Infection is the process by which germs (also called microbes or microorganisms) enter the body, multiply, and cause illness. The main types of germs are bacteria, viruses, protozoa (parasites), and fungal organisms (also called fungi).

Infections in people who have cancer or are getting cancer treatment can be more serious than those in people without cancer. They can also be harder to treat. It is important to find these infections and treat them quickly, before they worsen and spread. The good news is that patients and their families may be able to help prevent some infections by learning about them. Then they can take steps to avoid being exposed to dangerous germs. Certain medicines and other personal actions can also help prevent illnesses even if the patient is exposed to them. And if an infection occurs, it helps to know what to look for and what can be done.

This information will help you understand more about infections--especially those that are more common in people with cancer. You will also learn how to avoid them and what may be done if you do get an infection.

When a person has cancer, the cancer itself and certain types of cancer treatment can increase a person's risk of getting a serious infection. Once the cancer is gone and treatment is finished, the risk of infection usually goes down to a more normal level. For most people, this high-level risk for serious infection lasts for a limited time.

The risk of infection depends on the type of cancer and the treatment a person receives. Most people with cancer do not have much risk of developing the infections discussed here. For example, surgery does not weaken a person's resistance to infection nearly as much as a bone marrow transplant. (For more information see the separate ACS document, Bone Marrow and Peripheral Blood Stem Cell Transplants.) Some chemotherapy drugs are less likely than others to affect a person's resistance to infection. It is important to weigh the risk of infection and other side effects against the benefits of cancer treatment.

People with cancer might want to talk with their doctors before or during chemotherapy or radiation treatment to see how this information applies to them. Here are some questions to ask your doctor or cancer care team before and during cancer treatment:

• Will my cancer treatment make me more likely to get infections? 
• How severe is an infection likely to be, and how long might it last? 
• Will you take any special measures to prevent infections during this time? 
• What can I do to lower my risk of infection during this time? 
• How will I know if I have an infection? 
• What should I do if I think I have an infection? 
• If I get a fever, does that mean I have an infection? 
• How will you decide how to treat my infection? 
• What will you do if the treatment does not relieve my infection? 
• What are the likely side effects of the proposed treatments for infection?

How Does the Body Normally Resist Infections?

Your body has many ways to protect itself from infections. It helps to understand the body's normal protective mechanisms, and the changes that often happen in people with cancer. This may help explain why infections can develop so easily and be so serious in people with cancer.

Skin and Mucous Membranes

Skin is the body's largest organ and the most important physical barrier against infections. It is the first line of defense in protecting internal tissues against dehydration (drying out) and harmful germs. When there is a break in the skin, germs (sometimes from the air, but most often from the skin or objects in our environment) can enter the body and cause infection.

The mucous membranes, which form the moist, pink lining layer of the mouth, throat, nose, eyelids, urethra, vagina, and digestive (gastrointestinal) system, also provide an internal barrier against infection. These membranes normally help protect us from germs in the air we breathe, in the environment, and in our food and drink.

Cancer treatments such as chemotherapy, radiation therapy, surgery, and invasive procedures (for example, inserting catheters) can damage the skin or mucous membranes so that germs can get inside the body.

The Immune System and Blood Cells

If germs get through the skin and mucous membranes, the job of protecting the body then shifts to the immune system and some of its special blood cells. The immune system is a complex network of cells, signals, and organs that work together to help destroy germs that cause infections. Many of these special blood cells circulate in the bloodstream until they find germs to attack. Others spend part of their time in the blood and the rest of their time in immune system organs.

Blood is made when cells in the bone marrow, called stem cells, grow into different kinds of mature cells and are released into the bloodstream to do their work. There are three major kinds of blood cells:

• red blood cells (RBCs or erythrocytes), which carry oxygen to cells throughout the body 
• platelets (thrombocytes), which are needed to help plug up holes that form in blood vessels during injuries such as cuts, scrapes, or bruises 
• white blood cells (WBCs or leukocytes), which are needed to protect the body against germs

Unlike red cells and platelets, white blood cells are part of the immune system. There are different types of white blood cells, and they each have a key role in the body’s defense against germs.

The type of white blood cell we have in greatest numbers is called the neutrophil. They provide an especially important defense against most types of infections. For this reason, when predicting which people with cancer are likely to develop serious infections, having too few neutrophils is the biggest risk factor

Neutropenia is the medical term used to describe a shortage of neutrophils. It is important to talk with your doctor and find out if your treatment will cause neutropenia.

There are other important types of white blood cells:

• lymphocytes (especially the T-lymphocyte and B-lymphocyte) 
• monocytes 
• macrophages

Each WBC type has a special role in fighting infections. The B-lymphocytes make antibodies that recognize and kill some germs. They also can mark germs to be destroyed. The T-lymphocytes produce signaling substances called cytokines that tell other cells what to do. Lymphocytes can also fight viruses. Some treatments, especially those given during bone marrow transplants, can cause a shortage of lymphocytes.

Monocytes and macrophages help lymphocytes recognize germs. Monocytes and macrophages can surround and digest germs that have been coated by antibodies (proteins your body makes to respond to invasion by a foreign substance). They are important in fighting bacteria, fungal organisms, and parasites.

Risk Factors for Infections in People with Cancer

Certain types of cancer directly damage the immune and blood systems or interfere with their work. In lymphomas (Hodgkin and non-Hodgkin) and certain types of leukemias that develop from immune system cells, cells that once protected the body change and begin to interfere with the immune system. Other types of cancer can also affect immunity.

