Micro: Streptococci

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1

what is the first branch of streptococci differentiation based on

shape (cocci vs. bacilli)

2

after shape what is the main differentation of cocci

ability to grow in air

3

after distinguishing which cocci grow in air, what is the differentiation based on between strep and staph

catalase

positive (staph)
negative (strep)

4

after distinguishing staph from strep what is the next step

bile soluble or optochin sensitive

5

is s. pneumo bile solube or optochin sensitive

yes

6

what coccus group grows on bile-esculin agar

group D strep/enterococcus

7

how do you distinguish group D strep

growth in 6.5% NaCl

8

what bacteria grows in 6.5% NaCl

enterococcus

9

what bacteria doesn't grow in 6.5% NaCl

group D strep

10

with respect to lack of growth on bile-esculin agar what is the next differentiative characteristic of streptococcus

hemolysis pattern on blood agar

11

what hemolysis pattern indicates incomplete or partial lysis of RBCs

alpha/gamma

12

what hemolysis pattern indicates complete lysis of RBCs

beta

13

what is the beta hemolytic, bacitracin sensitive strep

group A

14

what is the alpha/gamma hemolytic strep that does not grow on bile-esculin agar

viridans strep

15

what is the bacitracin insensitive strep that is hippurate hydrolyzed or CAMP

group B

16

what is the alpha hemolysis pattern

green zone around colonies growin on blood agar plate due to incomplete lysis of red blood cells

17

what is the beta hemolysis pattern

clear zone around the colonies due to complete lysis of RBCs

18

what is the gamma hemolysis pattern

no lysis and therefore no change in agar appearance

19

what are the indications for different Lancefield groupings

carbohydrate on cell walls

20

what are the main clinical indications of s. pneumo

respiratory tract infections
meningitis

21

what are the two respiratory tract infections from s. pneumo

pneumonia
bronchitis
otitis media

22

what is the most common cause of pneumonia in adults

s. pneumo

23

when does incidence increase in s. pneumo pnemo

over 40

24

what is the s. pnemo pneumonia case fatality rate

5% but higher in elderly

25

how can there be estra pulmonary sites of infection from s. pneumo pneumonia

bacteremia

26

how do the abrupt symptoms usually start in s. pneumo pnsumo

severe shaking chills

27

what are the symptoms of s. pneumo pneumo

high fever in most
productive cough with rusty sputum
dyspnea, weakness

28

what is an uncommon complication with effective antibiotic treatment

empyema

29

how many children will have otitis media at least once by age 6

75-95%

30

how many cases of penumococci account for otitis media

50%

31

what could meningitis result from in s. pneumo pneumo

bacteremia
sinusitis by direct extension
skull fracture with communication between nasopharynx and subarachnoid space

32

how many people will have s. pneumo colonize the upper respiratory tract

5-50% of population

33

how is s. pneumo transmitted

respiratory droplets (coughing)

34

what are the virulence factors of s. pneumo

polysaccharide capsule
produces IgA protease

35

how many antigenic types have been detected of s. pneumo

85

36

what is the role of the polysaccharide capsule

retards phagocytosis

37

what types of infection predispose for s. pneumo lung infection

viral respiratory infections

38

how do viral respiratory infections help s. pneumo to invade the lungs

mucociliary clearnace

39

what type of thing favors the development of bacteremia and sepsis from s. pneumo

splenectomy or functional splenectomy

40

what does s. pneumo look like in the lab

gram stain smear and culture shows lancet shaped cocci in pairs (diplococci)

41

what is the hemolysis pattern of s. pnemo

alpha hemolytic

42

what inhibits s. pnemo

optochin

43

what is the treatment for s pneumo

penicillin, 3rd gen cephalosporin and second antibiotic (vancomycin) in case of resistance for menintgitis

44

what is the mechanism for resistance to penicillin for s. pneumo

mutation of transpeptidase enzymes (PBP: penicillin binding proteins)

45

what are preventive measures of s. pneumo

23 valent vaccine against capsular polysaccharide for anyone with increased risk of s. pneumo infection and all adults over 65

7 valent conjugated vaccine (pneumococcal polysaccharide and diptheria toxoid) to prevent invasive pneumococcal infections in children

46

what are the clinical infections involved with s. pyogenes (group A)

pharyngitis

other tissues:
impetigo and cellulitis (skin)
erysipelas (skin and subcutaneous tissues)
pneumonia (lung) with empyema

47

what is pharyngitis called

strep throat

48

what are the immediate complications of pharyngitis due to s. pyogenes

peritonsillar abscess, otitis media, mastoiditis

49

what are the s. pyogenes sicknesses that are infections plus prominent manifestations of toxins

scarlet fever
TSS
necrotizing fasciitis

50

what are the nonsuppurative diseases of s. pyogenes

acute glomerulonephritis
rheumatic fever

51

what happens in acute glomerulonephritis

immune complexes bound to glomeruli (type III hypersens)

52

who does rheumatic fever usually afflict after sore throat

6-15 aged children

53

what is ARF

immunologic reaction against host tissue (heart and joint tissue primiarliy) induced by cross-reacting antigens on the streptococci and human tissue

54

how long after pharyngitis does ARF affect children

1-5 weeks

55

what usually prevents ARF

early antibiotic treatment

56

what are the "major" criteria for ARF

carditis
polyarthritis
chorea
erythema marginatum rash
subcutaneous nodules

57

what are the "minor" criteria for ARF

previous rheumatic fever or HD
arthralgia
fever
acute phase reactions (blood test)
prolonged PR interval (ECG)

plus supporting evidence of preceding streptococcal infection (increased ASO, positive throat culture, recent scarlet fever)

58

how much of population is genetically predisposed to ARF

10%

59

where does s. pyogenes live

on throat and skin

60

how is s. pyogenes transmitted

droplets and direct contact

61

what are the virulence factors of s. pyogenes

LTA
streptokinase
M protein
hyaluronidase
C5a peptidase
streptolysins S and O
streptococal pyogenic exotoxins (SPE) types A, B, and C
streptococcal DNase
exotoxin B

62

what is LTA

polymmer of 25 glycerolphosphate subunits boudn to palmitate (lipid)

63

what does LTA do

sticks to fibronectin (a host protein that coats epithelial cells of oropharynx) and allows organism to adhere to epithelial surfaces

64

what does streptokinase do

dissolves clost by activating plasminogen (forms plasmin) which breaks down fibrin in clots

65

what is streptokinase used to do

dissolve unwanted clots like in heart attack patients

66

what is the role of M protein

binds fibrinogen, fibrin, and their degradation products to form a dense coating on the organism's surface

blocks complement deposition

overall: inhibits phagocytossi

67

how many different M protein serotypes are there

80

68

what are two important M protein type categories

rheumatogenic and nephritogenic

69

what does hyaluronidase do

hydrolyzes the ground substance of CT to aid spread

70

what does C5a peptidase do

leaves C5a and destroys its chemotactic signal

71

what are streptolysins S and O

S- oxygen stabile
O- oxygen labile

HEMOLYSINS

72

is streptolysin S antigenic

no

73

what is the ASO titer

antibody vs. streptolysin O, important in diagnosing streptococcal infection

74

what can streptolysins be important for

lysing cells, tissue necrosis

75

what are the types of SPE

a, b, c

76

what produces the red rash of scarlet fever

SPE (erythrogenic toxin)

77

what is SPE A associated with

shock-inducing strep infections (TSS) by stimulation of TNF and IL-1 release

78

what is SPE A's TSS similar to

staphylococcal TSS

79

what does streptococcal DNase do

depolymerizes DNA in necrotic tissues

80

is streptococcal DNase antigenic

yes

81

what does exotoxin B do

protease that rapidly destroys tissue

82

what produces exotoxin B

strains of s. pyogenes that cause necrotizing fasciitis

83

what is inolved in the lab diagnosis for s. pyogenes

gram stained
beta-hemolytic, bacitraicin sensitive
elevated ASO titer (non suppurative)
group determined by antiserum vs. cell wall polysaccharide (quick strep throat test)

84

what is the treatment for pyogenes

penicillin

85

is there a vaccine for pyogenes

nope

86

what ar ethe clinical symptoms of s. agalactiae

endometritis and postpartum sepsis in mother
neonatal meningitis and sepsis in newborn

87

how is s. agalactiae (grou B strep) transmitted

flora of vagina, transmission to newborn at time of birth

88

what are the virulence factors of s. sgalactiae

none ided

89

what are the lab findings and diagnosis

beta hemolysis on blood agar
CAMP positive
hippurate hydrolysis positive
group determined by antiserum against cell wall plysacch

90

what is the treatment of s. agalactiae

penicillin, no vaccine available

91

what is the prevention of s. agalactiae

culture pregnant women and treat mother and newborn if culture positive

92

what are the two groups of group D strep

nonenterococci (s. bovus) and enterococcus

93

what is S. bovus normal flora of

GI and GU tracts

94

what is nonenterococcus a rare cause of

endocarditis and UTI

95

what is s. bovus associated with

colon cancer

96

what are members of the enterococcus family

s. faecalis
enterococcus faecium

97

what types of infections are associated with enterococcus

UTI
endocarditis
wound infections

98

why are enterococcus infections difficult to treat

antibiotic resistance

99

how are enterococcal infections often acquired

nosocomially with weakened host defenses and chronic illness

100

how is enterococcus transmitted

normal flora of the colon
may colonize urethra and female genital tracts

101

how can antibiotic resistant enterococcus transmitted

contact and environmental suraces in hospitals, most from endogenous flora

102

what are the toxins and VFs of eneterococcus

none

low virulence and tends not to cause infections in patients with intact host defenses

103

what is involved in the lab diagnosis involved in enterococcus

grows in 6.5% NaCl and hydrolyzes esculin in presence of 40% bile

104

how is enterococcus treated

penicillin+aminoglycoside
vancomycin

105

what type of resistanct is very important to enterococcus

vancomycin

106

what is the resistant move that enterococcus made

substitute for D-ala-D-ala so it is not in peptidoglycan

107

what is anaerobic streptococci called

peptostreptococcus

108

where does peptostreptococcus reside normally

GI and female genital tract

109

what is peptostreptococcus sometimes involved in

intra-abdominal absecesses

110

what is part of the viridans group

s. sanguis
s. mutans

111

what are the clinical manifestations of s. viridans

endocarditis
miscellaneous (pneumonia, sinusitis, otitis media, bacteremia, dental caries)

112

how many of bacterial endocarditis are accounted for by s. viridans

50%

113

what does s. viridans most commonly occur in

people with abnormal heart valve

114

what are the primary symptoms of endocarditis

fever and heart murmur

115

what are secondary manifestations of endocarditis

septic emboli
cutaneous findinds (Janeway's lesions, Osler's nodes)
glomerulonephritis (immune complex deposition)
CHF, mycotic aneurysms

116

what are s. viridans normal flora of

oropharynx

117

how do s. viridans enter the bloodstream

irritation of oral mucsa, then infect heart valves

118

what are the virulence vactors of s. viridans

some make dextrans that enhance adherence to heart valves and increase risk factor for endocarditis

119

how is lab diagnosis for s. viridans made

alpha/gamma hemolytic on blood agar

many isolates non-groupable by antigenic tests for cell wall carbohydrate antigens

120

what is treatment of s. viridans

penicllin plus aminoglycoside

prophylactic antibiotics for patient with prosthetic heart valves or prior history of endocarditis who undergo dental procedures