2 WHY IS THIS IMPORTANT?Parasitic infections affect billions of people in the world.Fungal infections are usually opportunistic infections and have increased with the number of immunocompromised individuals.Parasites can be divided into two groups:Protozoans – microscopic, single-celled eukaryotes.Helminths – macroscopic, multicellular worms.
3 SIGNIFICANCE OF PARASITIC INFECTIONS Parasitic infections are a major problem worldwide.More than 500 million people are infected with malaria.More than 2 million (mostly children) die each year from malaria.Entamoeba are intestinal parasites that infect 10% of the world population.Trypanosoma parasites infect 16 million people in Latin America each year.
5 FUNGAL INFECTIONSThe study of fungi is known as mycology and scientist who study fungi is known is a mycologistA fungus is a member of a large group of eukaryotic organismsMicroorganisms such as yeasts and molds, as well as the more familiar mushroomsOver 60,000 species of fungi are knownFungi are important for the environment.They are normally harmless to humansFungi can be opportunistic pathogens.
6 StructureThe main body of most fungi is made up of fine, branching, usually colourless threads called hyphae ( PG 310)Several of these these hyphae, all intertwining to make up a tangled web called the myceliumMost fungi are multinucleate and multicellular organisms with cross wall called septa or aseptate (coenocytic)Yeasts are unicellularOne major difference is that most fungi have cell walls that contain chitin, unlike the cell walls of plants, which contain cellulose
8 ReproductionLife cycle involves the fusion of hyphae from two individuals (Male & FeamleEach parent hyphae has haploid nucleiThe fusion of hyphae is called plasmogamy.The fused hyphae containing haploid nuclei from two individuals is heterokaryotic.In some cases, plasmogamy results in cells with one nucleus from each individual. This condition is called dikaryotic.Two nuclei that originated from different individuals fuse to form a diploid zygote.Meiosis then produces either four haploid nuclei or four haploid cells.
9 YEASTS AND MOLDS Molds - multicellular Yeasts - unicellular The simplest form of growth is budding.Buds are called blastoconidia.Seen in yeasts.
12 The life cycle of Rhizopus stolonifera ( bread mold). .
13 ….Reproductive structures in Breadmold ….Reproductive structures in Breadmold.
14 Classification of Fungi By Reproductive Structures (PG 312)OomycetesWater MoldsMotile sexual sporesExample: Potato blight Phytophthora
15 …..Classification of Fungi ZygomycetesUnenclosed zygospores produced at ends of hyphaeExample: Black bread mold RhizopusAscomycetesAscospores are enclosed in asci (sac-like structures) at the ends of hyphae or yeastsExamples: Penicillium, Saccharomyces
17 …..Classification of Fungi BasidiomycetesBasidiospores are produced on a club-shaped structure called a basidiumExample: Mushrooms, CryptococcusDeuteromycetes“Imperfect fungi”No sexual stage is known for these fungiMany parasitic fungi fall into this classExamples: Candida, Epidermophyton
18 CLASSIFICATION OF PATHOGENIC FUNGI Fungal diseases are classified into 4 groups:Superficial mycosesMucocutaneous mycosesSubcutaneous mycosesDeep mycoses
19 SUPERFICIAL MYCOSESFungal infections that do not involve a tissue response:Piedra – colonization of the hair shaft causing black or white nodulesTinea nigra – brown or black superficial skin lesionsTinea capitis – folliculitis on the scalp and eyebrows
20 …SUPERFICIAL MYCOSES Favus – destruction of the hair follicle. Pityriasis – dermatitis characterized by redness of the skin and itching:Caused by hypersensitivity reactions to fungi normally found on skinMostly seen in immunocompromised patients.
21 CUTANEOUS AND MUCOCUTANEOUS MYCOSES Associated with:SkinEyesSinusesOropharynx and external earsVagina
22 …CUTANEOUS AND MUCOCUTANEOUS MYCOSES Ringworm – skin lesions characterized by red margins, scales and itching:Classified based on location of infectionTinea pedis – on the feet or between the toesTinea corporis – between the fingers, in wrinkles on the palmsTinea cruses – lesions on the hairy skin around the genitaliaTinea capitis – scalp and eyebrowsOnychomycosis – chronic infection of the nail bedCommonly seen in toesHyperkeratosis – extended scaly areas on the hands and feet
24 …CUTANEOUS AND MUCOCUTANEOUS MYCOSES Mucocutaneous candidiasis – colonization of the mucous membranesCaused by the yeast Candida albicansOften associated with a loss of immunocompetenceThrush – fungal growth in the oral cavityAn indicator of immunodeficiency.Vulvovaginitis – fungal growth in the vaginal canalCan be associated with a hormonal imbalance
25 SUBCUTANEOUS MYCOSESLocalized primary infections of subcutaneous tissue:Can cause the development of cysts and granulomas.Provoke an innate immune response - eosinophilia.