It is usually the treatments used to fight the cancer, not the cancer itself that changes the immune system. The treatments can cause short- or long-term damage. For example, long-term damage happens when immune system organs such as the spleen are removed. A splenectomy (surgical removal of the spleen) is sometimes done to remove cancer or learn the extent of its spread. Chemotherapy, radiation therapy, or a combination of both can lead to short-term immune system damage.

Some people with cancer have a higher risk of infection because of the changes in their body’s defense systems. Cancer and treatments for cancer can affect these systems in different ways.

Immune Suppression, Leukopenia, and Neutropenia

Chemotherapy, radiation therapy, surgery, stem cell transplant, bone marrow transplant, steroids, or the cancer itself can suppress the immune system (sometimes called immunosuppression). These factors can lower the number of white blood cells (WBCs) and other immune system cells the body makes, and can cause them to work less effectively. A person may develop an infection when there aren’t enough WBCs, especially neutrophils, to destroy germs.

The medical term for a low white blood count is leukopenia. Blood normally has between 4,000 and 10,000 WBCs per cubic millimeter (mm3). When looking at the risk of infection, however, doctors look for a decrease in the number of neutrophils, called neutropenia.

In blood tests, the normal range for neutrophils is between 2,500 and 6,000 per mm3 of blood. It is possible for a person to have a normal total WBC count, but still be neutropenic. But usually the WBC count is low when the neutrophil count is low.

Absolute Neutrophil Count

Doctors use the absolute neutrophil count or ANC to determine the stage the immune system is in after chemotherapy. You might want to keep track of your ANC so you will know if you are at risk of getting an infection.

Normally, neutrophils make up 50%-70% of all the WBCs. To find out the actual number of neutrophils, also known as the absolute neutrophil count, multiply the percentage of neutrophils by the total number of WBCs. Neutrophils are sometimes called "segs" or "polys," and young neutrophils are called "bands." If there are bands listed as a percentage of WBCs, those are added to the neutrophils before multiplying.

The numbers for the absolute neutrophil count are taken from the results of a blood test called the differential WBC count. For example, if a patient's WBC count is 1,000 and the percentage of neutrophils is 70% (in other words, 7 out of every 10 WBCs counted were neutrophils), and there are no bands, then the ANC is:

(70/100) x 1,000 = 700

Another example is if the patient’s WBC is 1300, with 60% neutrophils and 5% bands. The bands are added with the neutrophils (60% + 5% = 65%), and the ANC is:
(65/100) x 1,300 = 845 (or, using a decimal, 0.65 x 1,300)

An ANC less than 1,000 is considered to be neutropenia. The lower the ANC drops and the longer it lasts, the higher the risk for serious infection. If the ANC drops below 500 for a few days, a person is at higher risk of infection. If the ANC is 100 or less for over a week, the risk of serious infection is extremely high.

As the ANC gets lower, the usual signs of infection, such as pus, pain, swelling, and redness may be absent. This is because these signs are caused by neutrophils fighting off germs. So having few neutrophils can mean there may be no signs of the body fighting back, even though the germs are there. This makes it hard to know if you have an infection. Fortunately, another WBC (the monocyte) can still cause fever (an increase in body temperature) in the person who has neutropenia. In people with severe neutropenia, fever may be the only sign of an infection.

When the ANC is 1,000 or lower, doctors will assume that a fever is caused by an infection and will start treatment with antibiotics right away. The longer the neutropenia lasts and the lower the neutrophil count, the higher a person's risk for a serious infection. During this time infections must be found and treated as quickly as possible.

Tumor-Related Problems

Cancer cells can invade and replace the normal cells in the bone marrow. The cancer cells compete with the normal bone marrow cells for space and nutrients. If too many normal marrow cells are destroyed or pushed out of the bone marrow, the remaining cells will not be able to make enough WBCs to fight infection.

Cancer can also damage parts of the immune system without getting into the bone marrow. A tumor can grow through the skin or mucous membrane, breaking natural barriers and allowing germs to enter. Tumors may also reduce blood flow to the normal tissues by pressing on them or their blood supply. Tumors in the lungs may block normal mucous drainage, which can lead to infections. Damaged tissues are more prone to infections.

Cancer cells can also release chemicals that interfere with immune cells. This is a well-known effect of many cancers that start in immune system cells (such as lymphomas, leukemias, and multiple myeloma). It can happen with other cancers too.

Nutrition and Metabolism

All cells need nutrients to grow and work. Changes in eating habits, such as lower intake of vitamins, minerals, calories, and protein can reduce immune function. Poor nutrition makes the immune system less able to find and destroy germs, so people who are malnourished (do not take in enough calories and nutrients) are more likely to develop infections.

People with cancer often are malnourished for many reasons:

•  The cancer itself may make it hard to eat or digest food. This is common in people with cancers of the digestive system, mouth, or throat. 
• Cancer treatments such as radiation therapy and chemotherapy may cause a loss of appetite and nausea. 
• People with cancer often need extra calories and protein to maintain adequate nutrition for their immune system cells and other tissues. 
• Recovery from surgery increases the body's need for nutrients. 
• Cancer cells use up nutrients, leaving less available to meet the needs of normal tissues.

For these reasons, people with cancer often need help from nutritionists, dietitians, and doctors to maintain their nutrition. Dietary supplements, tube feedings, or even intravenous (IV, through a vein) feedings may be useful in some cases.

Surgery

Any type of major surgery can suppress the immune system, but the reason for this is not very clear. Within hours of surgery, researchers have seen decreases in immune function. Anesthesia (the drugs used to make the patient sleep) may play a role. Complete immune system recovery may take from 10 days to many months.

Surgery also breaks the skin and mucous membranes and exposes internal tissues to germs. The wound caused by surgery (incision) is a common site of infection.

