Final answer:
Viral infections typically have few treatment options; they often require supportive care while the immune system works to eliminate the virus. Antiviral drugs exist for some viruses but they are specific and not as broadly applicable as antibiotics for bacteria. Fungal infections are also challenging to treat due to the similarities between fungal and human cells.
Step-by-step explanation:
The microorganism which has few treatment options available and infections often have to run their course is a virus. Infections caused by viruses usually do not respond to antibiotics, and treatment often involves supportive care while the body's immune system fights the virus. There are antiviral drugs available for some specific viral infections, but they are not universal and must be used strategically. Unlike bacterial infections that can be treated with antibiotics, viral infections often require a different approach because viruses are not alive in the traditional sense and use the host's own cells to replicate.
On the other hand, fungal infections can be tricky to treat as well. This is due to the fact that the cells of fungi are eukaryotes, like human cells, which makes targeting them without affecting human cells more difficult. Additionally, the options for antifungal drugs are more limited when compared to antibiotics or antiviral medications.