caused most commonly by Candida, Cryptococcus, Aspergillus, Pneumocystis, Rhizopus, Mucor, Nosema and Encephalitozoon, and Pneumocystis, but any fungus may cause an opportunistic infection if a patient is immunocompromised.
the most common opportunists...
The most common cause is C. albicans, but incidence of infections due to other species of Candida is increasing.
Systemic candidiases are generally treated with
fluconazole or capsofungin drugs
Malassezia furfur septicemia
occurs primarily in premature neonates on intravenous lipid emulsions; it usually resolves if lipid supplements are stopped.
yeast that possesses an antigenic polysaccharide capsule.
It is found in weathered pigeon droppings.
Cryptococcal meningitis or meningoencephalitis
initial symptoms include headache of increasing severity, usually with fever, followed by typical signs of meningitis and sometimes personality changes.
diagnosed by cerebrospinal fluid (CSF) latex particle agglutination test for Cryptococcus, India ink wet mount, and culture following lysis of white blood cells in CSF.
treated with amphotericin B plus 5-fluorocytosine or fluconazole.
variety of infections and allergic diseases that are caused by Aspergillus fumigatus, A. niger and other species of Aspergillus.
ubiquitous, filamentous fungus (one of our major recyclers) whose airborne spores (conidia) are constantly in the air.
characteristic septate hyphae branching dichotomously at acute angles (so it is monomorphic).
Allergic bronchopulmonary aspergillosis
an allergic disease in which the organism colonizes the mucous plugs formed in the lungs but does not invade lung tissues. It is diagnosed by the finding of high titers of immunoglobulin E (IgE)
(fungus ball) is a roughly spherical growth of Aspergillus in a preexisting lung cavity; growth does not invade the lung tissues. an "air sign" shift will be seen with a change in the position of the patient.
most common in patients with severe neutropenia starting in lungs or spreading from sinus colonization. It requires aggressive treatment with voriconazole or lipid formulation of amphotericin B.
infections caused by nonseptate fungi (phylum Zygomycota, genera Rhizopus, Absidia, Mucor, and Rhizomucor). occurs with acidotic diabetes or leukemia and in these patients it is very invasive, having a predilection for invading blood vessels and the brain and causing rapid decline to death.
presents with facial swelling and blood-tinged exudate in the turbinates and eyes, mental lethargy, blindness, and fixated pupils.: must be diagnosed rapidly, usually by a KOH mount of necrotic tissue or exudates from the eye, ear, or nose.
4. Treatment: must be rapid! Management consists of (1) control of diabetes, (2) surgical debridement, and (3) aggressive treatment with amphotericin B or posaconazole.
changes in infections caused by Pneumocystis jiroveci...
have been reclassified as a fungus based on molecular biologic techniques such as ribotyping and DNA homology
Pneumocystis jiroveci is seen using...
seen in alveoli by methenamine silver or calcofluor stain or tissue.
Interstitial plasma cell pneumonitis
occurs in malnourished infants, transplant patients, patients on antineoplastic chemotherapy, and patients on corticosteroid therapy. Radiographs show a patchy, diffuse appearance, sometimes referred to as a ground-glass appearance.
responsible for approximately one third of deaths in AIDS patients.
causes morbidity and mortality when CD4+ counts decrease to less than 200/mm3 unless prevented with prophylaxis
Pneumocystis jiroveci diagnosis:
diagnosed by microscopy of biopsy specimen or alveolar fluids (Giemsa, specific fluorescent antibody, toluidine blue, methenamine silver, or calcofluor stains). Presence of serum antibodies is not a useful indicator of infection because almost all healthy and immunocompromised individuals have antibodies to Pneumocystis, suggesting exposure is common.
Pneumocystis jiroveci treatment:
treated prophylactically with trimethoprim-sulfamethoxazole or trimethoprim and dapsone.
Microsporidiosis occurs in...
immunocompromised individuals but may also occur in those who are immunocompetent. Infection by Microsporidia involves a variety of organs and systems, most notably, intestine, lung, kidney, brain, sinuses, muscle, and eyes.
Enterocytozoon bieneusi and Encephalitozoon intestinalis are...
microsporidia associated with gastroenteritis
Which of the following was once thought to be a protozoan but is now considered to be included with the fungi?