Streptococcus Pneumoniae

Question 1

List the microbial features of streptococcus

Answer 1

Facultative anaerobic
Gram positive cocci
Non sporing.
Non acid fast
Non motile.
Catalase negative.
Hemolytic on horse blood agar (Alpha,beta, gamma).
Encapsulated or noncapsulated

Question 2

Enterococcus is in what Lancefield classification

Answer 2

Group D

Question 3

What is the feature of alpha hemolytic streps

Answer 3

no complete hemolysis.

They form greenish tinge due H2O2 that converts hemoglobin to methemoglobin.

Question 4

When was strep pneumonia first identified or isolated?

Answer 4

pneumoniae was first isolated in 1881 by sternberg in the USA and Louis Pasteur in France.

Question 5

List disease caused by s.pnemonia.

MOSS PEe

Answer 5

meningitis,
sinusitis,
otitis media,
endocarditis,
septic arthritis,
peritonitis,

Question 6

Source of infection of S.pnemo

Answer 6

Nasopharynx colonization.

20-40% in healthy children
10% in healthy adultd.

Question 7

Mode of transmission of S.pneumonia

Answer 7

Inhalation of contaminated respiratory droplets

Question 8

The rate of invasive pneumococcal disease in persons per year is

Answer 8

15/100000

Question 9

Incidence of pneumococcal is up to 10 folds higher in population race

Answer 9

African-Americans

Question 10

At what age is invasive pneumococcal commoner

Answer 10

<2yrs or>65yrs

Question 11

List the risk factors of Strep Pneumonia.

Tip: it’s associated with things that impairs immune system.

Answer 11

Antibody deficiency.
Complement deficiency.
Neutropenia or impaired neutrophil fxn.
Asplenia
Corticosteroids.
Malnutrition.
Alcoholism.
Chronic conditions (liver, renal, asthma, diabetes,COPD)
Overcrowding.

Question 12

VIRULENCE FACTORS

Question 13

Function of capsular polysaccharide

Answer 13

Activates complement,
Inhibts phagocytosis.

Question 14

Function of Cell wall polysaccharide;

Answer 14

Activate complement and cytokines

Question 15

Function of Pneumococcal surface protein A

Answer 15

Blocks complement deposition,
Hence inhibiting phagocytosis

Question 16

Fxn of PsaA(pneumococcal surface adhesin A)

Answer 16

Adherence

Question 17

Fxns of pspC

Answer 17

Inhibts phagocytosis by binding to complement factor H

Question 18

What is the fxn of pneumolysine

Answer 18

Direct fxn: binding to cholesterol,form cell membrane pores, depreciating cell integrity,leads to cell death.

Indirect; Mediate inflammatory response by activating Chemokines and cytokines.

Question 19

Fxn of autolysin

Answer 19

Releases bacteria components resulting in trigger of cytokine cascade.

Question 20

Fxn of Neuraminidase

Answer 20

Mediates adherence by digesting sialic acid on cells exposing binding receptor sites

Question 21

ANTIMICROBIAL RESISTANCE

Question 22

Penicillin resistance is seen as a mutation in which of the penicillin binding proteins;

Answer 22

pbp2B(low resistance)
Pbp2X(high resistance)

Question 23

pbp2B resistance can be overcome using high dose of Antibiotics T/F.
Why?

Answer 23

True..
This because It confers low resistance

Question 24

List the two genes involved in macrolide resistance

Answer 24

ErmB: erythromycin ribosomal methylase B
MefA: macrolide efflux A

Question 25

Clinical manifestation

Answer 25

Let’s go😂

Question 26

List the clinical features of streptococcus pneumoniae

Answer 26

Most common; Lobar pneumonia and pyogenic Meningitis.

Non invasive; Otitis media, sinusitis

Invasive: Endocarditis
pericarditis,
septic arthritis
Osteomyelitis.
Primary peritonitis (less common)
Abscess.
Empyema,
Parapneumonic effusions.

Question 27

DIAGNOSIS!!!

Answer 27

Let’s go!

Question 28

What are Biochemical diagnosis of Strep Pneumonia

Answer 28

Catalase negative.
Optochin sensitive,
10% soluble in bile solutions.
Inulin positive (a fermenter)

Question 29

List the microscopy features of streptococcus pneumoniae

Answer 29

Gram positive cocci in pairs.
Lanceolate or flame shaped.

Question 30

List the culture features of streptococcus pneumoniae

Answer 30

Culture medium; Routine media.

Features;
Alpha hemolysis; present with greenish tinch.

Central autolysis of colonies(Draughtsman colony or Carom coin)

Colony is occasionally mucoid

Uniform turbidity of culture.

Question 31

What is used in serotyping?

Answer 31

Quellung’s reaction to identify capsulated organisms which strep pneumonia tests positive for.

Question 32

Treatment!!!

Question 33

What are the treatments

Answer 33

PMIC<0.1mg/l : use penicillin and amplicilin.

PMIC: 0.1-1.0mg/l :
Meningitis: Ceftriaxone and cefotaxime.
Non menigeal: high dose penicillin.

PIMC: >2.0mg/l :
Vancomycin+_ Rifampicin
Use Ceftriaxone for non menigeal cases
High dose of ampicillin, carbapenems, fluroquinolones.

Question 34

Pneumococcal Meningitis will benefit from adjunct corticosteroids T/F

Reasons?

Answer 34

True,
It confers antiinflammatory roles to Meningitis

Question 35

VACCINATION!!

Answer 35

PCV 13; for children..<2yrs

PPV23 for adults>65

Question 36

How many times is PCV 23 administered and at what ages

Answer 36

3 times
2 months, 4 months, 12months

Question 37

List the risk groups that require PPV23

Answer 37

Sickle cell anaemia
Asplenia
Chronic kidney disease/ nephrotic syndrome.
Coeliac disease.
HIV,
Drugs; can led to immunosuppression.
Chronic diseases like(cardiac, respiratory, fever, cardiac,)
Diabetes.
PTS with cochlear implants.
C.S.F leak