Prophylactic Antibiotics Useful With Antibiotic Impregnated External Ventricular Drains (EVDs)?

Inclusion Criteria: * patients over the age of 18 years * patients diagnosed with a subarachnoid hemorrhage, intracerebral hemorrhage, or acute ischemic stroke who require an EVD for management of their underlying condition. In certain cases (a small minority), an EVD must be replaced due to failure (i.e., blood clot interrupting flow). In such cases, patients will be re-dosed with antibiotics prior to catheter exchange in typical fashion and continue in their previously randomized treatment group Exclusion Criteria: * patients who were on antibiotics within the week prior to admission * patients with leukopenia (\<5000) at baseline * patients with signs of meningitis, ventriculitis or any other infection at presentation * patients who are pregnant or prisoners * patients aged \< 18 years old