Surgery is often used to diagnose, stage, or treat people with cancer. Things that raise the risk of infection after surgery include:

• how long the person was in the hospital 
• the extent of the surgery 
• how long the operation lasted 
• the amount of bleeding during surgery 
• nutritional status of the patient 
• prior cancer treatment such as chemotherapy or radiation 
• other medical problems such as diabetes, heart, or lung problems

People with cancer may get antibiotics before surgery to lower their risk of infection. Because surgery is commonly used to treat people with cancer, it is important to be aware of the chance of infection after surgery.

Chemotherapy

Chemotherapy or chemo is the most common cause of a weakened immune system in people getting cancer treatment. The effects on the immune system depend on many factors, including:

• which chemo drugs are used 
• chemo doses (how much is given at once) 
• schedule (how often it is given) 
• prior treatments for cancer 
• age 
• nutritional status 
• type of cancer 
• stage of the cancer

Some drugs have a greater effect on the bone marrow than others. However, drugs may have different effects on the production of white blood cells, red blood cells, and platelets. Generally, white blood cells are affected by chemo drugs the most.

Radiation Therapy

The effects of radiation therapy on the cells of the bone marrow are similar to the effects of chemotherapy. Specifically, people may develop leukopenia or neutropenia, which will increase their risk for infections.

Several factors affect the degree of leukopenia from radiation therapy. These include:

• the total radiation dose 
• the radiation schedule 
• how much of the body is treated with radiation

Unless a person’s entire body is treated with radiation (total body irradiation or TBI), he or she usually does not have extremely low blood counts. This is because radiation is most often given to just one area of the body, while chemotherapy affects the entire body. Still, depending on the dose and type of radiation, the skin or mucous membranes may be damaged, making them less able to keep germs out.

Today, radiation treatments are given over many sessions rather than in one large dose. This helps decrease the amount of immune suppression and risk of infections.

Biotherapy or Immunotherapy

Biotherapy, also known as biologic therapy or immunotherapy, is given to strengthen the immune system's ability to recognize and attack cancer cells. Although these treatments promote immune reactions against cancer cells, they sometimes interfere with immunity against infections. Because of this, people who receive biologic therapies may be at risk for immune suppression and neutropenia. Their WBC count may drop, but will return to normal after the therapy is stopped.

Hematopoietic Stem Cell Transplant (Bone Marrow Transplant)

Hematopoietic stem cell transplant (HSCT) is the term now used to include both bone marrow transplant (BMT) and peripheral blood stem cell transplant (PBSCT). These transplant therapies use very high doses of chemo and/or total body irradiation (TBI) to try and kill all the cancer cells in the body. In the process of killing the cancer cells, the blood-forming stem cells of the patient's normal bone marrow are also killed. Because of this, stem cells (from the bone marrow or blood) are removed from the patient before chemo is given. Or, if possible, they may be taken from a donor. Once the cancer cells are killed, the stem cells are given to the patient to restore immune function.

The use of intensive chemotherapy in transplant therapies, sometimes combined with TBI, causes more severe neutropenia over a longer period of time. These treatments, especially when used together, also damage the ability of the skin and mucous membranes to keep germs out of the body.

For these reasons, very strict precautions are taken to try and protect transplant patients from getting infections. This usually includes keeping the transplant patient in a special area of the hospital until white blood cell counts begin to reach normal (which often takes weeks), limiting their exposure to outside people or other sources of germs, and watching them closely for signs of infection, such as fever.

Patients who receive stem cells from other people may also need medicine to prevent a serious problem called graft versus host disease. These medicines suppress the immune system. For more information on these procedures, see the American Cancer Society document Bone Marrow and Peripheral Blood Stem Cell Transplants.

Types of Infections That Affect People with Cancer

People with cancer may get many different types of infections. These infections differ in their risk factors, the symptoms they cause, their prognosis (outlook), and how they are treated. When looking at the different types, it is useful to think of 2 key aspects of the infection -- the part of the body affected and the type of germ causing the infection.

Areas of the Body Affected by Infections

The patient's signs and symptoms (for example, the location of any pain, redness, or swelling) and the results of imaging tests (such as x-rays, CT scans, nuclear medicine scans, etc.) help to identify where the infection is.

The common sites of infection in people with cancer include

• the skin and mucous membranes 
• the digestive system (esophagus, stomach, and intestines) 
• the respiratory system (sinuses, throat, and lungs) 
• the urinary system (bladder and kidneys) 
• the nervous system (brain and spinal cord) 
• the skin and tissue around a vascular access device (VAD). The VAD is a tube or catheter placed in the vein that is used to draw blood and give IV medicines or fluids.

The medical names for various types of infections sometimes simply add, "itis," after the English, Latin, or Greek name of a tissue or organ. Knowing some of these terms can help patients understand their medical conditions so that they can take a more active part in their own treatment decisions. For example:

Medical term	BodySite affected by infection
Cellulitis	Deep layers of skin
Mucositis	Any area of mucous membranes
Stomatitis	Mucous membranes of the mouth
Esophagitis	Mucous membranes of the esophagus (tube connecting the throat and stomach)
Gastroenteritis	Stomach and intestines
Enteritis	Mucous membranes of the small intestine
Colitis	Mucous membranes of the large intestine
Enterocolitis	Mucous membranes of the small and large intestines
Sinusitus	Sinuses
Pharyngitis	Mucous membranes of the throat
Bronchitis	Tubes leading into the lungs
Pneumonitis or pneumonia	Lungs
Urinary tract infection or UTI	Urinary system in general
Cystitis	Urinary bladder
Pyelonephritis	Kidneys
Hepatitis	Liver
Osteomyelitis	Bone
Meningitis	Covering layer of the brain and spinal cord
Encephalitis	Brain
Retinitis	Retina (part of the eye)
Conjunctivitis	Eye
Myocarditis	Heart
Pericarditis	Membranes covering the heart

Types of Germs that Cause Infections in People with Cancer

Infections are grouped according to the type of germs that cause them. Bacteria, viruses, protozoa (parasites), or fungi may cause infections in people with cancer. Most of the infections in people with cancer are caused by germs that normally live on the skin, in the intestines, or in the environment. These germs usually do not cause infections in people with normal defense and immune systems. But if the normal barriers and immune system are weakened, these germs can begin to grow and cause damage to tissues. These infections are often called opportunistic infections, because the germs use the opportunity of a patient's weakened defenses to cause illness.

