Presentation on theme: "OPPORTUNISTIC FUNGAL INFECTIONS"— Presentation transcript:
1 OPPORTUNISTIC FUNGAL INFECTIONS Smilja Kalenic, MD, PhDClinical Hospital Centre Zagreb, CroatiaMy everyday job is clinical microbiology and hospital infections in a 1670 bed University hospital.We have many compromised patients suffering from opportunistic fungal infections, and every year we can see more and more such patients and more fungal species involved.So, these infections are for me a great challenge in diagnosis and in prevention.
2 LEARNING AND PERFORMANCE OBJECTIVES to learn about the most frequent opportunistic fungi and to understand main risk factors for developing infectionto be able to predict the most probable agent of invasive fungal infection in a particular compromised patient state and to be able to act preventivelyAdditional Internet readings:updates/fungal
3 FUNGI EUCARIOTIC ORGANISMS TWO BASIC FORMS: - YEASTS - MOLDS Yeasts are unicellular organisms, reproducing by budding and division; molds are multicellular organisms growing in filaments called hyphae, forming mycelium and reproducing by conidia and spores. Both yeasts and molds have sexual and asexual reproduction. Rare fungi have other forms (cysts, spherulas). Fungi have a rigid cell wall with mannans, glucans and chitin in it, and with ergosterol in the cell membrane.
4 MYCOSES 1. SUPERFICIAL 2. CUTANEOUS 3. SUBCUTANEOUS 1. Affects stratum corneum only; Malassezia furfur rarely causes opportunistic fungemia2. Affects superficial keratinized tissue only (about 40 related fungi)3. Fungi from soil or vegetation, reach subcutaneous tissue by traumatic inoculation; rarely cause systemic disease.
5 4. ENDEMIC (PRIMARY, SYSTEMIC): MYCOSES4. ENDEMIC (PRIMARY, SYSTEMIC):Histoplasma capsulatum, Coccidioides immitis, Blastomyces dermatitidis, Paracoccidioides brasiliensis4. Fungi geographically restricted to specific endemic areas. They are primary pathogens (true pathogenic fungi), living in soil mixed with guano (H. capsulatum, C. immitis), or not clearly defined soil (B. dermatitidis, P. brasiliensis). They cause pneumonia and systemic disease in a previously healthy persons.
6 - Candida (different species) - Pneumocystis carinii (?) MYCOSES5. OPPORTUNISTICendogenous- Candida (different species)- Pneumocystis carinii (?)“Endogenous” means that the fungus is a part of a normal human flora. “Exogenous”(see next slide) means that the fungus does not normaly live in/on human body, although it can transiently contaminate human body surfaces (especially respiratory tract).P.carinii is most probably a part of normal flora of lungs of many mammals, including humans.
7 - Cryptococcus neoformans MYCOSES5. OPPORTUNISTICexogenous- Cryptococcus neoformans- Aspergillus (different species)- Zygomycetes- MANY OTHER FUNGISome of many other opportunistic fungi are: Penicillium marneffei, Fusarium, Bipolaris, Exophiala, Scedosporium, Sporothrix, Pseudallescheria. True pathogenic (endemic) fungi cause more severe infections in compromised host than in otherwise healthy people. If a patient, undergoing therapy which will compromise him/her, was exposed, he/she has to take fluconazole for the reactivation prevention.
8 Candida albicans and other Candida species Harmless inhabitants of the skin and mucous membranes of all humansNormal immune system keeps candida on body surfacesAs Candida is present in practically all humans, it has many opportunities to cause endogenous infections in compromised host - so, Candida infections are the most frequent opportunistic fungal infections.Other Candida species are: C.tropicalis, C.krusei, C.parapsilosis, C.glabrata, C.gullermondii, C.lusitaniae, C.kefyr and many more.
9 MAIN DEFENSE MECHANISMS AGAINST CANDIDA I. skin and mucous membranes integritypresence of normal bacterial floraIf normal bacterial flora is disturbed by antimicrobial therapy, then Candida overgrowths on mucosal surfaces, and with its pseudohyphae internalizes (translocates) itself to deeper layers and causes mucosal infections. The same happens if skin and mucous membranes integrity is broken.
10 MAIN DEFENSE MECHANISMS AGAINST CANDIDA II. phagocytosiskilling, mostly in polymorphonuclear cells, less in macrophagesT-cells (CD4)Neutrophil leukocytes are probably responsible for resistance to invasive candidiasis, and CD4 T-cells are responsible for resistance to mucocutaneous candidiasis. If neutrophil number or function is disturbed, after translocation, Candida goes to lymphatic and blood, spreading throughout the body and causing infection in virtually all organs.
11 THE MOST IMPORTANT RISK FACTORS 1. Neutropenia2. Diabetes mellitus3. AIDS4. SCID5. Myeloperoxidase defects6. Broad-spectrum antibiotics1. The most profound neutropenia (less than 100 neutrophils/L) is seen in bone marrow and hematopoietic stem cells transplant patients, but occurs also in patients with malignancies treated with intensive chemotherapy.2. In diabetic patients, fusion of lysosome in phagocytes is greatly impaired.3.,4. CD4 T-cells defects are important risk factors.
12 THE MOST IMPORTANT RISK FACTORS 7. Indwelling catethers8. Major surgery9. Organ transplantation10. Neonates11. Severity of any illness12. Intravenous drug addicts
13 CLINICAL FORMS OF CANDIDIASIS 1. Cutaneous and mucosalcandidiasisOral trush, oezophagitis (AIDS patients, diabetic patients, patients on corticosteroid therapy, T-cell deficiency); vulvovaginal infection (diabetes, pregnancy, antibiotic therapy); cutaneous candidiasis (skin trauma, burns, maceration); onychomycosis; mucocutaneous candidiasis in SCID patients
14 CLINICAL FORMS OF CANDIDIASIS 2. Invasive (systemic, disseminated, hematogenous) candidiasisTreatment: amphotericin B (neutropenic patients), fluconazole (nonneutropenic patients), caspofungin (a new drug - inhibitor of glucan synthesis - very promising because of low toxicity and good spectrum).The bigest threat to the therapy is a development of strains resistant to fluconazole.
15 If phagocytic system is normal, invasive infection stops here INVASIVE CANDIDIASISUsually begins with candidemia (but in only about 50% of cases candidemia can be proven)If phagocytic system is normal, invasive infection stops hereMost cases of candidemia in surgical patients end this way.C.albicans is found in over 75% in blood culture of non-neutropenic and non-cancer patients, while other species are found in more than 50% of neutropenic and cancer patients.
16 mortality of candidemia is 30-40% INVASIVE CANDIDIASISIf phagocytic system is compromised, infection spreads to many organs and causes focal infection in these organsmortality of candidemia is 30-40%The most frequent organs involved are kidney, skin (maculonodular lesions), eye, heart, liver, meninges.Prevention of candida infections in severely immunocompromised patient can be done by use of peroral fluconazole (azole antifungal drug) during deepest immunosupression
17 DIAGNOSIS OF INVASIVE CANDIDIASIS Gram stain and isolation from blood, CSF or peritoneal fluidisolation and/or pathology positive of organ involvedother tests are of lower significance for the diagnosisCSF - cerebrospinal fluidOther tests: isolation from urine, respiratory secretions, wound secretion; isolation from organs without pathology slide positive; serology; antigens and metabolites detectionPCR - promising, not yet standardized
18 EPIDEMIOLOGYAlthough candidiasis is endogenous in most cases, cross infections are described, especially in intensive care unit patients.Handwashing is the most important activity to prevent spread of many hospital pathogens, and of Candida too.
19 Pneumocystis cariniiPresent in lungs of many mammals, including humans, in persistent but harmless infectionP.carinii is present worldwide and seroepidemiological studies show that most humans are infected in early childhood. Natural reservoir, the source and mode of transmission are not known, possibly P.carinii spreads by aerosols.
