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LAST EXAMMMMMM Year I > micro- Gram + bacteria > Flashcards

micro- Gram + bacteria Flashcards

1
Q

how do you differentiate between staph and strep cocci

A

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

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2
Q

Differentiate beta and alpha hemolytic strep

A

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

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3
Q

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

A

metabolite of Hb

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4
Q

what is the third type of hemolytic strep

A

gamma

cannot hemolyze RBC

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5
Q

What are the Lancefield Ag on strep

A

C carbohydrates classified as A B C DE thru S

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6
Q

What are the 5 human significant strep infections

A

A B D
strep pneumoniae
viridans group

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7
Q

What is another name for group A beta hemolytic strep

A

streptococcus pyogenes

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8
Q

What diseases is strep pyogenes responsible for

A

scarlet fever, rheumatic fever, post streptococcal glomerulonephritis

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9
Q

What are the antigenic properties found on strep pyogenes

A

C carbohydrate

M protein

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10
Q

What is the role of the M protein of strep pyogenes

A

inhibits activation of C’ and protects organism from phagocytosis

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11
Q

What is the bodys response to M protein of strep pyogenes

A

B cells generate Ab against M protein

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12
Q

What enzyme is responsible for the hemolytic ability of strep pyogenes

A

streptolysin O

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13
Q

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

A

anti-streptolysin O

ASO titers

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14
Q

What other toxins does strep pyogenes produce

A 
Streptolysin S aids in hemolysis
pyrogenic exotoxin on some
streptokinases
hyaluronidase
DNAase
anti C5a-peptidase
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15
Q

