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New and Emerging Microbial Pathogens > Lecture 10 > Flashcards

Lecture 10 Flashcards

1
Q

What diseases can Streptococcus pneumoniae cause

A

Pneumonia

Sepsis

Meningitis

Otitis media

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2
Q

Classification of S. pneumoniae

A

Phylum: Firmicutes
Class: Bacilli
Order: Lactobacillales
Family: Streptococcaceae
Genus: Streptococcus
Species: pneumoniae

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3
Q

Is S. pneumoniae gram positive or negative

A

Positive

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4
Q

Bacterial pneumonia

A

5% fatality

Airway blockage

Collapsed lungs

lung abscesses

Empyema

Pericarditis

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5
Q

Meningitis

A

fatal for 1 in 12 children and 1 in 6 older adults

Developmental delay or hearing loss

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6
Q

Bacteraemia

A

Fatal for 1 in 30 children and 1 in 8 adults

Loss of limbs

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7
Q

Explain an overview of how S. pneumoniae causes disease

A
  1. Colonization at nasal epithelium
  2. Transmission by shedding
  3. Invasion:
    Aspiration -> Pneumonia -> Bacteraemia -> Meningitis

Local spread -> Otitis media

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8
Q

Severe infection symptoms

A

Pneumonia:
- Chest pain
- Cough
- Fever and chills
- Rapid breathing
- Confusion in adults

Meningtitis:
- Confusion
- Fever
- Headache
- Photophobia
- Stiff neck
- Poor eating/drinking/vomiting in babies

Bacteremia:
- Fever
- Chills
- Low alertness

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9
Q

What populations does S. pneumoniae primarily affect?

A

Vulnerable populations:

IPD incidence in UK between 2014-19:
3.6/100,000 in 18-44 years
6.3/100,000 in 18-48 months

IPD incidence in Malaysia between 2014 and 2017:
45/100,000 in <5 years
12/100,000 in 6-64 years
48/100,000 in >65 years

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10
Q

Which continents are more affected by S. pneumoniae

A

Africa and Southern/South East Asia are the worst affected

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11
Q

Explain the meningitis belt

A
  • Across Sahel region
  • Hot, dry, dusty
  • 52% N. meningitidis
  • 29% S. pneumoniae (serotype 1)
  • Epidemic strains Men A, X, C and W135
  • Dry season
  • 1 million cases from 1993-2012 reported to WHO
  • CFR is 8.5%
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12
Q

What type of disease is pneumococcal meningitis

A

Seasonal disease

Higher rates of disease during Winter time than summer time

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13
Q

What pneumococcal serotypes were causing the most disease between 2014-19 in UK in 18-44yrs and 13-48 months

A

18-44yrs:
- 8, 12F, 9N, 3, 22F

13-48 months:
- 12F, 15B/C, 10A, 23B, 24F

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14
Q

What pneumococcal serotypes were causing the most disease between 2014-17 in Malaysia

A

6A, 6B (50% also the highest AMR), 13, 14, 19A, 19F, 35F and NTs.

Non-typeable serotypes account for 4.9% (12/245) of the isolates collected in 1 MofH study 2014-2017. 86% of serotypes are covered by the vaccine.

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15
Q

Pneumococcal-epithelial interactions

A
  1. S. pneumoniae forms colonies on mucus layer
  2. Bacteria penetrate epithelium:
    inducing inflammatory signals
    altering junctional proteins and the cytoskeleton
    Trigger surface molecule upregulation
  3. Host cells sense pathogens via TLRs:
    Activates inflammatory cascades
    Protein coat involved in adhesion
  4. Immune cells monitor for pathogens
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16
Q

What elevates epithelial responses to infection

17
Q

Pneumococcal vaccines

A

PCV7 (Wyeth in 2000) - Recommended for children under 23 months, or children aged 24-59 months if at high risk for pneumococcal infection due to preexisting condition

PCV10 (GlaxoSmith Kline in 2009) - Recommended for children under the age of 1

PCV13 (2010 by Pfizer) - Recommended for children aged 2-59 months, or children aged 60 months to 18 years who are at increased risk of pneumococcal infection or adults over 65 or adults aged 19 or over who have immunocompromising conditions e.g. asplenia or CSF leaks

PPSV23 (Merck and Co in 1983) - Adults over 50 or children over 6 who are at high risk of infection

18
Q

Pneumococcal carriage effect after vaccines

A

Not reduced carriage in LMICs

Worldwide pneumonal carriage had not decreased after vaccine rollouts

19
Q

What is a significant issue with antibiotics against S. pneumoniae

A

Highly resistant to specific antibiotics

20
Q

What did population based serology show?

A

Limited induction of serotype 3-specific antibodies by vaccine or natural exposure

IgG titer increases with age with 19F serotype

IgG titer decreases with age with 3 serotype

21
Q

Why does the IgG titer of serotype 3 decrease

A
  • Large sugar coating
  • Associated with IPD - empyema, bacteraemia, cardiotoxicity, and meningitis with fatality rate of 30-47%
  • Vaccine evasion and antibiotic resistant
  • Evolved metabolism
  • Prevalent serotype in HIC and LMICs
22
Q

Pneumococcal carriage immunity

A

Once exposed, adults can sustain immunity for up to 12 months against the bacterium

Older adults aged over 65 however cannot do this

23
Q

EHPC model

A

Serotype 3 found at higher density in saliva than 6B

Different niche

31 participants developed Sx including sore throat, fever, headache, earache, respiratory and nasal symptoms.

New and Emerging Microbial Pathogens (15 decks)

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