صفحه 1:
Streptococci
M@™Characters of Streptococci
- Gram positive cocci
- lum in diameter
- Chains or pairs
Usually capsulated
Non motile
- Non spore forming
Facultative anaerobes
Fastidious
Catalase negative (Staphylococci are catalase
positive)
صفحه 2:
Classification of
Streptococci
Streptococci can be classified according
to:
- Oxygen requirements
#Anaerobic (Peptostreptococcus)
#Aerobic or facultative anaerobic (Streptococcus)
- Serology (Lanciefield Classification)
- Hemolysis on Blood Agar (BA)
صفحه 3:
رک رت 00
Crassitcation
Se 12 لحل
اک لي ل ل ا |
One or more species per group
Classification based on C- carbohydrate antigen of cell
لونلا
- Groupable streptococci
WB and D (more frequent)
WIC, Gand F (Less frequent)
- Non-groupable streptococci
0
|
0001-0
0
صفحه 4:
‘TABLE 13-1 Medically Important Streptococei
Type species serogroup ی 0
8 ‘Catle, humans "Necneta meningtis anc sepsis and intectors in souls
5 0 We ram aed aia
Uoparrestrtry econ
Hernan, axils Suteutancais or oman abscesses, endocanits ia
Seats Homans Encocaie cari
نو Swine
‘Siutens 7 sited Huan aes, onde
و
Nona ior We human ae ard سم
موه موومووو نومه [isin and pulraray اه
Sonewnonse ام مود Humans ea presmonse ano cers
Shovis ave denied youpartigenssh ruttoratyvarentsteptecoos mayer
صفحه 5:
۶۱۱۱۹۱۱2 المت ره كر
Based on Hemolysis on Blood
ی
۱ ۱۲۱۵۲۱۵۱۷56 ۵0 ۸۵
a-hemolysis
رزیت ریت۱۱
Green discoloration around the colonies
‘e.g. non-groupable streptococci (S. pneumoniae & S.
viridans)
p-hemolysis
توت یات تا ا
“Clear zone of hemolysis around the لب
‘e.g. Group A & B (S. pyogenes & S. agalai
y-hemolysis
ENo lysis
‘e.g. Group D (Enterococcus. r
صفحه 6:
Hemolysis on Blood agar
ل رزیت یو
a-hemolysis. 7m
مروت زرم ۲
صفحه 7:
Group A streptococci
۲۳ Include only S. pyogenes
™@Group A streptococcal infections affect all ages
peak incidence at 5-15 years of age
1 90% of cases of pharyngitis
صفحه 8:
Pathogenesis and Virulence
Factors
@ Structural components
- M protein M, which interferes with opsonization and lysis
ات۱۹۵۰
- Lipoteichoic acid & F protein> adhesion
- Hyaluronic acid capsule, which acts to camouflage the
bacteria
@ Enzymes
- Streptokinases sac the spread of streptococci through tissue:
- Deoxynucleases
- C5a peptidase
lM Pyrogenic toxins that stimulate macrophages and
helper T cells to release cytokines
M@Streptolysins
~ 5 op.5)5 © lyse red blood cells, white blood cells, and
platelets
- Streptolysin S
صفحه 9:
Disease caused by. S. pyogenes
| ل
- Non-Invasive
Pharyngitis (“strep throat”)-inflammation of the pharynx
Miskin infection, Impetigo
- Invasive
1662۲۱6۲ ۲6۷۵۲-۲۵6 2۲ ۲عع(» ۲6 ۵ کطنوع 200 5۵۲6۵05
across the body
‘™iPyoderma-confined, pus-producing lesion that usually
,عع13 عط مه 5أناءع0 36205, 06 605
M@iNecrotizing fasciitis-toxin production destroys tissues
and eventually muscle and fat tissue
Non Suppurative
- Rheumatic fever: Life نار لل inflammatory
disease that leads to damage of heart valves
muscle
- Glomerulonephritits
۳ رت تا ار رای
‘inflammation of the 9 and nephrons which
obstruct blood flow through the kidneys |
صفحه 10:
Differentiation between f-
hemolytic streptococci
The following tests can be used to
differentiate between p-hemolytic
streptococci
- Lanciefield Classification
- Bacitracin susceptibility Test
aSpecific for S. pyogenes (Group A)
- CAMP test
aSpecific for S. agalactiae (Group B)
صفحه 11:
Bacitracin sensitivity
@ Principle:
- Bacitracin test is used for
presumptive identification of group
A
- To رکه between S. pyogenes|
(susceptible to B) & non group A sucl]
as S. agalactiae (Resistant to B)
- م will inhibit the growth ae
م A Strep. pyogenes giving zone ot
Thiet around the disk
W@ Procedure:
- Inoculate BAP with heavy suspension
of tested organism
- Bacitracin disk (0.04 U) is applied to
inoculated BAP
- After incubation, any zone of
inhibition around the disk is
considered as susceptible
صفحه 12:
3
CAMP test
lieve elo
- Group B streptococci produce extracellular protein (CAMP
factor)
- CAMP act synergistically with staph. B-lysin to cause lysis of
85865
Mi Procedure:
- Single streak of Streptococcus to be tested and a Staph.
aureus are made perpendicular to each other
- 3-5 mm distance was left between two streaks:
- After incubation, a positive result appear as an arrowhead
shaped zone of complete hemolysis
- S. agalactiae is CAMP test positive while non gp B
streptococci are negative
صفحه 13:
Positive Control:
Negative Control:
Group A or Group D Strep.
صفحه 14:
Differentiation between a-
hemolytic streptococci
ithe following definitive tests used to
differentiate between S. pneumoniae & viridans
تت
- Optochin Test
- Bile Solubility Test
- مهمع ممعع ملتاناما
صفحه 15:
Optochin Susceptibility Test
Mi Principle:
- Optochin (OP) test is presumptive test that is used to
identify S. pneumoniae
- S. pneumoniae is inhibited by Optochin reagent (<5
ug/ml) giving a inhibition zone =14 mm in diameter.
(۱۱ ۱
- BAP inoculated with organism to be tested
- OP disk is placed on the center of inoculated BAP
- After incubation at 370C for 18 hrs, accurately measure
the diameter of the inhibition zone by the ill
- 214 mm zone of inhibition around the disk is considered
as positive and <13 mm is considered negative
lS. pneumoniae is positive (S) while S. viridans is
negative (R)
صفحه 16:
متت زور نت راز رهز ۱9۰۹۰
4 لك 0
Optochin susceptible
S. pneumoniae
صفحه 17:
Bile Solubility test
۱
- S. pneumoniae produce a self-lysing enzyme to
inhibit the growth
- The presence of bile salt accelerate this process
Procedure:
Add ten parts (10 ml) of the broth culture of the organism
to be tested to one part (1 ml) of 2% Na deoxycholate
(bile) into the test tube
- Negative control is made by adding saline instead of bile
to the culture
- Incubate at 370C for 15 min
- ملم 15 مع366 غاناوعء عط لرمععم
صفحه 18:
لمك علد
صفحه 19:
۱۱ رز کر ار زره کرت 15۳۲۲۲
لبم زج rs be —!
CAMP test Bacitracin Hemolysis
لاع ألا و۳
Negative Susceptible B S. pyogenes
Positive Resistant 1 S:
agalactiae
, Differentiation between a-hemotytic
۳30001
Inulin Bile Optochi | Hemolysi
Fermentatio | solubilit 0 5
n y يت
۷
Not ferment | Soluble | Sensitive a 5:
9 pneumoniae
mm)
poe! (pet | سكب
oe ee
صفحه 20: