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Flashcards in micro- Gram + bacteria Deck (134):
1

how do you differentiate between staph and strep cocci

catalse test
streptococcal infections are catalase -
or look at grouping of gram stain

2

Differentiate beta and alpha hemolytic strep

beta completely lyse RBC leaving clear zone of hemolysis around the colony
alpha partially lyse RBC leaving greenish coloration

3

What is the molecule that is green after adding alpha hemolytic strep to blood agar plate

metabolite of Hb

4

what is the third type of hemolytic strep

gamma
cannot hemolyze RBC

5

What are the Lancefield Ag on strep

C carbohydrates classified as A B C DE thru S

6

What are the 5 human significant strep infections

A B D
strep pneumoniae
viridans group

7

What is another name for group A beta hemolytic strep

streptococcus pyogenes

8

What diseases is strep pyogenes responsible for

scarlet fever, rheumatic fever, post streptococcal glomerulonephritis

9

What are the antigenic properties found on strep pyogenes

C carbohydrate
M protein

10

What is the role of the M protein of strep pyogenes

inhibits activation of C' and protects organism from phagocytosis

11

What is the bodys response to M protein of strep pyogenes

B cells generate Ab against M protein

12

What enzyme is responsible for the hemolytic ability of strep pyogenes

streptolysin O

13

What type of titers do you take on a patient to confirm past strep pyogenes infection

anti-streptolysin O
ASO titers

14

What other toxins does strep pyogenes produce

Streptolysin S aids in hemolysis
pyrogenic exotoxin on some
streptokinases
hyaluronidase
DNAase
anti C5a-peptidase

15

What are the 4 types of disease that strep pyogenes causes in local invasion or exotoxin release

strep pharyngitis
strep skin infections
scarlet fever
strep TSS

16

What type of reactions/diseases are rheumatic fever and glomerulonephritis caused by strep pyogenes

delayed Ab mediated diseases

17

What is the presentation of strep pharyngitis

strep throat with red swollen tonsils and pharynx with purulent exudate on tonsils and high temp with swollen lymph nodes

18

What test should you order if you suspect strep throat

rapid antigen detection test RADT detecting the group A carb Ag

19

With a - RADT test in a child you suspect strep in what else should be done

throat culture

20

what type of skin infections can be caused by strep pyogenes

folliculitis, pyoderma,erysipelas, cellulitis, impetigo

21

What is impetigo

vesicular blistered eruption that becomes crusty and flaky

22

what is erysipelas

bright red rash with sharp border that advances from initial infection site

23

what is pyoderma

pustule on extremity or face that breaks down after 4-6 days to form a crust and leave depigmented area

24

What is a worrysome complication of skin infections from strep pyogenes

necrotizing fascitis

25

what is fourniers gangrene

necrotizing fasciitis involving male genitale area and perineum

26

The pyrogenic toxin or erythrogenic toxin of s pyrogenes can lead to what

scarlet fever

27

what does the rash of scarlet fever appear like

red that begins on trunk and neck spreads to extremities but spares face

28

what are risk factors for rheumatic fever

had recent strep pharyngitis
age 5-15

29

What are the manifestations of rheumatic fever

fever, myocarditis, arthritis, chorea, subcut nodules, rash "erythema marginatum" red margin from center

30

someone with recurrent strep pyogenes infections with initial myocarditis is at risk for developing what

rhemuatic valvular heart disease

31

what are signs of post streptococcal glomerulonephritis

kid with puffy face from retention of fluid by damaged kidney
dark colored urine from hematuria
hypervolemia secondary to fluid retention causing high BP

32

What is the other name for Group B beta hemolytic strep

step agalactiae

33

What does group B strep cause in neonates

meningitis, pneumonia and sepsis

34

what is the sign of meningitis in neonates

fever, vomiting, poor feeding and irritability

35

Dx of meningitis is made how

lumbar puncture

36

What are common causes of meningitis in a neonate under 3 mo age

E coli, L monocytogenes and Strep agalactiae (group b)