Naming Germs

Like all other living things, germs are given scientific names that are made up of first names (genus) and last names (species). These names tell biologists and health care workers which germs are related and may be similar to each other. For example, the biological names Felis domesticus (housecats) and Felis leo (lions) tell biologists the animals are related. (Scientific names are usually italicized, except for viruses.)

Likewise, Staphylococcus epidermidis and Staphylococcus aureus are related bacteria. But, like housecats and lions, they differ in important details. Staphylococcus epidermidis rarely causes infections in healthy people, but can cause infections in people with cancer who have an IV (intravenous) or vascular access device (VAD) and a low white blood cell count. Staphylococcus aureus can cause very serious infections in people with weakened or healthy immune systems. It is often resistant to many antibiotics. This means these infections can be very hard to treat.

Although most germs have first and last names, those that are very well known are often called by their first names only. Germs in this category include Pneumococcus, Candida, and Aspergillus. And like some people, germs with long names are sometimes more commonly known by their initials or nicknames. These include E. coli (Escherichia coli), Staph epi (Staphylococcus epidermidis), and CMV (cytomegalovirus).

Lab Tests to Identify Germs

Knowing the exact type of germ that is causing an infection is very helpful in choosing the best treatment. Different drugs are used for each of the main types of germs -- bacteria, viruses, fungi, and parasites. Even among bacteria, different types vary greatly in their ability to be killed by different antibiotics.

Sensitivity Tests Doctors know which germs tend to infect which organs of people with cancer, and they can often make an educated guess at which germs are probably causing a patient's infection. Many times patients who have had infections before have the same germ come back later and cause another infection. Educated guesses are very important because it can take many days to get the results of the tests that show the exact type of germ causing an infection. These are called sensitivity tests--they show the germ involved and the best antibiotic to kill it. Because infections in people with cancer may quickly get worse, treatment is usually started before test results are back. Medicine to treat an infection may then be changed after the lab tests have identified the specific germ.

Gram Stain Tests

Looking at samples from infected tissues under a microscope can give clues about the type of germ involved. Bacteria, fungi, and parasites are large enough to be seen under a regular microscope, though they are much too small to see without one. Sometimes, samples from the suspected site of infection can be taken and treated with a series of stains (dyes). This test is called a Gram stain. It changes the color of the germs to make them easier to recognize. It takes only a few minutes and the result often helps doctors choose the best antibiotics before other test results are available.

Culture

Germs most often need many days to grow in the lab before they can be seen. Samples from the suspected site of infection are placed in a nutrient broth or gel, and kept warm until the germs grow. This test is called a culture. After enough germs have grown, some are removed and tested so they can be identified.

Tests for Viruses

Viruses are too small to be seen with most microscopes. Instead, viruses are often identified by the types of changes they cause in cells they infect. Sometimes these changes can be seen in cells from samples taken directly from the patient. In other cases, samples must be added to test cells grown in lab dishes. If a virus is present, the test cells will undergo changes that can be recognized by the lab technologists.

Genetic Tests

New medical lab tests can quickly identify some germs by testing their DNA, RNA, or other substances. These tests are often useful in choosing the best treatment as fast as possible, before the infection causes serious damage.

Test Samples or Specimens

All of these tests require samples (specimens) from the patient. Types of samples include blood, urine, spinal fluid, wound drainage, and phlegm (sputum). If a patient has symptoms that point to a certain organ, samples will be taken to check for germs. For example, sputum samples may be taken if someone has a cough or shortness of breath. Urine samples may be taken from someone with blood in their urine or if they feel pain while urinating. Sometimes, samples will be taken before any symptoms start if a person is at high risk for developing infections (usually because of a very low WBC count). If an infection is found, treatment can be started before symptoms occur.

Bacterial Infections

Bacteria are the smallest forms of life. Biologists consider bacteria a separate life form that is different from both plants and animals. Bacteria cause most of the infections in people with cancer. Bacteria that commonly cause infections in people with cancer include:

• Pseudomonas aeruginosa 
• Klebsiella pneumonia 
• Escherichia coli (E. coli) 
• Salmonella 
• Clostridium difficile 
• Staphylococcus aureus 
• Staphylococcus epidemidis 
• Streptococcus viridans 
• Pneumococcus 
• Enterococcus

Viral Infections

Viruses are the smallest known infectious germs. Unlike bacteria, they are not truly alive because they cannot grow on their own. Viruses can only reproduce when they are inside living cells, such as human cells. Most viral infections in people with very low WBC counts are caused by varicella zoster virus (VZV, the chickenpox virus), herpes simplex virus (HSV, the virus that causes cold sores and genital herpes), and cytomegalovirus (CMV). Other viruses, such as respiratory and hepatitis viruses, may also cause problems.

Varicella Zoster Virus -- Shingles

Varicella zoster virus (VZV) can cause serious infections in people with cancer, especially children. Unlike many other infections, VZV infection never completely goes away. When healthy people recover from chickenpox, some of the virus remains in their nerve cells. If the person's immune system is weakened years later as a result of cancer or treatment, the virus can be reactivated causing a condition known as shingles. People with this condition have clusters of tiny, painful blisters along the path of nerves on the skin.

