Watch Out—Fungi a Danger to Cancer Patients (And others)

[Guest guest]

Watch Out—Fungi a Danger to Cancer Patients

Debra Wood, RN

Oncology Nursing News - New York,n,USA

http://www.oncologynursingnews.com/Watch-OutFungi-a-Danger-to-Cancer-Patients/ar\

ticle/150938/

LAKE BUENA VISTA, FLA—Fungus lives among us, typically causing minimal trouble

in healthy individuals. But for patients with compromised immune systems, a

fungal infection can often prove fatal.

" We're seeing a higher prevalence of fungal infections in our patient

population, " noted McCollom, RN, ND, CPON, a clinical manager at

Children's Medical Center Dallas. Dr McCollom spoke at the Association of

Pediatric Hematology/Oncology Nurses Annual Conference.

Statistically, fungal sepsis has increased 207% in the last 20 years. Fungal

infections develop in 19% of people with acute lymphocytic leukemia patients,

47% of those with acute myelogenous leukemia with remission induction therapy,

5% of autograft transplant patients, and 18% to 45% of persons undergoing an

unrelated allogeneic transplant. According to Dr McCollom, 30% to 95% of these

individuals will die.

Fungal spores float in the air. Once they land, they begin to grow in an

environment containing moisture, nutrients, and the right temperature.

Controlling moisture is the key to controlling fungal growth, advised Dr

McCollom.

People can inhale or ingest the spores. A healthy person's respiratory tract

cilia, normal flora, and immune system will prevent the fungus from becoming

harmful. But immunocompromised individuals often cannot fight off fungal

infections.

Many patients arrive for treatment colonized with fungi, and once their immune

system is suppressed by chemotherapy treatment, the fungi flourish.

Broadspectrum antibiotics, graft-versus-host disease, intravenous catheters, and

environmental contaminants also increase the risk of fungal infections.

Three Main Types of Fungi

Dr McCollom described 3 fungus types— Fusarium, Candida, and Aspergillus—that

commonly cause infection in patients.

Fusarium is found on plants and in the soil. Hence, Ms McCollom's hospital does

not allow patients to have potted plants. " It's the most emergent opportunistic

infection in humans, " she reported.

Fusarium is often drug-resistant and can cause superficial and systemic disease,

with resultant thrombosis.

" Patients with a malignancy or stem-cell transplant often have a poor outcome

[with this fungal infection] because the immune system is so suppressed, " Ms

McCollom explained. " We use combination therapy, but when [the disease is]

invasive, it's typically fatal. "

Candida is the most common mycosis worldwide and the fourth most common

bloodborne infection. This fungus is found on human skin, in the mucous

membranes, and throughout the body, and grows rapidly.

Another common fungus, Aspergillus, is found in soil, building materials,

spices, and the hospital environment. Although most people breathe it in daily

and it is then dispatched by the immune system, Aspergillus can be very invasive

and start to take over in an immunocompromised patient.

Symptoms of fungal infection include wheezing, cough, fever, bloody mucus, and

hemorrhage. Infections are diagnosed by x-ray; by computed tomography (CT) scan,

which might show a halo shadow around the fungal wall; by bronchial alveolar

lavage; and by biopsy.

Treatment

Providers typically begin antifungal treatment on patients with neutropenia who

have had a fever for 5 or more days, when a blood culture grows yeast, or when a

CT scan indicates something suspicious.

" You want a drug that's fungistatic and fungicidal, " counseled Virginia

Koepsell, RN, MSN, MBA, CPON, a nursing educator at Children's Medical Center

Dallas. (Fungistatic drugs are used to stop fungi growth; fungicides kill

fungi.) " The optimal [drug] has wide-spectrum activity, because you often don't

know what [the infection] is in the beginning, [and] is effective but has low

toxicity and low cost. "

The 3 drug classes used to treat fungal infections are azoles, polyenes, and

echinocandins, also known as fungins. They are often given in combination, with

the different agents using different mechanisms of action to combat the

infection. " You can bring down the drug dose to get less toxicity [with

combinations], and it decreases the emergence of drug resistance, " said Ms

Koepsell.

Azoles inhibit fungal growth by preventing formation of ergosterol, which is

vital for cell membrane integrity. An older azole, fluconazole, is fungistatic

but will not kill fungi. It is often used to treat Candida albicans.

Voriconazole is a newer drug that inhibits growth and kills the fungus. It's

commonly prescribed to treat Fusarium and Aspergillus infections. Voriconazole

is nephrotoxic when given intravenously. It is hepatotoxic in the IV and oral

formulations; therefore prescribers may need to decrease the dose of

cyclosporine or tacrolimus if those drugs are also ordered. A high-fat meal will

decrease absorption by 25%. About 30% of patients report visual disturbances

within 30 minutes of starting the dose, but these resolve within another 30

minutes.

Polyenes or amphotericin derivatives interact with the cell membrane to kill the

fungus. Amphotericin B has been used for more than 50 years, and although very

little resistance has developed, the drug has many toxicities. Nurses noticed

that when it was given with lipids, patients experienced fewer side effects, and

now it is available in 3 lipid formulations: Abelcet, Amphotec, and AmBisome.

AmBisome can be given in higher doses than amphotericin B, with fewer

toxicities, but it is more expensive. It causes potassium depletion and is not

compatible with normal saline. Because of sterility issues, nurses must

administer AmBisome within 6 hours of preparation. The patient should receive a

bolus of normal saline prior to starting the AmBisome intravenous infusion to

salt-load the kidneys and protect the renal tubules.

Echinocandins block synthesis of the fungal cell wall and are used in treating

Aspergillus and Candida. One such agent, caspofungin, is not compatible with

dextrose.

Providers also may add GM-CSF (granulocyte-macrophage colony-stimulating factor)

and interferon in an attempt to enhance the body's immune response, especially

when treating overwhelming fungal infections.

" We want to reverse the immunosuppression, " clarified Ms Koepsell. " In order for

the patient to get over the infection, we have to boost the white-cell count. "

Prevention

Hospitals have taken many measures to decrease the risk of fungal infections,

such as installing HEPA filters, controlling clutter, prohibiting flowers and

plants, and having nurses educate patients and their families about methods of

modifying the home environment.

Patients should avoid dusty areas and construction zones. If they must pass

through such an area, they should wear an N95 respirator. They should keep at

the home humidity level at 40% to 50%. " Fungal spores are greater in the natural

environment than in the hospital, where we have more control, " Ms McCollom said.

" Controlling the relative humidity will help. "

Patients should use air conditioners and dehumidifiers, but not fans. The home

should have adequate ventilation and bathrooms and basements should be tiled or

concrete, with no carpeting. Patients should not vacuum, dust, or reuse towels.

From the October 2009 Issue of ONN