Question

A 6 year old boy has fever and chills, cough, rapid breathing, difficulty breathing and chest pain. Culture from a sample shows a Gram-positive organism. Identify the image.

• A. Streptococcus pneumoniae
• B. Staphylococcus
• C. Propionibacterium
• D. Mycobacterium

Hint:

Alpha-hemolytic, lancet-shaped Gram-positive diplococci causing childhood community-acquired pneumonia.

Answer 1

The Correct Option is A

Step 1: Streptococcus pneumoniae (pneumococcus) is a Gram-positive bacterium responsible for the majority of community-acquired pneumonia, which fits the clinical picture of fever, chills, cough, rapid breathing and chest pain in this child.
Step 2: The image shows the typical lancet-shaped Gram-positive diplococci. S. pneumoniae is alpha-hemolytic, breaking down red blood cells by producing hydrogen peroxide (\(H_2O_2\)).
Step 3: This \(H_2O_2\) production damages DNA and kills lung cells, producing pneumococcal pneumonia; spread to the central nervous system can cause pneumococcal meningitis.
Step 4: Staphylococci appear as Gram-positive clusters and are usually beta-hemolytic; Propionibacterium is an anaerobic skin commensal; Mycobacterium is acid-fast and not seen as Gram-positive cocci. Hence the organism is Streptococcus pneumoniae.