Although these skin blisters are painful, the most serious part of VZV infection in people with a weakened immune system is that the virus may spread to other organs, resulting in pneumonia or encephalitis (infection of the brain). The risk of serious tissue damage is high in people with low WBC counts and whose immune systems are weakened by cancer. Unlike chickenpox infections in healthy people, VZV infections in people with cancer can be fatal.

Herpes Simplex Virus

Herpes simplex virus (HSV) is from the same family of viruses as varicella zoster. Like VZV, HSV causes mild infections in people with healthy immune systems, but it also remains in nerve cells. It can become reactivated if the person develops cancer years later. And like VZV, HSV can also cause pneumonia and encephalitis.

Cytomegalovirus

Cytomegalovirus (CMV) infection in otherwise healthy people is usually not serious. But in people with weak immune systems, CMV can cause serious pneumonia and retinitis, a serious eye infection that can lead to blindness if not treated.

Respiratory Viruses

Respiratory viruses (such as influenza, respiratory syncytial virus, and other seasonal viruses) can cause illness in those with normal immune systems, but illness may become severe in people with weak immunity. Respiratory viruses can affect the nose, throat, sinuses, breathing passages, and lungs. Pneumonia, which affects the lungs, is the most serious complication of infection with respiratory viruses. Pneumonia is more likely to happen when one of these viruses infects a person whose immune system isn’t working well. The best prevention for influenza is to be vaccinated every fall with the flu shot, and to have other household members vaccinated as well. Washing your hands frequently when these viral infections are going around will also help decrease the chances of infection. It is best for people with low WBC counts to avoid crowds and people with these kinds of infections. (See the section "Prevention of Infections in People with Cancer.")

Protozoal Infections

Protozoa are one-celled creatures that are considered the smallest and simplest form of animals. Although some protozoal infections can affect people with a healthy immune system, these infections are more common in less developed countries than in the United States. In the US, most protozoal infections happen in people with decreased immunity caused by organ transplants, cancer, AIDS, or other diseases. In the person with a weak immune system, these infections are difficult to treat and can be life-threatening. Common protozoa that can infect people with cancer include Pneumocystis jirovecii (formerly known as P. carinii), Toxoplasma gondii, and Cryptosporidium.

Pneumocystis jirovecii is usually classified as a protozoan, even though its DNA, RNA, and other components more closely resemble a fungus. It usually causes pneumonia, and rarely spreads to other organs.

Toxoplasma gondii is found in soil, cat waste, and undercooked meats. It can cause fever and lymph node swelling or no symptoms at all in adults with normal immune systems. It becomes inactive, but when the immune system is damaged the infection may reactivate and damage the brain or heart.

Cryptosporidium is a common cause of enteritis (intestinal infection) in people with weakened immune systems. It is spread by infected people and animals often by contaminated drinking water. It can cause severe diarrhea, malnutrition, weight loss, imbalances in blood chemistry, and dehydration.

Fungal Infections

In humans, fungi can live in balance with other microbes that normally live on or in the body without causing symptoms or damage. However, a fungal infection can occur when there are changes in this balanced environment. For example, damage to the skin or mucous membranes, low WBC counts, a weakened immune system, or decreased numbers of bacteria normally found on the body’s surfaces (which often happens with antibiotic treatment) can change the balance. Fungal infections can be serious and even fatal. Fungi that commonly infect people with cancer include Candida (yeast), Aspergillus, Cryptococcus, Histoplasma, Phycomycetes, and Coccidioides.

Candida

This is the most common cause of fungal infection. Candida can live in a healthy person without causing any problems. Sometimes it may cause a mild skin rash or vaginal discharge (yeast infection). But a person with a weakened immune system is at risk for a much more serious infection called thrush. It can affect the mouth and esophagus (swallowing tube) and may even spread to other organs.

Aspergillus

Aspergillus is a fungus that is often found in the air and in our environment. It is rarely a problem in healthy people but it can cause serious infections of the sinuses, lungs, kidneys, brain, and heart valves in people with cancer, especially those with very low WBC counts or those getting cancer treatments that suppress the immune system. This type of infection is often hard to diagnose and aggressive treatment is needed as soon as it is suspected.

Cryptococcus

Cryptococcus, which is found in the soil and in pigeon waste, is thought to be spread by breathing in the germ when it has dried out and gets stirred up into the air. In healthy people, it often causes a lung infection that goes away without symptoms. However, the fungus can remain inactive in the lungs for years. If the person's immune system becomes weakened, it can begin to grow and spread to other parts of the body. One of the most serious outcomes of this infection is meningitis, an infection of the membranes that surround the brain and spinal cord.

Histoplasma

Histoplasma is another fungus that often infects the lungs of healthy people without causing any symptoms or tissue damage. People become infected through contact with soil that contains bird or bat waste. Like Cryptococcus, the fungus may remain inactive for many years in the lungs of otherwise healthy people, but can become active if their immune system is weakened. In people with cancer, Histoplasma may cause a serious infection and may spread to the lymph system, liver, and spleen.

Prevention of Infections in People with Cancer

Infection is one of the most common life-threatening complications of cancer. It is very important that people being treated for cancer take precautions to reduce the risk of infection.

Immunizations and Live Virus Vaccines

People with weakened immune systems should not receive vaccines that contain live virus. There have been fatal infections caused by polio, measles, and smallpox because live virus vaccines were given to patients with weakened immune function. Certain preventive immunizations can be very helpful, and it is important to know which ones are safe for those with weak immune systems.

