Flashcards in BACTE LEC - Strep pdf Deck (80):
1
– they grow in the
presence of oxygen but cannot use oxygen for
respiration
Aerotolerant anaerobe
2
types of strep based on respiration (???)
Facultative anaerobe
• Aerotolerant anaerobe
• capnophilic
3
taxo A positive /
bacitracin(S)
group A strep
4
complications of group A [2]
Complications:
- rheumatic fever
- AGN
5
Infections of group A [3, PPT]
Infections:
- pharyngitis / strep throat
- pyodermal infections
- toxic shock syndrome
6
Test: detects activity
of L-pyrrolidonyl arylamidase or
pyrrolidonyl aminopeptidase
PYR
7
Meaning of PYR
(Pyrrolidonyl-anaphthylamide
8
group A strep antigenic structure
attached to the peptidoglycan of the cell wall and
extends to the cell surface
– essential for virulence
M protein
9
– Best defined virulence factor of group A strep
– Resists phagocytosis
– Adherence of bacterial cell to mucosal cells
M protein
10
Both are adhesion molecules that mediate
adherence to host epithelial cells. [group A[
Fibronectin-binding protein (protein F)
• Lipoteichoic acid
11
– Group A VF weakly
immunogenic; prevents opsonized
phagocytosis by neutrophils or macrophages;
allows bacterium to mask its antigens and
remain unrecognized by its host
Hyaluronic acid capsule
12
– hemolysis incubated anerobically;
oxygen labile; lyzes blood cells; highly
immunogenic, ASO test
SLO
13
– hemolysis incubated aerobically; oxygen
stable; lyzes WBC, nonimmunogenic
• SLS
14
Most common DNase [grp A]
DNase A,B
15
Pyodermal Infections of gp A[CISE]
–
Impetigo, Erysipelas, Cellulitis, scarlet fever
16
• Activates plasmin, turning itself into a tissue
degrader
Impetigo Caused by Streptococcus
pyogenes
17
- beta hemolytic (small zone)
- taxo A (-)
- CAMP test (+) / Hippurate hydrolysis(+)
Group B
18
Group B Virulence Factor
– prevents phagocytosis; ineffective
after opsonization; with sialic acid w/c inhibits
activation of the alternative pathway
• Capsule
19
Group B Virulence Factor
– most significant component of the
capsule; critical virulence determinant
• Sialic acid
20
Group B - No role in virulence [5]
• Hemolysin
• CAMP factor
• Dnase
• Hyaluronidase
• protease
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Group B – Clinical Infections [2]
- pneumonia or meningitis with bacetermia
• Mastitis in cattle
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Small-colony-forming-
S. anginosus (Viridans)
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Large-colony-forming (w/ Group A) –
pyogenic
streptococci
– S. dysgalactiae subsp. equisimilis – upper
respiratory tract, vagina, skin, spectrum of
infections – like Group A
24
nonenterococcus
• Opportunistic infections
Group D Streptococcus
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Species of Group D Streptococcus
– S. equinus
– S. bovis
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Lab ID:
- Alpha or nonhemolytic
- PYR (-)
- psuedocatalase
- Bile esculin(+)
- 6.5% NaCl (-)
Group D Streptococcus
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• Group D antigen
• Same infections as group D Strep
Enterococcus spp.
28
Lab ID
Varied hemolysis
- produce acid in CHO broth
- Arginine hydrolysis
- Tolerate 0.04 % tellurite (E. faecalis)
- Utilize pyruvate
- Produce acid from methyl-a-D-glucopyranoside (MGP)
- Growth around 100 ug efrotomycin disk
- motile
- PYR (+)
- Bile esculin(+)
- 6.5% NaCl(+), 45 degrees C, alkaline pH
Enterococcus spp.
29
#1 cause of bacterial pneumonia - lobar
(especially in the elderly and in those with
underlying disease) sinusitis, otitis media (most
common isolate in
s. pneumoniae
30
lab ID
- alpha hemolytic, CAP, brain-heart infusion agar,
trypticase soy agar with 5% sheep RBC;
s. pneumoniae
31
lab ID
dome shaped if young; coin with raised rim if old
s. pneumoniae
32
gram variable as culture ages
- gram (+) diplococci; lancet shape
- taxo P(+) / Optochin susceptible
- Bile solubility(+)
- Capsular Swelling(+)
s. pneumoniae
33
No Lancefield group antigens
• green – alpha hemolytic
• fastidious, some require CO2
• oropharyngeal commensals - oppportunistic
Viridans
34
5 groups under Viridans
S. mitis group
• S. mutans group
• S. salivarius group
• S. bovis
• S. anginosus
35
– Infections:
• - oropharyngeal commensals - oppportunistic
- endocarditis with transient bacteremia
- meningitis
- dental caries
- osteomyelitis
Viridans Group
36
- most common cause of SBE
Viridans Group
37
PYR (-)
• LAP (+) leucine-B-naphthylamide, is hydrolyzed to
B-napthylamine + paradimethylaminocinnamaldehyde (DMACA) = red
• alpha or non-hemolytic
Viridans Group
38
• Ferments sugars, VP, B-D-glucuronidase acitivity,
hippurate hydrolysis – for species within the
viridans group
- taxo P (-)
- Bile esculin(-)
Viridans Group
39
biochem characteristics
• Throat swab
• Growth of most interfering respiratory
micobiota will be inhibited by SXT, but S.
