Etiologic agents of infant to adult Flashcards
1
Q
what is the most common and serious manifestation due to Hib
A
meningitis
2
Q
what is the gram staining of Hib
A
gram negative non motile cocobacilli/ pleomorphic rod
3
Q
is Hib fastidious?
A
yes, fastidious growth requirements
4
Q
what are the virulence factors of Hib and why are they important
A
Exopolysaccharide- antiphagocytic
lipooligosaccharide (LOS)- meningeal inflammation
Peptidoglycan- enhanced meningeal inflammation
5
Q
what are the RF for Hib
A
- socioeconomic- crowding, smoking, short breast feeding
2. humoral immonodeficiences
6
Q
what is the pathogenesis of Hib in unvaccinated children
A
window of infection >6mo to 6yo
7
Q
what is the pathogenesis of Hib in vaccinated children
A
if child serconverts no window of infection
8
Q
clinical manifestation of Hib meningitis
A
insidious onset
antecendent upper resp. tract infection and/or ottis media followed by meningitis symptoms
9
Q
what are the possible sequelae for untreated Hib meningitis
A
permanent neuro damage
hearing loss
septic arthritis
purpura fulminans
10
Q
Diagnosis of Hib
A
Culture and ID same as any bacteria
11
Q
Treatment for Hib
A
ceftriaxone and dexamethasone
give steroid 15 min before AB
12
Q
Prevention of Hib
A
prophylaxis with AB to decrease carriage and incidence
Hib polysaccharide conj. vaccine
13
Q
what is the gram staining for s. pneumoniae
A
gram positive, lancet shape diplococci
14
Q
what is s. pneumoniae hemolytic status and is it fastidious
A
alpha hemolytic
Not Fastidious- grows on blood agar
15
Q
is s. pneumoniae catalase positive or negative and what does that mean
A
catalase negative
it is an aerotolerant anaerobe
16
Q
Is s. pneumoniae encapsulated?
A
yes
17
Q
what are s. pneumoniae’s virulence factors
A
antiphagocytic
lil or no crossreactivity
coagulase negative
18
Q
what agent is responsible for pts with reoccuring meningitis
A
s. pneumoniae
19
Q
which type of meningitis has the highest case of fatality rates
A
pneumococcal meningitis
20
Q
what age is affected by s. pneumoniae the most
A
peaks in the young <5yo and the elderly
21
Q
what season does s. pneumoniae peak
A
peaks late fall early winter but it is generally year round
22
Q
what are the RF for s. pneumoniae
A
- antecedent RT infections or pneumococcal pneumonia
- if there is a CSF leak by deformity or trauma can lead to reoccurring infection
- IPD
23
Q
what protein if detected in nose or ear drainage shows CSF leak
A
B2-transferrin
24
Q
what is the primary site of damage in most bacterial meningitis
A
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