26 …SUBCUTANEOUS MYCOSES There are several types:Sporotrichosis – traumatic implantation of fungal organismsParanasal conidiobolae mycoses – infection of the paranasal sinusesCauses the formation of granulomas.Zygomatic rhinitis – fungus invades tissue through arteriesCauses thrombosisCan involve the CNS.
27 DEEP MYCOSESDeep mycoses Usually seen in immunosuppressed patients with:AIDSCancerDiabetesCan be acquired by:Inhalation of fungi or fungal sporesUse of contaminated medical equipmentDeep mycoses can cause a systemic infection – disseminated mycosesCan spread to the skin
29 ..DEEP MYCOSES Coccidiomycoses – caused by genus Coccidioides Primary respiratory infectionLeads to fever, erythremia, and bronchial pneumoniaUsually resolves spontaneously due to immune defenseSome cases are fatal
30 …DEEP MYCOSES Histoplasmosis – caused by Histoplasma capsulatum Often associated with immunodeficiencyCauses the formation of granulomasCan necrotize and become calcifiedIf disseminated, histoplasmosis can be fatal.
32 …DEEP MYCOSES Aspergillosis – caused by several species of Aspergillus Associated with immunodeficiencyCan be invasive and disseminate to the blood and lungsCauses acute pneumoniaMortality is very high.Death can occur in a matter of weeks.
33 Common Fungal Diseases Additional Information to read:CandidiasisDermatomycosesRespiratory Fungal Infections
34 Candidiasis Cause: Candida albicans Dimorphic fungus of the class DeuteromycetesGrows as yeast or pseudohyphaeSpread by contact; often part of normal floraOpportunistic infections commonVulvovaginitisOral candidiasis (thrush)Intestinal candidiasis
35 DermatomycosesDermatomycoses are any fungal infection of the skin or hair.Caused by many different species and are generally named after the infected area rather than the species that causes it.Dermatomycoses are one of the most frequent sources of lesions on the skin.
36 …Dermatomycoses Cause: Several genera of dermatophytic fungi Trichophyton, an ascomyceteMicrosporum, an ascomyceteEpidermophyton, a deuteromyceteGrow on skin, hair, nailsTransmitted by contact with infected persons or animals
37 …DermatomycosesTinea is a fungus that can grow on your skin, hair or nails.As it grows, it spreads out in a circle, leaving normal-looking skin in the middle- look like a ring.At the edge of the ring, the skin is lifted up by the irritation and looks red and scaly.To some people, the infection looks like a worm is under the skin.Because of the way it looks, tinea infection is often called "ringworm." no worm under the skin!!Pictures!!!!
38 ….DermatomycosesTinea infections: Red, scaly or blister-like lesions; often a raised red ring; “ringworm”Tinea pedisTinea corporisTinea capitisTinea favosaTinea barbaeTinea crurisTinea unguium
39 Respiratory Fungal Infections CryptococcosisCryptococcus neoformansA yeast of class BasidiomycetesSoil; esp. contaminated with bird droppingsAirborne to humansGelatinous capsules resist phagocytosisRespiratory tract infectionsOccasional systemic infections involving brain & meninges
40 …. Respiratory Fungal Infections HistoplasmosisHistoplasma capsulatum, an ascomyceteAirborne infectionTransmitted by inhalation of spores in contaminated sporesAssociated with chicken & bat droppingsRespiratory tract symptoms; fever, headache, cough, chest pains
41 ….Respiratory Fungal Infections BlastomycosisBlastomyces dermatitidis, an ascomyceteAssociated with dusty soil & bird droppingsSkin transmission: via cuts & abrasionsRaised, wart-like lesionsAirborne transmission: via inhalation of sporesRespiratory tract symptomsOccasional internal infections with high fatality rate
42 References http://www.microbiologybytes.com/introduction/myc2.html Microbiology, A clinical Approach -Danielle Moszyk-Strelkauskas-Garland Science 2010https://files.kennesaw.edu/faculty/jhendrix/bio 2261/home.htmlLecture PowerPoints Microbiology Principles and Exploration 7th edt. J G Black ; J Wiley Pub.