Emerging (val)ganciclovir resistance during treatment of congenital CMV infection: a case report and review of the literature.

BACKGROUND: Congenital cytomegalovirus (cCMV) infection is an important illness that is a common cause of hearing loss in newborn infants and a major cause of disability in children. For that reason, treatment of symptomatic patients with either ganciclovir or its pro-drug valganciclovir is recommended. Treatment duration of 6 months has been shown to be more beneficial than shorter courses; however, there is uncertainty regarding emergence of resistance strains, secondary effects and long term sequelae.

CASE PRESENTATION: Here we present a female infant with symptomatic cCMV who was treated from day 5 of life with oral valganciclovir. In spite of close monitoring of her drug levels and increments of her treatment dose according to weight gain, she developed ganciclovir resistance after 4 months of treatment, with increasing viraemia and petechiae. Adherence to treatment was assessed and felt to be good. Clinically, although she had marked developmental delay, she was making steady progress. In view of the development of resistance treatment was stopped at 5 months of age. No secondary effects of ganciclovir were noted during the whole course.

CONCLUSIONS: There were few cases in the literature reporting resistance to ganciclovir for cCMV before the new recommendations for a 6 months treatment course for this infection were published. As demonstrated in our patient, surveillance with periodic viral loads and drug monitoring are vital to identify emerging resistance and optimise antiviral dosing according to weight gain.