Dalia Kamal Eldien Mohammed. INTRODUCTION Systemic mycoses due to primary pathogens originate...
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Primary systemic fungal infection lecture NO -15- Dalia Kamal Eldien Mohammed
Dalia Kamal Eldien Mohammed. INTRODUCTION Systemic mycoses due to primary pathogens originate primarily in the lungs and may spread to many organ systems
INTRODUCTION Systemic mycoses due to primary pathogens
originate primarily in the lungs and may spread to many organ
systems. Organisms that cause systemic mycoses are inherently
virulent. In general primary pathogens that cause systemic mycoses
are dimorphic. These infections usually result from inhalation of
fungal spores, which can cause a localized pneumonia as the primary
manifestation of infection. In immunocompetent patients, systemic
mycoses typically have a chronic course; disseminated mycoses with
pneumonia and septicemia are rare. Symptoms include fever, chills,
night sweats, anorexia, weight loss, malaise, and depression may
occur. Various organs may be infected, causing symptoms and
dysfunction.
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Common systemic infections are: Histoplasmosis ; Generalized
involvement of the reticuloendothelial system (liver, spleen, bone
marrow) Blastomycosis; Single or multiple skin lesions or
involvement of the prostate Coccidioidomycosis: Bone and joint
infections, skin lesions, and meningitis
Paracoccidioidomycosis
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Histoplasmosis Histoplasmosis is an infection caused by the
fungus Histoplasma capsulatum. The fungus lives in the environment,
particularly in soil People can get histoplasmosis after breathing
the spores from the air. Although most people who breathe in the
spores dont get sick, those who do may have a fever, cough, and
fatigue. Many people who get sick will get better on their own
without medication. In some people, such as those who have weakened
immune systems, the infection can become severe, especially if it
spreads from the lungs to other organs. Histoplasmosis cant spread
from the lungs between people or between people and animals.
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Symptoms Symptoms of histoplasmosis are similar to those of
pneumonia include: Fever Cough Fatigue (extreme tiredness) Chills
Headache Chest pain Body aches
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Diagnosis The symptoms and signs of histoplasmosis are not
specific enough to establish the diagnosis. Some of the many
diagnostic laboratory tests available include the following:
Microscopic examination of samples of infected tissues Cultures of
body fluids or tissues to identify the fungus Detection of surface
markers of Histoplasma in a urine test Blood tests to measure
antibody response to Histoplasma
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Specimen; bone marrow aspirate or biopsy material,
bronchoalveolar lavage fluid or biopsy material from lung, sputum,
urine or skin lesions Direct microscopy: using 10% KOH and Parker
ink or calcofluor white mounts. Microscopically, they are composed
of hyaline septated hyphaes with micro and macroconidias in various
developmental stages. Tissue sections should be stained using PAS
(Periodic Acid Schiff) digest, Grocotts methenamine silver (GMS) or
Gram stain Culture: Sabouraud agar, following incubation at 25C for
6 to 12 weeks. Under these conditions, the fungal colonies are
initially smooth, but become filamentous, cottony, and brownish
with the age
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The conversion from the mold phase to the yeast phase is
necessary for accurate diagnosis of H. capsulatum. Conversion is
achieved using enriched media such as blood agar or Brain-heart
infusion agar (BHI) with cystein incubated at 3537C. After
conversion, smooth white to brown colonies can be observed that are
yeast by microscopic examination.
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Histoplasma capsulatum macro& microconidias with septated
hyphae
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A PAS stain highlights H.capsulatum infection in the liver
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Treatment Mild cases of histoplasmosis that are limited to the
lungs will resolve without specific treatment in about a month.
Severe or disseminated cases of histoplasmosis require treatment
with antifungal medications. Itraconazole (Sporanox, Onmel),
fluconazole (Diflucan), and amphotericin B
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Blastomycosis Blastomycosis is a systemic mycotic disease
caused by the dimorphic fungus Blastomyces dermatitidis. The
disease primarily affects dogs and humans, but has been reported in
cats, horses, sea lions, lions, wolves. Blastomycosis cannot be
spread from person to person or from animals to people. The fungus
lives in moist soil and in association with decomposing organic
matter such as wood and leaves. Lung infection can occur after a
person inhales airborne, fungal spores from the environment;
however, many people who inhale the spores do not get sick. The
symptoms of blastomycosis are similar to flu symptoms include
fever, chills, cough, muscle aches, joint pain, and chest pain.,
and the infection can sometimes become serious if it is not
treated.
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Diagnosis tissues or body fluids, such as blood, sputum, bone
marrow, liver, or skin and see if the fungus will grow from these
samples in a laboratory. Blastomycosis can also be diagnosed by
looking at a small sample of infected tissue under a microscope, to
examine the yeast cell. An antigen test can detect the presence of
the fungus in a urine or serum sample, and a blood test can measure
prior exposure to the fungus by detecting Blastomyces
antibodies
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Yeast of Blastomyces dermatitidis
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Coccidioidomycosis Valley fever, also called
coccidioidomycosis, is an infection caused by the fungus
Coccidioides immitis or Coccidioides posadasii. People can get
valley fever by breathing in the microscopic fungal spores from the
air, although most people who breathe in the spores dont get sick.
Usually, people who get sick with valley fever will get better on
their own within weeks to months, but some people will need
antifungal medication. C. immitis is a dimorphic saprophytic fungus
that grows as a mycelium in the soil and produces a spherule form
in the host organism.