37

what bacteria causes meningitis later in infant's life, after 3 mo

N gonorrhea
H influenza

38

What can group B strep cause in pregnant women

still birth, sepsis spontaneous abortion

39

What are the groups included in strep viridans

mitis, salivarius, mutans and Anginosus

40

Viridans group strep is indigenous to what area

the GI tract

41

Most of viridans strep are what category

alpha hemolytic producing greenish discoloration on blood agar

42

What are the main types of infections caused by viridans streptococci

dental infections
endocarditis
abscesses

43

What is the cause of endocarditis in viridans strep

from the dental manipulations that may enter blood and thus lead to subacture bacterial endocarditis

44

what is the clinical presentation of subacute bacterial endocarditis SBE

low fever, fatigue, anemia and heart murmurs

45

What type of endocarditis is caused by staph infections

acute infective
usually from IV drug use
shaking chills, high fevers and rapid valve destruction

46

What other bacteria can lead to subacture bacterial endocarditis

group D strep

47

What family of strep virdans causes absecesses

anginosus species that are microaerophilic

48

If the Strep intermedius bacteria from anginosus family is growing in the blood what should you order

CAT with contrast to look for abscess in hiding organ

49

What are the 2 groups of group D strep

enterococcus and non-enterococci

50

enterococci faecalis and faecium are found where

in GI, part of normal flora
growing well in bile

51

What tpe of infections do the enterococci cause

subacute bacterial endocarditis, UTI, biliary tract infections, bacteremia

52

What type of infections do enterococci commonly cause in hospitals

prosthetic valve endocarditis sepsis after IV catheters

53

What are the enterococcie resistant to

ampicillin and vancomycin

54

infection with strep bovid (non-enterococci strep) is assoc with what

colon cancer

55

What does strep pneumococcus commonly cause in adults? children?

adults- meningitis and most common cause of pneumonia in adults
children- otitis media

56

What is the shape of strep penumococcus

diplococci, no lancefield Ag

57

what is the major virulence factor of s. pneumococcus

the capsule of polysaccharides

58

What lab tests do you order to confirm S. pneumococcus

quellung (swelling with methylene blue)
optochin sensitivity- cannot grow on petri dish with optochin but viridans can(both alpha hemolytic)

59

what is the clinical presentation of S pneumococcal pneumonia

sudden
shaking chills
high fevers
chest pain
SOB
one or more lungs fill up with white pus and exudate seen as consolidated lobe
yellow-green sputum that has gram + lancet shaped diplococci

60

what are the 3 main bacteria that cause otitis media in children

S pneumoniae
H influenza
M catarrhalis

61

S pneumococcus is becoming resistant to what

penicillins

62

how do you differentiate enterococci and nonenterococci with the agar

enterococci grow in bile and 6.5%NaCl
non-enterococci only grow in bile

63

What are the 3 main strains of staph

aureus, epidermidis, saprophyticus

64

How can staph aureus be differentiated from other beta hemolytic cocci

golden pigment on sheep blood agar

65

which staph is coagulase +

staph aureus only

66

What proteins does S aureus have to disable our immune system

Protein A, coagulase, hemolysins, leukocidins, penicillinase, novel penicillin binding protein