Flu Shots

The flu shot can reduce the risk of pneumonia or lung infection. It is usually given at least 2 weeks before chemo or between chemotherapy cycles. It can be given 6 months after a bone marrow or stem cell transplant, and every year after that. Flu-mist^®, the nasal mist version of the flu vaccine, contains live virus. It is not recommended for people with cancer or their household members

Polio and Smallpox

Children who have weakened immune systems should get inactivated virus vaccines and not the oral poliovirus vaccine. Their siblings and others who live with them should get the same type of vaccines. The oral poliovirus vaccine contains a live virus. This makes it possible for people who get this vaccine to transmit the poliovirus to people with weakened immune systems. Live virus vaccines can usually be given at least 3 months after all immune-suppressing treatment has stopped, but the time varies. For information on smallpox vaccination, see the American Cancer Society document Smallpox Vaccine and Cancer.

Measles-Mumps-Rubella

People who have severely weakened immune systems should not get the measles-mumps-rubella (MMR) vaccine because it contains live virus. Unlike polio and Flu-mist®, however, it is safe for other household members to get it.

If the patient being treated for cancer is exposed to someone with measles, it is important to let the doctor know right away. Sometimes, measles immune globulin (a blood product that contains antibodies to the measles virus) can be given to help fight measles before they start.

Varicella (Chickenpox)

People with blood tests that do not show immunity to the chickenpox virus (or varicella zoster virus; VZV) are not given this vaccine, which is also live, while their immune systems are suppressed. It is okay for household members of the person with weakened immunity to get the varicella vaccine.

A person with weak immunity who has been exposed to chickenpox should call their doctor as soon as possible. They may need to get VZV immune globulin (a blood product that contains antibodies to the VZV virus) right away, and no later than 72 hours after exposure. Cancer therapy may be stopped and restarted after the end of the VZV incubation period, usually about 21 days. When signs of VZV infection appear in a person with cancer, the doctor may hold off on cancer therapy that causes immune suppression until scabs have formed. See the section, "Viral Infections" for more information about shingles a serious condition caused by this virus.

General Precautions

Here are some more steps that may help to prevent illness:

• Always know when your absolute neutrophil count (ANC) is low. Ask your doctor or nurse. 
• Be aware of the signs and symptoms of infection and report any that you have to your doctor or nurse. Get your flu shot every fall, and encourage other members of your household to get it too. (Avoid the nasal mist flu vaccine. It is not recommended for people with poor immune function, nor is it recommended for members of their households.)

While your ANC is low, do what you can to help prevent an infection:

• Avoid large crowds of people and anyone with a fever, flu, or other infection. 
• Keep yourself clean by bathing each day, giving extra attention to feet, groin, armpits, and other moist, sweaty areas. 
• After bathing, check for redness, swelling, and soreness where any tubes or catheters enter your body. 
• Wash your hands with warm water and soap after using the bathroom, blowing your nose, coughing, or sneezing. 
• Wear gloves for gardening and wash up afterward. 
• Wash your hands before eating, and before touching your face or mucous membranes (eyes, nose, mouth, etc). 
• Avoid having manicures, pedicures, false nails, and nail tips. 
• Avoid hot tubs. 
• Wear shoes at all times in the hospital, outdoors, and at home to avoid injury and to avoid getting extra germs on your skin. 
• Use an electric shaver instead of a razor. Do not share shavers. 
• If you cut or scrape your skin, clean the area right away with soap and warm water. Cover the area with a clean bandage to protect it. If the bandage gets wet or dirty, clean the injury and put on a new bandage. Tell your doctor if you notice redness, swelling, pain, or tenderness. 
• Keep your mouth clean by brushing your teeth twice each day. Ask your doctor or nurse if it is okay to gently floss your teeth every day. Talk to your doctor or nurse if you notice your gums bleeding. Your doctor or nurse may give you a special mouthwash to help clean your mouth. Do not use alcohol-based mouthwash. 
• Prevent constipation and straining to have a bowel movement by drinking 2 quarts of fluid each day, and exercising each day. If needed, your doctor may give you medicine that softens your stool. Ask your doctor or nurse about stool softeners, and let them know if you are having bowel problems. Do not put anything in your rectum, including thermometers and suppositories. Keep the groin area and anal area clean, using soft moist cloths (such as disposable baby wipes). 
• Women should not use tampons, vaginal suppositories, or douche. 
• Use water-based lubricants during sex to avoid injury or abrasion. Use latex or plastic condoms to reduce the risk of sexually transmitted infections. 
• Do not keep fresh flowers or live plants in your room. 
• Do not clean up droppings from your pets. Do not clean bird cages or fish tanks. Let someone else do this for you. 
• Cat litter boxes should be placed away from kitchens and food areas. Litter boxes should be cleaned every day, also by someone else. 
• Avoid touching soil that may contain feces (stool) of animals or people. 
• Avoid wading, playing, or swimming in ponds, lakes, or rivers. 
• Avoid changing diapers, or wash your hands thoroughly afterward. 
• Avoid all stagnant water, for example, in vases, denture cups, and soap dishes. 
• Use hot water to clean your dishes. 
• Do not share bath towels or drinking glasses with others, including family members. 
• Avoid chicken coops, caves, and any place where dust from the ground is being blown into the air, such as construction sites. 
• Talk with your doctor or nurse if you are planning any travel during this time.

