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Flashcards in Etiologic agents of infant to adult Deck (116):
1

what is the most common and serious manifestation due to Hib

meningitis

2

what is the gram staining of Hib

gram negative non motile cocobacilli/ pleomorphic rod

3

is Hib fastidious?

yes, fastidious growth requirements

4

what are the virulence factors of Hib and why are they important

Exopolysaccharide- antiphagocytic
lipooligosaccharide (LOS)- meningeal inflammation
Peptidoglycan- enhanced meningeal inflammation

5

what are the RF for Hib

1. socioeconomic- crowding, smoking, short breast feeding
2. humoral immonodeficiences

6

what is the pathogenesis of Hib in unvaccinated children

window of infection >6mo to 6yo

7

what is the pathogenesis of Hib in vaccinated children

if child serconverts no window of infection

8

clinical manifestation of Hib meningitis

insidious onset
antecendent upper resp. tract infection and/or ottis media followed by meningitis symptoms

9

what are the possible sequelae for untreated Hib meningitis

permanent neuro damage
hearing loss
septic arthritis
purpura fulminans

10

Diagnosis of Hib

Culture and ID same as any bacteria

11

Treatment for Hib

ceftriaxone and dexamethasone
give steroid 15 min before AB

12

Prevention of Hib

prophylaxis with AB to decrease carriage and incidence
Hib polysaccharide conj. vaccine

13

what is the gram staining for s. pneumoniae

gram positive, lancet shape diplococci

14

what is s. pneumoniae hemolytic status and is it fastidious

alpha hemolytic
Not Fastidious- grows on blood agar

15

is s. pneumoniae catalase positive or negative and what does that mean

catalase negative
it is an aerotolerant anaerobe

16

Is s. pneumoniae encapsulated?

yes

17

what are s. pneumoniae's virulence factors

antiphagocytic
lil or no crossreactivity
coagulase negative

18

what agent is responsible for pts with reoccuring meningitis

s. pneumoniae

19

which type of meningitis has the highest case of fatality rates

pneumococcal meningitis

20

what age is affected by s. pneumoniae the most

peaks in the young <5yo and the elderly

21

what season does s. pneumoniae peak

peaks late fall early winter but it is generally year round

22

what are the RF for s. pneumoniae

1. antecedent RT infections or pneumococcal pneumonia
2. if there is a CSF leak by deformity or trauma can lead to reoccurring infection
3. IPD

23

what protein if detected in nose or ear drainage shows CSF leak

B2-transferrin

24

what is the primary site of damage in most bacterial meningitis

hippocampus die to neuronal loss

25

How would you be able to diagnose petechial-purpuric skin lesions (SPG) between s. pneumoniae and n. meningitides?`

s. pneumoniae will not be found in skin leision

26

Diagnoisis of s. pneumoniae

Culture and ID like any bacteria

27

what is the treatment for s. pneumoniae meningitis

IV cefotaxime and infussuion with vancomyosin and adjunctive dexamethasone (>17yo) until strain is proven to penicillin sensitive

28

what would you treat penicillin sensitive s. pneumoniae with

penicillin

29

why is vancomycin tolerance clinically importantant

related to relapse cases esp. pediatric pneumococcal meningitis

30

what is the best prevention for s. pneumoniae meningitis

conjugated s. pneumoniae vaccine (7 valent)

31

what is step is necessary if you discover pt. with n. meningitides?

n. meningitides is a reportable disease

32

what are the two pathogenic species of neisseria

n. meningitides
n. gonorrhoeae

33

where are non pathogenic species of neisseria located?

Normal flora of URT and mucosal surfaces

34

how do pathogenic and non-pathogenic neisseria differ

non pathogenic are non-encapsulated variants of pathogenic species

35

what is the gram staining of n. meningitides

Gram-negative diplococci kidney bean shape

36

is n. meningitides oxidase positive or negative

positive

37

is n. meningitides fastidious?

