Prospective, multicenter, observational clinical registry of adult patients with acute infectious meningitis across approximately 30 public and private hospitals in Brazil. The study will include adults, 18 years old and older, with suspected acute infectious meningitis. Data will be collected during hospitalization and post-discharge to evaluate clinical management, treatment and short and long-term outcomes. The study aims to generate real-world evidence on current practices and outcomes to support improvements in national care protocols.

This is a middle-income real-world prospective clinical registry study. Clinical and laboratory data will be collected during hospitalization and follow-up visits after discharge.

Data collection will include empirical antibiotic therapy timing and type, time from hospital admission to antibiotic's first dose, corticosteroid therapy initiation, vaccination status per the Brazilian National Immunization Program, neurological sequelae and access to specialized rehabilitation services post-discharge.

Primary outcomes will be all-cause mortality, length of hospital stay, rate of re- hospitalization and sensorineural hearing loss incidence.

Secondary outcomes will be etiology-specific mortality, functional outcomes (measured by modified Rankin Score and Barthel Index Brazilian version), guideline-based therapies by etiology, neurological sequelae incidence stratified by etiology (e.g., motor deficits, cerebrovascular complications) , serious adverse events and access to rehabilitation.

Findings will be used to inform public health system and clinical care in Brazil.

Inclusion Criteria:

• Fever (axillary temperature ≥37.8°C) followed by two or more of the following symptoms: severe headache, vomiting, altered consciousness (confusion, drowsiness, or irritability), photophobia (increased sensitivity to light), presence of seizures OR
• Fever accompanied by at least one meningeal irritation sign, such as neck stiffness, Kernig's sign, or Brudzinski's sign OR
• Sudden onset of fever and appearance of petechial skin rash or hemorrhagic suffusions

Exclusion Criteria:

- Refusal to provide consent for study participation

Adult, ≥ 18 years old, suspect acute meningitis infection