Opportunistic Fungal Infections
Opportunistic mycosis a fungal or fungus-like
disease occurring in an animal / human’s with a compromised immune system. Opportunistic organisms are normal resident flora that become pathogenic only when the host's immune defenses are altered, as in immunosuppressive therapy, in a chronic disease, such as diabetes mellitus, or during steroid or antibacterial therapy that upsets the balance of bacterial flora in the body.
Common Opportunistic Fungus
We find the highest frequency of
opportunistic fungal infections come in the following order:
1.Candidiasis 2.Aspergillosis 3.Cryptococcosis
Candida as Opportunistic Infection
called as Monoliasis, Can infect Skin, Mucosa, or Internal Organs Called as Yeast Like fungus Currently important cause of opportunistic fungal infection.
What are Candida
Exist in Mouth, Gastrointestinal tract. Vagina, skin in 20 % of normal Individuals. Colonization increases with age,in pregnancy Hospitalization Immunity Depends on T lymphocytes, and effective Immunity Important etiological agent presenting as opportunistic infection in Diabetus and HIV patients
Morphology and Culturing
Ovoid shape or spherical budding cells
and produces pseudo mycelium Routine cultures are done on Sabouraud's Glucose agar, Grow predominantly in yeast phase A mixture of yeast cells and pseudo mycelium and true mycelium are seen in Vivo and Nutritionally poor media.
Macroscopic and Microscopic appearance of Candida spp
Pseudohypal structures in Candida
Normal Flora to Pathogenic fungi
As Candida is present in practically all
humans, it has many opportunities to cause endogenous infections in compromised host - so, Candida infections continues to most frequent opportunistic fungal infection.
Occurs in Patients who carry more yeasts in Mouth,
Gastrointestinal system, Predisposed with Individuals with 1 On antibiotic or/and Steroid Therapy 2 Immunosupressed 3 Recipients with organ transplantation 4 Infancy – Old age – Pregnancy - On Antibiotic therapy - 5 Indisposed with trauma Occluding lesions, - 6 Immuno Supression, Major event in AIDS patients - 7 Diabetus mellitis. - 8 Zink and iron deficiencies
Pathogenesis and Pathology
Mucosal infections occur superficially –Discrete
white patches on mucosal surface. Can affect tongue Infants and old persons are affected In Immune compromised /AIDS. Oral candidois is commonly seen Vaginal Candidosis causes itching soreness white discharge, White colored lesions, Pregnancy in advanced stage, Majority experience one episode in a life time
Predisposition after Surgery and Therapeutic Approaches
Immuno Supression Use of IV catheters Use of cytotoxinc drugs and cortosteriods Use of Urinary Catheters
Important species of Candida in Human infections
C.albicans C.tropicalis C.glabrata C.Krusei
Prominent Infections with Candida
Oral Thrush produced by Candia albicans
Many cases of AIDS are suspected by observation of Oral Cavity
Skin scrapings, Mucosal scrapping, Vaginal secretions Culturing Blood and other body fluids, Observations
Microscopic observation after Gram staining. Gram + yeast cells.
Isolation of Candida
from various specimens confers diagnosis Serology Molecular Methods
Gram staining – A
rapid method KoH preparation Methylamine silver staining
Easier to culture on
Sabouraud's dextrose agar Culturing in routine Blood culture Media Culturing urine - A semiquative estimations are essential Colony forming units essential in attributing infections
Easier Identification of species as C.albicans
Germ tube test
identifies C.albicans from other Candida species. Majority of Diagnostic laboratories depend on this test.
Emerging Methods for detection of Candida Infections
Molecular Methods PCR
A Capsulated yeast –
A true yeast.. A sporadic disease in the past. Most common infection in AIDS patients.
Structure of C.neoformans
A true yeast Round 4 – 10 microns Surrounded by Mucopolysaccharide capsule. Thick in vivo Negative staining with India Ink and Nigrosin 60% of the infected prove positive by India Ink preparation on examination of CSF KoH preparations in Sputum and other tissues, PAS and Mucicaramine staining helps confirmation.
As Seen in India Ink preparation
CSF -Culturing on
Sabouraud's agar, and incubated at 370 c for upto to 3 weeks Cultures appear as Creamy, white, yellow Brown colored Simple urease test helps in confirming the isolate.
