Microbiology: Exam 4

Dracunculus medinensis (Guinea worm)

used to infect about 35 million people in Africa, southwestern Asia, the West Indies and northeastern South America -incidence reduced 99.99% to 22 cases in 2015 -if the worm does not reach the skin, it dies and causes little reaction -in superficial tissue, it liberates a toxic substance that produces inflammatory reaction in the form of a sterile blister -the worm lies beneath the blister -contamination of the blister produces abscesses, cellulite, extensive ulceration and necrosis -host infected by water containing infected copepods (water fleas) -nematodes

Mechanisms of Action of Antiprotozoans and Antihelminthics

many anti parasitic drugs most likely interfere with biosynthetic pathways of protozoan parasites or neuromuscular function of worms (causing paralysis)

Tinea corporis

mycosis of the body (ringworm)

Tinea pedia

mycosis of the foot (Athlete's foot)

Tinea unguium (onychomycosis)

mycosis of the nails

Tinea capitis

mycosis of the scalp

Tinea axillaris

mycosis of the underarm

mycelium

collection og hyphae (mushrooms, puff balls)

Fungi: dimorphic

grow as either a yeast or mold, depending on environmental conditions and temperature (usually a yeast at body temperature)

mechanical vector

involves mechanically transporting a microbe from one place to another (i.e. a microbe carried on a fly's legs)

Plasmodium species (Malaria)

-200 million global cases of malaria leading to a mortality of more than one million people per year -periodic epodes of high fever and shaking chills (paroxysms), followed by periods of profuse sweating (occurs when the red blood cells burst and release merozoites) -Tertain malaria (P. vivid and P. ovale) recurs every 48 hrs -Quartan malaria (P. malaria) recurs every 72 hrs -P. falciparum is the most common and deadly; irregular episodes -vector is the Anopheles mosquito

Polyenes

-Amphtericin B produced by Streptomyces binds to ergosterol increasing the permeability of the cell membrane and causing cell lysis drug of choice for most systemic fungal infections, but has many adverse side effect -Nystatin has the same activity used to treat oral and esophageal fungal infection and vaginal candidiasis

systemic mycoses

-Coccidiodes immitis causes Valley fever through inhalation of arthrospore mold in soil causing mild pneumonia -Histoplasma capsulate causes Spelunker's disease through inhalation of conidia mold in soil or yeast in tissue causing mild respiratory symptoms -Blastomyces dermatitidis found as yeast in tissue (Broad-based bud) through inhalation of conidia that causes chronic granulomatous disease and ulcerations on skin and bone

multiple fissions (Schizogony)

-multiple DNA division resulting in a cell with many single-celled infectious organisms -release of these parasites at regular intervals produce the characteristic cyclic symptoms of malaria

yeast

a spore that germinates to produce round, oval, or elongated single cells that reproduce mostly by budding (some by fission) forming moist or mucoid colonies

systemic opportunistic mycoses

-Cryptococcus (Filobasideiella) neoformans can cause meningitis through inhalation of minimally encapsulated spore causing pneumonia (violence factors-capluse, melanin production, growth w/m macrophages) -Candida albicans caused by normal flora and can lead to thrush and blood stream infections and diagnosed through yeast, pseudohypahe, and germ tube formation -Apsergillus fumigatus/flavus exist only as molds in the soil and affect the pulmonary cavities of immune comprised people (Aflatoxin production from flavus)

binary fission

-DNA replication followed by division of 2 cells longitudinally (flagellates) or transversely (ciliates) -if protozoa has both flagella and cilia the method of replication decides how they are classified

Intestinal and luminal protozoa

-Giardia lamblia -Cryptosporidium parvum/hominis -Entamoeba histolytica

Blood and tissue protozoa

-Leishmaniasis -Trypanosoma brucei -Trypanosoma cruzi -Plasmodium -Toxoplasma gondii

Free-living meningitis-causing Amoebas

-Naegleria fowleri -Acanthamoeba

superficial mycoses

-Pityriasis versi color (tinea versicolor) causes chronic superficial fungal infection leadting to hypo/hyper-pigmented patches on skin; exposure to sunlight leads to tanning of patches around skin but not the fungus (Malassezia species) -Tinea nigra causes dark brown to black painless patches on the soles of hands and feet (Exopliala werneckii)

economic importance of fungi

-Saccharomyces used in production of beer, wine, and bread -cheese production -Penicillin, griseofulvin as well as other antimicrobials -fungi grow in a drier, more acidic, and higher-osmotic pressure environment than bacteria this they're involved in spoilage of fruits, grains, vegetables, and jams -yeast genetically engineered to produce human insulin

Toxoplasmosis

-Toxoplasma gondii -life cycles consists of two phases (intestinal in cats only and extraintestinal occurs in all infected animals) -transmission occurs via oocysts (cat feces) or bradyzoites (raw or undercooked meat) -transplacental transmission possible (can cause spontaneous abortion, still birth, child born with mental or physical retardation, blindness) -women must minimize contact with cats and not empty cat's litter box while pregnant. Also, do not ear raw or undercooked meat -problem in immunocompromised individuals (Toxoplasma encephalitis)

Sexually transmitted protozoa

-Trichomonas vaginalis

hyphae

-a single filament that may be interrupted at various intervals by septa or be continuous -Haustoria can be penetrate animals or plant cell walls to gain nutrients -Rhizoids are short root-like hyphae which anchors saprophytic fungi onto substrate

fungi causes disease in one of four ways in humans

-allergic reaction results from inhaling fungal spores (hay fever or asthma) -react to fungal toxin (mycotoxins) that can have hallucinogenic properties (LSD) with some species producing aflatoxin implicated in cancer -mycoses fungus that grow in the body -destroy food supply causing starvation

arthropods: ticks

-arachnids (which lack wings and antennae; have four pairs of legs; fused thorax and abdomen) -live in low vegetation, wait for host passing by -burrow into skin with mouthparts -may go unnoticed for days; feeds continually -wood tick Dermacentor anderson i transmits Rocky Mountain spotted fever (bacterium Rickettsia rickettsia) -Ixodes scapularis transmits Lyme disease (bacterium Borrelia burgdorferi) -saliva of some ticks can produce tick paralysis especially in children; recovery follows removal

Trematodes or Flukes

-bilaterally symmetrical flat and leaf shaped -sucker allows attachment while fluids are withdrawn from the host -most species are hermaphroditic (both sex organs in same worm) -lifecycle may include one or more intermediate hosts -larval from within the egg -one or more intermediate hosts (e.g. snail) following escape form the egg -Cercariae (last stage): tail bearing larva that is released from the intermediate host and is ready to attach to a susceptible host ex. Schistosoma spp.

algae reproduction

-binary fission for most single-celled algae involves mitosis -fragmentation for some single-celled and most multicellular filamentous species -sexual reproduction (meiosis) occurs regularly in most algae -gametes (haploid cells with half chromosomal content) fuse together to become a diploid cell with a full complement of chromosomes known as the zygote

treatments for Helminths

-cause paralysis of worms -intestinal Nematodes are treated with Mebendazole, thiabendazole, and albendazole paralyze the roundworms so they are passed out in the stool; other drugs will irritate the worms causing them to migrate out of the small intestine to other organs which can be fatal (ex. Pyrantel palmate and Piperazine) -Filariasis (Onchocerca and Wucheria) can be treated with Ivermectin isolated from Streptomyces in soil, which binds to glutamate-gated chloride channels causing increased Cl- permeability that paralyzes the worms

subcutaneous mycoses

-caused by saprophytic fungi (normal soil inhabitants) -gain entry following trauma to skin -usually remain localized to the subcutaneous tissue or spread along lymphatics to local nodes -Sporothrix schenckii (sporotrichosis) are dim-orphic fungus that are harzardous for gardeners causing local pustule or ulcer with nodules along the draining lymphatics -Phialophora and Cladosporium (chromoblastomycosis) cause wart-like lesion with crusting abscesses extending along the lymphatic system

Chaga's Disease

-caused by the bite of a Triatomine bug infected with Trypanosoma cruzi -Trypomastigotes tunnel into the human host, transform into amastigotes which invades the skin, macrophages, lymph nodes, and spread in the blood to distant organs -a hard, red area develops at site of entry followed by systemic spread with fever, malaise, and swollen lymph nodes -infected include the heart and CNS -acute phase=fever, malaise, swollen lymph nodes, meningoencephalitis, acute myocarditis (resolves in about a month) -intermediate phase=low levels of parasites in blood and positive antibody responses against T. cruzi but no symptoms (most people remain here for life) -chronic phase=organs primarily affected are the heart and hollow organs (colon, esohpagus) leads to dementia, megacolon, megaesohpagus, heart damage, heart failure

African Sleeping Sickness

-caused by the bite of a Tsetse fly infected with Trypanosoma brucei -following bite, the trypomastigote (flagellated motile form) spreads via the bloodstream to the lymph nodes and CNS -initial painful skin ulcer heals w/n two weeks followed by fever, headache, dizziness, and lymph node swelling that takes place due to systemic spread -fevers are intermittent due to variable surface glycoproteins (VSG) -CNS symptoms develop such as daytime drowsiness (thus sleeping sickness), slurred speech, problems walking, coma, death -two forms -West African sleeping sickness (Trypanosoma brucei gambiense) is notable for slowly progressing symptoms -East African Sleeping Sickness (Trypanosome brucei rhodesiense) is more sever with death occurring w/n weeks

Giardia lamblia (Mastigophora)

-causes giardiasis -transmission: ingestion of cyst in fecally contaminated food and water, contaminated streams, day-care centers, mental hospitals -not killed by chlorination -boiling and filtration kills cysts -clincial findings: trophozoite adheres to small intestinal wall via sucking disk and interferes with fat absorption -causes non-bloody, foul-smelling diarrhea w/ nausea, anorexia, flatulence, and abdominal cramps

Azoles

-chemically synthesized drugs that inhibit cytochrome P450 which is an enzyme that is in the sterol biosynthesis pathway that leads from Ianosterol and ergosterol resulting in depletion of ergosterol and increased fungal cell membrane permeability -Imidazoles: Ketoconzaol used for chronic mucotaneous candidiasis with adverse side affects and Miconazole/Clotrimazole used for topical fungal infections -Triazoles (less toxic than imidazole): Fluconazole used for cutaneous and vaginal candidiasis and meningitis, Itraconazole (broad-spectrum anti0fungal), and Posaconazole excellent acitivity against Candida and Aspergillus

Phylum Ciliophora

-cilia completely covers organisms; found near oral cavity and helps to propel food into the opening (cytosome) -includes Balantidium coli (causes users in large intestines)

Visceral Leishmaniasis- Kala-azar (L. donovani)

-common in young malnourished children -fever, anorexia, weight loss, and abdominal swelling (from enlargement of the liver=hepatomegaly, and spleen=splenomegaly) due to invasion of fixed reticuloendothelial cells (fixed phagocytic cells) of these organs -often fatal

Nematodes or Roundworm

-cylindrical tapered body with a tubular digestive tract that extends from the mouth to the anus -male and female nematods -composed of free-living organisms (in soil and water) and those that are parasites of humans, and other animals, and plants -infestations of the GI tract and blood stream or other tissues -ex. Enterobius vermicularis (Human pinworm) -ex. Ascaris lumbricoides and Ascaris suum (intestinal roundworms of humans and pigs) -ex. Necator spp. and Ancylostoma spp. (Hookworms) -ex. Trichuris spp. (whipworms) -ex. Dracunculus medinensis (Guinea worm) -Microfilariae

Entamoeba histolytica

-diarrhea ranging from mild asymptomatic disease to severe dysentery -may invade the intestinal mucosa causing erosions (10% of infected individuals) -may penetrate portal blood circulation forming abscesses in the liver and lung often resulting in death (100,000 deaths worldwide)

anti fungal drug targets

-ergosterol synthesis -cell wall synthesis -cell division -nucleic acid synthesis

anti-malarial drugs

-erythrocytic cycle (acute malaria) can be treated with Chloroquine (prevents crystallization of heme in RBC), Amodiaquine (active against merozoites), and Mefloquine (most effective in this group and effective as prophylaxis and treatment of acute malaria) -exo-eryhtrocytic cycle (persistent malaria) can be treated with Primaquine-Sulfadoxine (kills liver holdouts, gametes, and prevent recurrences of P. vivax and P. ovale) and Quinocide -Artimisinin isolated from TCM plant (Artemisia annually) generates reactive free radicals within parasite that damage membrane, but resistance is growing -control using insecticides and repellents (with DEET), mosquito nets, and proper clothing

biological vector

-essential part of the life cycle -pathogen can multiply w/n the vector (i.e. growth of Leishmania and Plasmodium inside sand fly and Anopheles sp. mosquito)

molds

-filamentous fungi that are well adapted to absorb nutrients -froms hyphae to gain nutrients -from mycelium (collection of hyphae)

Loa loa (eye worm)

-filariae -vector is the deer fly -the organisms migrate sunder the skin at a rate of up to an inch every two minutes -the swelling appears simultaneously, persists fro 4 to 7 days and disappears, and is known as fugitive or Calabar swelling -the worm usually causes no serious problems,s. except when passing through the orbital conjunctive or the nose bridge -nematodes

Onchocerca volvulus

-filariae that causes blinding filariasis; rive blindness -vector is female black fly that breeds around rivers and streams -results in nodular and erythematous lesions in the skin and subcutaneous tissue due to a chronic inflammatory response to persistent worm infection -after mating the offspring (microfilariae) can migrate through the dermis and connective tissue and eye (leading to blindness) -nematode

