G.B., a 55-year-old woman recently diagnosed with carcinoma of the large bowel, is admitted to the..

G.B., a 55-year-old woman recently diagnosed with carcinoma of the large bowel, is admitted to the hospital for an elective colorectal surgical resection; the surgery is expected to last 5 hours. Physical examination reveals a cachectic woman with a 9-kg weight loss during the previous 3 months (current weight, 60 kg). Increased frequency of bowel movements and chronic fatigue are noted; all other systems are normal. Laboratory data include the following: Hemoglobin (Hgb), 10.4 g/dL (normal, 12.1–15.3 g/dL; SI units, 104 g/L) Hematocrit (Hct), 29.7% (normal, 36%–45%; SI units, 0.297) Prothrombin time (PT), 15 seconds (normal, 10–13 seconds) Stool guaiac is positive. Vital signs are within normal limits. G.B. is taking no medications and has no history of drug allergies. The following orders are written to begin at home on the day before surgery: (a) clear liquid diet; (b) mechanical bowel cleansing with polyethylene glycol-electrolyte lavage solution (CoLYTE, GoLYTELY); and (c) neomycin sulfate 1 g and erythromycin 1 g orally (PO) at 1 PM, 2 PM, and 11 PM. Comment on the appropriateness of the oral route of administration of antibiotic prophylaxis for G.B.