Fever and other signs of infection in a person with a weak immune system are treated as medical emergencies. Antibiotics need to 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. Antibiotics (which can be anti-bacterial, anti-viral, anti-fungal, or anti-protozoal drugs) are started quickly. After the exact germ is identified, the antibiotic may be continued if the germ is sensitive to it, or a new medicine may be started if the tests show it 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 is 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 each 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” under the section, “How does the doctor know what kind of infection a person with cancer has?”)
If the infection does not 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 might be 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, antibiotics are started after samples for lab tests have been taken, but 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. Often, 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. The good thing is that there are a handful of newer drugs, such as quinupristin/dalfopristin (Synercid®), linezolid (Zyvox®), daptomycin (Cubicin®), tigecycline (Tygacil®), and televancin (Vibativ®) 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 agents. HSV may be treated with acyclovir, valacyclovir (Valtrex®), famciclovir (Famvir®), ganciclovir, or foscarnet (Foscavir®). These same drugs are used to treat cytomegalovirus (CMV), or valganciclovir (Valcyte®) may be used.
If you have chronic hepatitis B, certain cancer treatment drugs can cause it to become active. There are drugs to fight hepatitis B that can be used, such as lamivudine (Epivir-HBV®), adefovir (Hepsera®), entecavir (Baraclude®), telbivudine (Tyzeka®), and tenofovir (Viread®). Your doctor may give you one of these drugs to keep your hepatitis B infection under control during cancer treatment.
Influenza that cannot be prevented by vaccination may be treated with zanamivir (Relenza®) or oseltamivir (Tamiflu®).
Other viruses are less common, but may be treated with other anti-viral drugs.
Protozoal infections
Protozoa seldom cause problems for healthy people, but they can be hard to treat in people with weak immune systems.
Toxoplasma is often treated with pyrimethamine (Daraprim®) plus sulfadiazine or clindamycin (for people who are allergic to sulfadiazine). Other drugs can be used, too.
There is no one treatment for Cryptosporidium infection, which causes severe diarrhea. Treatment is aimed at building up the immune system, treating the diarrhea, and avoiding dehydration.
Fungal infections
Anti-fungal drugs like nystatin and clotrimazole may sometimes be used for people with Candida infections limited to the mouth and throat. For Candida in the esophagus, fluconazole (Diflucan®) or another anti-fungal drug is used. For more serious Candida infections (such as infections in the blood), drugs like amphotericin B or one of its special formulas (Abelcet®, Amphotec®, or AmBisome®) may be given in the vein. Doctors may use a newer family of drugs called echinocandins, such as caspofungin (Cancidas®), mycafungin, or anidulafungin, but these must also be given intravenously (IV).
Amphotericin and voriconazole (Vfend®) are most often used to treat Aspergillus infection.
Cryptococcus and Histoplasma infections are usually treated with anti-fungal drugs like amphotericin, fluconazole, or itraconazole. Posaconazole may be used as a way to try and prevent fungal infections when the ANC is very low.
The usual treatment for people with Pneumocystis jirovecii infection is trimethoprim-sulfamethoxazole (TMP/SMX, Septra®, or Bactrim®). If this drug combination causes side effects, dapsone, atovaquone (Mepron®), pentamidine (Nebupent®), or other drugs may be used.
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