Streptococcus Pneumocococcus Multiple Choice Question And Answers

Question 1. Boy presented with skin ulcer on leg. Culture reveals beta-hemolytic Streptococci. Culture from school children with sore throat some days back also revealed beta-hemolytic Streptococci. What is the characteristic which can tell both the strains are same or different?

1. C-carbohydrate Ag
2. M protein
3. Emu protein
4. Mec A gene

Answer. (1) (C-carbohydrate Ag)

• β hemolytic Streptococci was obtained from two cases-Boy with skin ulcer and children with sore throat.
• To know the relatedness between Beta hemolytic Streptococci, Lancefield grouping is done
• Lancefield grouping is based on C-carbohydrate Ag.

Read And Learn More: Micro Biology And Immunology Multiple Choice Question And Answers

Question 2. Identify the organism based on Bacitracin sensitivity disk test given below?

1. Streptococcus pyogenes
2. Staphylococcus aureus
3. Clostridium
4. Corynebacterium

Answer. (1) (Streptococcus pyogenes)

Bacitracin susceptibility test is done for Streptococcus pyogenes/group A (sensitive), to differentiate it from Streptococcus agalactiae/group B (resistant)

Question 3. Coral cuts are associated with:

• Staphylococcus aureus
• Vibrio vulnificus
• Pseudomonas aeruginosa
• Streptococcus species

Answer. (4) (Streptococcus species)

Explanation: Coral injury (scuba diving) may sometime be accompanied with a secondary bacterial infection Infections transmitted in the marine environment include (decreasing order of frequency) such as Streptococcus species, Escherichia coli, Pseudomonas aeruginosa, Mycobacterium marinum, Staphylococcus aureus, Vibrio cholerae, Vibrio vulnificus, or Vibrio parahaemolyticus.

Question 4. Agent causing Rheumatic fever:

1. Alpha hemolytic Streptococci
2. Beta hemolytic Streptococci
3. Gamma hemolytic Streptococci
4. Staphylococcus aureus

Answer. (2) (Beta hemolytic Streptococci)

Question 5. Streptococcus toxin which is responsible for connective tissue breakdown?

1. Hyaluronidase
2. Streptolysin O
3. Streptolysin S
4. Streptococcus pyogenic exotoxin

Answer. (1) (Hyaluronidase)

Question 6. Which streptococcal antigen cross-reacts with synovial fluid?

1. Carbohydrate (group A)
2. Cell wall protein
3. Capsular hyaluronic acid
4. Peptidoglycan

Answer. (3) (Capsular hyaluronic acid)

• Capsular hyaluronic acid cross-reacts with synovial fluid
• Structural components of Strepto pyogenes cross reacts with human tissues

Question 7. A child presents with infective skin lesion of the leg. Culture showed hemolytic colonies which were gram + ve cocci in chains. The test to confirm the organism is:

1. Bile solubility
2. Optochin sensitivity
3. Bacitracin sensitivity
4. Catalase positive

Answer. (3) (Bacitracin sensitivity)

• Hemolytic colony with gram-positive cocci in chain is suggestive of β hemolytic Streptococcus.
• Option c: Bacitracin sensitivity is used to differentiate between β hemolytic
  Streptococci Group A- Bacitracin sensitive and Group b: Bacitracin resistant
• Option a and b: Bile solubility and Optochin sensitivity are used to differentiate Pneumococcus and S. Viridans
• Option d: Catalase test is used to differentiate Streptococcus and Staphylococcus.

Question 8. Treatment for streptococcal necrotizing fasciitis:

1. Surgical debridement
2. Penicillin
3. Clindamycin
4. Metronidazole
5. Vancomycin

Answer. (1, 2, 3) (Surgical debridement, Penicillin, Clindamycin)

• Treatment of Necrotizing fasciitis: Surgical debridement (most crucial) + Penicillin G + Clindamycin
• If single option to be selected: Then Answer should be Surgical debridement
• Harrison 17/e p 886 states: ‘Drainage and debridement are central to the management of necrotizing fasciitis; antibiotic treatment is a useful adjunct, but surgery is life-saving’.