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After Coccidioides infection, Coccidioidomycosis begins with
Valley fever, which is its initial acute form. If left untreated,
it can progress to the chronic form and then to disseminated
Coccidioidomycosis. Therefore may be divided into the following
types: Acute coccidioidomycosis Chronic coccidioidomycosis
Disseminated Coccidioidomycosis, which includes primary cutaneous
coccidioidomycosis significantly higher in individuals with altered
cellular immunity due to disease ( HIV infection, lymphoma),
medical treatment (corticosteroid therapy), or pregnancy
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Primary coccidioidomycosis: Most patients are asymptomatic, but
nonspecific respiratory symptoms resembling those of influenza,
acute bronchitis, or, less often, acute pneumonia or pleural
effusion sometimes occur. Symptoms, in decreasing order of
frequency, include fever, cough, chest pain, chills, sputum
production (hemoptysis), and sore throat. Progressive
coccidioidomycosis: Nonspecific symptoms develop a few weeks,
months, or occasionally years after primary infection; they include
low-grade fever, anorexia, weight loss, and weakness.
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Diagnosis Specimen include sputum, pleural fluid, CSF, exudate
from draining lesions, or biopsy specimens. Eosinophilia may be an
important clue in identifying coccidioidomycosis. The diagnosis is
suspected based on history and typical physical findings, when
apparent; chest x-ray findings can help confirm the diagnosis,
which can be established by fungal culture & microscopy
Microscopic examination of specimens to check for C. immitis
spherules are usually 20 to 80 m in diameter, thick-walled, and
filled with small (2 to 4 m) endospores. Endospores released into
tissues from ruptured spherules may be mistaken for non budding
yeasts. Cultures (routine on fungal media) Serologic testing using
an immuno diffusion kit (for IgG and IgM antibodies) and complement
fixation (for IgG antibodies) are the most useful tests.
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Coccidioidomycosis Spherules with endospores
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Lactophenol analine blue preparation of C. immitis
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Paracoccidioidomycosis Paracoccidioidomycosis (also known as
"Brazilian blastomycosis,""South American blastomycosis and
"paracoccidioidal granuloma") is a fungal infection caused by the
fungus Paracoccidioides brasiliensis. The only etiological agent,
Paracoccidioides brasiliensis is geographically restricted to areas
of South and Central America. P. brasiliensis is a thermally
dimorphic fungus The habitat of the infectious agent is not known,
but appears to be aquatic In biopsies, the fungus appears as a poly
gemulating yeast with a pilot's wheel-like appearance.
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Paracoccidioidomycosis is a chronic granulomatous disease that
characteristically produces a primary pulmonary infection, and then
disseminates to form ulcerative granulomata of the buccal, nasal
and occasionally the gastrointestinal mucosa. The disease in its
inception and development is similar to blastomycosis and
coccidioidomycosis.
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pathogenicity Paracoccidioidomycosis is a systemic mycosis,
Strong evidence indicates this fungus infects the host through the
respiratory tract. It frequently involves mucous membranes, lymph
nodes, bone, and lungs. like other systemic mycoses, it can cause
disease in immunocompetent & immunosuppression patients. Also
uniquely, it rarely causes disease in fertile-age women, probably
due to a protective effect of Estrogen Primary infection is thought
to be auto limited. In young people, a progressive form of the
disease occurs with high fever, generalized lymphadenopathy, and
pulmonary involvement with milliary lesions.
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Symptoms Infected lymph nodes become swollen and may drain pus,
but there is little pain. The lymph nodes most commonly infected
are those in the neck and under the arms. Painful ulcers may form
in the mouth. If the lungs are affected, people may have a cough
and difficulty breathing. The liver and spleen may enlarge.
Symptoms last a long time but are rarely fatal. The 2 general
clinical categories of paracoccidioidomycosis are: (1)
acute/sub-acute (juvenile paracoccidioidomycosis) (2) chronic form
(adult paracoccidioidomycosis).
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Clinical material: Skin scrapings, sputum and bronchial
washings, cerebrospinal fluid, pleural fluid and blood, bone
marrow, and tissue biopsies from various visceral organs. Direct
Microscopy: (a) Skin scrapings should be examined using 10% KOH and
Parker ink or calcofluor white mounts (b) Exudates and body fluids
should be centrifuged and the sediment examined using either 10%
KOH and Parker ink or calcofluor white mounts (c) Tissue sections
should be stained using PAS digest, Grocott's methenamine silver
(GMS) or Gram stain. interpretation: demonstrating the presence of
large, 20-60 um, round, narrow base budding yeast cells with
multiple budding "steering wheels" from any specimen should be
considered significant. Diagnosis
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Culture: Clinical specimens should be inoculated onto primary
isolation media, like Sabouraud's dextrose agar and Brain heart
infusion agar supplemented with 5% sheep blood. Interpretation: A
positive culture from any of the above specimens should be
considered significant. Serology: Identification: Clinical history,
tissue pathology, culture identification with conversion to the
yeast phase at 37C are important characters.
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Paracoccidioidomycosis Captains Wheel Ships wheel
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Treatment The antifungal drug itraconazole is the treatment of
choice Amphotericin B is also effective, but because of its side
effects, it is reserved for very severe cases.
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This is the last lecture in mycology, I wish all of you luck
and success