STREPTOCOCCUS
BASMAH ALMAARIK Lab # 6
STREPTOCOCCI All are Gram Positive Cocci arranged in chains
(short or long)
All are Catalase -ve
+ ve- ve
GRAM STAIN
Staphylococci Streptococci
CULTURE
Fastidious organism no growth on NA
Grows well on BAP
Facultative anaerobe
Grow at 37C need 24 to 48 hour .
STREPTOCOCCUS CLASSIFICATION
Alpha hemolyticS. viridansS. pneumoniae
Beta hemolytic:Group A, B, C, G & D
Lancefield grouping according to antigens in their cell wall
Non-hemolytic:Enterococcus (formally known as Group D)
HEMOLYTIC STREPTOCOCCI Alpha hemolysis on BAP (partial
hemolysis).
Beta hemolysis on BAP(complete hemolysis).
No hemolysis on BAP
BETA HEMOLYTIC STREPTOCOCCI
Lancefield grouping depending on antigens in their cell wall, they are classified into groups : A, B, C, D, F, and G.
Facultative anaerobes, grows at 37˚C for 24h.
Need 5-10% CO2
GRAM STAIN
BETA HEMOLYTIC STREPTOCOCCI
Group A (S. pyogenes). Bacitracin
Group B (S. agalactiae) CAMP test. Hippurate hydrolysis.
Group D (Enterococcus) Grow in high salt conc. Esculin hydrolysis Tolerate high tempreture
BETA HEMOLYTIC STREPTOCOCCI
S. Pyogenes(Group A Strep) S. Agalactiae(Group B Strep)
Catalase –ve.
Bacitracin sensitive.
Catalase –ve.
Bacitracin resistant .
S. AGALACTIAE(GROUP B STREP)
CAMP test:
Streak a Staph.aureus across a blood agar plate.
Inoculate test organism at right angles to it.
The tested organism must not touch the staphylococcal inoculum.
37˚C X 24 hr
S. AGALACTIAE(GROUP B STREP)
S.aureus produce beta-lysin.
S.agalactiae produce extracellular protein CAMP factor.
Both react together synergeticly to produce enhanced haemolysis arrow shape haemolysis.
CAMP TEST +VE AND -VE
S. AGALACTIAE(GROUP B STREP)
Hippurate hydrolysis test :
hippuratehydrolase enzyme hydrolizehippurate benzoic acid + glycine
We add ninhydrin reagent which will react with glycine to give us purple color.
S. AGALACTIAE(GROUP B STREP)
Bacterial suspenstion in 1% sodium hippurate
Incubate 2 hours at 37˚C
Add ninhydrine reagent.
Incubate for 10 min.
Purple color +ve
No purple color -ve
ENTEROCOCCUS (GROUP D STREP)
• Grow at wide range of temperature 10˚C - 45˚C.
Mainly non hemolytic on blood agar but can show alpha or beta-haemolysis.
Non-fastidious can grow on nutrient agar.
GROW IN HIGH SLAT CONCENTRATION Inoculate the organism
in a tube of broth containing 6.5% NaCl.
Incubate overnight at 37oC.
Turbid growth can tolerate high salt conc +ve
Clear no growth can’t grow in high salt conc. -ve
ESCULIN HYDROLYSIS The organism can hydrolyze esculin and
produce black color in the media.
It can also grow in the presence of 40% bile salt.
ESCULIN HYDROLYSIS
Black color esculin hydrolysis +ve
GROWTH IN HIGH HEAT .
1. Make a suspension of the organism.2. Inoculate on a blood agar (0 time) 3. Incubate organism suspension in water bath
45˚C X 10 min sub-culture to BAP
Repeat step 3 tow more times.
Then incubate the BAP 37 ˚C x 24 hr.
RAPID IDENTIFICATION TEST FOR BETA-HEAMOLYTIC STREPTOCOCCI
YOUR WORK FOR TODAY
1. Do gram stain and show it to the instructor
2. Do camp test with group A and B3. Do bacitracin sensitivity with group A4. Do esculin hydrolysis test with group D5. Do salt tolerance test with group D6. See instructors hippurate test
(Demonestration)7. See instructors rapid identification kit for
Beta-heamolytic stryptococci (Demonestration)
Top Related