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Y1 - Microbio Exam 2 > 13_Haemophilus influenzae Neisseria meningitidis, Neisseria gonorrhoeae > Flashcards

13_Haemophilus influenzae Neisseria meningitidis, Neisseria gonorrhoeae Flashcards

1
Q

hemophilus influenzae

  1. what type causes meningitius?
  2. carriers/ transmission?
  3. gram neg or pos?
  4. shape?
A
  1. type B
  2. carried in human nasopharynx by healthy people; transmitted by aerosol droplets
  3. gram negative
  4. coccobacilli
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2
Q

what is meant by Haemophilus influenzae being pleomorphic?

A

the ability of some micro-organisms to alter their shape or size in response to environmental conditions

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3
Q

what conditions can result from nontypable strains of haemophilus influenzae?

A

Unencapsulated strains are termed nontypable (NTHi) because they lack capsular serotypes; these types cause:

  • Otitis media
  • Sinusitis
  • Chronic bronchitis
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4
Q

pathogenesis of haemophilus influenzae:

  1. # of serotypes based on capsules
  2. which type causes bacteremia, meningitis, and epiglottitis?
  3. which strains have a capsule? what is this capsule called?
A
  1. 6 Serotypes based on capsules; designated by letters “a” to “f”
  2. ONLY TYPE B can be invasive, causing bacteremia, meningitis, and epiglottitiis
  3. TYPE B strains have a capsule; Capsule is PolyRibosylribitol Phosphate (PRP)
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5
Q

relationship between incidence of H. influenzae meningitis during first 5 years of life, an dthe levels of type B capsular polysaccharide antibodies?

A

As incidence decreases, the number of H.i.b. (anti-H. influenzae type B capsular polysaccharide antibodies) increases

  • inversely related
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6
Q

H. influenzae vaccine:

  1. structure
  2. antibody responsiveness?
  3. what happens when antibodies react to capsule?
A
  1. Purified PRP polysaccharide covalently complexed
    to a protein carrier
2. Purified PRP **_does not induce antibody responses in
 children \< 2 years_**. The conjugate vaccine is effective
 in infants (*the protein carrier converts the T-independent polysaccharide to a T-dependent antigen)*
  1. Antibodies to capsule promote phagocytosis directly and by complement fixation
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7
Q

effects of vaccines on incidence of H. influenzae

A

Vaccine efficacy eliminates incidence of H. influenzae type B

(decreases occurrence to near 0)

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8
Q

what are the different types of Haemophilus vaccines?

A

monovalent vaccine

combination vaccine

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9
Q

Haemophilus influenzae:

diagnosis?

treatment?

A
  • diagnosis
    • Requires 2 factors not found in blood agar to grow:
      • X factor: hematin (hemin)
      • V factor: NAD (nicotinamide adenine dinucleotide)
    • Grow on chocolate agar, w/ lysed RBCs plus hematin and NAD;
    • Fastidious: grows best in increased CO2
  • treatment
    • third generation cephalosporins
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10
Q

Which is the best answer with regard to Haemophilus influenzae?

  1. Causes influenza
  2. Frequently infects young adults
  3. There is no vaccine
  4. Protection is by antibody
A

Protection is by antibody

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11
Q

other name for neisseria meningitidis?

other name for neisseria gonorrhoeae?

are both: gram negative or positive? what is shape?

A
  • neisseria meningitidis –> meningococcus
  • neisseria gonorrhoeae –> gonoccocus

Both are GRAM NEGATIVE DIPLOCOCCI

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12
Q

what is this gram stain of?

A

meningococcal meningitis

(cerebral spinal fluid (CSF) gram stain)

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13
Q

What are the key symptoms of Neisseria meningitidis?

A
  • Stiff neck, abrupt onset of fever, hypotension, purpura, thrombocytopenia and petechial rash
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14
Q

What condition (with of the same symptoms EXCEPT STIFF NECK) presents similarly to Neisseria meningitidis?

A

Sepsis and septic shock

(Sxs: brupt onset of fever, hypotension, purpura, thrombocytopenia and petechial rash)

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15
Q

What are the top 3 clinical manifestations of Neisseria meningitidis?

A
  • *Meningitis: 47.3%
  • Bacteremia: 43.3%
  • Pneumonia: 6.0%
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16
Q

N. meningitidis: epidemiology

  1. carriers
  2. transmission
  3. incidence/ mortality
A
  1. ONLY HUMAN HOST; carried in nasopharyngeal flora of 10% of healthy people
  2. Tx: by inhalation of respiratory droplets
  3. 349 cases in 2017 in US; case fatality is 10-15% depending on group
17
Q

Where were the 2 major outbreaks of Meningitis?

A
  • Nigeria: 14,518 suspected cases, 8% fatality
  • Northern Ghana: 133 cases serogroup W
18
Q

What are the virulence factors of Neisseria?

A
  • Capsules are Neisseria virulence factors
  • Neisseria meningitidis virulent strains are encapsulated
  • CAPSULES ARE ANTI-PHAGOCYTIC;
    • can be shed into blood or lymph to bind up antibodies, acts like a decoy, using up the antibodies ineffectively
19
Q

N. meningitidis pathogenesis:

  1. how do they attach?
  2. travel to..
  3. if progresses to meningitis?
  4. what is found in the membrane?
A
  1. attach by pili to nonciliated epithelia of naspharynx
  2. penetrate through cells and invade blood stream
  3. if progresses to meningitis, then crosses the blood-brain barrier and invade the meninges
  4. LOS(lipooligosaccharide), a form of lipopolysacchride is found in the membrane
20
Q

What is LOS and what can it affect?

