A mother brings her lethargic, feverish baby into the emergency department. The mother states that her baby is not up to date on her immunizations. The baby is diagnosed with meningitis and the doctor performs a spinal tap. The cerebrospinal fluid (CSF) Gram stain shows many tiny gram-negative rods. What is the most probably identification of this organism?

The correct answer is - Haemophilus influenzae serotype b .

Explanation:

Meningitis is a medical condition that is characterized by the inflammation of the protective membrane of the spinal cord or spine and brain in an individual. Commonly it is caused by the infection by the bacteria or viruses that cause the swelling to the protective membrane of the spine and brain.

In this case, it is mention that the cause of the meningitis is due to the gram-negative rods that means it is a bacterial infection and HiB or Haemophilus influenzae serotype b  that cause invasive disease in most commonly in kids below the age of 5 such as meningitis and pneumonia.

Thus, the correct answer is - Haemophilus influenzae serotype b .