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

A

strep pharyngitis
strep skin infections
scarlet fever
strep TSS

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16
Q

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

A

delayed Ab mediated diseases

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17
Q

What is the presentation of strep pharyngitis

A

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

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18
Q

What test should you order if you suspect strep throat

A

rapid antigen detection test RADT detecting the group A carb Ag

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19
Q

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

A

throat culture

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20
Q

what type of skin infections can be caused by strep pyogenes

A

folliculitis, pyoderma,erysipelas, cellulitis, impetigo

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21
Q

What is impetigo

A

vesicular blistered eruption that becomes crusty and flaky

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22
Q

what is erysipelas

A

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

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23
Q

what is pyoderma

A

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

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24
Q

What is a worrysome complication of skin infections from strep pyogenes

A

necrotizing fascitis

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25
Q

what is fourniers gangrene

A

necrotizing fasciitis involving male genitale area and perineum

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26
Q

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

A

scarlet fever

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27
Q

what does the rash of scarlet fever appear like

A

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

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28
Q

what are risk factors for rheumatic fever

A

had recent strep pharyngitis

age 5-15

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29
Q

What are the manifestations of rheumatic fever

A

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

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30
Q

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

A

rhemuatic valvular heart disease

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31
Q

what are signs of post streptococcal glomerulonephritis

A

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

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32
Q

What is the other name for Group B beta hemolytic strep

A

step agalactiae

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33
Q

What does group B strep cause in neonates

A

meningitis, pneumonia and sepsis

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34
Q

what is the sign of meningitis in neonates

A

fever, vomiting, poor feeding and irritability

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35
Q

Dx of meningitis is made how

A

lumbar puncture

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36
Q

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

A

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

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37
Q

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

A

N gonorrhea

H influenza

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38
Q

What can group B strep cause in pregnant women

A

still birth, sepsis spontaneous abortion

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39
Q

What are the groups included in strep viridans

A

mitis, salivarius, mutans and Anginosus

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40
Q

Viridans group strep is indigenous to what area

A

the GI tract

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41
Q

Most of viridans strep are what category

A

alpha hemolytic producing greenish discoloration on blood agar

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42
Q

What are the main types of infections caused by viridans streptococci

A

dental infections
endocarditis
abscesses

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43
Q

What is the cause of endocarditis in viridans strep

A

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

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44
Q

what is the clinical presentation of subacute bacterial endocarditis SBE

A

low fever, fatigue, anemia and heart murmurs

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45
Q

What type of endocarditis is caused by staph infections

A

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

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46
Q

What other bacteria can lead to subacture bacterial endocarditis

A

group D strep

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47
Q

What family of strep virdans causes absecesses

A

anginosus species that are microaerophilic

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48
Q

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

A

CAT with contrast to look for abscess in hiding organ

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49
Q

What are the 2 groups of group D strep

A

enterococcus and non-enterococci

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50
Q

enterococci faecalis and faecium are found where

A

in GI, part of normal flora

growing well in bile

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51
Q

What tpe of infections do the enterococci cause

A

subacute bacterial endocarditis, UTI, biliary tract infections, bacteremia

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52
Q

What type of infections do enterococci commonly cause in hospitals

A

prosthetic valve endocarditis sepsis after IV catheters

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53
Q

What are the enterococcie resistant to

A

ampicillin and vancomycin

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54
Q

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

A

colon cancer

55
Q

What does strep pneumococcus commonly cause in adults? children?

A

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

56
Q

What is the shape of strep penumococcus

A

diplococci, no lancefield Ag

57
Q

what is the major virulence factor of s. pneumococcus

A

the capsule of polysaccharides

58
Q

What lab tests do you order to confirm S. pneumococcus

A

quellung (swelling with methylene blue)

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

59
Q

what is the clinical presentation of S pneumococcal pneumonia

A

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
Q

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

A

S pneumoniae
H influenza
M catarrhalis

61
Q

S pneumococcus is becoming resistant to what

A

penicillins

62
Q

how do you differentiate enterococci and nonenterococci with the agar

A

enterococci grow in bile and 6.5%NaCl

non-enterococci only grow in bile

63
Q

What are the 3 main strains of staph

A

aureus, epidermidis, saprophyticus

64
Q

How can staph aureus be differentiated from other beta hemolytic cocci

A

golden pigment on sheep blood agar

65
Q

which staph is coagulase +

A

staph aureus only

66
Q

What proteins does S aureus have to disable our immune system

A

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

67
Q

What protects S aureus from opsonization

A

Protein A

68
Q

what prevents S aureus from phagocytosis

A

coagulase

69
Q

what do the hemolysins do in S aureus

A

destroy RBC neutrophils, macrophages and platelets

70
Q

What do leukocidins of S aureus do

A

destroy WBC

71
Q

What produces Panton-Valentine leukocidin PVL

A

the CA-MRSA

72
Q

What proteins are in S aureus that tunnel through tissue

A

hyaluronidase
staphylokinase
lipase
protease

73
Q

what lyses formed fibrin clots in S aureus

A

the staphylokinase

74
Q

what facilitates S aureus to colonize in sebaceous glands

A

lipases

75
Q

What are the toxins that S aureus produces

A

exfoliatin
enterotoxins
TSST1

76
Q

what is exfoliatin

A

causes skin to slough off

scalded skin syndrome from S aureus

77
Q

what is the role of enterotoxin from S aureus

A

food poisoning

78
Q

how does TSST1 work from S aureus

A

binds MHC II and massive T cell activation

79
Q

What diseases are caused by S aureus exotoxin release

A

Gastroenteritis
TSS
Scalded skin syndrome

80
Q

What diseases are caused by S aureus from direct organ invasiveness

A 
pneumonia
meningitis
osteomyelitis
acute bacterial endocarditis
septic arthritis
skin infections
bacteremia/sepsis
UTI
81
Q