A
  • LOS(lipooligosaccharide), a form of lipopolysacchride is found in the membrane; a truncated lipopolysaccharide
  • Release of LOS is toxic and causes endotoxic shock
21
Q

N. meningitidis virulence factors:

purpose

A

Neisseria fights via several virulence factors to stay and multiply extracellularly

22
Q

Antibody to capsule alone is protective:

evidence?

A
  1. Shows that Ab levels correlate w/ protection
  2. Shows that passive antibody (polyclonal or monoclonal) alone confers protection in rodents
  3. shows that vaccination with purified capsule is protective
23
Q

What are the vaccines available for Meningococcal disease?

A
  1. 2 quadravalent conjugate vaccines are licensed in the US; these vaccines are composed of the capsular polysaccharides of serogroups A, C, W-135, and Y linked to diphtheria toxoid or to a mutated, inactive diphtheria toxin as a carrier (carrier is T-dependent)
  2. Two new vaccinres for serogroup B were licensed in 2014 and 2015
24
Q

What features/tests do you look for to diagnosis N. meningitidis in the lab?

A
  • Features:
    • Kidney-bean shaped Gram negative diplococci
    • Neutrophils in CSF
  • Tests: Nucleic acid amplification tests
    • Or test for antigen in CSF using latex agglutination
25
Q

Treatment for N. meningitidis

A
  • 3rd generation cephalosporins: Cephtriaxone or cefotaxime (or penicillin)
  • Case contact prophylaxis uses rifampin, ciprofloxacin, or ceftriaxone
26
Q

Neisseria diplococci:

shape?

A
  • Kidney bean shape
27
Q

Neisseria gonorrhoeae:

gram stain, nickname, disease

A
  • Gram negative diplococci
  • Called GC (as abbreviation for Gonococcus)
  • Disease: Gonorrhea; also called the Clap (clapoire)
28
Q

Neisseria Gonorrhoeae:

  1. transmission,
  2. symptoms
  3. treatment
A
  1. Sexually transmitted (STI - sexually transmitted infection, or STD - sexually transmitted disease) - human to himan
    • *Asymptomatic carriage (esp by females), provides a reservoir of organisms that can be transmitted to sex partners
  2. Symptoms
    • Males - painful urination w/ purulent pus; exudate shows intracellular diplococci in neutrophils on microscopy
    • Females - *30% are asymptomatic; can see pain on urination, vaginal discharge, abdominal pain
  3. Tx: if no tx, can resolve in several weeks in med
29
Q

Neisseria gonorrhoeae:

pathogenesis

A
  1. Lipooligosaccharide (LOS) is found in outer membrane –> has endotoxic activity;
  2. Attachments:
    • Pili
    • Opa proteins - outer membrane proteins; opa=opacity, for change in colony appearance
  3. Invasion: pathogen-directed endocytosis into nonciliated epithelial cells; attachment by pili and Opa proteins
  4. Organisms USUALLY stay localized in mucosal tissue, but occasionally can get disseminated gonococcal infection (DGI); or gonococcal arthritis (where organisms lodge in a joint like elbows or knees)
30
Q

what modification to LOS can block complement activation?

A

polysaccharide has sialic acid residues;

Sialylated LOS blocks complement activation

31
Q

Neisseria gonorrhoeae:

evasion of host responses

A
  1. *Antigenic variation (even in a single host)
    • pili variation, and opa variation
  2. Survival in phagocytes (neutrophil PMNs)
    • Gonococci make catalase which interferes w/ peroxide-mediated killing mechanisms inside of PMNs (phagocytes)
  3. Sialylated LOS blocks complement activation
32
Q

Why is there no vaccine for Neisseria gonorrhoeae?

A

There are too many antigenic variants;

Pilus vaccines were tried and failed

33
Q

Neisseria gonorrhoeae:

clinical manifestations

A
  1. Men: urethral strictures, epididymitis, prostatitis
  2. Women: PID (pelvic inflammatory disease); fallopian tube inflammation w/ scarring, strictures, pelvic pain, ectoptic pregnancy
    • women are most at risk bc the disease is more frequently asymptomatic in women –> as such, consequence goes untreated
  3. Both sexes can have disseminated gonococcal infections: arthritis, (rareles meningitis)
34
Q

Neisseria gonorrhoeae:

  1. diagnosis
  2. culture
A
  1. diagnosis:
    • men: visualization of intracellular diplococci in smear of urethral exudate (presumptive diagnosis)
    • women: must do cultures to establish diagnosis; *cervical or rectal swabs
  2. culture:
    • Gonococci are fastidious and fragile
      • Grow on chocolate agar
      • For urogenital, anal, or throat swabs, use Thayer-martin or Martin-Lewis agar (which is cholocate agar + Abx that inhibit other normal flora)
    • Nucleic acid amplification tests (NAAT)
35
Q

Neisseria gonorrhoeae:

treatment

A
  • Injectable ceftriaxone in combination with oral azithromycin or doxycycline are current drugs of choice. Increasing antibiotic resistance a problem.
  • %30% of patients with GC are co- infected with Chlamydia.
36
Q

In comparing N. gonorrheae and N. meningitidis, pick the one true statement:

  1. N. gonorrheae is transmitted by sheep, but N. meningitidis only infects humans.
  2. Both of these organisms usually become systemic.
  3. Both organisms grow as diplococci.
  4. Neither organism has a capsule.
A
  • *Both organisms grow as diplococci
37
Q

What are the similarities and differences of Neisseria Gonorrheae and Neisseria Meningitidis?

A

Key Differences:

  • N. gonorrhoeae – carried by asymptomatic females/ recovering males
  • No capsule
  • Usually loalized

Wherease N. meningitidis - nasopharynx - capsule - systemic disease

Y1 - Microbio Exam 2 (18 decks)

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