Cryptococcus neoformans Serotypes
A true yeast 4 serotypes - A,B,C,D A and D - C.neofromans var neoformans B and C - C.neoformans var gatti. Many infections are caused by C.neofromans var neoformans. Found in wild/Domesticated birds. Pigeons carry C.neofromans, Birds do not get infected.
Pigeons and Red river gum tress harbors the Cryptococcus in nature
Life cycle of C.neofromans
Enters through lungs - inhalation of
Basidiospores of C neoformans Enters deep into lungs, Men acquires more infections, and women less infected. Self limiting in most cases, Pulmonary infections can occur. Present as discrete nodules - Cryptococcoma.
Can infect normal humans Abnormalities of T lymphocyte function
aggravates, the clinical manifestations. In AIDS 3- 20% develop Cryptococcosis. Present with Chronic meningitis , Meningo encephalitis Manifest with – head ache low grade fever, Visual abnormalities ,Coma – fatal Treatment reduces the morbidity and cure in non immuno supressed expected.
Can manifest with involvement of ,Skin,
mucosa,organs,Bones,and as Disseminated form.
Can mimic like Tuberculosis,
CSF Microscopic observation under India Ink
preparation Direct microscopy - Gram staining Cultures on Sabouraud dextrose agar, Serological tests for detection of Capsular antigen CSF findings mimic like Tuberculosis IN CSF - latex test for detection of Antigen Blood cultures, ELISA
Immune competent Fuconazole,Itraconazole Immune Deficient – Amphotericin B Flu cytosine AIDS patients are not totally cured , Relapses are frequent with fatal outcome. Rapid resistance with Fluconazole. Avoid contact with Birds
In nature > 100 species of Aspergillosis
exist, Few are important as human pathogens 1 A.fumigatus 2 A.niger 3 A.flavus 4 A.terreus 5 A.nidulans
Fungal spores enters through respiratory tract
Cultured as Mycelial
fungus Separate hyphae with distinctive sporing structures Spore bearing hyphae – Conidiophores terminates in a swollen cell vesicle surrounded by one or two rows of cell ( Streigmata ) from which chains of asexual conidia are produced
Pathogenesis - varied clinical presentations
Allergic Aspergillosis – Atopic individuals, with
elevated IgE levels 10-20% of Asthmatics react to A.fumigatus Allergic alveoitis follows particularly heavy and repeated exposure to larger number of spores Maltsters Lung – causes allergic alveolitis, who handle barley on which A.claveus has sporulated during malting process
Aspergilloma – A fungal
ball, fungus colonize Preexisting (Tuberculosis ) cavities in the lung and form compact ball of Mycelium which is later surrounded by dense fibrous wall presents with cough, sputum production Haemoptysis occurs due to invasion of blood vessels
Invasive Aspergillosis occurs in immunocompromised with underlying disease Neutropenia Most common predisposing factor A.fumigatus is the most common infecting species
In Bone marrow recipients leads
to high mortality Lung sole site in 70 % of patients Fungus invades blood vessels, causes thrombosis septic emboli Can spread to Kidney and heart.
Endocarditis A rare
complication Open heart surgeries are risk factors Poor prognosis
Paranasal granulomas Caused by
A.flavus,A,fumigtus may invade paranasal sinuses spread to bone to orbit of the eye, and Brain
Also called as Mucor Mycosis or Phycomycosis Saprophytic mould fungi Major Causative agents Rhizopus,
Mucor, Absidia. Patents may manifest with Rhinocerbral Zygomycosis
Majority are with
Broad aseptate mycelium with many number of asexual spores inside a sporangium which develops at the end of the aerial hyphae
Non septate hyphae Having branched sporangiophores with sporangium at terminal ends
Shows non septate hyphae Sporangiophores in groups they are above the Rhizoids
Important Clinical Manifestations
Zygomycosis associate with Diabetus mellitus, leukemia, or lymphomas Causes extensive Cellulitis, and tissue destruction.
