Cryptococcus & Zygomycosis: Acquisition & Manifestation

• Opportunistic mycoses are fungal infections that occur more frequently or are more severe in individuals with weakened immune systems

Why Opportunistic Mycoses?

• Opportunistic mycoses thrive on the low immunity of the body, resulting from a condition that causes a disease state
• Some can be pathogenic to immunocompetent individuals
• Rising numbers of immunosuppressed patients globally makes understanding this special group critical
• Diagnosis can be difficult, bugs can be resistant, and treatment options increase morbidity and mortality

Predisposing Conditions

• Candida is associated with antibiotic therapy, catheters, diabetes, corticosteroids, and immunosuppression
• Aspergillus is associated with leukemia, TB, corticosteroids, immunosuppression, and IV drug abuse
• Cryptococcus is associated with diabetes, TB, corticosteroid and immunosuppression
• Zygomycetes is associated with diabetes, cancer and IV therapy

Opportunistic Infections

• Candidiasis is commonly caused by Candida spp.
• Cryptococcosis is caused by Cryptococcus neoformans and is rare or common
• Aspergillosis is caused by Aspergillus fumigatus and is rare or common
• Zygomycosis is caused by Rhizopus, Mucor, Rhizomucor, Absidia, etc., and is rare
• Pneumocystosis is caused by Pneumocystis jirovecii and is rare
• Invasive fungal infections may be endogenous like Candida, or often exogenous like Aspergillus, Cryptococcus and Zygomycetes
• Histoplasmosis, Blastomycosis, Coccidioidomycosis, and Paracoccidioidomycosis are invasive fungal infections resulting from Reactivation
• Tissue damage and presence in a normally sterile site are driving factors of invasion

Candidiasis

• Part of man's normal flora is found in the GIT, vagina, and on the skin.
• Could also be transmitted sexually and as a nosocomial infection.
• The most important opportunistic systemic mycosis worldwide.
• Infections affects all organs in the body, skin and the mucosa
• Colonization increases with age, in pregnancy, and with hospitalization

Candida Species

• Candida albicans is a species.
• C. dublinensis is a species of Candida.
• C. tropicalis is a species of Candida.
• C. krusei is a species of Candida.
• C.parapsilosis is a species of Candida.
• C.glabrata is a species of Candida.
• C.gullermondii is a species of Candida.
• C.lusitaniae is a species of Candida.
• C.kefyr is a species of Candida.

Candidiasis Pathogenesis

• Candida overgrows in colonized sites
• Invades non-colonized sites due to breach in skin and mucosal barriers
• Candida cells elaborate polysaccharides, proteins, and glycoproteins to stimulate host defenses, facilitate the attachment, and invasion of host cells; this includes biofilms

Candidiasis – Pathogenesis 2

• Defense mechanisms against candidiasis is by phagocytosis and polymorphonuclear cells.
• Invasive disease typically starts with candidemia
• Candida infection that spreads effects the kidney, skin, eye, heart, liver, and the meninges
• Candidemia mortality rate is 30-40%

Candidiasis – Pathogenesis 3

• Chronic mucocutaneous candidiasis (CMC) is a group of syndromes with persistent, severe, and diffuse granulomatous cutaneous candida infections affecting skin, nails, and mucous membranes
• Cell-mediated immunity defects cause candida
• Autoimmunity and hypoparathyroidism cause candidiasis

Candidiasis: Clinical Presentation

• Oropharyngeal candidiasis presents as oral thrush, glossitis, stomatitis, and angular cheilitis
• Cutaneous candidiasis presents as intertrigo, diaper candidiasis, paronychia, and onychomycosis
• Vulvovaginal candidiasis and balanitis are types of candidiasis
• Candidemia is Candida septicemia and causes disseminated candidiasis

Systemic Candidiasis Symptoms

• Oesophagitis is a manifestation.
• Diarrhoea is a manifestation.
• Bronchopulmonay candidiasis is a manifestation.
• Pyelonephritis is a manifestation.
• Cystitis is a manifestation.
• Endocarditis and Myocarditis are manifestations.
• Endophthalmitis is a manifestation.
• Meningitis is a manifestation.
• Arthritis is a manifestation.
• Osteomyelitis is a manifestation.
• Peritonitis is a manifestation.

