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Fungi, Protozoa, and Helminthes

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Presentation on theme: "Fungi, Protozoa, and Helminthes"— Presentation transcript:

1 Fungi, Protozoa, and Helminthes

2 Fungi

3 Kingdom Fungi Divided into 2 groups:
macroscopic fungi (mushrooms, puffballs, gill fungi) microscopic fungi (molds, yeasts) Majority are unicellular or colonial

4 Fungal Organization Mold Yeast Thermal dimorphism
Hyphae Mycelium Yeast Soft, uniform texture and appearance Thermal dimorphism grow as molds at 30°C and as yeasts at 37°C


6 Fungal Organization - Mold
Fungal Cell Structure Cell walls contain chitin Energy reserve is glycogen Nonmotile Produce wind-blown spores Grow toward food source Conidia / spores

7 Fungal Organization Yeasts Unicellular (bicellular) False hyphae
Beta-glycan cell wall structure

8 Fungal Nutrition All are heterotrophic Majority harmless saprobes
Some are parasites Live on the tissues of other organisms, but none are obligate

9 Fungal Reproduction Primarily through spores formed on reproductive hyphae Asexual reproduction spores are formed through: Budding or mitosis Sporangiospores Conidia Arthrospore Chlamydospore Blastospore Phialospore Microconidium or macroconidium porospore



12 Reproductive strategies
Sexual reproduction Spores are formed following fusion of male and female strains and formation of sexual structure Sexual spores and spore-forming structures are one basis for classification Zygospores Ascospores Basidiospores

13 Zygospores

14 Ascospores

15 Basidiospores

16 Yeast Budding “cloning” Sometimes form pseudohypha

17 Fungal Classification
Yeast verse Mold Asexual verse Sexual (reproductive strategies) Terrestrial or water

18 Fungal Classification
Subkingdom Amastigomycota Terrestrial inhabitants including those of medical importance: Zygomycota – zygospores; sporangiospores and some conidia Ascomycota – ascospores; conidia Basidiomycota – basidiospores; conidia Deuteromycota*** – majority are yeasts and molds; no sexual spores known; conidia

19 Fungal Classification
Subkingdom Mastigomycota

20 Diagnosis and identification require:
macroscopic and microscopic observation of: asexual spore-forming structures and spores hyphal type colony texture and pigmentation physiological characteristics genetic makeup culturing in selective and enriched media Reverse important!!!!

21 Roles of Fungi Adverse impact Beneficial impact
mycoses, allergies, toxin production destruction of crops and food storages Beneficial impact decomposers of dead plants and animals sources of antibiotics, alcohol, organic acids, vitamins used in making foods and in genetic studies

22 Characterization of Fungal Infections
Systemic Subcutaneous Cutaneous Superficial Opportunistic

23 Systemic fungal infections by true pathogens

24 Histoplasma capsulatum
Histoplasmosis typically dimorphic distributed worldwide most prevalent in eastern & central regions of US grow in moist soil high in nitrogen content inhaled conidia produce primary pulmonary infection may progress to systemic involvement of a variety of organs & chronic lung disease amphotericin B, ketoconazole

25 Coccidioides immitis Coccidioidomycosis distinctive morphology
blocklike arthroconidia in the free-living stage arthrospores inhaled from dust Creates spherules and nodules in the lungs lives in alkaline soils in semiarid, hot climates endemic to southwestern US amphotericin B treatment


27 Blastomyces dermatitidis
Blastomycosis dimorphic free-living species distributed in soil midwestern and southeastern US inhaled conidia convert to yeasts & multiply in lungs symptoms include cough, chest pains and fever chronic cutaneous, bone, & nervous system complications amphotericin B

28 Blastomyces dermatitidis

29 Paracoccidioides brasiliensis
Paracoccidioidomycosis distributed in Central & South America lung infection occurs through inhalation or inoculation of spores systemic disease not common ketoconazole, amphotericin B, sulfa drugs

30 Subcutaneous Mycoses

31 Sporothrix schenckii Sporotrichosis (rose-gardener’s disease)
dimorphic very common saprobic fungus that decomposes plant matter in soil infects appendages and lungs Lymphocutaneous variety occurs when contaminated plant matter penetrates the skin pathogen forms a nodule spreads to nearby lymph nodes Potassium iodide orally Amphotericin B in unresponsive cases

