Streptococcus Pneumoniae

Question 1

Bacterias which cause pneumonia

Answer 1

S. pneumonia
S. aureus
Group A streptococcus
Klebsiella pneumonia
H. influenza

Question 2

Streptococci species and their typical hemolysis

Answer 2

S.pyogens (β)
S.agalactiae (β)
E.faecalis (α or β or none)
S.bovis (α or none)
S.pneumoniae (α)
Viridans (α)

Question 3

Streptococci are catalase +ve or -ve

Answer 3

Catalase -ve

Question 4

S.pneumoniae morphology

Answer 4

Lancet shaped
Gram +ve
Occur in pairs
Capsulated pairs
Nonmotile and nonsporing

Question 5

Transmission occurs through

Answer 5

Respiratory droplets

Question 6

Risk factors for pneumonia

Answer 6

Respiratory viral infections
Pulmonary congestion
Malnutrition
Immunodeficiency
Stress
Alcoholism

Question 7

Antigenic structure includes

Answer 7

1) capsule polysaccharide: type specific antigen. Diffuses into infective tissue & culture medium so called as specific soluble substance (SSS)
2) C carbohydrate antigen: species specific antigen.

Question 8

Virulence factors

Answer 8

Polysaccharide capsule (antiphagocytic)
Pneumolysin: membrane damaging toxin
Autolysin: helps to release bacterial toxins

Question 9

Types of infections

Answer 9

Non-invasive
-otitis
-sinusitis
-recurrent bronchitis
Invasive
-pneumonia
-sepsis
-meningitis

Question 10

Clinical findings

Answer 10

Abrupt onset of fever
Chills
Productive cough
Pleuritic chest pain
Dyspnea, tachypnea, hypoxia
Rusty colored sputum

Question 11

Specimen to be collected for lab

Answer 11

Sputum
CSF
Blood
Synovial fluid
Laryngeal swab (children)

Question 12

Lab tests for pneumococcus

Answer 12

Quellung reaction
Optochin sensitivity

Question 13

Quellung reaction?

Answer 13

When pneumococci on slide mixed with antiserum and methylene blue, the capsule will swell. Used for rapid identification

Question 14

Optochin sensitivity?

Answer 14

A disc impregnated with optochin is placed on the agar dish. The growth of s.pneumoniae will be inhibited.

Question 15

Beta hemolytic streptococci?

Answer 15

Completely lyse the RBCs, leaving a clear zone of hemolysis around the colony

Question 16

Alpha hemolytic streptococci?

Answer 16

Partially lyse the RBCs, leaving a greenish discolouration of the culture surrounding the colony

Question 17

Gamma hemolytic streptococci?

Answer 17

Unable to lyse the RBCs. (Non-hemolytic)

Question 18

Hemolysis of s.pneumoniae on blood agar

Answer 18

After incubation for 18h, the colonies are small dome shaped and glistening
Further 24-48h, the colonies become flat with raised edges called as Draughtsman or carrom coin appearance.

Question 19

Treatment

Answer 19

Severe infections- penicillin G
Mild infections- oral penicillin V
Penicillin allergic patients- erythromycin or azithromycin

Question 20

Vaccine for s.pneumoniae

Answer 20

Prevnar 13 (13-valent pneumococcal conjugate vaccine)
Pneumovax 23 (23-valent pneumococcal unconjugated vaccine) given to healthy individuals 50y or older

Question 21

Fungi causing chronic pneumonia

Answer 21

Histoplasma capsulatum
Blastomyces dermatitidis
Coccidioidomycosis

Question 22

Fungi causing pneumonia in immunocompromised patients

Answer 22

Pneumocystis jiroveci
Candida species
Aspergillus species
Phycomycetes
Cryptococcus neoformans

Question 23

Lancefield group of S.pyogens

Answer 23

A

Question 24

Lancefield group of S.agalactiae

Answer 24

B

Question 25

Lancefield group of E.faecalis

Answer 25

D

Question 26

Lancefield group of S.bovis

Answer 26

D

Question 27

S.pneumoniae causes

Answer 27

Pneumonia in adults
Otitis media in children
Bacterial meningitis in adults
Tracheobronchitis

Question 28

Major virulence factor of pneumococcus

Answer 28

Polysaccharide capsule