Candidiasis: Diagnosis

• Possible Specimens are Blood, CSF, Peritoneal fluid, Urine, Respiratory secretions, and Wound effluents
• Direct microscopy involves the use of KOH, calcofluor white, and stain
• Culturing on SDA, Chromagar at the correct temperature, to see true hyphae
• PCR is a testing method
• MALDI-ToF is a testing method
• Serology for β,(1,3)-D-glucan, and Mannan is a testing method

Candidiasis: Treatment

• Oral thrush is treated with nystatin, azoles
• Systemic candidiasis is treated with amphotericin B ± flucytosine, fluconazole, or caspofungin
• Chronic mucocutaneous candidiasis responds well to oral ketoconazole and other azoles, requires life-long treatment
• Remove the identified inciting event for treatment

Cryptococcosis

• Phyla Basidiomycota, is a true yeast
• Cryptococcus neoformans commonly live in soil and in bird (pigeon) droppings worldwide
• Cryptococcus gatti - lives in trees
• Thick mucopolysaccharide capsule leads to phagocytosis
• Melanin occurs
• C. neoformans is the leading cause of Meningitis
• An estimated one million new cases and 600,000 deaths per year

Cryptococcosis – Pathogenesis

• Acquired by inhalation of desiccated aerosolized yeast cells or possibly the smaller basidiospores (sexual)
• Activates neutrophils for phagocytosis
• In otherwise healthy humans inhaled yeast cells can cause asymptomatic or self limiting pneumonia
• Neurotropism- CNS and Meningoencephalitis can results
• May present as discrete nodules in the brain - Cryptococcoma

Cryptococcosis

• T-cell deficiency e.g HIV (AIDS patients: 3-20%) is the main risk factor
• Corticosteroid therapy is a risk factor.
• Organ transplantation is a risk factor.
• Diabetes mellitus is a risk factor.
• Hematological malignancy (30% in patients with CNS lymphomas) is a risk factor.
• Fungal infection is found in wild/Domesticated birds (Pigeon) and eucalyptus tree
• Pigeons carry C.neoformans, but do not get infected

Cryptococcosis – Clinical Manifestation

• Primary infection in the lungs may mimic TB
• Can spread to skin, eye, adrenals, bone and prostate
• Cryptococcal meningitis is the most common disseminated manifestation
• Chronic meningitis has differentials including brain tumor, brain abscess, degenerative central nervous system disease
• Meningism, headaches, and disorientation result
• Cryptococcoma; signs of SOL
• AIDS 5-8%

Cryptococcosis – Diagnosis

• Specimens are needed for analysis.
• Negative staining with India ink /Nigrosin.
• Cerebrospinal fluid examination shows an increase in lymphocytes, low glucose levels, and elevated protein
• Cultures on Sabouraud dextrose agar-mucoid, brownish colonies
• Detection of cryptococcal antigen present in serum or CSF leads to diagnosis
• Latex agglutination.
• Enzyme immunoassay

Cryptococcosis : Treatment

• Induction for a certain duration.
• Maintenance for a certain duration.
• Consolidation for a certain duration.
• Amphotericin B.
• 5-Flucytosine.
• Fluconazole effective for prevention of recurrence
• Relapses with fatal outcomes common in AIDS patients.

Aspergillosis

• Only a few of the more than 100 species of Aspergillus are human pathogens
• Aspergillus spp. are moulds (saprophytes) - live in soil, on plants
• Abundant during construction and when dust is spread
• Small conidia that are aerosolised
• Common species are: A.fumigatus, A.flavus, A.niger, A.terreus, A.nidulans

Aspergillosis: Risk Factors

• Chronic granulomatous disease of childhood.
• Haematological malignancies e.g acute leukemia.
• Bone marrow and organ transplantation(25 – 40%).
• IV drug abuse.
• HIV/AIDS.
• Diabetes mellitus and Tuberculosis
• COPD and Alcoholism
• Corticosteroid therapy

Aspergillosis - Pathogenesis

• Wide spectrum of diseases
• Ubiquitous
• Incubation: between 36 hours to months
• Factors that an organism contributes to disease type and severity result from spore size, organism growth rate, adherence to host epithelial surfaces and toxin/enzyme production Alveolar macrophages in lungs engulf and kill conidia when capable
• Otherwise germinate, produces hyphae and invades

