There is a huge array of antibiotic, antifungal, antiviral and immune modulating therapies available to fight infections. Which to use depends on the organism involved and the site of infection. Someone with multiple myeloma , as well as some other patients, might benefit from the boost to the immune system provided by intravenous immune globulin. Someone with a herpes virus might need an antiviral drug like acyclovir. Someone with a serious fungal infection might be give an antifungal drug like amphotericin B or Fluconazole.
In an ideal world, the infecting organism would be identified quickly and the most effective drug against it would immediately be given. But cultures and lab test results may take 24 to 48 hours to get. While the offending organism still isn't known, what is called "empirical" therapy will begin, meaning that broad spectrum drugs will be directed against the most likely culprit. Someone with leukemia, for example, with a fever and a low white blood cell count would be given a combination of broad spectrum antibiotics effective in treating the kinds of bacteria known to infect this type of patient.
Once the organism is identified, treatment can be modified, if necessary. The broad spectrum drugs may be replaced by a specific antibiotic most effective against the bacteria or may be continued if tests show they are likely to be effective. If the fever and low white cell count continue after a week or 10 days of antibiotic therapy, an antifungal drug might be added.
Length of Treatment When to stop antibiotic treatment depends on the situation. If you've had fever and a low white cell count but neither the organism nor the site of infection could be identified, then antibiotics will usually be continued until the fever is gone and your white cell count is returning to normal.
