The Streptococci Diverse collection of cocci. Gram-positive - - PowerPoint PPT Presentation

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The Streptococci Diverse collection of cocci. Gram-positive - - PowerPoint PPT Presentation

Dec 31, 2022 97 likes •537 views

The Streptococci Diverse collection of cocci. Gram-positive Strong fermenters Strong fermenters Chains or pairs Facultative anaerobes significant pathogens Non-motile Catalase Negative Genus:

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SLIDE 1

The Streptococci

  • Diverse collection of

cocci.

  • Gram-positive
  • Strong fermenters

Genus: Streptococcus and Enterococcus 1

  • Chains or pairs
  • significant pathogens
  • Strong fermenters
  • Facultative anaerobes
  • Non-motile
  • Catalase Negative
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SLIDE 2

Classification 1

Genus: Streptococcus and Enterococcus 2

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SLIDE 3

Classification 2

  • The pyogenic group
  • The mitis group
  • The anginosus group

Genus: Streptococcus and Enterococcus 3

  • The anginosus group
  • The salivarius group
  • The bovis group
  • The mutans group
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SLIDE 4

Haemolytic activity

  • β-haemolysis

http://medicine.ucsd.edu/NizetLab/streptoco ccipage/Hemolysis.jpg

  • α-haemolysis

http://www.kcom.edu/faculty/chamberlain/

Genus: Streptococcus and Enterococcus 4

http://www.kcom.edu/faculty/chamberlain/ Website/lab/idlab/hemo.jpg

  • Another useful site:

http://www.aic.cuhk.edu.hk/web8/Strep.htm

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SLIDE 5

Lancefield Grouping

  • Serological classification

– Means of distinguishing PYOGENIC Streps

  • Differences in cell wall polysaccharides

Genus: Streptococcus and Enterococcus 5

  • Differences in cell wall polysaccharides
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SLIDE 6

Streptococcus pyogenes

  • Lancefield Group A
  • Most prevalent
  • Exclusively human pathogens

Genus: Streptococcus and Enterococcus 6

  • Exclusively human pathogens
  • Infection Types

– Suppurative – Toxin related – Non-suppurative

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SLIDE 7
  • Str. pyogenes

. pyogenes - suppurative suppurative

  • non

non-invasive invasive

– pharyngitis skin infection, impetigo pharyngitis skin infection, impetigo

  • invasive bacteremia

invasive bacteremia

Genus: Streptococcus and Enterococcus 7

  • invasive bacteremia

invasive bacteremia

– toxic shock toxic shock-like syndrome like syndrome – "flesh eating" bacteria "flesh eating" bacteria

  • pyrogenic toxin

pyrogenic toxin

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SLIDE 8

Suppurative Suppurative (continued 1)

(continued 1)

  • Pyrogenic toxin

– superantigen superantigen – T cell mitogen T cell mitogen

Genus: Streptococcus and Enterococcus 8

– T cell mitogen T cell mitogen – activates immune system activates immune system

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SLIDE 9

Suppurative Suppurative (continued 2)

(continued 2)

  • Scarlet fever

Scarlet fever

– rash rash – erythrogenic toxin erythrogenic toxin

Genus: Streptococcus and Enterococcus 9

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SLIDE 10

Non-suppurative

  • rheumatic fever
  • inflammatory disease

inflammatory disease

  • life threatening

life threatening

  • chronic sequalae

chronic sequalae

Genus: Streptococcus and Enterococcus 10

  • chronic sequalae

chronic sequalae

  • fever

fever

  • heart

heart

  • joints

joints

  • rheumatic NOT rheumatoid arthritis

rheumatic NOT rheumatoid arthritis

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SLIDE 11

Non-suppurative 2

  • Rheumatic fever
  • (penicillin: terminates pharyngitis & decreases

carditis)

  • Acute glomerulonephritis (immune complex

disease of kidne)

Genus: Streptococcus and Enterococcus 11

disease of kidne)

  • Rheumatic fever –etiology
  • M protein ( cross-reacts heart myosin;

autoimmunity)

  • cell wall antigens (poorly digested in vivo persist

indefinitely)

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SLIDE 12
  • Str. pyogenes: Pathogenesis (1)
  • Lancefield Group A
  • Human pathogen
  • Suppurative infections

– Respiratory tract

Genus: Streptococcus and Enterococcus 12

– Respiratory tract – Soft tissue infections (http://www.4um.com/tutorial/icm/softiss.htm) – Toxin associated infections

  • Spectrum of infection resembles that of Staph.

aureus BUT virulence characteristics DIFFER

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SLIDE 13

Location of virulence associated factors Pathogenesis (2)

