FUNGAL INFECTION IN IMMUNOCOMPROMISED PATIENTS

An immunocompromised host is a patient who does not have the ability to respond normally to an infection due to an impaired or weakened immune system. This inability to fight infection can be caused by a number of conditions including illness and disease (e.g. diabetes, HIV), malnutrition, and drugs.

A fungus is just a type of germ. They can range from tiny, barely visible specks that float around in the air, all the way up to large growths like mushrooms. Fungi (the plural of fungus) are all around us and don’t usually cause any problems. However occasionally they can settle down and grow in places where they shouldn’t: places on our bodies like our skin, nails, between our toes and, in women, the vaginal area. This can happen even in people who are fairly healthy and is usually easy to treat with creams or pills.

Invasive fungal infection is a major cause of morbidity and mortality in immunocompromised patients. The precise prevalence of disease is not known but population-based surveillance estimates it at 12–17 per 100 000 population. Candidosis and aspergillosis remain the most significant problems in the UK. Invasive Candida infections are most commonly seen in critically ill patients in intensive care units (ICUs) and very low birth weight infants. Reported mortality in patients with candidaemia ranges from 36% to 63%, although mortality in ICU patients has decreased in recent years, possibly due to more prompt initiation of antifungal therapy.

Antibiotic Use

Antibiotics are medicines designed to kill harmful bacteria that are causing infection or illness. Sometimes these drugs can also reduce the helpful bacteria that live in the body. When these populations are reduced, fungi may take the opportunity to colonize.

Corticosteroid Use

Corticosteroids are a group of drugs that reduce inflammation. They effectively treat many skin disorders. Unfortunately, these drugs also can reduce our immune response and improve conditions for fungus growth.

Medical Conditions

Individuals with diabetes and some cancers, such as leukemia, are more susceptible to fungal infections than the general population.

Compromised Immune System

The immune system is a set of chemical and cellular responses that attack disease-causing organisms and help prevent their growth. A number of factors can depress this system. These include chemotherapy (cancer-killing drugs) and acquired immune deficiency syndrome (AIDS).

A depressed immune system less effectively fights off all types of infection. Thus a fungus that normally would be controlled by the immune system may begin to grow.

Environmental Factors

Fungi require moisture to grow and reproduce. Fungal infections are more prevalent in warm, moist areas of the body, such as the mouth and vagina. Also, sweaty clothes and shoes can enhance fungus growth on the skin. Exposure to fungi is more frequent in communal areas with moisture, such as locker rooms and showers.

Hereditary Factors

Some people seem to have a genetic predisposition toward fungal infections. They may contract infections more easily than others exposed to the same conditions. Whether this is due to differences in immune response, skin chemistry, or other factors is not known.

Transmission of Fungal Infections

Fungal infections can be passed from person to person or from objects and surfaces to a person. Also, an individual can transfer infection to other parts of the body by touching.

The symptoms of the illness depend on the specific infection and which organs have been affected. General symptoms of illness may include:

• Fever
• Cough
• Loss of appetite

Lungs: Invasive lung fungal infection typically result in a progressive dry cough, shortness of breath, pain when taking a deep breath and fever. These symptoms may progress to the point of life threatening acute respiratory distress syndrome. Haemoptysis (the coughing up of blood): is also sometimes seen, particularly if inflammation of the large airways is present.

Bone:  Bone infection can develop from spread through the blood or rarely via direct spread from an overlying ulcer and infected skin. Fever and pain in the affected bone are the cardinal symptoms.

Brain: Brain involvement by systemic fungal infection has a particularly high mortality associated with it. Symptoms suggesting involvement of the brain include headaches, seizures and deficits in normal brain control over movement or sensation.

Meningitis (inflammation of the tissue surrounding the brain) can develop, particularly with candidiasis and cryptococcosis. Symptoms usually include headache, stiff neck and irritability.

Eyes:  Almost any of the eye structures may be infected by fungal infection. The symptoms depend on which part of the eye is infected but may include visual blurring, dark or black images floating in the visual field, pain and a red eye.

Skin: A variety of skin changes may be seen in association with systemic fungal infection. The skin lesions depend partly on which fungus is the cause.