pyogenes and S. agalactiae will grow. – may
have variable results – do PYR
Bacitracin susceptibility
40
biochem characteristics
• B-lysin producing strain of S. aureus
• Disk impregnated with the B-lysin
CAMP test
41
biochem characteristics
– a drop of
extracted B-lysin on a colony enhanced
hemolysis
Rapid CAMP test (spot CAMP)
42
biochem characteristics
• Hippuricase / hippurate hydrolase hydrolyzes
sodium hippurate to form sodium benzoate
and glycine
• Nihydrin
• Deep purple
Hippurate Hydrolysis
43
biochem characteristics
hydrolyzes sodium hippurate to form sodium benzoate
and glycine
Hippuricase / hippurate hydrolase
44
biochem characteristics
Detects activity of L-pyrrolidonyl arylamidase
or pyrrolidonyl aminopeptidase
• PYR impregnated disks serve as the substrate
to produce a-naphthylamine which is detected
in the presence of Ddimethylaminocinnamaldehyde (DMCA)
red
PYR Hydrolysis
45
biochem characteristics
• Hydrolyzes peptide bonds adjacent to a free
amino group
• The substrate, leucine-B-naphthylamide, is
hydrolyzed to B-napthylamine + paradimethylaminocinnamaldehyde (DMACA)
red
LAP
46
biochem characteristics
• Small colony forming B-hemolytic anginosus
group with groups A or C antigens vs. large
colony forming pyogenic strains with the same
antigens
• Detects acetoin production from glucose
• 5% a-naphthol + 40 % KOH; RT x 30 mins
red or pink color
VP
47
biochem characteristics
• Enzyme in large colony forming B-hemolytic
Groups C and G Strep
• (-) in small colony forming B-hemolytic
anginosus group
B-D-Glucoronidase
48
biochem characteristics
• cfb gene – encodes CAMP-factor protein
• ptsI (phosphotransferase) – Group A, C and G
can be distinguished
Nucleic Acid Probes
49
biochem characteristics
• Autocatalytic enzyme amidase
• Organism’s cell wall lyses during cell division
• Suspension in solution of Na deoxycholate
lyses solution becomes clear
Bile Solubility
50
biochem characteristics
• Incubate overnight at 35 degrees C in a CO2
incubator
• Zone of inhibition > 14 mm with a 6 mm disk
or >16 mm with a 10 mm disk
• Do bile solubility if zone is smaller
Optochin Susceptibility
51
biochem characteristics
• For non hemolytic, catalase (-), g(+) cocci
• 40 % bile; ability to hydrolyze esculin (for
Group D and Enterococcus)
• Enterococcus and Aerococcus grow in 6.5%
NaCl broth
Bile Esculin and Salt Tolerance
51
A-naphthylamine detected in the lresence of
Dimethylcinnamaldehyde
52
DMCA meaning
Dimethylcinnamaldehyde
53
Uncommon human pathogens
Group C and G strep
54
VF of e faecalis
Extracellularw serine protease
Gelatinase
55
VF of e faecalis which contribute to colonization and adherence to heart valves
Extracellularw serine protease
Gelatinase
56
Enterococcus with cytolysin
E faecalis
57
SBE meaning
Subacute bacterial endocarditis
58
Chemical reaction of s pneumoniae
CRP + C substance = ppt
59
Treatment for strep pneumoniae
Penicillin
60
Treatment for strep pneumoniae if penicillin resistant
Erythromycin and chloramphenicol
61
Strep with antigen c similar to c carbohydrate of lancefield grouping
S pneumoniae
62
How manu serotypes are there for strep pneumoniae based on capsular antigens
82
63
Sterile pleural effusion
Empyema
64
Opportunistic, oropharyngeal commensals
Viridans
65
CM for strep pneumoniae
CAP
BHI
TSA with 5% sheep RBC
66
Colonial characteristic of spneumon if young
Dome shaped
67
Colonial characteristic of spneumon if old
Coin with raised rim
68
Lancet shape strep
Pneumoniar
69
Group of strep
Fastidious
Some require CO2
Viridans
70
DMACA
Dimethylaminocinnamaldehyde
71
5 classif schemes [HPCBS]
Hemolytic pattern on BAP
Physiologic characteristics
Serologic grouping [lancefield]
Capsular polysaccharide
Biochemical characteristics
72
Meaning of LAP
Leucine Aminopeptidase
73
Motility of strep
Nonmotile
74
Motility of enterococcus
Motile
75
C carbohydrate present in all except
Viridans group
76
Lancefield classif based on
Cell wall structure
77
AGN meaning
Acute glomerular nephritis
78
Large colony isolates
S. dysgalactiae subspecies equisimilis
79