Question

A child was brought with complaints of high fever, multiple seizures, headache, and neck rigidity. CSF analysis showed low glucose, high protein, and many polymorphs. The CSF culture showed pleomorphic gram-negative bacilli. What is true about the causative organism?

• A. It is bacitracin sensitive
• B. Produces non-lactose fermenting colonies on MacConkey agar
• C. Exhibits satellitism around Staphylococcus aureus colonies
• D. It exhibits alpha hemolysis on sheep blood agar

Answer 1

The Correct Option is C

To identify the causative organism based on the provided clinical details and lab findings, we must examine several key indicators. The child's symptoms—high fever, multiple seizures, headache, and neck rigidity—along with the cerebrospinal fluid (CSF) analysis showing low glucose, high protein, and many polymorphs suggest a bacterial meningitis. The CSF culture revealed pleomorphic gram-negative bacilli. Among the given options, one key characteristic is helpful in identifying the organism:

• Pleomorphic gram-negative bacilli, along with the unique characteristic of exhibiting satellitism around Staphylococcus aureus colonies, strongly indicates the presence of Haemophilus influenzae.
• Satellitism: Haemophilus influenzae requires factor X (heme) and factor V (NAD) for growth. When cultured with Staphylococcus aureus, the latter produces NAD as it grows, allowing H. influenzae to grow in satellite colonies around it.

Based on these observations, the true statement about the causative organism is: Exhibits satellitism around Staphylococcus aureus colonies.

Characteristic	Description
Bacitracin sensitivity	Not applicable to H. influenzae
Non-lactose fermenting colonies on MacConkey agar	H. influenzae does not grow on MacConkey agar
Satellitism around Staphylococcus aureus	Characteristic of H. influenzae
Alpha hemolysis on sheep blood agar	Not a feature of H. influenzae