prosthetic valve , rarely normal valves. It is fatal if not treated.
Dental caries: see above.
Lysis of bacteria by serum enzyme and lysosomal enzyme.
No vaccine available
Treatment
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Dental prophylaxis : One hour before
procedure in case of abnormal valve with
ampicillin
Ampicillin +/- aminoglycoside in case of
endocarditis
Vancomycin in penicillin allergic patient
Treatment
VGS, NVS,
sreptococcus
MIC
<0.1 ug/mI
MIC >0.1 —0.5 ug/mI
Native valve
prosthetic valve
PenG
PenG 6wk
+Gentamicin 2wk
PenG 6wk +
Gentamicin 4wk
PenG 4wk
+Gentamicin
2wk
Enterococcus
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Fecal strep separated genus/by molecular
Enterococcus Faecalis and E.Faecium
Extracellular Aerobic Gram positive cocci single in
chains or pairs
Gray –white or variable colony on BAP
Non Motile, Not capsulated, no Glycocalx and No
Exotoxin
Adhesion to defective heart valves and urinary tract
Antibiotics resistant
Laboratory Tests
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Catalase : -ve
Hemolysis: Alpha, Beta or Gamma
6.5% NaCl : Growth
PYR : + ve and LAP : +ve
Growth at 45 oC
40% Bile Salt: +ve
Bile Esculin : +ve
CAMP Test : -ve
Lancefield ; group D (CHO C)
Source and Transmission
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Normal Flora in GIT in human
Harsh condition Abiquitous /
soil,water,plants, GIT, GU human
15 Spp/E.faecalis80-90% of clinical isolate
Bacteremia after urinary tract infection, Intraabdominal route or via indwelling catheters
Exogenous acquisition in the hospital
(nosocomial)
Clinical
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Urinary tract infection (UTI) : Nosocomial,
upper and lower UTI
Bacteremia: From UTI , Intra-abdominal
infection or indwelling catheter ( Intravenous
or hemodialysis) , common in I’C patients
Sub-Acute Endocarditis : After bacteremia,
affects abnormal or prosthetic valves , it is
fatal if not treated
Host defense and immunity is unknown
Treatment and prevention
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Ampicillin in case of UTI by E.faecalis
Vancomycin in case of E.faecium
Ampicillin or Vancomycin + gentamicine in
case of endocarditis
Streptogramin or Linazolid in case of
Vancomycin Resistant Enterococcus (VRE)
Infection control measures in case of VRE
outbreak
No vaccine available
Endocarditis
Enterococcus,
MIC >0.5 ug/ul,
Native valve
Prosthetic valve
PenG or Amp
total 6 wk
plus Gent for 4-6
wk
Streptococcus Bovis
( Streptococcus gallolyticus NEW NAME)
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Group D streptococci
Aerobic extracellular Gram positive cocci in
chains or pairs
Gray-white colony on BAP
Non-Motile, Non-Capsulated and Glycocalyx
No Valulant factors
Laboratory Tests
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Catalase : -ve
Hemolysis: Alpha, Beta or Gamma
6.5% NaCl : No growth (opposite to enterococcus)
PYR : -ve (opposite to enterococcus)
No Growth at 45 oC (opposite to enterococcus)
40% Bile Salt: +ve (opposite to viridans)
Bile Esculin : +ve (opposite to viridans)
CAMP Test : -ve
Lancefield ; group D (CHO C)
Two biotypes I &II
Clinical
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Normal Flora in GIT
Infection after diruption of GI epithelium in case of
malignancy
Bacteremia from GIT
Endocarditis after bacteremia, fatal if not treated
Colonic cancer has strong association with S.bovis
bacteremia
IgA, IgG and PMNs
Treatment penicillin or vancomycin( rarely resistant
to vancomycin)
No vaccination available
Summary
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