DIAGNOSIS

• Culture and examination of a sample
• Blood tests

If doctors suspect a primary fungal infection, they ask people questions that can help with the diagnosis, such as the following:

• Where they have traveled and lived to determine whether they may have been exposed to certain fungi, perhaps years previously
• Whether they are taking any drugs that can suppress the immune system
• Whether they have a disorder than weakens the immune system

Doctors then take a sample to be grown in a laboratory (cultured) and examined under a microscope. The sample may be sputum or blood, but occasionally, doctors must take a sample from the lungs. To take a sample from the lungs, doctors insert a flexible viewing tube (a bronchoscope) through the mouth and into the airways. Fluid is squirted through the tube, then suctioned back into the tube, bringing cells and any fungi (or other microorganisms) with it. Sometimes biopsy or surgery is necessary to obtain a sample.

If the diagnosis is unclear, blood tests may be done. These tests check for antibodies (which are produced by the person’s immune system in response to foreign substances, including fungi), antigens (molecules from foreign substances that can trigger an immune response in the body), or other evidence of the fungi.

Underlying conditions can predispose a patient to fungal infections. For example, if someone with a fungal infection has diabetes, his or her sugar level may need to be brought under control before treatment can be effective.

A depressed immune system may need to be treated for antifungals to work. When someone affected has been using antibiotics or corticosteroids, they may have to stop or taper those medications in order to aid fungus treatment.

Medications to Treat Fungal Infection

A doctor generally matches the medication, topical or oral, to the organism against which it is effective. One oral antifungal used commonly over the years, griseofulvin, is effective for treating tinea capitis, for example, but not candida and certain mold infections. The drug ketoconazole is effective against tinea versicolor but not against other fungal infections.

Many new broad-spectrum antifungal agents effectively treat a wide range of organisms. Thus, doctors can start patients on a regimen of antifungals without waiting for culture results. These newer antifungals include itraconazole, terbinafine, fluconazole, and isavuconazonium). Typical courses for each:

• Itraconazole: “pulse” therapy—1 week on, 3 weeks off
• Terbinafine: continuous once-daily therapy
• Fluconazole: continuous once-weekly therapy
• Isavuconazonium: capsules or intravenous (IV) administration

Side effects of oral antifungals include nausea, gastrointestinal distress, diarrhea, abdominal pain, skin rashes, headache, and fatigue. Typically, a small number of patients taking these medications have one of these unusual reactions. If the side effects are bothersome or create concern, the drug can be discontinued. The doctor may order a blood test to check liver function, especially during long-term therapy, if the patient has an already weakened liver, or is using high doses of medication.

Other drugs include:

• Amphotericin B
• Caspofungin

Surgery may be required depending on the type of invasive fungal infection.

There are steps you can take to reduce your risk of getting a fungal infection and stop an infection from spreading. Here are some tips.

• Dry your skin well after you have a bath or shower.
• Wash your socks, clothes and bed linen regularly to remove any fungi.
• Wear clean flip-flops or plastic shoes in communal areas, such as showers, saunas and swimming pools.
• Wear loose fitting clothes made of cotton, or a breathable material that’s designed to keep moisture away from your skin.
• Don’t share towels, hairbrushes or combs as they could be carrying fungi.
• Alternate your shoes every two or three days to give them time to dry out.
• If you have diabetes, keep your blood sugar under control.
• If someone in your family has scalp ringworm, soak pillows, hats, combs or scissors with bleach and water.

• https://patient.info/health/fungal-infections
• Lamagni TL, Evans BG,  Shigematsu M, et al. Emerging trends in the epidemiology of invasive mycoses in England and Wales (1990–9), Epidemiol Infect , 2001, vol. 126 (pg. 397-414)
• Kibbler CC, Seaton S,  Barnes RA, et al. Management and outcome of bloodstream infections due to Candida species in England and Wales, J Hosp Infect , 2003, vol. 54 (pg. 18-24)
• Blot SI, Vandewoude KH,  Hoste EA, et al. Effects of nosocomial candidemia on outcomes of critically ill patients, Am J Med , 2003, vol. 113 (pg. 480-5)
• Blot SI, Hoste EA,  Vandewoude KH, et al. Estimates of attributable mortality of systemic Candida infection in the ICU, J Crit Care , 2003, vol. 18 (pg. 130-1)
• http://www.healthcommunities.com/fungal-infections/symptoms.shtml
• https://www.msdmanuals.com/home/infections/fungal-infections/overview-of-fungal-infections