|
What Are Infections and Who Is at Risk?
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 ANC can be calculated using the following formula:
ANC =(% of neutrophils)/100 x WBC count
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 100.5oF
- 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
|