NO

38

what are the virulence factors for n. meningitides?

group specific polysaccharides and LOS

39

why is the capsular polysacchride in n. meningitides impiortant

anti-phagocytic

40

what agent does the capsular poly saccharide of n. meningitides type most closely resemble and what do they have in common

E. Coli K1
they both have sialic acid which are human antigens and are poorly immunogenic

41

why is the LOS in n. meningitides so important

consists of an endotoxin (Lipid A)
can be antiphagocytic through molecular mimicry
Lipid A can cause DIC

42

what is the case rate endemic patterns of n. meningitides in the US

case rate is low (.5-1/100,000)

43

which serotype of n. meningitides causes the most infections in the US

serotype B

44

what is special about serotype Y n. meningitides

more likely cause pneumonia in older population

45

what countries is n. meningitides a hyperepidemic or epidemic

Africa and middle eastern countries

46

does US have n. meningitides epidemics?

potentially, specific serogroups are associated with epidemic which occur in cycles

47

how is n. meningitides transmitted

via aerosols and resp. droplets

48

what is the POE and initial site of colonization of n. meningitides

nasopharynx

49

what is the reservoir of neisseria spp.

humans

50

which age is most commonly affected by n. meningitides

1 month to 22yo olds

51

what are the age relationships with n. meningitides infections

infants and children
older children/adolescents
young adults esp. military and college students in dorms

52

what is the seasonality to n. meningitides

late fall -> winter -> early spring

53

what the RF for n. meningitides infection

1. susceptibility (dorms, military)
2. predisposing conditions/ actions (RT infect, smoke, binge drinking, bars, crowding, poor)
3. Susceptible populations with disease predominates

54

what is the pathogenesis

after colonization of nasopharynx n. meningitides invades blood the the meninges

55

DIC is cause by thrombosis from loss of what to things

thrombomodulin and protein C receptor

56

what is required to decrease DIC in your patients whith n. meningitides

give activated Protein C

57

What type of immunity is helpful with n. meningitides

humoral anticapsular AB (protection) which most people have some groups
Functional compliment system

58

what are the EARLY signs and symptoms for 16yo and younger pts with n. meningitides meningitis

early symptoms of sepsis (72% of pts) around 8 hours these symptoms include leg pain, cold extremities, abnormal skin color

59

what are the LATE signs and symptoms for 16yo and younger pts with n. meningitides meningitis

late symptoms: meningism, impaired consciousness occurs 13-22 hours after early symptoms

60

what are EARLY signs and symptoms of n. meningitides in adults

early symptoms: mild pharyngitis w.o exudate, slight fever, headache or flu-like with emesis

61

what are LATE signs and symptoms of n. meningitides in adults

late: classic symptoms of meningitis can occur without early signs, also rash on ankles and wrist moving centrally if septicemia is present

62

what are the possible sequelae with n. meningitides infections

nerve deafness
cns damage
necrosis of large area can result in amputation

63

what is waterhouse-friderichsen symdrome

fulminant meningococcemia
-circulatory shock due to SIRS which results in septic shock
-bilateral hemorrhagic necrosis of adrenals which causes low cortisol and leads to hypotension and DIC
It is not limited to only n. meningitides

64

what are signs of purpura fulminans

hypothermia, seizure, shock, thrombocytopenis, leukocytosis purpura
it is not limited to n. meningitides

65

what serogroup of n. meningitides has the highest motality rate with purpura fulminans

serogroup C

66

what other diseases besides meningitis, pupura fulmanins and waterhouse-frriderichsen syndrome can occur with n. meningitides

meningococcemia without CNS localization
Pneumonia
endocarditis

67

diagnosis of n. meningitides if skin lesions are present

gram stain biopsy can reveal n. meningitides

68

what step is important to do before establishing treatment of n. meningitides

MBC- many n. meningitides are resistant to AB

69

what steps should be taken with potential n. meningitides carries

obtain nasopharyngeal culture to find carriers

70

what is the treatment for n. meningitides carriers

rifampin

71

what is the treatment for n. meningitides pt with disease

ceftriaxone or cefotaxime, or penicillin G or rBPI

72

when does mortality rates of n. meningitides meningitis increase?

meningococcal meningitis with meningococcal septicemia
without shock (20%) HIGH
with shock (60%) VERY HIGH

73

Prevention of n. meningitides

vaccine (2 different types)
do not give non-conj to children <55yo

74

what serotype does n. meningitides vaccine not cover

B, which accounts for 1/3 of cases in US

75

what type of species is c. neoformans?

fungus

76

which form of cyptococcus is a major causative agent world wide

grubii (CnVG, serotype A)

77

where does c. neoformans predominate

Central europe

78

what is the infectious and pathogenic form of CnVN in humans

asexual yeast

79

what is the distribution of CnVN or CnCG

worldwide, found in soil and pigeons and birds are carriers which disseminates fungi

80

how does c. neoformans differ from other systemic mycosis

It is not thermally dimorphic!