32 Lymphocutaneous Sporotrichosis

33 Mycetoma when soil microbes are accidentally implanted into the skin
progressive, tumorlike disease of the hand or foot due to chronic fungal infection may lead to loss of body part caused by Pseudallescheria or Madurella

34 Cutaneous Mycoses

35 Cutaneous Mycoses Dermatophytoses
infections strictly confined to keratinized epidermis (skin, hair, nails) ringworm & tinea 39 species in the genera Trichophyton, Microsporum, Epidermophyton communicable among humans, animals, & soil infection facilitated by moist, chafed skin

36 Examples of dermatophyte spores. (a) Regular, numerous
microconidia of Trichophyton. (b) Macroconidia of Microsporum canis, a cause of ringworm in cats, dogs, and humans. (c) Smooth- surfaced macroconidia in clusters characteristic of Epidermophyton.

37 Dermatophytoses Ringworm of scalp tinea capitis
affects scalp & hair-bearing regions of head hair may be lost Ringworm of body tinea corporis occurs as inflamed, red ring lesions anywhere on smooth skin Ringworm of groin tinea cruris “jock itch” affects groin & scrotal regions Ringworm or foot & hand tinea pedis & tinea manuum spread by exposure to public surfaces; occurs between digits & on soles Ringworm of nails tinea unguium persistent colonization of the nails of the hands & feet that distorts the nail bed

38 Ringworm Treatment Topicals: lamisil or griscofulvin 1-2 years
ointments containing tolnaftate, miconazole or menthol & camphor lamisil or griscofulvin 1-2 years

39 Superficial Mycoses

40 Superficial Mycoses Tinea versicolor causes mild scaling, mottling of skin Malassezia furfur White piedra is whitish or colored masses on the long hairs of the body Trichosporan beigelli Black piedra causes dark, hard concretions on scalp hairs Piedraia hortae

41 Hortaea werneckii Tinea nigra
Dematiaceous yeast-like hyphomycete found in tropical and subtropical areas Extremely halophilic environments Slow growing

42 Opportunistic Pathogens

43 Candida albicans Candidiasis widespread yeast
infections can be short-lived, superficial skin irritations to overwhelming, fatal systemic diseases budding cells of varying size may form both elongate pseudohyphae & true hyphae forms off-white, pasty colony with a yeasty odor

44 Candida albicans Normal flora of oral cavity, genitalia, large intestine or skin 20% of humans Account for 80% of nosocomial fungal infections Account for 30% of deaths from nosocomial infections

45 Candida albicans Thrush Vulvovaginal yeast infection
occurs as a thick, white, adherent growth mucous membranes of mouth & throat Vulvovaginal yeast infection painful inflammatory condition of the female genital region causes ulceration & whitish discharge Cutaneous candidiasis occurs in chronically moist areas of skin and burn patients


47 Cryptococcus neoformans
Crypotcoccosis widespread encapsulated yeast inhabits soils around pigeon roosts common infection of AIDS, cancer or diabetes patients

48 Cryptococcus neoformans
infection of lungs leads to cough, fever, and lung nodules dissemination to meninges and brain causes severe neurological disturbance death

49 Pneumocystis (carinii) jiroveci
causes pneumonia (PCP) most prominent opportunistic infection in AIDS patients forms secretions in the lungs that block breathing can be rapidly fatal if not controlled with medication small, unicellular fungus

50 Aspergillus Aspergillosis very common airborne soil fungus 600 species
8 involved in human disease inhalation of spores causes fungus balls in lungs and invasive disease in the eyes, heart, & brain amphotericin B & nystatin


52 Zygomycosis Zygomycota are extremely abundant saprobic fungi
found in soil, water, organic debris, & food Genera most often involved are Rhizopus, Absidia, & Mucor usually harmless air contaminants invade the membranes of the nose, eyes, heart, & brain of people with diabetes, malnutrition with severe consequences

53 Mycotoxicoses Fungal toxins lead to mycotoxicoses
usually caused by eating poisonous or hallucinogenic mushrooms aflatoxin toxic and carcinogenic grains, corn peanuts lethal to poultry and livestock Stachybotrys chartarum sick building syndrome severe hematologic and neurological damage