67

What protects S aureus from opsonization

Protein A

68

what prevents S aureus from phagocytosis

coagulase

69

what do the hemolysins do in S aureus

destroy RBC neutrophils, macrophages and platelets

70

What do leukocidins of S aureus do

destroy WBC

71

What produces Panton-Valentine leukocidin PVL

the CA-MRSA

72

What proteins are in S aureus that tunnel through tissue

hyaluronidase
staphylokinase
lipase
protease

73

what lyses formed fibrin clots in S aureus

the staphylokinase

74

what facilitates S aureus to colonize in sebaceous glands

lipases

75

What are the toxins that S aureus produces

exfoliatin
enterotoxins
TSST1

76

what is exfoliatin

causes skin to slough off
scalded skin syndrome from S aureus

77

what is the role of enterotoxin from S aureus

food poisoning

78

how does TSST1 work from S aureus

binds MHC II and massive T cell activation

79

What diseases are caused by S aureus exotoxin release

Gastroenteritis
TSS
Scalded skin syndrome

80

What diseases are caused by S aureus from direct organ invasiveness

pneumonia
meningitis
osteomyelitis
acute bacterial endocarditis
septic arthritis
skin infections
bacteremia/sepsis
UTI

81

What are signs of gastroenteritis

vomiting, diarrhea, abdominal pain and occasional fever 12-24 hrs

82

where are areas that TSST1 is released

infected sutures, cutaneous and subcut infections, infections following childbirth and abortion

83

What are the signs of TSST1 caused TSS

sudden fever, nausea vomiting, and watery diarrhea
few days develop diffuse erythematous rash
palms and soles have fine peeling
blood pressure may drop and could have severe organ system dysfunction

84

What toxins cause scalded skin syndrome

exfoliative A and B toxins

85

a hospitalized patient just recovering from flu has avbrupt onset fever, chills and lobar consolidation with destructed parenchyma. what is culprit

staph caused pneumoniae

86

What are signs of meningitis, cerebritis and brain abscess from staph

high fever, neck stiffness, HA, obtundation, coma and focal neurologic signs

87

In a 10 y/o there is warm swollen tissue over bone with systemic fever and shakes. likely Dx?

staph caused osteomyelitis

88

what are signs of acute endocarditis from staph

high fever 103 and higher
chills, myalgias

89

staph caused septic arthritis is common in what age groups

pediatrics and adults >50

90

What does impetigo look like if caused by staph

honey colored crust
usuall around mouthy

91

what type of skin infections are caused by staph

cellulitis, impteigo, local abscesses, furuncles, carbuncles

92

What makes staph aureus R to methicillin

the penicillin binding protein 2A

93

What is most useful antibiotic agaisnt MRSA

vancomycin

94

Staphy epdermidis is found where

normal to our skin flora
typically contaminates blood cultures from skin punture

95

how do you determine if blood contaamination of S epidermidis is from systemic infection or just that local spot

take two samples at different distances

96

S epidermidis is the most common infection where

prosthetic devices because of its production of biofilms that attach to the devices

97

What are the 2 leading causes of UTIs in young females

E coli is 1
2 is S saprophyticus

98

What is the main difference between Bacillus and Clostriudium even though they are both spore formers

Bacillus is aerobic
Clostridium is anaerobic

99

When are humans usually exposed to bacillus anthracis

dealing with soil from animals or infected animal products like wool or hides

100

What are the virulent genes in B anthracis spores and what activates them

pXO1 and pXO2
activated by inc temp to 37 degress so when introduced to host

101

what are the modes of transmission for B anthracis

germinate through skin abrasians- cutaneous
inhalation- respiratory
ingested- GI

102

what part of the body do the B anthracis invade

blood stream after macrophages

103

Describe the malignant pustule and what causes it

painless round black lesion with rim of edema caused by B anthracis that can proliferate and enter blood stream
resolve 80-90% of the time

104

What does pulmonary anthrax cause

spores are taken up mby macrophages and taken to hilar and mediastinal lymph nodes where they germinate resulting in mediastinal hemorrhage and widening(enlarged area above heart in CT)

105

What is the presentation of ingestion of B anthraces

vomiting, abdominal pain and bloody diarrhea

106

What exotoxins are encoded in pXO1- B anthracis

Edema factor (A subunit) increase cAMP
Protective Ag: promotes entry of EF into phagocytic cells (B subunit)
Lethal Factor: zinc metalloprotease that inactivates protein kinase and stimulates macrophage release of TNFa and IL1-beta

107

What does pXO2 encode for- B anthracis

genes to synthesize the poly glutamyl capsule
D glutamic acid

108

What are the two enterotoxins released by B cereus and what do they cause?
Tx?

