Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Micro- Winter > CNS Infections- N. meningitidis > Flashcards

CNS Infections- N. meningitidis Flashcards

1
Q

The non-pathogenic species of Neisseria:

A

are normal flora of URT & other mucosal surfaces in the human body.

-Many nonpathogenic species are non-encapsulated variants of the encapsulated/disease-causing strains of N. meningitidis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Description of Neisseria meningitidis

aka meningococcus

A
  • Gram-negative, kidney-bean shaped, diplococcus
  • oxidase positive
  • fastidious
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Virulence Factors- All infectious meningococcus are encapsulated and are grouped based largely on ____________.

Important groups are ____________. Capsular polysaccharide is _________. Group-specific antibodies do not significantly cross-react.

A

the serological differences in capsular types

A, B, C, Y, W-135, X

antiphagocytic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Type B capsule of Neisseria and E. coli K1 capsule have the same chemical composition (sialic acid); sialic acid is a human self antigen, hence they ____________.

A

are poorly immunogenic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Neisseria possess ______ instead of LPS:

A

Lipooligosaccharide (LOS)

  1. consists of Lipid A (endotoxin) + extended core (no antigenic side chain).
  2. is antiphagocytic by molecular mimicry
  3. causes Disseminated Intravascular Coagulopathies (DIC) because contains lipid A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Major serogroups are B, C, Y. ______ causes ½ of all infection in the US.

Serogroup Y infected patients are more likely to be __________.

A

Serogroup B

older and manifest with pneumonia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Countries where meningococcal disease is hyperendemic or epidemic are __________.

In North America vs the rest of the world: Specific serogroups of meningococci are associated with ____________.

A

Africa and Middle Eastern countries

epidemics, which occur in cycles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Transmission is via _________

A

aerosols, respiratory droplets.

POE and initial site of colonization is the nasopharynx.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

____ are the only reservoir for all Neisseria sp.

A

humans
Carriers are common in epidemics, but few develop disease; carriers are are largely responsible for spread of disease via aerosols

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Age most commonly affected

A

Infants → Young adults (1 month → 22 y-o-age)

  1. infants and children (1 month → 24 months-o-age).
  2. older children/adolescents (6 → 19 y-o-age).
  3. young adults (19 → 22 y-o-age)
    a. military recruits.
    b. college students living in dorms.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Seasonality

A

Late fall → winter → early spring

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Risk Factors for infection (lots)

A
  • Close contact, crowding
  • Susceptibility (lack of group-specific antibodies).
  • Living in a college dormitory or basic training in the military (increased risk of exposure to new groups of meningococci)
  • antecedent RT may predispose host to infection
  • intimate kissing
  • tobacco smoke exposure (direct or passive)
  • bar patronage
  • household crowding
  • binge drinking
  • low socioeconomic status
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Susceptible populations

A
  • Infants-Young adults (1 month → 22 y-of-age).
  • Families (familial spread)
  • Genetic predisposition to infection (properdin or complement deficiencies)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

S/S for people aged 16 years or younger

A
  • Early symptoms of sepsis occurred within 8 hours of infection (leg pains, cold hands and
  • Late symptoms: meningism and impaired consciousness occur about 13 to 22 hours after onset of early symptoms
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

S/S for adults

A
  • Early symptoms may occur and consist of only mild pharyngitis without exudate, slight fever, and headache at onset OR several days of flu-like symptoms with emesis.
  • Then the classic symptoms of meningitis occur OR classic symptoms without early symptoms occur
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Other S/S of Neisseria meningitidis for all age groups

A

Besides the classic clinical manifestations of meningitis:
-petechial (non-blanching, hemorrhagic) rash on ankles and wrist (first) then trunk, thigh, forearms may appear if septicemia also present

17
Q

Patients may survive disease without or with significant sequelae, which include:

A
  • nerve deafness
  • CNS damage
  • necrosis of large areas of skin or tissues often results in amputation
18
Q

Waterhouse-Friderichsen syndrome (fulminant meningococcemia)

A
  • circulatory shock due to SIRS → severe sepsis or septic shock.
  • bilateral hemorrhagic necrosis of adrenals → low cortisol leves → hypotension.
  • disseminated intravascular coagulation
  • Waterhouse-Friderichsen syndrome is NOT limited to N. meningitidis; this disease is seen in certain other fulminant bacterial diseases.
19
Q

Purpura Fulminans

AKA symmetrical peripheral gangrene (SPG) is meningococcemia +/- meningitis:

A
  • hypothermia.
  • seizures
  • shock
  • thrombocytopenia
  • leukocytosis
  • purpura: meningococcus IS IN the lesions
  • highest mortality rate (15→50%) occurs with Group C disease, esp. in persons with purpura fulminans, even with appropriate treatment
  • Purpura fulminans is NOT limited to N. meningitidis; this disease is seen in certain other fulminant bacterial diseases
20
Q

Other meningococcal infections

A
  • pneumonia or endocarditis

- meningococcemia may be seen without CNS localization

21
Q

Lab tests

A
  • Microscopic examination and culture of skin lesions (aspirant or biopsy). If petechial or purpuric lesions are present, Gram-stain of lesion biopsy will often (50% of the time) reveal meningococcus.
  • Obtain nasopharyngeal cultures to screen for carriers, treat carriers with Rifampin
22
Q

Determine antibiotic sensitivity – resistance to many drugs is documented; ____ requried.

