This is a single center, prospective, open label assessment of β-D-glucan surveillance with preemptive anidulafungin therapy versus standard care for the prevention of invasive candidiasis in at-risk surgical intensive care unit (SICU) patients. Subjects will be stratified by APACHE II score and randomized in 3:1 fashion to either biweekly surveillance using the β-D-glucan assay or standard care. Subjects in the active monitoring arm will receive intravenous anidulafungin should the β-D-glucan exceed 60 pg/mL on a single determination. Subjects in the standard care arm will have biweekly blood draws for β-D-glucan, but the specimens will be batched and tested retrospectively. Antifungal use in the standard care arm is at the discretion of the treating physicians. The primary study end-points are the feasibility of a preemptive antifungal strategy in a SICU setting, β-D-glucan test characteristics, and the safety and tolerability of preemptive anidulafungin. Risks associated with study participation include the risks associated with blood draws, study drug related side effects, and the potential for loss of confidentiality.