A 50-year-old male with a past medical history of hypertension presents to the emergency department with right upper quadrant abdominal pain, nausea, and fevers. He is noted to have an elevated white blood cell count and total bilirubin of 5 mg/dL. Further evaluation with an abdominal ultrasound shows a dilated common bile duct to 8 mm with a visualized obstructing gallstone within the lumen. All of the following are appropriate antibiotic choices EXCEPT:A. Pipercillin-Tazobactam 3.375 g IV every 6 hours
Correct Answer: D
Empiric antibiotic choices should include those with coverage of enteric pathogens, which can later be narrowed based on culture data. Most common pathogens include gram negative aerobic enteric organisms (Escherichia coli, Enterobacter species, Klebsiella species), gram positive organisms (Streptococcus and Enterococcus species) and anaerobes. Though unlikely in this patient, history of healthcare-associated infections or infection with drug-resistant organisms may require additional empiric coverage. All choices except ceftriaxone are effective against the spectrum of common pathogens relevant in ascending cholangitis. Though ceftriaxone is effective against various gram positive and negative organisms, it is not effective against anaerobes.