Genus: Streptococcus and Enterococcus 13

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SLIDE 14

Virulence factors:Pathogenesis (3)

  • Any attributes that are conducive to the

process of infection

  • adherence,
  • evasion of the host immune system and

Genus: Streptococcus and Enterococcus 14

  • evasion of the host immune system and
  • tissue damage
  • Variability
  • Genetic info transfer via “transduction”
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SLIDE 15

Transduction

Genus: Streptococcus and Enterococcus 15

www.panspermia.org/transduction.jpg

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SLIDE 16

Virulence factors: adhesion

  • Principal mechanism

– F protein===fibronectin

Genus: Streptococcus and Enterococcus 16

  • Adherence
  • Entry of the organism INTO the cell

– Lipoteichoic acid – M protein

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SLIDE 17

Virulence factors: M protein

  • Resistance to phagocytosis
  • Fibril
  • Cytoplasmic membrane
  • Cell wall
  • Polymorphism in gene encoding variability

Genus: Streptococcus and Enterococcus 17

  • Polymorphism in gene encoding variability
  • >80 forms
  • Strains may have :

– More than 1 type on their surface and – M-like

  • Bind to host serum proteins
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SLIDE 18

Virulence factors: Capsule

  • Hyaluronic acid capsule

– Some strains

  • Severe infections

Genus: Streptococcus and Enterococcus 18

  • Severe infections
  • Mucoid colonies on blood agar
  • Anti-phagocytic effect

– Variable significance

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SLIDE 19

Streptococcus agalactiae

  • Lancefield Group B
  • Primary habitat is the human colon; other

areas include

– throat

Genus: Streptococcus and Enterococcus 19

– throat – vagina (10-40 %)

  • Bovine mastitis
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SLIDE 20
  • Str. agalactiae: Pathogenesis
  • virulence factors

– haemolysins, – capsule polysaccharide; (9 different types)

Genus: Streptococcus and Enterococcus 20

– capsule polysaccharide; (9 different types) – C5a peptidase (only the human pathogenic strains), – hyaluronidase (not all strains) , – various surface proteins

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SLIDE 21
  • Str. agalactiae: Pathogenesis 2
  • CAMP

– Means of lab recognition of Str. Agalactiae

Genus: Streptococcus and Enterococcus 21

http://gold.aecom.yu.edu/id/micro/camp.htm

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SLIDE 22
  • Str. agalactiae: Features
  • Infections in Neonates

– Early onset (at or T<12 h of birth) – Late onset (T> 7 days but T<3 months)

Genus: Streptococcus and Enterococcus 22

  • Newborn babies become infected in three

ways:

– before birth – during birth – after birth

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SLIDE 23

Early onset disease

  • Risk factors for early onset disease include:
  • Premature delivery;
  • Multiple births;
  • Premature rupture of membranes before the onset of

labour;

  • Prolonged rupture of membranes lasting more than 18

Genus: Streptococcus and Enterococcus 23

  • Prolonged rupture of membranes lasting more than 18

hours before delivery;

  • Urinary tract infection in mother caused by Group B Strep;
  • Lack of antibody in mother against type of Group B Strep

carried in birth canal;

  • Fever in mother during labour;
  • History of previous newborn with Group B Strep disease.
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SLIDE 24

Late onset disease

  • Bacteraemia alone or in conjunction with other

conditions –purulent meningitis –pneumonia, –septic arthritis,

Genus: Streptococcus and Enterococcus 24

–osteomyelitis –conjunctivitis –sinusitis – otitis media – endocarditis – peritonitis

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SLIDE 25

Infection in the adult

  • Pregnancy / recent post partum

– Ascending spread

– Abortion, chorioamnionitis,post partum sepsis, – other infections e.g. pneumonia in the post partum period

Genus: Streptococcus and Enterococcus 25

  • Non pregnant adults

– sepsis, pneumonia, soft tissue infections, and UTI – complicated by bacteraemia.

  • Elderly
slide-26
SLIDE 26

Other Pyogenic Streptococci

  • http://www.spjc.edu/hec/vettech/VTDE/AT

E2639L/Microchart.htm

Genus: Streptococcus and Enterococcus 26

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SLIDE 27
  • Str. suis

(Group R streptococcus)

  • septicaemia and meningitis in pigs.
  • occasionally infect people

Genus: Streptococcus and Enterococcus 27

  • occasionally infect people
  • Through contaminated pork or infected pigs, and
  • cause septicaemia, meningitis, and respiratory tract

infections.

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SLIDE 28

Streptococcus pneumoniae

  • pneumococcus

– oropharyngeal flora of 5-70% of the population – highest isolation rate in children during the winter months.