Food Safety

Food safety is very important when your white blood cell (WBC) count is low. Infections can be picked up from food and drinks. You can reduce this risk as well by doing the following:

• Avoid raw milk or milk products and any milk or milk product that has not been pasteurized, including cheese and yogurt made from unpasteurized milk 
• Do not eat raw or undercooked meat, fish, chicken, eggs, or tofu 
• Do not eat cold smoked fish 
• Do not eat hot dogs, deli meats, or processed meats (unless they have been cooked again just before eating) 
• Avoid any food that contains mold (for example, blue cheese, including that in salad dressings) 
• Avoid uncooked vegetables and fruits 
• Avoid uncooked grain products 
• Avoid unwashed salad greens 
• Do not eat vegetable sprouts (alfalfa, bean, and others) 
• Avoid fruit and vegetable juices that have not been pasteurized 
• Avoid raw honey (honey that has not been pasteurized) 
• Do not eat raw nuts or nuts roasted in their shells 
• Do not drink beer that has not been pasteurized (home brewed and some microbrewery beers); also avoid brewer’s yeast 
• Do not eat any outdated food 
• Do not eat any cooked food that has been left at room temperature for 2 hours or more 
•  Avoid any food that has been handled or prepared with unwashed hands 
• Talk with your doctor about any dietary concerns you may have, or ask to talk with a registered dietitian.

Use of Medicines to Prevent Infections

Sometimes, antibiotics (which can be antibacterial, antiviral, and/or antifungal drugs) are given when a person’s neutrophil count is very low even though there is no evidence of an infection. This is only done when there is a high risk of serious bacterial, viral, or fungal infection. It is most often done if the person is expected to have severe neutropenia for a week or longer, with the hope of keeping the person from getting an infection .The drugs are stopped when the neutrophil count begins to improve. Using these drugs in this way does not prevent all infections, so it is still important to use the same precautions as people who are not taking preventive antibiotics.

Use of Growth Factors

Colony-stimulating factors (CSFs), also known as growth factors, are proteins your body produces that help your blood cells, including WBCs, grow. You may be given a CSF to keep your neutrophil count (ANC) from dropping. Or, you may get it when your ANC is low to help treat an infection, especially a more serious one. Examples of these CSFs include filgrastim (Neupogen^®) and pegfilgrastim (Neulasta®), which affect neutrophils. Sargramostim (Leukine^®) is an example of a CSF that affects neutrophils, monocytes, and macrophages. These medicines shorten the length of time a person is neutropenic and make the neutropenia (shortage of neutrophils) and leukopenia (shortage of white blood cells) less severe. Growth factors do have some side effects, but they can reduce the risk of infection in the patients who need them. You can call the American Cancer Society at 1-800-ACS-2435 for more information on each of these drugs.

Early Recognition of Infection in People with Cancer

It is important to watch for early signs of infection. Then treatment can be started as early as possible. This advice is especially important for patients who have a low white blood cell count. Signs and symptoms of an infection include:

• body temperature, taken by mouth, of more than 100.5^oF
•  sore throat 
• cough or shortness of breath 
• nasal congestion 
• burning during urination 
• shaking chills 
• redness, swelling, or warmth at the site of an injury, surgical wound, or vascular access device (VAD)

Fever is especially important because it is often the first sign of an infection in people with cancer. Usually patients are instructed to call their doctor or nurse if they have a fever greater than 100.5oF or if they have other signs and symptoms of infection. Ask your doctor for specific instructions. Be sure you know how to reach your health care team after office hours and on weekends.

It is important for people with cancer and their families and friends to be aware of the following:

• the patient's risk for infection 
• how long the WBC count is likely be low after treatment 
• the importance of taking the patient's temperature, how to take it accurately, and how often to check it 
• when to report a fever or other signs and symptoms of infection to the doctor or nurse 
• the importance of basic hand washing and hygiene practices for the patient and those they come in contact with 
• the importance of cleaning around the anus after each bowel movement and urination 
• how to take good care of the mouth and check for sores and fungal infections 
• good care of vascular access devices (VADs) 
• where to look for signs of infection (skin, mouth, and VAD sites) 
• the importance of good nutrition, a balanced diet, and drinking plenty of fluids 
• the importance of sleep and exercise and how to conserve energy 
• the importance of taking medications as prescribed and being sure your doctor is aware of all medicines you are taking (prescription, over-the-counter, vitamins, herbs, and supplements) at each doctor visit 
• ways to prevent dryness of the skin and mucous membrane (such as using lotion or using a vaporizer for humidity) 
• the need to talk with your cancer care team or doctor before getting any immunizations and before close contact with children or adults who have recently been immunized (vaccinated)

Treatment of Infection in People with Cancer

Fever and other signs and symptoms of infection in a person with a severely weakened immune system are considered 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 antibacterial, antiviral, antifungal, or anti-protozoal medicines) are started before all the lab results are back. After the specific germ is identified, the antibiotic may be continued if the germ is sensitive to it, or a different medicine may be given.

In the past, patients were almost always admitted to the hospital for treatment of these infections, and many still are. However, some patients are able to take their antibiotics in pill form. Some patients who need intravenous (IV) antibiotics may be able to get them in clinics, doctor's offices, or at home. But home care is only possible with infections that are unlikely to become more serious. The patient must have a responsible adult at home with them at all times, and be properly equipped to handle everything at home. The patient must also be close enough to the hospital or clinic to get there quickly and will need to have a telephone. The doctor or cancer care team must be able to get lab results and see the patient daily for the first few days. If all goes well, they still will need to stay in close contact during treatment. Otherwise, the patient may need to be admitted to the hospital.

While treatment is being started, the patient is watched closely and lab results are checked every day. The white blood cell count and neutrophil count are checked often. Antibiotics may be changed as the final germ identification (culture) results come in. In some cases, white blood cell growth factors (colony-stimulating factors) are given to speed up recovery of the white blood cells. If the infection does not respond to treatment, an infectious disease specialist may be consulted. These doctors specialize in treating infections and may recommend extra testing and different treatments, depending on the situation.

