Opp mycosis Flashcards
What is opp mycoses disease?
Diseases caused by fungal pathogens, which are incapable of causing disease in a healthy person, but cause severe disease ( and sometimes killing ) in people susceptible when the hosts defenses are lowered ( immunocompromised)
Who are the patients susceptible to opportunistic fungal infections?
- Blood / marrow / solid organ transplantation
- Those born in a premature birth ( born before the full term )
- Major surgery (especially GI tract surgery)
- Uncontrolled diabetes melitus
- AIDS
- Neoplastic disease like cancer
- Immunosuppressive therapy
- Advanced age
Opp don’t cause infections in healthy but cause in immunocompromised
What are the types of fungal pathogens ?
- Endogenous (كان نومة جامدة)
- Candida sp.
- Pneumocystis jiroveci
Maybe even more than our own cells
Living inside the body in healthy people but cause disease if immunity goes down - Exogenous ( زيجو سبير و لا كريب )
- Cryptococcus neoformans
- Aspergillus sp.
- Zygomycetes
Organisms come from outside the body —> infect the immunocompromised by going inside the body
What are the Tcells opportunists?
They happen when there is deficiency or malfunction in Tcells
Ex : Cryptococcus neoformans ( exo ) Pneumocystis jiroveci ( endo ) Candida sp. (endo)
What’s really the phagocyte oppurtunists?
Happen when there is def in phagocytes ( monocytes and neutrophils )
Ex:
Aspergillus sp. ( exo )
Zygomycetes ( exo )
Candida sp. ( endo )
What is candida ?
Most prevalent pathogen
Harmless inhabitant of the skin and mucous membranes of all humans
Normal immune system keeps candida on body surfaces ##
What are the Main defense mechanisms against Candida species?
- Skin and mucous membranes integrity —> if intact and not broken —> stay outside and don’t enter the body
- Presence of normal bacterial flora —> compete with them
3. Phagocytosis: killing, mostly in polymorphonuclear cell, less in macrophages ( neutrophils / macrophages / monocytes )
- T cells : CD4+ T cells
What are the species of candida
C. albicans is the most commonly isolated from clinical material.
But mainly 95% : ( can agpt 3la elso2al 🙂)
- C. albicans (50-70%)
- C. glabrata (~14%)
- C. parapsilosis (~9%)
- C. tropicalis (~7%)
Remaining 5% of Candida BSI ( blood stream infections )includes other rare species.
What is candidemia?
Candida blood stream infections also called BSI
What is candidiasis ?
Disease caused by candida
What are the types of candidiasis?
1. Localized (cutaneous and mucosal candidiasis) affecting A. mouth B. throat C. skin D. vagina E. fingers F. nails G. bronchi H. lungs I. gastrointestinal tract
or become
- Invasive: Systemic, disseminated, hematogenous ( spreads through the blood ) candidiasis
BSI/candidemia is INVASIVE
What are the types of localized candidiasis ?
- Oropharyngeal candidiasis
- Vulvovaginal candidiasis
- Cutaneous (skin) candidiasis
What is the oropharyngeal candidiasis?
THRUSH
- Thick / white / adherent growth
- Occur in:
A.tongue
B. Mucous membranes of the mouth and throat - In patients with severe immunological impairment:
A. HIV
B. Leukemia
C. Diabetes mellitus
What is vulvovaginal candidiasis ?
- Painful / inflammatory condition of the vagina
- Cause
A. ulceration
B. Curd-like, whitish vaginal discharge
3. Associated with: A. broad spectrum antibiotics B. 3rd trimester C. low vaginal PH D. Diabetes mellitus
What is cutaneous / skin candidiasis?
occurs in:
A. chronically moist areas of skin
B. in burn patients
What are invasive candidiasis ?
Usually begins with candidemia (but in only about
50% of cases candidemia can be proven in susceptible people —> 50% undiagnosed )
- Usually, if the phagocytes are normal and it’s function is ok —> invasion stops
- If phagocytes are compromised —> injections are spread to many organs —> focal infections in kidneys / liver / brain and cause meningitis
- Mortality is 30-40%
How can we diagnose candidiasis in lab?
- Vaginal —> high vaginal Swabs —> direct microscopy by gram staining —> yeasts with pseudohyphae ( short chain of cells resulting from the lack of separation of daughter cells following budding
- Candidemia —> blood culture —> candida release carbohydrates in the blood ( serum of the patients )which are glucan and mannan which can be detected —> antigen detection
What is aspergillosis?
Diseases of genus aspergillosis —> A. fumigatus is the most common species
- Very common
- Airborne —> major route is respiratory and nasal ( portal of entry )
- Present in soil —> airborne soil fungus
- usually occurs in lungs – spores germinate in lungs and form fungal balls or aspergilloma (a ball-like mass of the fungus A. fumigatus in the lung).
- Can also infect/colonize sinuses, ear canals, eyelids, and conjunctiva
- Invasive aspergillosis: Can spread from the lungs to produce necrotic pneumonia, and infection of brain, heart, and other organs.
- Serious opportunistic threat to AIDS, leukemia, and transplant patients
What are the RF of invasive aspergillosis?
- Prolonged neutropenia —> no of neutrophils is low for long time —> may be bcz of using antibiotics for long time
- High doses corticosteroids therapy of several weeks
- Organ transplant recipients receiving immunosuppression in order to maintain the transplant
- Chronic granulomatous disease (CGD): a primary immunodeficiency ( the immune system or part of it is not developed ) in which phagocytes are unable to kill certain types of bacteria and fungi —> become susceptible
How can we diagnose aspergillosis in lab?
