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MHD Block III > Neisseria/Hemophillus-Bordetella 9/3/15 > Flashcards

Neisseria/Hemophillus-Bordetella 9/3/15 Flashcards

1
Q

What virulence factor of Neisseria meningitidis has 13 serogroups?

A

Polysaccharide capsule: -Main groups: A, B, C, Y, W-135 (all immunogenic except B)

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2
Q

What is the purpose of the capsule in Neisseria meningitidis?

A

-Bloodstream invasion and survival/CNS penetration -Avoids phagocytosis until opsonized

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3
Q

What persons are at increased risk for Meningococcal Disease?

A

Sporadic cases or outbreaks in closed populations:

  • MSM
  • College students
  • Microbiologists
  • Persons with asplenia or terminal C’ deficiency
  • Travelers to hyperendemic regions (Africa, S. Arabia)
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4
Q

What is the route of pathogenesis for Neisseria meningitidis?

A

-Attach to mucosal cells -Cross cells -Get into blood -Cross BBB and into subarachnoid space

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5
Q

What are the major clinical manifestations of N. meningitidis?

A
  • Meningococcemia: profound sepsis, shock, hemorrhage with skin manifestations
  • Meningitis: headache, mental status changes, neurological signs, petecheae
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6
Q

What lab tests are used to diagnose N. meningitidis, and what are the morphological and culture characteristics?

A
  • Gram stain: CSF, gram negative “kidney bean” diplococci -Cultures: –CSF –Blood –Skin
  • Culture characteristics:

–Oxidase positive

**Oxidize glucose and maltose

–Nonselective media (blood or chocolate)

–Growth enhanced in CO2

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7
Q

What treatment options are available for N Meningitidis infections?

A

-Penicillin -Ceftriaxone -Penicillin G if sensitive

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8
Q

What type of vaccine is used for N. Meningitidis?

A

-Polysaccharide containing all serogroups (except B) -Conjugated with diphtheria toxoid

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9
Q

What groups of people are targeted for the N meningitidis vaccine?

A

-Adolescents age 11-12 -At risk adults

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10
Q

The following prophylactic antibiotics are used to prevent which bacterial strain: -Rifampin -Ciprofloxacin -Ceftriaxone

A
  • N. meningitidis
  • Can’t Raid the CNS
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11
Q

What virulence factors do Neisseria gonorrhoeae have that allow for adhesion?

A
  • Pili
  • Opa: adherence proteins that confer opaque appearance to colony (localized)

–If transparent = disseminated disease

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12
Q

Describe antigenic diversity in N. gonorrhoeae pili.

A

-DNA recombination

–pilS to pilE

–Occurs within the host

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13
Q

Describe antigenic diversity in N. gonorrhoeae Opa.

A

-Switch On/Off –Alteration in number of 5 nucleotide repeats turns on or off expression

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14
Q

How is N. gonorrhoeae acquired?

A

Intimate sexual contact: transmission across mucosal surfaces

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15
Q

What bacterial strain has an asymptomatic reservoir (50% W, 5+%M)?

A

N. gonorrhoeae

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16
Q

List some primary locations (local) of clinical disease in N. gonorrhoeae infection and describe the symptoms.

A
  • Urethra: burning on urination, purulent, prolific discharge
  • Cervix: possible discharge without fever
  • Anus: Proctitis
  • Pharynx: from oral sex
  • Conjunctivitis:

–MTC transmission

–Give topical antibiotics to infants at time of delivery

–Redness and inflammation

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17
Q

List some secondary locations (disseminated) of clinical disease in N. gonorrhoeae infection and describe the symptoms.

A

-Epididymis/Prostate:

–pain

–fever

–testicular swelling in males

-Endometrium/Fallopian tubes:

–PID

–fever

-Bones:

–Arthritis

–Pus in knee arthritis

-Skin:

–dermatitis: pustules in center

–skin lesions

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18
Q

Describe the characteristics of N. gonorrhoeae in culture.

A
  • Chocolate agar and CO2
  • Oxidase positive
  • Oxidize glucose ONLY, not maltose

“GO CO Co2”

19
Q

Name 3 lab techniques for N. gonorrhoeae identification.

A
  • Gram
  • Culture
  • PCR (very sensitive) –urine, oral, anal, genital samples possible
20
Q

What is the major treatment option for N. gonorrhoeae?

A

Ceftriaxone (Injection) + azithromycin (for C. trachomatis co-infection)

21
Q

Describe the morphology and staining of Haemophilus influenzae.

A

Small, gram negative coccobacilli

22
Q

What virulence factor are the serotypes of H. influenzae based upon?

A

The polysaccharide capsule (anti-phagocytic)

(serotypes a-f)

serotype b = polyribitol phosphate

23
Q

In the 2 or less age group, which bacterial strain is responsible for meningitis, septicemia, and cellulitis?

A

H. influenzae

24
Q

In the 2-5 age group, which bacterial strain is responsible for epiglottitis and pneumonia?

A

H. influenzae

25
Q

What type of vaccine was created for the type B serotype of Haemophilus influenzae?

A

Conjugated, polyribitol vaccine in 1987

26
Q

What strain of bacteria is associated with the following symptoms in children:

-Acute supraglottic cellulitis/epiglottitis (swelling/discharge and may block airway)

A

H. influenzae (type B)

27
Q

What bacterial strain is associated with the following symptom in children:

-Purple erythema in the cheek and periorbital area

A

H. influenzae (type B)

28
Q

What would be the second differential diagnosis of the following symptoms:

  • Otitis media
  • Sinusitis (acute/chronic)
  • Bronchitis (esp COPD)
A

Non-typeable (uncapsulated) H. influenzae

29
Q

What type of agar does Haemophilus influenzae require?

A

chocolate

30
Q

Describe the colony characteristics of H. influenzae.

A

Nonmotile, non-sporeforming

31
Q

What growth factors are required by H. influenzae from the blood?

A
  • X factor: Hematin
  • V factor: NAD
  • both supplied by lysed blood cells only
32
Q

What antibiotic therapy would be used for severe disease caused by H. influenzae?

A

Cephalosporins (2nd/3rd)

(25-50% produce beta-lactamase = ampicillin resistant)

33
Q

Describe the morphology/staining of Bordetella pertussis.

A

Small, Gram negative coccobacilli

Even smaller than H. influenzae

34
Q

What does B. pertussis cause clinically?

A

Pertussis (whooping cough = the 100 day cough)

35
Q

What major factors determine the structure and virulence of B. pertussis?

A

Adhesins

Pertussis toxin (PT)- exotoxin

Tracheal cytotoxin- peptidoglycan fragment

36
Q

Describe the function of 2 adhesins of Bordetella pertussis.

A

Pertactin (surface protein)

Filamentous hemagglutinin (Fha)

  • Both contain Arg-Gly-Asp sequence promoting binding to integrins of ciliated resp. cells
  • Both bind to CR3 on MACs to promote phagocytosis without respiratory burst (intracell. survival)
37
Q

Describe the A subunit of the Pertussis Toxin (PT)

A

A-S1 (enzymatic): ADP-ribosylation of regulatory G protein

  • prevents inactivation of adenylate cyclase (increase in cAMP)
  • causes increased resp. secretions/mucus production and lymphocytosis
38
Q

Describe the B subunit of PT.

A

B-S2-S5 (binding)

  • S2: subunit binds to glycolipid on ciliated cells
  • S3: binds to receptors on phagocytic cells
39
Q

What does tracheal cytotoxin of B. pertussis do?

A

Peptidoglycan fragments damage respiratory cells

Causes extrusion of ciliated tracheal epithelial cells

Stimulates IL-1 release (fever)

40
Q

True or false:

Bordetella pertussis invades respiratory tract cells.

A

False

-It never invades, only adheres, destroys, and causes symptoms

41
Q

What lab findings help diagnose B. pertussis?

A
  • Lymphocytosis (high count)
  • Charcoal blood agar: Strict aerobe, non-motile, difficult and slow to grow

**PCR is typically used

42
Q

What treatment options are available for Bordetella pertussis?

A

Azithromycin

Alternate = Trimethoprim/sulfamethoxazole

43
Q

Describe the vaccine options for B. pertussis.

A

Subunit vaccines with diptheria and tetanus

  1. DTap = infant
  2. Tdap = adolescent/adult

MHD Block III (12 decks)

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