  • diplococcus

Genus: Streptococcus and Enterococcus 28

  • diplococcus
  • an important pathogen

– polysaccharide capsule

  • genetically very flexible
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SLIDE 29

Streptococcus pneumoniae: Pathogenesis 1

  • Capsule

http://www.indstate.edu/thcme/micro/s- pneum2.html

Genus: Streptococcus and Enterococcus 29

pneum2.html

  • Antiphagocytic

http://www.medschool.lsumc.edu/Micr/COU RSES/DMIP/opson.htm http://medtech.cls.msu.edu/ISL/immunology/

  • psonize.htm
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SLIDE 30

Streptococcus pneumoniae: Pathogenesis 2

  • IgA1 protease
  • Pneumolysin

– Neutrophil chemotaxis

Genus: Streptococcus and Enterococcus 30

– Neutrophil chemotaxis – Phagocytosis and the respiratory burst http://www.cellsalive.com/nbt.htm

  • Autolysin
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SLIDE 31

Clinical features: pneumonia

  • Predisposing conditions
  • Person-to-person spread is uncommon.
  • Possible causes include:

Genus: Streptococcus and Enterococcus 31

– Aspiration into the lower respiratory tract – Terminal events – Immune deficiencies

slide-32
SLIDE 32

The Commensal Streptococci: Viridians Streptococci

  • Viridans group dominant resident oral flora

– Mitis – Salivarius

Genus: Streptococcus and Enterococcus 32

– Salivarius

  • Inhibit colonization of many pathogens

– Bacteriocins – H2O2

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SLIDE 33

Viridans streptococci

  • ill defined group of species
  • α- haemolysis on blood agar,
  • may have a variety or no Lancefield

antigens.

Genus: Streptococcus and Enterococcus 33

antigens.

  • The most common are Str. sanguis, mitis,

mutans and salivarius.

  • Most are commensals of the mouth and

upper respiratory tract.

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SLIDE 34

Bacteriocins

  • http://www.biochem.ucl.ac.uk/bsm/PLASMID/Ba

cteriocins.htm

  • Agents
  • Encoded in the genetic material carried by

plasmids

Genus: Streptococcus and Enterococcus 34

plasmids

  • There purpose is to of kill or inhibit closely related

species or even different strains of the same species

  • Specific
  • Survival in an overpopulated environment
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SLIDE 35

Mitis group

  • Str. mitis, Str. oralis, Str. sanguis and Str. gordonii
  • Colonize tooth surfaces & mucosal membranes
  • May enter the bloodstream
  • In healthy individuals,

Genus: Streptococcus and Enterococcus 35

  • In healthy individuals,

cleared from circulation within 1 h

  • Not so with other predisposing factors present

post-streptococcal rheumatic fever

  • were the primary cause of infective endocarditis
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SLIDE 36

Mutans group

  • Str. mutans and Str. sobrinus

– Exclusively colonize tooth enamel – Only after eruption

Genus: Streptococcus and Enterococcus 36

– Only after eruption

  • Lactic acid producers
  • may cause subacute bacterial endocarditis.
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SLIDE 37

Anginosus Group

  • Str. anginosus , Str. intermedius & others
  • regular commensals

– tooth surfaces

Genus: Streptococcus and Enterococcus 37

– tooth surfaces – gingival crevices.

  • isolated from abscesses and other purulent
  • pportunistic infections
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SLIDE 38

Bovis Group

  • Str. Bovis
  • Various animal species
  • Human gut

Genus: Streptococcus and Enterococcus 38

  • Human gut
  • Occasionally causes

– Bacteraemia – Subacute endocarditis

  • Associated with colon carcinoma
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SLIDE 39

Enterococcus

  • natural habitat in the human intestines

– E. faecalis – E. faecium

  • Associated diseases

– Urinary tract infection ( in hospitals, sporadic outbreaks) – Infective endocarditis

Genus: Streptococcus and Enterococcus 39

– Infective endocarditis – Biliary tract infections – Suppurative abdominal lesions – Peritonitis

  • Poor prognosis
slide-40
SLIDE 40

On Line Medical Encyclopedia

e.g. Hypogammaglobulinaemia

http://www.amershamhealth.com/medcyclopaed ia/Volume%20III%201/HYPOGAMMAGLOB

Genus: Streptococcus and Enterococcus 40

ia/Volume%20III%201/HYPOGAMMAGLOB ULINAEMIA.asp

slide-41
SLIDE 41

Genus: Streptococcus and Enterococcus 41

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SLIDE 42

In conclusion

  • http://www.geocities.com/SouthBeach/Port/

3008/strepto.html

Genus: Streptococcus and Enterococcus 42