Cryptococchosis

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[edit] Cryptococcosis

Introduction:

This condition is also known under the alternative diagnostic names "tolurosis" or "blastomycosis". It is a fungal infection, which is transmitted by Cryptococcus neoformans that is found in soil worldwide. Some patients are very sensitive to this pathogen, particularly AIDS patients, but also patients with Hodgkins lymphoma, patients on longterm high doses of corticosteroids or sarcoidosis patients.

The encapsulated yeast form of C. neoformans enters the body through inhalation of dust contaminated with the pathogen. In the lungs of a healthy host a self-limited cryptococcal infection would ensue. However, in a patient whose immune system is paralyzed such as with AIDS a severe pneumonia will develop. The infection then spreads throughout the system with skin lesions, subcutaneous nodules and disease in liver, kidneys, spleen, joints, bones, prostate and other organs. Even the central nervous system is often affected in AIDS patients with cryptococcal meningitis.

Signs and symptoms:

During the acute lung infection phase symptoms would include coughing, chest wall pain and difficulties breathing.

Skin involvement looks quite varied with pustules, papules, acne like and even basal cell cancer like lesions (a case with before and after treatment pictures). If the physician is in doubt what the lesions are, one or two of them could be biopsied for analysis by the pathologist. Single lesions in bone, abdominal organs or kidney may not give any symptoms, because they are pain free and are self-limiting in a person with a normal immune system. Headaches, blurred vision, behavioral changes, confusion, agitation and depression can all be symptoms of a beginning cryptococcal meningitis.

Diagnostic tests:

Mostly the diagnosis is made by culture from body fluid samples such as urine, blood, phlegm or cerebrospinal fluid (CSF). Smears of biopsy specimens can be examined after special staining techniques by an experienced laboratory physician or technician.

The characteristic encapsulated budding yeasts of C.neoformans with cryptococcal capsular polysaccharide have a unique appearance that can readily be distinguished from other pathogens by the experienced observer. Finally there is a latex test for capsular antigen, which is a specific blood test, particularly, if the titers are higher than 1:8. For pulmonary lesions X-rays, CT scans, bronchoscopy with biopsy are employed to lead to a diagnosis. With any palpable lesion such as in skin or in the subcutaneous tissue skin biopsy would be considered. With meningitis lumbar puncture to obtain CSF has to be done in order to diagnose the condition.

Treatment:

Treatment has to be individualized according to the situation. It depends whether the patient is immuno-competent or immunocompromised as in an AIDS patient.

The patient with a normal immune system may not need treatment for a localized lung infection with cryptococcus, as it would often be self limiting. However, in order to be certain that the assumption of "localized disease" is correct it is wise for the physician to examine and culture the CSF (to rule out meningitis), the urine (rule out kidney involvement) and examine the skin for any abnormal lesions. Patients with a normal immune system can be treated for mild disease with fluconazole (brand name: Diflucan) orally. More severe infection would have to be treated with flucytosine (brand name: Ancobon) orally, but side-effects (kidney and bone marrow toxicity) has to be monitored. Some centers can measure flucytosine levels, which would be desirable to avoid toxic levels. Serious disease is treated with intravenous amphotericin B in combination with or followed by oral flucytosine.

In AIDS patients responses are often incomplete. Treatment is therefore often combined antifungal drug therapy and the course is longer or ongoing. The physician starts with intravenous amphotericin B and oral flucytosine (brand name: Ancobon). If after two weeks the cryptococcosis is cured, a preventative maintenance dose of fluconazole (brand name: Diflucan) is given orally. Blood tests are usually done to show that the antigen titers for cryptococcosis are negative before treatment can be stopped (Ref. 1, p.1220).

Infections overview

Fungal infections

References:

1.The Merck Manual, 7^th edition, by M. H. Beer s et al., Whitehouse Station, N.J., 1999. Chapter 158.

2.The Merck Manual, 7^th edition, by M. H. Beers et al., Whitehouse Station, N.J., 1999. Chapter 113.

3. The Merck Manual, 7^th edition, by M. H. Beers et al., Whitehouse Station, N.J., 1999. Chapter 164.

4.David Heymann, MD, Editor: Control of Communicable Diseases Manual, 18th Edition, 2004, American Public Health Association.