Patients received a short induction treatment with ganciclovir i.v (Cymevene®; F. Hoffmann-La Roche Ltd, Basel, Switzerland) at the dose of 5 mg/kg/12h, by a peripherical vein infusion of one hour, during 5 days followed by treatment with oral valganciclovir (Valcyte®; F. Hoffmann-La Roche Ltd, Basel, Switzerland) at 900 mg/12h during 16 days, after meals, until complete a total of 21 days of treatment. In patients with impaired renal function ganciclovir i.v. and oral valganciclovir doses were adjusted at each visit according to estimated Glomerular Filtration Rate (GFR) by Cockcroft-Gault equation, as recommended by the manufacturer.