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.
T.V.Rao M.D
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
Candidosis
Candidiasis also 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
Normal flora
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.
Systemic Candidosis
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
T.V.Rao MD
Predisposition after Surgery and Therapeutic Approaches
Post operative 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
Laboratory Diagnosis
Skin scrapings,
Mucosal scrapping,
Vaginal secretions
Culturing Blood and other body fluids,
Observations
Microscopic observation after Gram staining. Gram + yeast cells.
Laboratory Diagnosis
Isolation of Candida from various specimens confers diagnosis
Serology
Molecular Methods
Microscopy
Gram staining – A rapid method
KoH preparation
Methylamine silver staining
Culturing
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
T.V.Rao MD
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
Cryptococcosis.
Cryptococcus neoformans
A Capsulated yeast – A true yeast..
A sporadic disease in the past.
Most common infection in AIDS patients.
Structure of C.neoformans
Morphology
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
Culturing
CSF -Culturing on Sabouraud's agar, and incubated at 37 0 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
Pathogenesis
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.
T.V.Rao MD
Pathogenesis
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.
Pathogenesis
Can manifest with involvement of ,Skin,
mucosa,organs,Bones,and as Disseminated form.
Can mimic like Tuberculosis ,
Laboratory Diagnosis .
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
Treatment
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
ASPERGILLOSIS
Aspergillosis
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
Morphology
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
T.V.Rao MD
Pathogenesis
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
Pathogenesis
Invasive Aspergillosis
occurs in immunocompromised with underlying disease
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