Clinical specimens:
- Respiratory: Fresh sputum, bronchoalveolar lavage, biopsy ( if it is tissue ) etc.
- Disseminated: Skin lesions biopsy
- Direct microscopy ( LIGHT MICROSCOPE ): Septate ( branches between the 2 fungi ), dichotomously branched hyphal fragments (digested in 10 % KOH-calcofluor —> staining —> yellow color )
- Culture ( grow them ):Multiple specimens on Sabouraud glucose
agar with antibiotics (chloramphenicol)to suppres bacterial growth at 37oC —> Blood culture positivity: <5% - Serologic diagnosis ( using antibodies in the lab ) to detect the Antigen (galactomannan) detection
A. Sensitivity > 60%: in more than 60% we can get the antigen
B. Specificity > 90%: show that 90% + tests are true +
What are zygomycosis ?
Group of fungi known as zygomycetes
Frequency is rising
Fatality remains high —> they die 🙃
What are the most observed clinical manifestations of zygomycosis?
- Rhino-orbital
- cerebral —> affect the nervous system
- pulmonary zygomycosis
What are the other cases described for zygomycosis ( not main )?
- gastrointestinal
- cutaneous
3 disseminated - miscellaneous (many different types)
What are the RF of zygomycosis for
A. Rhino-orbital
B. Pulmonary / systemic
C. Cutaneous
D. Gastrointestinal
A. Ketoacidosis ( Acidosis caused by the increased production of ketone bodies, as in diabetic acidosis ) / hyperglycemia
B. Prolonged neutropenia / Immunosuppressive therapy
C. Severe burns
D. Malnutrition / ulcers
Diagnosis of zygomycosis?
histo- pathologically
2 stains available:
1. H and E : Hematoxylin and Eosin —> pink color
- GMS : Gomori-methenamine stain —> green
What are the Pneumocystis jiroveci?
- small, unicellular fungus (yeast)
- present in lungs of many mammals, including humans —> Persistent but harmless infection
- Main defense mechanism is T-cell mediated
- Causes Pneumocystis pneumonia (PCP), the most prominent opportunistic infection in AIDS patients
- This pneumonia forms secretions in the lungs that block breathing and can be rapidly fatal if not controlled with medication
- Mononuclear infiltration, edema and fibrosis are major histopathologic findings
What are the major histopathlogic finding in pneumocystisis?
Mononuclear infiltration
edema
fibrosis bcz of the damage of the tissues there
Diagnosis of pneumocystis ?
- Immunofluorescence microscopy: detect the pathogen in the tissues by fluorescent microscope and antigen is detected by antibodies
- Staining by ( cyst wall stains )
A. Toluidine Blue O (TBO)
B. calcofluor white (CW) - Staining by ( trophozoite stains )
A. Grocott’s methenamine silver stain (GMS)
B. Diff-Quick (DQ) - Detect the presence of the DNA of the fungus by polymerase chain reaction ( PCR )
What is crytptococcosis ?
- systemic fungal infection that may involve any organ of the body, primary site of infection is the lung
- Caused by ( جيت نيو كريب )
- Cryptococcus neoformans
- Cryptococcus gattii
- Widespread yeasts present in soil around pigeon roosts
- Prominent feature: thick polysaccharide capsule, which causes evasion from phagocytosis
- Infection is always exogenous (IMP)
- is not transmitted from human to human
- Common infection of AIDS, cancer or diabetes patients
- Infection of lungs leads to cough, fever, and lung nodules
- Skin, bones and visceral organs may also become involved.
- Dissemination ( spread ) to meninges and brain ( prefer to go there )can cause severe neurological disturbance and death
What are the types of invasive mycoses? ( In order of importance )
- Candidiasis
- Aspergillosis
- Zygomycosis
What are the syms on the exposed individual with cryptococcosis?
The majority of the exposed individuals have asymptomatic ( bcz the immune system control the infection ) or subclinical infection —> NORMAL HEALTHY PEOPLE
CLINICAL signs and syms NOT SHOWN
IMMUNOCOMPROMISED PEOPLE —> infection become clinical and can spread to other parts of the body
What are the RF for cryptococcosis?
- The RF
- Characteristic of the RF
- World- wide or not?
- Who predispose this infection
- Immunocompromised host —> infection can spread to the brain and meninges —> COMMONEST cause of fungal meningitis ex: C.Neoformans
- AIDS-defining illness —> in HIV infected people when you see C.neoformans that is an indication that he is an AIDS patient —> no of CD4 lymphocyte sis very low —> 200cells/mm3
- world wide
- Happens in patients with
A. Hodgkin’s disease
B. lymphoreticular malignancies
C. steroid therapy
How to diagnose cryptococcosis?
1. demonstration of encapsulated yeast cells in:( by India ink under light microscope A. CSF B. tissue biopsy 3. BAL —> bronchoalveolar lavage 4. urine
- Blood culture ( + in 35-70% of AIDS patients )
- Detection of cryptococcal capsular polysaccharide antigen ( technique: Latex agglutination/ELISA) in spinal fluid esp CSF ( found in the capsule )
A. Specificity and sensitivity —> : > 90%
Summary of diagnosis of fungal infection
• Clinical: fever, pulmonary symptoms, skin lesions, sinus tenderness, pain, etc. —> not specific indications
Radiological
– Chest x-ray
– CT scans of chest, sinuses, abdomen
Microbiological —> SPECIFIC
• Histological: biopsy of suspect lesions
- Serological: Antibody (limited) and antigen tests (galactomannan and cryptococcoal antigen)
- Molecular: Nucleic acids (PCR)
• Cultivation
– Blood cultures
– Culture of suspect lesions by biopsy
– BAL fluid culture in patients with pneumonia
