Ganciclovir is primarily used to treat which of the following conditions?

Ganciclovir is primarily utilized in the treatment of cytomegalovirus (CMV) infections, particularly in patients with compromised immune systems, such as those with HIV/AIDS or those undergoing organ transplantation. It is an antiviral agent that targets the replication of DNA viruses, making it effective against CMV retinitis, which is a sight-threatening condition often seen in patients with advanced HIV infection.

While Herpes Simplex Virus (HSV) keratitis is treated with acyclovir or valacyclovir, ganciclovir is specifically indicated for CMV-related pathologies, rather than HSV infections. Choices involving fungal and bacterial infections are not appropriate for ganciclovir, as it does not have antifungal or antibacterial properties.

Thus, ganciclovir serves a critical role in managing CMV retinitis, particularly in immunocompromised individuals, but it is not indicated for other viral conditions like HSV keratitis, nor for fungal or bacterial infections.