What are signs of gastroenteritis

A

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

82
Q

where are areas that TSST1 is released

A

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

83
Q

What are the signs of TSST1 caused TSS

A

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
Q

What toxins cause scalded skin syndrome

A

exfoliative A and B toxins

85
Q

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

A

staph caused pneumoniae

86
Q

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

A

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

87
Q

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

A

staph caused osteomyelitis

88
Q

what are signs of acute endocarditis from staph

A

high fever 103 and higher

chills, myalgias

89
Q

staph caused septic arthritis is common in what age groups

A

pediatrics and adults >50

90
Q

What does impetigo look like if caused by staph

A

honey colored crust

usuall around mouthy

91
Q

what type of skin infections are caused by staph

A

cellulitis, impteigo, local abscesses, furuncles, carbuncles

92
Q

What makes staph aureus R to methicillin

A

the penicillin binding protein 2A

93
Q

What is most useful antibiotic agaisnt MRSA

A

vancomycin

94
Q

Staphy epdermidis is found where

A

normal to our skin flora

typically contaminates blood cultures from skin punture

95
Q

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

A

take two samples at different distances

96
Q

S epidermidis is the most common infection where

A

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

97
Q

What are the 2 leading causes of UTIs in young females

A

E coli is 1

2 is S saprophyticus

98
Q

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

A

Bacillus is aerobic

Clostridium is anaerobic

99
Q

When are humans usually exposed to bacillus anthracis

A

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

100
Q

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

A

pXO1 and pXO2

activated by inc temp to 37 degress so when introduced to host

101
Q

what are the modes of transmission for B anthracis

A

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

102
Q

what part of the body do the B anthracis invade

A

blood stream after macrophages

103
Q

Describe the malignant pustule and what causes it

A

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
Q

What does pulmonary anthrax cause

A

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
Q

What is the presentation of ingestion of B anthraces

A

vomiting, abdominal pain and bloody diarrhea

106
Q

What exotoxins are encoded in pXO1- B anthracis

A 
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
Q

What does pXO2 encode for- B anthracis

A

genes to synthesize the poly glutamyl capsule

D glutamic acid

108
Q

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

A

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
Q

What is the clinical presentation of botulism intoxication

A

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

110
Q

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

A

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

111
Q

How does tetany result form tetanus toxin

A

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

112
Q

Clinical presentation of C tetani intoxication

A

severe m spasms- lockjaw

risus sardonicus from facial mm spasms

113
Q

What are the 3 types of patients with tetanus skin wounds

A

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

114
Q

What are the 3 infections of C perfringens

A

cellulitis/wound infection
Clostridial myonecrosis
Diarrheal illness

115
Q

What does a wound infection of C. per look like

A

moist, spongy with crackles from gas called crepitus

116
Q

What does Clostridial myonecrosis look like

A

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

117
Q

Describe diarrhea with C per.

A

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

118
Q

What is a precursor do C. difficile infection

A

braod spectrium antibiotic use

119
Q

What is the new C difficile out there

A

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

120
Q

What test to you order immediately if you suspect C dificile

A

PCR toxins A B

sometimes EIA

121
Q

What are the basic Tx antibiotics for C dificile

A

metronidazole- oral or IV

Vancomycin- must be taken orally

122
Q

what does diphtheria look like

A

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

123
Q

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

A

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

124
Q

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

A

Potassium tellurite- turns black within 24 hrs

Loefflers coagulated blood serum- add methylene blue and should see rod shaped pleomorphic bacteria

125
Q

What do you give a patient you suspect diphtheria

A

Antitoxin that binds toxin only
Penicillin or erythromycin
DPT vaccine

126
Q

How do the AB toxins of diphtheria work

A

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

127
Q

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

A

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

128
Q

what is a fast way to differentiate listeria from diphtheria

A

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

129
Q

What population is listeria more dangerous in

A

pregnant women, neonates, elderly and immunocompromised

130
Q

When is listeria infection most common in pregnant women

A

3rd trimester

avoid soft cheeses, cold cuts etc

131
Q

when is neonatal meningitis due to listeria present

A

2 weeks postpartum

132
Q

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

A

those with lymphoma or corticosteroids or receiving oral transplantation

133
Q

describe our immune response to listeria infection

A

cell mediated immunity

killing the bacteria while in our macrophages

134
Q

what is confirmatory test for meningitis

A

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

LAST EXAMMMMMM Year I (24 decks)

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