In addition to treatment with medicines, nutrition counseling and stress management may help increase the immune function of people with cancer and may prevent infections. Nutrition counseling should include the importance of a high intake of calories, protein, and vitamins. A low microbial diet (or neutropenic diet) may be suggested. Patients should avoid uncooked herbs and spices, raw fruits and vegetables, cold cuts, raw eggs, undercooked meats, and soft cheeses (see Food Safety under General Precautions, above.) Other therapies such as biofeedback, humor, music therapy, guided imagery, counseling, and meditation may be helpful for stress management and may have a positive effect on the immune system.

Bacterial Infections

When treating bacterial infections, antibiotic therapy is started after samples for lab tests have been taken but before these test results have identified the organism. Antibiotics are selected based on the likely microbe involved and the site of infection. Most often, broad-spectrum antibiotics that will treat many different bacteria are chosen . Sometimes a few antibiotics are combined. Excessive use of antibiotics is avoided, however, because this can cause some bacteria to develop resistance to these drugs. For example, some strains of Staphylococcus have become resistant to most antibiotics that can be given by mouth, and even intravenous (IV) vancomycin, which was once used to treat them. Such germs are said to be drug resistant because they no longer respond to antibiotics that killed them in the past. Germs change and adapt all the time. Fortunately, there are a handful of new drugs, such as quinupristin/dalfopristin (Synercid^®), linezolid (Zyvox^®), and daptomycin (Cubicin^®) 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 antibacterial antibiotics have been available for more than 50 years, antiviral drugs were not developed until much more recently. Herpes simplex virus and varicella zoster are usually treated with drugs like acyclovir, an antiviral agent. Ganciclovir, foscarnet, or valganciclovir is more commonly prescribed for cytomegalovirus (CMV).

Protozoal Infections

Protozoa generally cause few problems for healthy people, but they are hard to treat in those with low WBC counts. The usual treatment for people with Pneumocystis jirovecii infection is trimethoprim-sulfamethoxazole (Bactrim^®). If people have side effects from these drugs, then dapsone, atovaquone, or pentamidine may be used. Toxoplasma is often treated with pyrimethamine plus sulfadiazine or clindamycin for people who are allergic to sulfadiazine.

Fungal Infections

Oral antifungal antibiotics like nystatin and clotrimazole are used for people with Candida infections in the mouth and throat. Depending on the medication, the patient swishes and swallows the solution or lets the medication dissolve in their mouth. For Candida in the esophagus, fluconazole (Diflucan®) or another antifungal drug is used. For more serious Candida infections (such as infections in the blood), medications such as amphotericin B or one of its newer formulas may be given intravenously. Amphotericin is most often used to treat Aspergillus infection. Cryptococcus infection is usually treated with amphotericin, flucytosine, and/or fluconazole.

Where Can I Get More Information on Infections?

American Cancer Society Publications

Fever and Neutropenia: Treatment Guidelines for Patients with Cancer

Bone Marrow and Peripheral Blood Stem Cell Transplants (also available in Spanish)

Caring for the Patient with Cancer At Home: A Guide for Patients and Families (also available in Spanish)

Chemotherapy Principles

Nutrition for the Person With Cancer During Treatment: A Guide For Patients and Families

Understanding Chemotherapy: A Guide for Patients and Families (also available in Spanish)

References

American Cancer Society and National Comprehensive Cancer Network. Fever and Neutropenia: Treatment Guidelines for Patients with Cancer, v II. March 2006.

Centers for Disease Control and Prevention. General recommendations on immunization: Recommendations of the Advisory Committee on immunization practices (ACIP) and the American Academy of Family Physicians (AAFP). MMWR, 2002; 51(RR02); 1-36.

Dean GE, Haeuber D, Rivera L. Infection. In: McCorkle R, Grant M, Baird S, Frank-Stromborg M, eds. Cancer Nursing: A Comprehensive Textbook. 2nd edition. Philadelphia, Pa: W.B. Saunders Company; 1996: 963-978.

Ellerhorst-Ryan JM. Infection. In: Yarbro CH, Frogge MH, Goodman M, Groenwald SL, eds. Cancer Nursing: Principles & Practice. 5th Edition. Boston, Mass: Jones & Bartlett, 2000: 691-708.

Heymann DL (ed) Control of Communicable Diseases Manual, 18th ed. Washington DC: American Public Health Association, 2004.

Jassak P, Haeuber D. Protective Mechanisms. In: Gross J, Johnson BL, eds. Handbook of Oncology Nursing. 3rd Edition. Boston, Mass: Jones & Bartlett, 1998: 417-439.

King CR. Outpatient management of myelosuppression. Clinical Perspectives in Oncology Nursing, 1995; 1:1-12.

Madeya ML. Oral complications from cancer therapy: Part 1--Pathophysiology and secondary complications. Oncology Nursing Forum, 1996; 23:801-807, 820-821.

Morra M, Potts E. Choices. New York, NY: Avon Books, 1994.

National Comprehensive Cancer Network. Prevention and Treatment of Cancer-related Infections. V.2. July 2007.Available at: http://www.nccn.org/professionals/physician_gls/PDF/infections.pdf. Acessed September 26, 2007.

Schafer SL. Infection due to leukopenia. In: Yasko JM, eds. Nursing Management of Symptoms Associated With Chemotherapy. 4th Edition. Bala Cynwyd, Pa; Meniscus; 1998: 135-162.

Segal BH, Walsh TJ, Gea-Banacloche JC, Holland SM. Infections in the cancer patient. In: DeVita VT Jr, Hellman S, Rosenberg SA, eds. Cancer: Principles and Practice of Oncology, 7th ed. Philadelphia, Pa: Lippincott Williams &Wilkins; 2004:2461-2514.

10/09/2007