extensive tissue destruction. Spread from Nasal mucosa to turbinate bone,paranasal sinuses ,orbit, and Brain Rapdily fatal if untreated
Severe immuno compromised may
manifest as primary cutaneous lesions Rarely infects Burns patients But lesions can be less severe than Brain lesions
more reliable than culturing A certain Diagnosis needs Biopsy Nasal discharges Sputum, rarely contain many fungal elements
Contain non septate
hyphae in thromboses vessels or sinuses surrounded by leukocytes or giant cells
In Koh preparation
shows broad aseptate branching mycelium, and distorted hyphae But staining with Methenamine silver is more sensitive. Staining with PAS not helpful
Always depend on
clinical history and presentation for certain diagnosis Cultured on Sabouraud's dextrose agar.
Pathology and Pathogenesis
Spread from nasal mucosa Spread to turbinate bones Para nasal sinuses ,
orbit, brain Associated with uncontrolled diabetes mellitus In leukemia patients , Lymphoma patients, Leads to fatal outcome, Improved with Anti fungal treatment. Spread to lungs disseminated infection,.
Early Diagnosis highly essential for
effective cure High doses of I V Amphotericin B Surgical interventions Control of Diabetus a basic requirement for better clinical outcome
Identified as most Important opportunistic fungal infection in the Era of AIDS
Pneumocystis jiroveci – causes pneumonia in
immunocompromised In the past considered as Protozoan Now Molecular biologic studies prove as Fungus Related to Ascomycetes Many Animals harbor in lungs in Rats, Ferrets, Rabbits, Causes the diseases in human if immunocompromised
found in rats Pneumocystis jiroveci in human species
Corticosteroid therapy Transplant recipients Antineoplastic therapy Transplant recipients When retroviral treatment is not started,a major cause of death in AIDS patients. Infections of the other organs is on raise, Spleen,Lymphnodes, Bone marrow,
4- 6 microns, contains 4 to 8 nuclei Stained with Silver stain, toludine blue, Calcoflour white Trophozites present in a tight mass P.Jiroveci is an extracellular pathogen
Life cycle of P.Jiroveci
P.Jiroveci is extracellular pathogen, In AIDS patients – infiltration of alveolar
spaces with plasma cell leads to interstitial plasma cell pneumonias Plasma cells are absent in AIDS related Pneumocystis pneumonia Blockade of oxygen exchange interface, results in Cyanosis
1 Bronchoalveloar lavage 2 Lung biopsy 3 Induced sputum Stains preferred 1.Giemsa 2 Toludine blue 3 Methenamine silver 4 Calcofluor white
X ray of Chest supports the Diagnosis
Culturing yet not possible Direct Fluorescent method with
Monoclonal's a rapid and emerging method Serology – For epidemiological purpose only to establish prevalence of Infection.
Immunity - Pneumoctistis
In the absence of immuno Supression
P.Jiroveci does not cause disease. Cell Mediated immunity plays a dominant role in resitance to Infection. Infection not seen until CD4 counts drop to <400/microliters.
Acute cases are treated with
Trimethoprim-Sulphamehoxazole Pentamidine, Isothionate are very effective compounds
Treating with TMP-SMZ Aerolized Pentamidine is effective and
locally reaches higher concentration in the lungs.
Causes serious disseminated infection, Papular skin lesions in AIDS Common in South east Asia
A dimorphic fungi Mould at 250 c Yeast at 370c Intracellular yeast like appearance as in
Histoplasmosis The fungi are associated with Bamboo rat
Typical microscopic appearance of P.marneffi
Dimorphic chaterization of Pencillum marneffi
Pathology and Pathogenesis
Inhalation of Conidia Primary site of infection RES Present with Chills, Fever Malaise Hepato
splenomegaly Probably AIDS defining infection
Microscopy Tissues, skin Lymph node bone marrow Use of special stains Culturing on Sabouraud dextrose agar Immunoblot methods PCR
Some times Amphotericin B may be
considered. Major Antifungal treatments are speculative
Other Opportunistic Fungus
Advances in Medicine have resulted in increase
in fungal infections Devastating systemic infections have been caused by species of 1. Fusarium 2 Paecilomyces 3 Bipolaris 4 Curvilaria 5 Alternaria
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Dr.T.V.Rao MD Email email@example.com