A 62-year-old man is brought to the emergency department due to fever, headache, confusion, and vomiting for the past 2 days. His medical history is significant for liver transplantation secondary to Wilson disease, hypertension, and type 2 diabetes mellitus. The patient's medications include long-acting insulin, amlodipine, and tacrolimus; he has no medication allergies. Temperature is 39.2 C (102.6 F), blood pressure is 120/75 mm Hg, pulse is 102/min, and respirations are 18/min. He is awake but confused. Funduscopy shows no abnormalities. His neck is stiff. Cardiac and pulmonary examinations are normal. White blood cell count is 17,000/mm³ with neutrophilic predominance. Serum creatinine is 1.1 mg/dL. Blood cultures are drawn. CT scan of the head is unremarkable. Lumbar puncture results are pending. Which of the following is the most appropriate empiric antibiotic therapy for this patient?

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11ec25c8_d461_0eba_bc81_7fa9e29d4371_MD0003_00 This patient's presentation of fever, headache, nuchal rigidity, vomiting, and altered mental status is consistent with acute bacterial meningitis. Evaluation of bacterial meningitis includes blood cultures and lumbar puncture (LP). A head CT scan should be performed prior to LP to rule out intracranial mass in patients with certain risk factors (eg, immunocompromised state, previous central nervous system disease, new-onset seizures, papilledema, altered mental status, focal neurologic deficits). Antibiotic therapy is generally initiated after obtaining an LP and blood cultures; however, if LP must be delayed for neuroimaging, antibiotics should be started immediately after drawing blood cultures. Empiric treatment for bacterial meningitis depends on risk factors and specific pathogens. In immunocompromised patients (eg, transplant recipients on immunosuppressants), the treatment of choice is cefepime or ceftazidime plus vancomycin plus ampicillin. Cefepime is a fourth-generation cephalosporin that covers most of the major organisms of bacterial meningitis (eg, Streptococcus pneumoniae, Neisseria meningitidis, group B streptococci, Haemophilus influenzae) as well as Pseudomonas aeruginosa. Vancomycin provides coverage against cephalosporin-resistant pneumococci, and ampicillin covers Listeria monocytogenes. Patients should also empirically receive dexamethasone to help prevent the neurologic complications (eg, deafness, focal deficits) of S pneumoniae meningitis, but it should be discontinued once pneumococcal meningitis is ruled out. (Choice A) Cefepime and ampicillin would cover most organisms responsible for meningitis, including Pseudomonas and Listeria; however, vancomycin is also necessary in this patient to cover cephalosporin-resistant pneumococci. (Choices C and E) Ceftazidime (or meropenem) and vancomycin are indicated for patients with neurosurgery/shunt or penetrating trauma to the skull who have symptoms of meningitis. This regimen covers methicillin-resistant Staphylococcal aureus, coagulase-negative staphylococcus, and gram-negative rods (eg, Pseudomonas); however, it does not adequately cover Listeria. (Choice D) Ceftriaxone alone is effective in the treatment of meningitis due to H influenzae or N meningitidis. Educational objective: Empiric antibiotics must not be delayed while awaiting results of CT scan or performing lumbar puncture to diagnose bacterial meningitis. Cefepime plus vancomycin plus ampicillin is the regimen of choice for immunocompromised patients with suspected bacterial meningitis. Corticosteroids should be started at the same time as antibiotics and discontinued if cultures show an organism other than Streptococcus pneumoniae. References: Epidemiology, diagnosis, and antimicrobial treatment of acute bacterial meningitis. (http://www.ncbi.nlm.nih.gov/pubmed/20610819) Bacterial meningitis in older adults. (http://www.ncbi.nlm.nih.gov/pubmed/23801036) Corticosteroids for acute bacterial meningitis. (http://www.ncbi.nlm.nih.gov/pubmed/17253505)

A 62-Year-Old Man Is Brought to the Emergency Department Due