streptococcus pneumoniae staphylococci gram positive cocci lecture 46 l.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
Streptococcus pneumoniae Staphylococci (Gram positive cocci) Lecture 46 PowerPoint Presentation
Download Presentation
Streptococcus pneumoniae Staphylococci (Gram positive cocci) Lecture 46

Loading in 2 Seconds...

play fullscreen
1 / 32

Streptococcus pneumoniae Staphylococci (Gram positive cocci) Lecture 46 - PowerPoint PPT Presentation


  • 320 Views
  • Uploaded on

Streptococcus pneumoniae Staphylococci (Gram positive cocci) Lecture 46. Faculty: Dr. Alvin Fox. S. pneumoniae diplococci Pneumococcus autolysin bile solubility test optochin susceptibility capsule Quellung reaction. Staphylococcus aureus opportunistic diseases

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Streptococcus pneumoniae Staphylococci (Gram positive cocci) Lecture 46' - chaka


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
streptococcus pneumoniae staphylococci gram positive cocci lecture 46
Streptococcus pneumoniaeStaphylococci(Gram positive cocci)Lecture 46

Faculty: Dr. Alvin Fox

keywords
S. pneumoniae

diplococci

Pneumococcus

autolysin

bile solubility test

optochin susceptibility

capsule

Quellung reaction

Staphylococcus aureus

opportunistic diseases

food poisoning/enterotoxins

toxic shock syndrome

toxic shock toxin

exfoliative toxin/scalded skin syndrome

α, β, γ and δ cytotoxins

leucocidin

lipase

hyaluronidase

protein A

coagulase (+)

MRSA methicillin resistant S. aureus

Staphylococcus epidermidis

coagulase (–)

KEYWORDS
s pneumoniae4
S. pneumoniae
  • leading cause of pneumonia
    • particularly young and old
    • after damage to upper respiratory tract

*e.g. following viral infection

  • bacteremia
  • meningitis
  • middle ear infections (otitis media)
s pneumoniae5
S. pneumoniae
  • α hemolytic
  • pneumolysin
    • degrades red blood cells under aerobic conditions
  • grows well on sheep blood agar
  • no group antigen
diagnosis spinal fluid
Diagnosis - spinal fluid
  • direct Gram staining
  • detection of capsular antigen
autolysis identification after growth
Autolysis – identification after growth

lipoteichoic acid

autolysin

Bile

teichoic acid

-choline

peptidoglycan

autolysin

Cell membrane

c polysaccharide
C polysaccharide
  • Teichoic acid
    • Precipitates in serum
    • C-reactive protein
slide9

Identification

optochin resistant

optochin sensitive

capsule
Capsule
  • prominent
    • virulent strains
  • anti-phagocytic
  • carbohydrate antigens
    • vary among strains
capsule11
Capsule
  • immunity
    • serotype specific
  • vaccine contains multiple serotypes

- recommended susceptible population

  • young children
  • elderly
quellung reaction
Quellung reaction
  • using antisera
  • capsule "fixed"
  • visible microscopically
pathogenesis
Pathogenesis
  • Teichoic acid
    • complement activation
    • large numbers of inflammatory cells at infection site
therapy
Therapy
  • S. pneumoniae
    • most strains susceptible to penicillin
    • resistance is common
staphylococci
STAPHYLOCOCCI
  • Gram positive
  • Facultative anaerobes
  • Grape like-clusters
  • Catalase positive
  • Major components

of normal flora

    • skin
    • nares
slide17

One of commonest opportunistic

infections (nares) hospital and community:

  • pneumonia
  • osteomyelitis
  • septic arthritis
  • bacteremia
  • endocarditis
  • abscesses/boils
  • other skin infections
food poisoning
Food poisoning
  • not an infection
  • food contaminated by humans
    • growth of bacteria
    • production of enterotoxin
  • onset and recovery both occur within few hours
food poisoning19
Food poisoning
  • Vomiting
  • nausea
  • diarrhea
  • abdominal pain
slide20

Associated with outbreak

of toxic shock syndrome.

toxic shock syndrome
Toxic shock syndrome
  • fever
  • rash
  • desquamation
  • vomiting
  • diarrhea
toxic shock syndrome22
Toxic shock syndrome
  • Toxic shock toxin
    • Dissemination
  • Organism
    • no dissemination
s aureus
S. aureus
  • babies
    • scalded skin syndrome
      • exfoliatin
lytic exotoxins
Lytic exotoxins:
  • αtoxin
  • β toxin (sphingomyelinase C)
  • γtoxin
  • δtoxins
    • detergent-like
  • leucocidins
protein a inhibits phagocytosis
Protein A inhibits phagocytosis

PHAGOCYTE

Fc receptor

Protein A

immunoglobulin

BACTERIUM

spread
Spread
  • tissue-degrading enzymes
    • lipase
    • hyaluronidase
identification
Identification
  • Sheep blood agar
  • β hemolytic
  • yellow pigmented(aureus)
  • mannitolfermentation
  • coagulase-positive
  • phage-typing, rarely performed
antibiotic therapy
Antibiotic therapy
  • Resistance to penicillin
    • penicillinase
  • β lactam antibiotics (including methicillin for MRSA)
    • often ineffective
    • modified penicillin binding proteins
  • Vancomycin
    • current drug of choice
    • resistance has been observed
staphylococcus epidermidis
Staphylococcus epidermidis
  • major member, skin flora
  • opportunistic infection
  • - less common than S.aureus
  • nosomial infections
    • shunts, catheters
  • artificial heart valves/joints
identification30
Identification
  • Sheep blood agar
    • non-hemolytic
    • Non-pigmented
  • Does not ferment mannitol
  • Coagulase negative
staphylococcus saprophyticus
Staphylococcus saprophyticus
  • urinary tract infections
  • coagulase-negative
    • not usually differentiated from S. epidermidis
slide32

Summary Figure (Identification Scheme)

Note: S. viridansis ALPHA hemolytic and negative for all the tests below

GRAM POSITIVE COCCI

Catalase

-

+

Streptococcus

(pairs & chains)

Staphylococcus

(Clusters)

Hemolysis/Test

Coagulase

-

+

+

BETA:

Bacitracin

S.

pyogenes

(group A)

S. aureus

S.

epidermidis

+

CAMP/

Hippurate

S.

agalactiae

(group B)

Beta hemolytic

Non-hemolytic

+

mannitol

mannitol

ALPHA:

Optochin

/Bile Solubility

S.

pneumoniae

yellow

white

+

+

GAMMA OR ALPHA: Bile

Esculin

6.5%

NaCl

Group D

Enterococcus

-

+

Bile

Esculin

6.5%

NaCl

Group D

Non-

Enterococcus