Sepsis, Endocarditis & Antimicrobial Principles

Identify Infection Without Missing Its Mimics

Sepsis is life-threatening organ dysfunction associated with a dysregulated response to infection. In the neuro-ICU, altered consciousness, fever, tachycardia, leukocytosis, or hypotension may also arise from seizures, central fever, drug withdrawal, pulmonary embolism, endocrine crises, or sympathetic hyperactivity. A positive culture can represent contamination or colonization. Use the clinical syndrome and likely source, while beginning emergency stabilization promptly when sepsis is probable.

Assess airway, oxygenation, perfusion, lactate trends, urine output, skin findings, devices, and potential infection sources. Obtain appropriate cultures before antibiotics when this does not cause an important treatment delay. A normal lactate does not exclude sepsis, and an elevated lactate can reflect adrenergic stimulation or impaired clearance in addition to hypoperfusion. Repeated assessment is more useful than interpreting a single number in isolation.

Current Timing and Circulatory Guidance

The 2026 Surviving Sepsis Campaign recommends immediate antimicrobial therapy, ideally within one hour of recognition, for probable or definite sepsis, including shock. For possible sepsis without shock, it supports rapid, time-limited investigation and treatment within three hours if concern persists. A low likelihood of infection without shock permits close monitoring while further evaluation proceeds. This framework avoids treating every unexplained fever as proven sepsis while preserving urgency when serious infection is likely.

For sepsis-induced hypoperfusion or shock, the guideline suggests at least 30 mL/kg of IV crystalloid within three hours, with explicit consideration of individual context and frequent reassessment. Do not mechanically administer additional fluid despite pulmonary edema or evidence of poor fluid tolerance. Unstable shock may warrant concurrent vasopressors and fluid. Norepinephrine is a principal first-line pressor; temporary peripheral administration through an appropriate monitored site can avoid delay while central access is arranged.

A usual initial MAP target around 65 mm Hg may need modification when intracranial pressure or another neurologic condition requires a higher perfusion pressure. The guideline generally favors balanced crystalloids but specifically suggests 0.9% saline in sepsis with TBI. Avoid supplemental albumin in TBI. These distinctions are important because a general ICU recommendation cannot be transferred automatically to every neurologically injured patient.

Choose Antibiotics for the Actual Infection

A loading dose and a maintenance dose answer different pharmacokinetic questions. Do not automatically reduce an urgently needed loading dose simply because renal function is impaired. Subsequent dosing must account for clearance, volume of distribution, dialysis, and organism susceptibility. Prolonged beta-lactam infusion can improve time-dependent exposure in selected settings, but compatibility and delivery must be reliable.

Reassess daily, narrow therapy when microbiology and the clinical course permit, and discontinue treatment when an alternative diagnosis is established. Procalcitonin is an adjunct in selected decisions rather than a substitute for clinical assessment. Antibiotics alone may fail when infected hardware, an obstructed urinary tract, an undrained abscess, or another source remains uncontrolled.

Endocarditis and Neurologic Complications

Infective endocarditis should be considered when bacteremia, embolic infarcts in multiple territories, new valve findings, persistent fever, or a relevant device or exposure is present. Obtain blood cultures and echocardiographic evaluation. TEE may be required when TTE is nondiagnostic and suspicion remains, especially with prosthetic valves or devices. Lack of a loud murmur does not exclude infection.

Neurologic events include septic embolic infarction, hemorrhagic transformation, infected intracranial aneurysm, meningitis, and abscess. A thunderclap headache or new hemorrhage may require vascular imaging. IV thrombolysis for stroke associated with infective endocarditis is hazardous because hemorrhagic complications can occur; selected mechanical interventions require specialist assessment. Valve-surgery timing after a neurologic complication balances uncontrolled infection or cardiac failure against hemorrhage and operative risks.

Encephalopathy in the Immunocompromised Host

Immunosuppressed patients may have infection without robust fever or CSF inflammation. Consider the immune defect, time since transplant or treatment, prophylaxis, exposures, and imaging pattern. Opportunistic infections and treatment toxicity can coexist. Broad coverage may be needed initially, but each additional drug creates interaction and toxicity risks, including calcineurin-inhibitor interactions, beta-lactam neurotoxicity, and marrow suppression. Consult infectious diseases and pharmacy rather than treating all post-transplant encephalopathy with one generic regimen.

Sources checked October 17, 2026: 2026 adult Surviving Sepsis Campaign and IDSA healthcare-associated CNS infection guideline.