Aspergillosis - Clinical Manifestation 1

• Allergic Bronchopulmonary Aspergillosis is has elevated IgE levels, with 10-20% of Asthmatics react to A. fumigatus and can cause asthma
• Asthma, recurrent chest infiltrates, eosinophilia, and both type I (immediate) and type III (Arthus) skin test
• Aspergilloma: A fungal ball where fungus colonize preexisting cavities from TB, sarcoidosis, emphysema in the lung and form compact ball of mycelium surrounded by dense fibrous wall
• Can be Asymptomatic
• Symptomatic as cough, dyspnea, weight loss, fatigue, and hemoptysis(rarely invasive)

Aspergillosis - Clinical Manifestation 2

• Invasive Aspergillosis: Aspergillus develop in lung tissue causing invasive infection then spread can occur to other organs
• Gastrointestinal tract, kidney, liver, or other organs, producing abscesses
• Chronic necrotizing pulmonary aspergillosis for moderate immunocompetence
• Non-invasive Aspergillus: nasal sinuses, ear canal, the cornea, or the nails

Aspergillosis - Diagnosis

• Possible Specimens are respiratory secretions, bronchoalveolar lavage, Lung biopsy
• Can conduct serum of blood
• Direct microscopy with KOH and calcofluor white.
• Cultures on SDA with Speciation based on conidial arrangement, Histology, Serum antigen tests

Aspergillosis - Treatment

• Amphotericin B
• Itraconazole and new triazoles such as posaconazole for Amphotericin resistant species.
• 5 -Flucytosine.
• Steroids for Allergic attacks in ABPA.
• Surgery may be indicated.
• Prevented by avoiding exposure to conidia (abundant in constructions and uncompleted buildings).

Zygomycosis

• Phylum Glomeromycota.
• Molds found everywhere with high mortality.
• Major agents include rhizopus, Rhizomucor, Absidia, and Mucor.
• Major risk factors can be Diabetic ketoacidosis, Haematologic malignancies and 3rd degree burns
• Can be due to corticosteroids therapy, bone marrow transplantation, dialysis with the iron chelator deferoxamine

Zygomycosis- Pathogenesis

• Acquired through inhalation of spores or neutropenia
• There is impaired phagocytosis by alveolar macrophages and polymorphonuclear leucocytes
• Neutrophil dysfunction and accumulation of sugar and acids enable relentless growth of organisms
• Hyphae invades the walls of blood vessels once a primary infection is established results in the dissemination of mycotic thrombi and the formation of metastatic foci in many organs
• High invasiveness is appreciated in tissues

Zygomycosis – Clinical Presentation 1

• A life-threatening form of zygomycosis known as Rhinocerebral mucormycosis
• Begins in the paranasal sinuses following inhalation of sporangiospores, may extend to involve orbit, palate, face, nose, brain, andResults in septic necroses of tissues of nasopharynx and orbit
• Pulmonary zygomycosis follow inhalation of sporangiospores into the lungs, and can be accompanied by fever, shortness of breath, cough haemoptysis
• Direct inoculation of traumatic breaks in the skin and mucous membranes may lead to primary mucocutaneous infection

Zygomycosis- Diagnosis

• Skin scraping come from cutaneous lesions.
• Sputum and needle biopsies come from pulmonary lesions.
• Nasal discharges, scrapings and aspirates come from sinuses in patients with rhinocerebral lesions.
• Biopsy comes from disseminated disease.
• Direct microscopy uses aseptate to pauci-septate hyphae of zygomycetes
• Rapidly growing molds can be cultured
• Morphology varies among the species.

Zygomycosis

• Early diagnosis
• Reverse underlying predisposing risk factors, if possible
• Surgical debridement; and
• Prompt antifungal therapy (Amphotericin B, Capsofungins) are used

Other Opportunistic Infections

• Pneumocystis jiroveci
• Penicillium marneffei
• Fusarium
• Bipolaris
• Exophiala
• Scedosporium
• Sporothrix
• Wangiella
• Curvularia
• Alternaria

Mass Spectrometry

• Identification of microorganisms is done by a mass spectrometric profile of the proteins, largely rRNA proteins, of the organism
• The proteins absorbed in matrix get laser activated
• The laser is used to transfer energy and heat
• The molecules move through the vacuum depending on mass to charge ratio
• Molecular database for identification

Explore the primary routes of acquisition and common manifestations of Cryptococcus neoformans and zygomycosis (mucormycosis). Key aspects include risk factors, likely outcomes in healthy individuals, and diagnostic findings. The disseminated manifestation and pathogenesis of these infections are discussed.