This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: CNS infections, Subject name: Pediatrics
A 10-month-old child presents with 2 weeks history of fever, vomiting and alteration of sensorium. Cranial CT scan reveals basal exudates and hydrocephalus, the most likely etiological agent is: 
Select and explain. 
A. Mycobacterium tuberculosis, B. Cryptococcus neoformans, C. Listeria monocytogenes, D. Streptococcus pneumoniae
A: Mycobacterium tuberculosis
Answer: A: Mycobacterium tuberculosis 
Explanation: - History suggests the diagnosis of Tuberculous meningitis caused by Mycobacterium tuberculosis - It is one of the most severe forms of TB Pathogenesis: Primary infection - Bacillemia - Seeding of meninges (RICH's FOCI)- Rupture -Tubercular meningitis Clinical features: Stages: 1. Prodromal stage (fever, anorexia, vomiting, irritability) 2. Focal deficits, seizures, meningeal signs 3. Coma, neurological sequelae Investigations: CNS IMAGING (CT Head) Basal exudates Image showing basal exudates Hydrocephalus Tuberculoma with perilesional edema CSF STUDY: Opening pressure elevated Cell count - 500/mm3 (lymphocytic predominance) Elevated proteins & Low glucose Cob-web coagulum Diagnosis is confirmed if CSF culture / PCR is +ve for mycobactacterium tuberculosis / acid fast bacilli TREATMENT - ATT + Steroids