81

what parts of c. neoformans are not involved in infection

contains a sexual cycle but hyphae and spores are not cause of infections

82

what the virulence factors for c. neoformans

1. capsule (antiphagocytic, pevents Ag processing)
2. phenoloxidase production (antiphag, and resistant to Amphotericin B)

83

how common is c. neoformans in HIV and AID pts

3rd most common CNS infection

84

how opportunistic is c. neoformans in HIV and AIDS pts

4th most common opportunistic infection

85

what is the transmission of c. neoformans

disease can occur in any population but is not believed to be person to person

86

what is the poe of c. neoformans

respiratory tract with spread to CNS

87

what is the age or gender relationship with c. neoformans

none

88

what is the seasonality of c. neoformans

none

89

what are the RF for Cg

tropical subtropical regions
rarely causes disease in HIV
incidence is rare

90

what are the RF for CnVN and CnVG

worldwide
immunocomprimised individials
rarely caused in healthy people (immunocompetent)

91

what is the primary site of infection in c. neoformans

lungs and cns

92

what are symptoms of c. neoformans infection in people with functional immune system

asymptomatic pulmonary infection

93

what are symptoms of c. neoformans infection in AIDS

fever, cough, dispnea, weight loss, headache, infiltrates on CXR
2-4 weeks to develo

94

what is meningoencephalitis

progression of infection to basal ganglia and cortical gray matter
ICP >250 is common in mortality

95

what are symptoms of meningoencephalitis

headache, fever lethargy. nausea, vomit. minimal nuchal rigidity, focal signs (mental status, memory/cognition)
ends with death

96

besides lung and CNS a c. neoformans in aids pts can disseminate to where

anywhere
skin, eye, bone, urinary tract are common

97

what is cryptococcal polysaccahridemia/antigenemia

positive serum Ag assay without any detection of fungi
since disease is fatal you sill treat any pt with positive serum Ag assay

98

what type of pathogen is c. neoformans

facultative intracellular pathogen of macrophage
replicates inside and is released without response from immune system

99

what would be seen with CSF examination with india ink in c. neoformans

5-7um spherical encapsulated yeast
cells of macrophage/monocyte lineage

100

what would be seen with CSF examination with gram staining c. neoformans

gram positive eucaryotic cells

101

what radiology test would you order in c.neoformans infection?

CXR or CT of lungs
and MRI or CT for meningitis

102

what is the treatment for n c. neoformans

high does amphotericin B with 5-fluorocytosine for 2w
Fluconazole (400mg) or itaconazole for 8 weeks
maintain fluconazole (200mg) life long
TREAT ICP

103

What are the two cellular forms of amoebaes

trophozoites are the feed form found in brain and environ
cyst are found in water never brain

104

which cell form of amoebas are resistant to freezing water and chlorination

cyst

105

where is N. fowleri found?

warm, freshwater lakes, puddles, ponds improperly chlorinated pools and brackish water in hot summer weather

106

what CNS disease can N. fowleri cause

amoebic and acute primary meningoencephalitis

107

what is the population at risk for N. fowleri

children and young adults
swimming in warm fresh water

108

of the worlds cases of N. fowleri what percentage occur in US

1/2

109

what is the POE of N. fowleri

nose

110

what is the pathogenesis of N. fowleri

implants in nasal mucosa which goes through cribiform plate and can be found in perivascular and subarachnoid space

111

What is the fulminate course of N. fowleri

2-7 days from onset to death

112

what are the signs and symptoms of N. fowleri

2 day incubation with signs similar to bacterial meningitis
after 1-2 days manifest with diffused encephalitis then coma and death from cardiorespiratory failure, cerebral edema

113

what is the most essential in diagnoising N. fowleri

Pt History!

114

what difference will be observed in the csf of amoeba compared to bacterial infection

similar except may observe amoeba in CSF

115

beside csf exam and pt history how else can you determine N. fowleri

lack of viral, bacterial and fungi findings
peripheral leukocytosis
Death occurs in a week
Brain biopsy would reveal Positive IFA, clusters of amoebic trophs, and intense PMNs in parychema

116

what is the treatment for N. fowleri

Amphotericin B and Miltefosine
Prognosis is poor