54 Parasites

55 Parasitology Study of eucaryotic parasites, protozoa and helminths
Cause 20% of all infectious diseases Less prevalent in industrialized countries Increasingly common in AIDS patients


57 Kingdom Protista Algae Protozoa

58 Protozoa 100,000 species Vary in shape, lack a cell wall
@ 25 are important pathogens Vary in shape, lack a cell wall Most are unicellular Colonies are rare Most are harmless, free-living in a moist habitat Some are animal parasites Spread by insect vectors All are heterotrophic Feed by engulfing other microbes and organic matter

59 Protozoa Most have locomotor structures Exist as trophozoite cyst
flagella, cilia, or pseudopods. Exist as trophozoite motile feeding stage cyst Dormant resting stage when conditions are unfavorable for growth and feeding All reproduce asexually, mitosis or multiple fission Many also reproduce sexually

60 Protozoan Classification
Difficult because of diversity Simple grouping is based on method of motility, reproduction, and life cycle

61 Protozoan Classification
Mastigophora primarily flagellar motility sexual reproduction cyst and trophozoite

62 Protozoan Classification
Sarcodina primarily ameba asexual by fission most are free-living

63 Protozoan Classification
Ciliophora Cilia trophozoites and cysts most are free-living, harmless

64 Protozoan Classification
Apicomplexa motility is absent except male gametes sexual and asexual reproduction complex life cycle – all parasitic

65 Protozoan Classification
Phyla grouping based on method of motility, reproduction, and life cycle:

66 Hemoflagellates: Vector-Borne Blood Parasites
Obligate parasites that live in blood and tissues of human host Spread in specific tropical regions by blood-sucking insects that serve as intermediate hosts Categorized according to cellular and infective stages

67 Protozoal Diseases

68 An Intestinal Ciliate: Balantidium coli
An occupant of the intestines of domestic animals such as pigs and cattle Acquired by ingesting cyst-containing food or water Trophozoite erodes intestine and elicits intestinal symptoms Healthy humans resistant Rarely penetrates intestine or enters blood Treatment – tetracycline, iodoquinol, nitrimidazine or metronidazole


70 Leishmania species Leishmaniasis Endemic to equatorial regions
Promastigotes are injected with sand fly bite convert to amastigote and multiply if macrophage is fixed the infection is localized systemic if macrophage migrates L. major

71 Entamoeba histolytica
Amebiasis Alternates between a large trophozoite Motile by means of pseudopods and a smaller nonmotile cyst Humans are the primary hosts Ingested Carried by 10% of world population


73 Entamoeba histolytica
Cysts swallowed and travel to small intestine alkaline pH and digestive juices stimulate cysts to release 4 trophozoites Trophozoites attach, multiply, actively move about and feed Asymptomatic in 90% of patients Ameba may secrete enzymes that dissolve tissues and penetrate deeper layers of the mucosa Causing dysentery, abdominal pain, fever, diarrhea and weight loss

74 Entamoeba histolytica
Life-threatening manifestations are Hemorrhage Perforation Appendicitis Amebomas Tumor-like growths May invade liver and lung Severe forms of disease result in 10% fatality rate Effective drugs are iodoquinol, metronidazole, and chloroquine

75 Giardia lamblia Giardiasis Pathogenic flagellate
Cysts are small, compact, and multinucleate Reservoirs include beavers, cattle, coyotes, cats, and humans Cysts can survive for two months in environment Usually ingested with water and food 10 to 100 cysts

76 Giardia lamblia Cysts enter duodenum, germinate, travel to jejunum to feed and multiply Diagnosis difficult because organism is shed in feces intermittently Treatment: quinacrine or metronidazole Agent is killed by boiling and iodine

77 Trichomonads: Trichomonas species
Small, pear-shaped 4 anterior flagella and an undulating membrane Exist only in trophozoite form 3 infect humans: T. vaginalis T. tenax T. hominis

78 Trichomonas vaginalis
Causes an STD called trichomoniasis Reservoir is human urogenital tract Strict parasite 3 million cases yearly Female symptoms foul-smelling, green-to-yellow discharge; vulvitis; cervicitis; urinary frequency and pain Male symptoms urethritis, thin, milky discharge, occasionally prostate infection Metronidazole Ping-pong effect!

79 Protozoal Diseases of the Blood and Nervous System
The Plasmodium Parasite Infects the Blood Malaria affects million people Four species of Plasmodium cause malaria P. vivax P. ovale P. malariae P. falciparum

80 Plasmodium: Malaria Dominant protozoan disease
Obligate intracellular sporozoan Female Anopheles mosquito is the primary vector blood transfusions, mother to fetus 2 million deaths each year

81 Plasmodium Africans with sickle-cell anemia gene Resistant!!!

82 Trypanosoma species and Trypanosomiasis
Distinguished by their infective stage trypomastigote elongate, spindle-shaped cell with tapered ends, eel-like motility 2 types of trypanosomiasis: T. brucei African sleeping sickness T. cruzi Chagas disease

83 Trypanosoma brucei African Sleeping Sickness Spread by tsetse flies
Biting of fly inoculates skin with trypomastigotes Multiplies in blood and damages spleen, lymph nodes and brain Harbored by reservoir mammals Two variants of disease caused by 2 subspecies: T.b.gambiense – Gambian strain; West Africa T.b. rhodesiense – Rhodesian strain; East Africa

84 Trypanosoma brucei Chronic disease symptoms are sleep disturbances, tremors, paralysis and coma. Blood, spinal fluid or lymph nodes Treatment before neurological involvement with melarsoprol, eflornithine Control involves eliminating tsetse fly

85 Trypanosoma cruzi Chagas disease Endemic to Central and South America
Reduviid bug (kissing bug) is the vector Bug feces is inoculated into a cutaneous portal Local lesion, fever, and swelling of lymph nodes, spleen, and liver Heart muscle and large intestine harbor masses of amastigotes Chronic inflammation occurs in the organs (especially heart and brain) Treatment nifurtimox and benzonidazole

86 Toxoplasma gondii Toxoplasmosis
Intracelllular apicomplexan parasite with extensive distribution Lives naturally in cats harbor oocysts in the GI tract Acquired by ingesting raw meats or substances contaminated by cat feces Most cases go unnoticed Except in fetus and AIDS patients Can suffer brain and heart damage Treatment: pyrimethamine and sulfadiazine

87 Parasitic Helminths

88 Parasitic Helminths Multicellular animals Parasitize host tissues
Organs for reproduction, digestion, movement, protection Mouthparts Attachment Digestion of host tissues Well-developed sex organs that produce eggs and sperm Fertilized eggs go through larval period in or out of host body

89 Helminths Flatworms (Phylum Platyhelminthes)
do not have respiratory or circulatory structures, or a digestive tract Cestodes (tapeworms) Trematodes or flukes Roundworms (Phylum Nematoda)

90 Flatworms Cestodes have a head region called a scolex
Fertilized eggs are produced in proglottids which break off and spread eggs Tapeworms generally live in host’s intestine, absorbing nutrients They have limited host range, but usually at least 2 hosts

91 Flatworms Trematodes have complex life cycles and often 2 hosts
Eggs develop into larvae (miracidia) in water, which invade snails Trematodes evade the immune system by having a surface similar to host cells

92 Roundworms (Phylum Nematoda)
Damage to the host often occurs by large worms burdens in vessels or intestines

93 Tapeworms Beef and pork tapeworm disease are caused by Taenia saginata and T. solium, respectively acquired by eating poorly cooked beef or pork scolex attached to the intestine, causing obstruction and mild diarrhea

94 Humans Host to at Least 50 Roundworm Diseases
Pinworm disease is caused by Enterobius vermicularis Infection of the intestines leads to diarrhea and anal itching Reinfection can occur if contaminated hands contact food or the mouth Worms die in a few weeks, even without treatment

95 Trichinellosis caused by Trichinella spiralis
T. spiralis lives in pig intestines and can encyst in skeletal muscles Transmission to humans occurs by eating raw or poorly cooked pork Symptoms include: pain vomiting nausea constipation Larvae can migrate to the tongue, eyes, and ribs

96 Hookworms have a set of hooks or suckers to attach to the upper intestine Hookworms suck blood from intestinal capillaries This cause blood loss and anemia Humans are the only host Larvae in soil penetrate the skin of bare feet and enter the bloodstream

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