20 Main defense mechanism is T-cell mediated Pneumocystis cariniiMain defense mechanism is T-cell mediatedcauses interstitial pneumonitis in compromised patientstreatment and prevention: cotrimoxasole or pentamidineMain risk factors are AIDS, transplantation, corticosteroid and antineoplastic therapy. About 20% of AIDS patients will develop P.carinii pneumonia despite prophylaxis, if CD4 count is >100 mm3.Diagnosis is made from bronchoalveolar fluid, induced sputum or lung biopsy - smears are stained with special stains, and the presence of cysts and trophozoits is diagnostic. P.carinii has not yet been isolated.
21 Cryptococcus neoformans Occurs worldwide in soil and in bird droppingsProminent feature: thick polysaccharide capsule, which causes evasion from phagocytosisCryptococci are found in large numbers in dry pigeon feces.In macrophages Cryptococci can survive and grow easily.
22 MAIN DEFENSE MECHANISMS AND PATHOGENESIS T-cells responsible for defenseCryptococcus reaches humans by inhalation of aerosolized yeast cellsMain risk factors are T-cell deficiency (AIDS patients), corticosteroid therapy, organ transplantation, hematological malignancy. About 10% of AIDS patients develop cryptococcal infection.Yeast cells are inhaled, and in otherwise healthy humans can cause asymptomatic or mild pneumonia; if risk factors are present, cryptococci spread through blood and have special predilection for meninges, but can disseminate in different organs too.
23 CHRONIC MENINGITIS IN AIDS-PATIENTS The most important clinical syndrometreatment: amphotericin B+/-flucytosinerecurrence prevention: fluconazoleDiagnosis is made from CSF - India ink smear (capsule!), isolation or capsular polysaccharide antigen test
24 EPIDEMIOLOGY OF CRYPTOCOCCOSIS Infection is always exogenous, is not transmitted from human to human
25 Aspergillus speciesAspergilli are worldwide occurring saprophytes, living in soil and on plants; they have small conidia that form aerosolsMost frequent species causing infections in compromised patients are: A.fumigatus, A.flavus, A.niger, A.terreus, A.nidulans and many other species. Especially abundant are aspergilli conidia when buildings are done and various dusts are spread around.
26 Main defense mechanism is phagocytosis Main risk factors are hematological malignancy,bone marrow transplantationand corticosteroid therapyIn patients with heart, liver and bone marrow transplantation, invasive aspergillosis can be found in as much as 25-40% of cases (post mortem mycology). Although aspergilli can disseminate to many organs, invasive pulmonary aspergillosis (IPA) is found in 70% of cases.
27 The most frequent syndromes are: - aspergilloma - invasive aspergillosis(high mortality rate)Treatment: amphotericin B,itraconazole, flucytosineand surgeryPrevention: avoid exposureto conidia (new buildings in the hospital!)Aspergilloma is formed when conidia are inhaled in a preexisting lung cavity (tuberculosis, emphysema); if there is not a cavity, aspergilli develop in lung tissue causing invasive infection (spreading through the tissue and involving blood vessels); then spread can occur to other organs.Diagnosis of aspergilloma is radiological (CT scan); invasive aspergillosis can be diagnosed from respiratory secretions or lung biopsy; test for circulating galactomannan is also diagnostic
28 Zygomycetes are ubiquitous saprophytes main host defense is phagocytosismain risk factors are diabetes, hematological malignancies, corticosteroid therapyMost frequent genera in the class Zygomycetes, causing disease in compromised host, are: rhisopus, rhizomucor, absidia, mucor, cunningamella.
29 Major clinical syndrome is: Rhinocerebral mucormycosis (infection of nasal passages,sinuses, eyes, cranial bonesand brain)Treatment: surgery andamphotericin BPrognosis: very poorPulmonary infection can also occur, with very high mortality rate.Diagnosis is made by direct smear and by isolation of molds from respiratory secretions or biopsy specimens.
30 OPPORTUNISTIC FUNGAL INFECTIONS ARE: difficult to diagnosedifficult to treatdifficult to preventmore and more frequenta great challenge for a future work in all fields