## **Core Concept**
The question revolves around the treatment of Cytomegalovirus (CMV) infection in an HIV-infected patient. CMV is a type of herpesvirus that can cause severe disease in immunocompromised individuals, such as those with HIV/AIDS. The treatment of CMV infection typically involves antiviral medications that target viral replication.

## **Why the Correct Answer is Right**
The correct answer, **Ganciclovir**, is a potent antiviral agent used to treat CMV infections. It works by inhibiting viral DNA synthesis. Ganciclovir is a guanosine analog that, after phosphorylation by viral enzymes, is incorporated into the viral DNA, causing chain termination. This mechanism effectively stops the replication of CMV. Ganciclovir is often used in immunocompromised patients, including those with HIV/AIDS, who develop CMV disease.

## **Why Each Wrong Option is Incorrect**
- **Option A: Zidovudine** is incorrect because it is primarily used to treat HIV infection, not CMV. It works by inhibiting the reverse transcriptase enzyme of HIV, which is essential for the replication of the virus.
- **Option B: Ribavirin** is incorrect because it is used to treat respiratory syncytial virus (RSV) infection, hepatitis C (in combination with other drugs), and some other viral infections, but it is not the first-line treatment for CMV.
- **Option D: Fosamprenavir** is incorrect because it is a protease inhibitor used in the treatment of HIV infection, not CMV.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that **Ganciclovir** and its oral prodrug **Valganciclovir** are the mainstays of treatment for CMV infection. These drugs are particularly important in immunocompromised patients, including those with HIV/AIDS, where CMV can cause severe and life-threatening disease.

## **Correct Answer:** . Ganciclovir