Question 9. Group A hemolytic pharyngitis is due to:

1. Local infection
2. Systemic toxicity
3. Attachment to mucosa
4. Local toxins

Answer. (3) (Attachment to mucosa)

The capsular polysaccharide may also play a role in GAS colonization of the pharynx by binding to CD44, a hyaluronic acid–binding protein expressed on human pharyngeal epithelial cells.

Question 10. True about Streptococcus agalactiae is/are:

1. Alpha hemolysis
2. Beta hemolysis
3. Bacitracin resistant
4. Coagulase-negative
5. Catalase positive

Answer. (2, 3) (Beta.., Bacitracin..)

• Streptococcus agalactiae is catalase negative, bacitracin resistant, CAMP +ve, group B β- haemolytic streptococci.
• Coagulase test is done to differentiate S.aureus from Coagulase negative staphylococci.

Question 11. A child presents with sepsis. Bacteria isolated showed β hemolysis on blood agar, resistant to bacitracin and a positive CAMP test. The most probable organism is:

1. S. pyogenes
2. S. agalactiae
3. Enterococcus
4. Pneumococcus

Answer. (2) (S. agalactiae)

Already explained

• Points favoring to S. agalactiae:
  • Septicemia in a child
  • β hemolysis on blood agar
  • Resistant to bacitracin and a positive CAMP test
• S. pyogenes: sensitive to bacitracin and CAMP test is negative.

Question 12. Which group of Streptococcus grow at 60°C?

1. A
2. B
3. C
4. D

Answer. (4) (D)

Group D Streptococci like Enterococci can grow >60°C.

Question 13. A patient admitted to an ICU is on central venous line for the last one week. He is on ceftazidime and amikacin. After 7 days of antibiotics, he develops a spike of fever and his blood culture is positive for gram positive cocci in chains, which are catalase negativFollowing this, vancomycin was started but the culture remained positive for the same organism even after 2 weeks of therapy. The most likely organism causing infection is:

1. Staphylococcus aureus
2. Viridans streptococci
3. Enterococcus faecalis
4. Coagulase-negative Staphylococcus

Answer. (3) (Enterococcus faecalis )

This is case of VRE (Vancomycin-resistant Enterococci)

Points in favor:

• Gram+ve cocci in chain and Catalase –ve points towards Streptococcaceae family
• Resistant to aminoglycoside, cephalosporins and vancomycin
• S, aureus and CONS are catalase +ve, hence they are ruled out.

Question 14. Which of the following organisms, when isolated in the blood, requires the synergistic activity of penicillin plus an aminoglycoside for appropriate therapy:

1. Enterococcus faecalis
2. Staphylococcus aureus
3. Staphylococcus pneumoniae
4. Bacteroides fragilis
5. Streptococcus Viridans

Answer. (1) (Enterococcus faecalis)

Question 15. The Gram stain image given below belongs to which of the following organism?

1. Nocardia
2. Streptococcus
3. Corynebacterium
4. Mycobacterium tuberculosis

Answer. (2) (Streptococcus)

Question 16. A patient of RHD developed infective endocarditis after dental extraction. Most likely organism causing this is:

1. Streptococcus viridans
2. Streptococcus pneumoniae
3. Streptococcus pyogenes
4. Staphylococcus aureus
5. Pneumococcus

Answer. (1) (Streptococcus viridans)

• MC cause of Native valve endocarditis: S. aureus
• MC cause of subacute endocarditis: MC agent Streptococcus Viridans
• MC Streptococcus Viridans causing endocarditis: S. sanguis
• Following tooth extraction, transient bacteremia occurs and Streptococcus Viridans gets lodged into pre damage valve.
• So, prophylactic antibiotic is implemented before tooth extraction in RHD patients.

Question 17. Quellung reaction is seen with:

1. Pneumococcus
2. Gonococcus
3. Streptococcus
4. Staphylococcus

Answer. (1) (Pneumococcus)

• Quellung reaction is seen with Pneumococcus; which refers to the capsular swelling can be demonstrated by adding type-specific antiserum

Question 18. The capsule of S.pneumoniae is made up of:

1. Polypeptide
2. Lipopolysaccharide
3. Polysaccharide
4. Glycopeptide

Answer. (3) (Polysaccharide)

Question 19. Gram stain shows most likely which organism:

1. Neisseria meningitidis
2. Staphylococcus aureus
3. Streptococcus pneumoniae
4. Streptococcus pyogenes

Answer. (3) (S. pneumoniae)

Gram-positive cocci in pair, lanceolate shaped with a halo (i.capsule) is suggestive of Streptococcus pneumoniae.