A heat labile toxin: nausea, abdominal pain, diarrhea 12-24 hours
A heat-stable toxin: like S aureus, short incubation period severe nausea, vomiting and limited diarrhea
Will resolve- no Antibiotics because preformed enterotoxin is the cause

109

What is the clinical presentation of botulism intoxication

b/l cranial nerve palsies, diplopia, dysphagia
general mm weakness
sudden respiratory paralysis

110

Where are infants at risk for ingestion C botulinum? symptoms? Tx?

fresh honey
constipated for 2-3 days
dysphagia and mm weakness "floppy"
give human botulism Ig IV

111

How does tetany result form tetanus toxin

taken up at NMJ and taken to CNS where it inhibits the inhibitory Ranshaw cell interneurons
stopping release of GABA and glycine

112

Clinical presentation of C tetani intoxication

severe m spasms- lockjaw
risus sardonicus from facial mm spasms

113

What are the 3 types of patients with tetanus skin wounds

immunized more than 10 yrs prior no booster
never immunized
already having developed tetanus

114

What are the 3 infections of C perfringens

cellulitis/wound infection
Clostridial myonecrosis
Diarrheal illness

115

What does a wound infection of C. per look like

moist, spongy with crackles from gas called crepitus

116

What does Clostridial myonecrosis look like

ferment carbs producing gas
CT shows pockets of gas in muscles and sub cut
thin black fluid exudesf rom skin

117

Describe diarrhea with C per.

watery diarrhea and sometimes hemorrhagic necrosis of the jejunum
cramping, fever and severe diarrhea
pseudomembranous colitis

118

What is a precursor do C. difficile infection

braod spectrium antibiotic use

119

What is the new C difficile out there

NAP1/BI/027
15-20x more potent
new toxin- binary toxin CDT

120

What test to you order immediately if you suspect C dificile

PCR toxins A B
sometimes EIA

121

What are the basic Tx antibiotics for C dificile

metronidazole- oral or IV
Vancomycin- must be taken orally

122

what does diphtheria look like

gray pseudomembrane of fibrin, leukocytes, necrotic epithelial tissue in pharynx

123

What do you do immediately if you suspect diphteria in a kid

do not flake off the membrane, get a culture from swab in throat and nasopharynx
gram test
give antibiotics while doing this

124

what type of agar do you use to grow C diphtheria on and what does it look like on each

Potassium tellurite- turns black within 24 hrs
Loefflers coagulated blood serum- add methylene blue and should see rod shaped pleomorphic bacteria

125

What do you give a patient you suspect diphtheria

Antitoxin that binds toxin only
Penicillin or erythromycin
DPT vaccine

126

How do the AB toxins of diphtheria work

B allows A to enter and inactivates elongation factor EF2 which is needed normally for translation mRNA "human antibiotic"

127

What other bacteria can lead to necrotizing pneumonia that looks like TB or nocardia? and differentiating factor?

rhodococcus equi
you will seed air fluid levels in the upper lung lobe nodules
also stains acid fast usually

128

what is a fast way to differentiate listeria from diphtheria

grow in 4-10degrees C because it likes low temp

129

What population is listeria more dangerous in

pregnant women, neonates, elderly and immunocompromised

130

When is listeria infection most common in pregnant women

3rd trimester
avoid soft cheeses, cold cuts etc

131

when is neonatal meningitis due to listeria present

2 weeks postpartum

132

listeria is the most common cause of meningitis in what specific population

those with lymphoma or corticosteroids or receiving oral transplantation

133

describe our immune response to listeria infection

cell mediated immunity
killing the bacteria while in our macrophages

134

what is confirmatory test for meningitis

lumbar puncture of CSF content that has nigh neutrophils and high protein
low glucose