STAPHYLOCOCCI PT2 Flashcards
staphute
bunches of grapes
kokkos
berries
Golden grapes
Catalase- producing
Facultative anaerobe, except S.
saccharolyticus (obligate anaerobe).
Non-Motile, Non-spore forming
Glucose fermenter
CHARACTERISTICS OF STAPHYLOCOCCI
They are normally inhabitants of our
skin, mucous membrane and intestine.
They are associated with human
infection and colonize various skin and
mucosal surfaces. Under a microscope,
they are spherical cells that appear in
clusters or sometimes singly.
STAPHYLOCOCCI
Gastroenteritis, Bacteremia, Sepsis, UTI,
Endocarditis, Boils, Furuncles,
Folliculitis, Impetigo and Osteomyelitis.
CLINICAL INFECTIONS OF STAPHYLOCOCCI
VIRULENCE FACTORS OF STAPHYLOCOCCI
Catalase enzymes
- Coagulase
- Hyaluronidase
- Staphylokinase
- Lipase
- DNAse
- Beta-Lactamase
- Enterotoxin
- Hemolysin
- Exfoliative
toxins
- Pyagenic
entoxin
- Protein
COAGULASE NEGATIVE STAPHYLOCOCCI
S.epidermidis AND S. saphrophyticus
most contaminant in the
instruments for catheterization and
prosthetic heart valve implantation. It is
also called as Bacterial endocarditis
S.epidermidis
most commonly
acquired urinary tract infection in
sexually active female
S. saprophyticus
Mediates the
breakdown of
hydrogen peroxide
(H2O2 ) into oxygen
and water
CATALASE TEST
POSITIVE REACTION FOR CATALASE TEST
cupious bubble formation
NEGATIVE REACTION FOR CATALASE TEST
No bubble formation
BAP CULTURE Colonies
4mm to 8 mm
Appear creamy, white or
light gold or “butter
looking” while other species
may have gray colonies
Beta haemolytic (S. aureus)
STAPHYLOCOCCI IN BAP CULTURE
Best criterion of
Pathogenicity of
Staphylococcus
aureus
COAGULASE TEST
Reagent USE IN COAGULASE TEST
Rabbit
plasma
Anticoagulant USE IN COAGULASE TEST
EDTA
Coagulase Test Two Methods
▫ Slide Method
▫ Tube Method
SLIDE METHOD POSITIVE ORGANISMS
▪ Staphylococcus aureus
▪ Staphylococcus lugdunensis
▪ Staphylococcus schleiferi
In Slide method: If positive, it will produce
white fibrin clots
in plasma
In Slide method: If it is negative, use
tube method to
confirm it before reporting it as negative
Sensitive but definitive method.
To detect extracellular or free coagulase
TUBE METHOD
TUBE METHOD POSITIVE
clot or coagulum formation
after 1 to 4 hrs of incubation
In Tube method: ▪ If no clot left at room temp for additional
20 hours
Tube method organisms
▫ Staphylococcus hyicus
▫ Staphylococcus intermedius
▫ Staphylococcus lutrae
▫ Staphylococcus delphini
▫ Staphylococcus schleiferi
performed to distinguish
S.aureus from S. epidermidis and S.
saprophyticus
Coagulase test
Conversion of fibrinogen to fibrin.
Fibrin means it will cause clot formation.
PRINCIPLE OF COAGULASE TEST
Differentiate the
pathogenic staphylococci
from non-pathogenic
Mannitol Salt Agar (MSA)
MANNITOL FERMENTATION TEST
pH indicator of Mannitol Fermentation test
phenol red
positive result in mannitol fermentation test
Yellow S. aureus colonies
(surrounded by yellow halo)
composition of mannitol fermentation test
1% Mannitol
7.5% salt or sodium chloride
phenol red as an indicator
Jet black colonies of S. aureus
TELLURITE GLYCINE AGAR
S. aureus is resistant
POLYMYXIN SENSITIVITY TEST
▫ Differentiate S. aureus from S. intermedius
- ▫ Positive: Pink (acetoin or what we call
acetyl methyl carbinol)
S.aureus is positive
VOGES-PROSKAUER (VP) TEST
Identify pathogenic species of
staphylococci that produces Dnase
▪ DEOXYRIBONUCLEASE (DNASE) TEST
Culture media used in DNASE
DNA-methyl green agar
POSITIVE REACTION FOR DNASE AND POSITIVE ORGANISM
Clear/colorless zone around organism
S. aureus
It lowers the viscosity of the exudates giving
the pathogen more mobility.
It detects the presence of DNAse.
▪ DEOXYRIBONUCLEASE (DNASE) TEST