Question 20. Patient is presented with cough with rusty sputum. On examination, lower lobe consolidation and bronchial breath sounds were hearIt gives a positive Quellung reaction. What is the probable Gram staining appearance?

1. Gram -ve bacilli
2. Gram +ve cocci
3. Gram+ve bacilli
4. Gram – ve diplococci

Answer. (2) (Gram + ve cocci)

• History of lobar consolidation –indicates lobar pneumonia
• Quellung test positive- indicates pneumococcal pneumonia
• Pneumococci are Gram-positive diplococci, lanceolate shaped

Question 21. Most common organism causing acute otitis media in a 4-8 year child?

1. Streptococcus pneumoniae
2. Moraxella catarrhalis
3. Staphylococcus aureus
4. Shigella

Answer. (1) (Streptococcus pneumoniae)

• Streptococcus pneumoniae is the MC cause of acute otitis media in children.

Question 22. Mechanism of development of resistance to penicillin in Streptococcus pneumoniae is:

1. Production of Beta-lactamase
2. Mutations in the proteins on the bacterial surface
3. Changes in the membrane permeability to penicillin
4. Production of an alternative penicillin-binding protein

Answer. (4) (Production of an alternative penicillin binding protein)

Alterations in the target enzymes for β-lactam antibiotics, the penicillin-binding proteins (PBPs), have been recognized as a major resistance mechanism in Streptococcus pneumoniae.

Question 23. A person presents with pneumoniHis sputum was sent for culturThe bacterium obtained was gram positive cocci in chains and alpha haemolytic colonies on sheep agar. Which of the following will help in confirming the diagnosis?

1. Novobiocin
2. Optochin
3. Bacitracin
4. Oxacillin

Answer. (2) (Optochin)

• α-hemolytic colonies and gram-positive cocci: Isolated from a sputum of a patient with fever and respiratory distress – Suggestive of:
  • Pneumococcal Pneumonia or
  • Pneumonia due to Str. viridans
• To differentiate Pneumococcus from Str. viridans—Optochin sensitivity test is done.

Question 24. The following statements are true regarding Streptococcus pneumoniae except:

1. It is bile-sensitive
2. The capsule of S. pneumoniae allows establishment of infection
3. It is an etiological agent of pneumonia and otitis media
4. Pneumococcal meningitis is the least virulent of the major bacterial meningitides

Answer. (4) (Pneumococcal meningitis is the least virulent of the major bacterial meningitis)

Among the major bacterial meningitides, Pneumococcus is one of the most virulent organism.

About Other Options

Pneumococcus is:

• Capsulated principle virulence factor
• Bile soluble
• MC cause of lobar pneumonia and otitis media.

Question 25. A 65-year-old patient presented to the emergency with high grade fever, chest pain, increased respiratory rate and cough with expectoration. His sputum was sent to the laboratory for gram straining which showed the presence of pus cells and grampositive cocci in pair. Which of the following will help in confirming the diagnosis?

1. Bacitracin sensitivity
2. Catalase test
3. Bile solubility
4. Coagulase test

Answer. (3) (Bile solubility)
Points in favor:

• Fever and ↑ respiratory rate, chest pain and cough with expectoration: Suggestive of Pneumonia
• Gram-positive cocci in pair was isolated from Sputum: Suggestive of Pneumococcus
• Test to differentiate Pneumococcus from commensal-like Strept Viridans: Bile solubility
  It can be differentiated from other commensal in sputum, i.Strept Viridans:
• Optochin sensitivity (Ethyl hydrocuprein)
• Bile solubility
• Out of this, Bile solubility is a better Option because:
• Few strains of Strept Viridans also can be sensitive to Optochin while few strains of Pneumococcus can be resistant.
• Bile solubility is a constant property of Pneumococcus, hence is of diagnostic importance.