A

MBC

23
Q

When taking a nasopharyngeal culture to screen for carriers, the carriers must then be treated with

A

Rifampin

24
Q

Treatment for Neisseria meningitidis

A

Antimicrobial therapy is ceftriaxone, or cefotaxime or penicillin G

(other treatment: : Bacteriocidal/permeability-increasing protein, recombinant rBPI)

25
Q

Prophylaxis of Health-Care workers

A
  • Wear a mask (face shield) within 3 feet of pt. known or suspected to be infected with meningococcemia (or other microbial agent) transmitted by droplet nuclei (>5μ) that can be generated during coughing, sneezing, talking, performing clinical procedures.
  • If no mask/shield is worn, consider antibiotic prophylaxis.
  • Risk is small, but possible; highest in those involved with airway management, i.e., the physician.
26
Q

Vaccines

A
  • Tetravalent/quadrivalent polysaccharide vaccine for Groups A, C, Y, W-135 (MPSV4)
  • Menomune (type II, T-independent antigen vaccine, administered subcutaneous)
  • Tetravalent/quadrivalent (groups A, C, Y, and W-135) polysaccharide, diphtheria toxoid conjugate vaccine (MCV4)
  • Menactra (T-dependent antigen vaccine, administered intramuscular, because SC misadministration results in lower serum Ab titer)
27
Q

Limitations to Menomune (type II, T-independent antigen vaccine)

(Is approved for 2 y/o and older)

A

Since capsular material is a type II, T-independent antigen:

  1. Poor immunogenicity in infants (
28
Q

The CDC advisory panel recommends that MCV4 (Menactra; T dependent) be administered to: (8 groups)

A
  1. all children aged 11 & 12 years.
  2. teens before entering high school if not already vaccinated.
  3. adults
29
Q

Vaccine is a T-dependent vaccine, so it should

A
  • stimulate immunity for more than eight years
  • eliminate nasopharyngeal carriage thus prevent transmission of infection.
  • Vaccine should reduce the prevalence of meningococcal disease by 75→ 90%
30
Q

The 4CMenB vaccine (Bexsero) is

A
  • approved by FDA for protection against serogroup b infection
  • made of 3 recombinant proteins:
    1. Factor H binding protein (fHbp)
    2. Neisseria adhesin A (NadA),
    3. Neisseria heparin binding antigen (NHBA),

-combined with detoxified outer membrane vesicles of strain NZ98/254, that caused an epidemic of serogroup B meningococcal disease in New Zealand

31
Q

Trumenba is

A

-approved by FDA for protection against serogroup b infection
-made of 2 recombinant lipidated factor H binding protein (fHbp) variants from N meningitidis serogroup B:
1 from fHbp subfamily A (A05)
1 from subfamily B (B01)

32
Q

CDC recommends that serogroup B vaccines (Bexsero & Trumenba) be administered to:

A
  • high risk populations*
    1. People with persistent complement component deficiencies.
    2. People receiving the drug eculizumab (Soliris) also are at increased risk because the drug binds to C5 and inhibits the terminal complement pathway
    3. Patients with anatomic or functional asplenia
    4. People at increased risk due to an outbreak of serogroup B meningococcal disease
33
Q

Serogroup B vaccines are not currently recommended for routine use in

A
  1. first-year college students living in residence halls
  2. military recruits
  3. all adolescents

physicians should determine vaccination needs for 16-23 year olds on an individual basis; recommendations for broader use of MenB vaccines in adolescents and college students will be considered separately by the ACIP

34
Q

Elimination of the carrier state (nasopharyngeal) by chemoprophylaxis with ___________ (unless fluoroquinolone-resistant N. meningitidis is detected in the area, if that is so, then _____ should NOT be administered

A

rifampin, ciprofloxacin, ceftriaxone or azithromycin

ciprofloxacin

*Administer chemoprophylaxis within 24 hours of identification of the index case and no longer than 14 days after onset v

35
Q

For clusters or small outbreaks prophylaxis with antibiotics is ________

(ex: for children K → 12; a second case of meningococcal disease within 30 days of the first/index case)

A

effective

36
Q

For large outbreaks (whole counties, cities, etc.), vaccination (if the strain responsible for the outbreak is A, C, Y, W-135) as well as antibiotic prophylaxis of family members and close contacts of persons with disease are _______

A

most effective

37
Q

Chemoprophylaxis should be given to “close contacts” who have come into droplet contact within the time frame of _________

A

within 1 week before the onset of the patient’s symptoms until 24 hours after appropriate antimicrobial therapy has been initiated

Close contacts who have previously received meningococcal vaccination should still be given chemoprophylaxis, because the vaccines do not confer 100% protection and immunity wanes with time.”

Micro- Winter (26 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions