How is infection treated in people with cancer?

Fever and other signs of infection in a person with a weak immune system are treated as medical emergencies. Antibiotics should be started right away. After a complete physical exam, lab tests will be done to try to find out exactly which germ is causing the infection and where the infection is. Then antibiotics (which can be anti-bacterial, anti-viral, anti-fungal, or anti-protozoal drugs) are started quickly. After the exact germ is identified, the antibiotics may be continued, or new medicines may be started if the tests show others would work better.

Where treatment is given

In the past, patients were almost always put in the hospital to treat these infections, and many still are. But some patients can take their antibiotics in pill or liquid form. And some patients who need intravenous (IV) antibiotics may be able to get them in clinics, doctor’s offices, or at home.

Home care is only used with infections that are not likely to become more serious. The patient must have an adequate home environment that’s safe for home care. They must have a responsible adult at home with them at all times, and be able to handle treatment at home. The patient must have a phone, and be able to get to the hospital or clinic quickly. The doctor or cancer care team must be able to see the patient every day for the first few days and do needed tests. If all goes well, they still will need to stay in close contact during treatment. Otherwise, the patient may need to be put in the hospital.

What treatment may be like

At first, the patient is watched closely and lab results are checked often. The white blood cell (WBC) count and absolute neutrophil count (ANC) are checked daily. Antibiotics may be changed when the final culture results come in. (The culture tells which germ is causing the infection; see “Lab tests to identify germs” in the section, “How does the doctor know what kind of infection a person with cancer has?”)

If the infection doesn’t get better, an infectious disease specialist may be called in. These are doctors who specialize in treating infections. This doctor may recommend extra testing and different treatments. In some cases, CSFs (colony-stimulating factors) may be given to boost the WBCs so the body can better fight the infection.

Each type of infection (bacterial, viral, protozoal, and fungal) is treated with different drugs. If you have any questions about drugs you are given or why you’re taking them, talk with your doctor or nurse.

Bacterial infections

When treating bacterial infections in people with weak immune systems, samples are taken for lab testing and antibiotics are started before these test results have identified the germ. Doctors think about the site of infection and the germ most likely causing it when choosing antibiotics to use at this point. Most often, antibiotics that will treat many different bacteria are chosen. These are called broad-spectrum antibiotics. Many times, 2 or 3 antibiotics are used at the same time.

Drug-resistant germs: Even in serious situations, overuse of antibiotics must be avoided because this can cause some bacteria to become resistant to these drugs. Such germs are called drug resistant because they no longer respond to the antibiotics that killed them in the past. Germs change and adapt all the time. For example, some strains of Staphylococcus (staph) have become resistant to most antibiotics. Staph can be resistant to methicillin and other antibacterial drugs. Staph that is resistant in this way is called methicillin resistant staph aureus, or multi-drug-resistant staph aureus. This is often shortened to the initials MRSA and may be pronounced MER-suh rather than being spelled out.

Some staph has now become resistant to intravenous (IV) vancomycin, which was once used to treat resistant infections. This is called vancomycin resistant staph aureus or VRSA (may be pronounced VER-suh). The good thing is that there’s a handful of newer drugs that can still work against some of these hard-to-kill germs. To avoid spreading drug-resistant bacteria to other patients, health care workers often wear disposable gowns and gloves when caring for people known to have these infections.

Viral infections

While anti-bacterial antibiotics have been available for around 70 years, anti-viral drugs are somewhat newer. Herpes simplex virus (HSV) and varicella zoster are most often treated with anti-viral drugs. These same kinds of drugs are used to treat cytomegalovirus (CMV).

If you have chronic hepatitis B, certain cancer treatment drugs can cause it to become active. There are drugs to fight hepatitis B. Your doctor may give you one of these drugs to keep your hepatitis B infection under control during cancer treatment. (See “Prophylactic antibiotics” in the section called “Use prescribed medicines to prevent infections.”)

Influenza that cannot be prevented by vaccination may be treated with an anti-viral drug. Other viruses are less common, but if they become a problem, they can be treated with anti-viral drugs, too.

Protozoal infections

Protozoa seldom cause problems for healthy people, but they can be hard to treat in people with weak immune systems.

Toxoplasma can be treated with a variety of drugs. But there’s no one treatment for Cryptosporidium infection, which causes severe diarrhea. In this case, treatment is aimed at building up the immune system, treating the diarrhea, and avoiding dehydration.

Fungal infections

People with Candida infections in the mouth, throat, and esophagus might be prescribed oral anti-fungal drugs. For more serious Candida infections (such as infections in the blood), anti-fungal drugs may be given in the vein (IV).

There are anti-fungal drugs to treat Aspergillus, Cryptococcus, Histoplasma, and Pneumocystis infections.

Some of these drugs are also used to try to prevent fungal infections when the ANC is very low. (For more on this, see “Prophylactic antibiotics” in the section called “Use prescribed medicines to prevent infections.”)