A 12-year-old boy presents with three weeks of daily fevers, significant abdominal pain, and a 3kg (6.6lb) weight loss. He has a new kitten at home. An abdominal CT scan reveals multiple hypodense lesions throughout his liver and spleen. A diagnosis of disseminated cat scratch disease is made. Which antimicrobial regimen has been shown to have the best clinical response for this hepatosplenic presentation?