Cestodes or Tapeworms

-flat, ribbon-shaped, segmented bodies -head (scolex) has suckers or hooks for attachment -Proglottids: reproductive segments containing both female and male sex organs -transmission oftentimes occurs following ingestion of contaminated undercooked or raw meat (beef, lamb, pork ,and fish) or fleas infected with dog or cate tapeworms ex. Pork tapeworm (Taenia solium)

malarial infection

-four types of malaria: P. vivax, P. ovale, P. malariae, and P. falciparum -exo-erythrocyte cycle (persistent malaria) -infection of liver cells occurs in all 4 types -enter the liver hepatocytes via the blood and undergo at least one liver cycle, releasing merozoites into the blood -erythrocytic cycle (acute malaria) -merozoites infect the RBCs in this stage

Protozoan environment

-free-living -found in marine, fresh water lakes, and terrestrial habitats -some are parasitic with host range from algae to humans -essential decomposers -require large amounts of moisture -eat bacteria and serve as food for largers species -help maintain ecological balance in soil -important in sewage disposal (results in decrease of sewage solids)

Naegleria fowleri

-free-living amoeba -fresh water (lakes)m, soil, thermal discharges of power plants, heated swimming pools, hydrotherapy.... -infection occurs when the amoeba enters the body through the nose -the amoeba then travels to the brain and spinal cord where it destroys brain tissue -can cause primary amoebic meningoencephalitis (PAM), a brain inflammation, which leads to the destruction of brain tissue and is usually fatal within a week -patients present with fever, headache, stiff neck, nausea, and vomiting -only 32 infections were documented in the US between 2001 and 2010 -survival rate <1%

algae habitats

-fresh water, salt water, soil -significant component of phytoplankton -major source of O2 -food source for microscopic animals in zooplankton -precede establishment of other organs in some environments -synthesize organic material

classifications of fungi

-groups based on sexual reporduction -Zygomycetes (Zygospores) -Basidiomycetes (basidiospores) -Ascomycetes (ascospores) -Deuteromycetes or Fungi Imperfecti (sexual reproduction has not been observed)

Toxocara canis and T. catti (visceral larva migrans)

-hookworm eggs from feces of infected dogs and care are swallowed by man and hatch in the intestine -the larvae penetrate the mucosa, enter the circulation and are carried to liver, lungs, eyes, and other organs where they cause inflammatory necrosis -nematodes

Ancylostoma braziliensis (cutaneous larva migrans, creeping eruption)

-hookworms prevalent in many tropical and subtropical countries and in the U.S. especially along the Gulf and southern Atlantic states -filariform larvae in animal feces (dogs and cats) can infect man and cause skin eruptions -since the larvae have a tendency to move around, the eruption can migrate in the skin around the site of infection -the symptoms last the duration of larval persistence (2 to 10 weeks) -nematodes

Enterobius vermicularis (Human pinworm)

-infects >400,00,00 people worldwide (10% of human population) -most common nematode parasite in North America and Europe -asymptomatic to mild gastrointestinal upsets -perianal itching, irritability, insomnia -vaginal irritation (adult pinworms) -eggs can be detected on perianal area using Scot tape test -worms can be detected in perianal area using flashlight -highly contagious -nematodes

Mucocutaneous Leishmaniasis (L. braziliensis)

-initial dermal ulcerations heals -ulcers appear in the mucous membranes of the nose and mouth that may erode the nasal septum, soft palate, and lips if left untreated

arthropods: mosquitoes

-insert feeding tube through host's skin -ingest blood; can pick up infectious agents, transfer to subsequent hosts -malaria, yellow fever, dengue fever, West Nile encephalitis transmitted by mosquitoes

Ascaris lumbricoides and Ascaris suum

-intestinal roundworms of humans and pigs -most common nematode parasite infection world-wide (25% of world population) -symptoms: ascaris pneumonia, blockage og gastrintestinal tract, migration w/n the wall intestine possibly leading to acute (fatal) peritonitis absorb blockage of bile or pancreatic duct -diagnosis eggs in feces of infected person -nematodes

Protozoan Structure

-lack cell wall, therefore shape is determined by material beneath plasma membrane -have membrane bound nucleus and organelles, but lack photosynthetic chloroplasts -have specialized structures for movement including cilia, flagella, pseudopodia, or polar filaments -food, water, and O2 readily diffuse through the cell membrane or pinocytosis/phagocytosis

Microfilarial infections

-major blood and tissue parasites of man are Filariae -threadlike roundworms belonging to the family Filariodiea -adult filariae live in the lymphatic tissue and give birth to pre larval forms called microfilariae -microfilariae burrow through tissue and circulate in the blood and lymphatic system -major blood and tissue nematodes include Wuchereria bancrofti and W. (Brugia) Malayi, Onchocerca volvulus, and Loa loa (eye worm) -spread by the bite of an arthropod -nematodes

Necator spp. and Ancylostoma spp. (Hookworms)

-many different species infecting about 8-9 million people and the dog and cat hookworms -mouth parts of hookworms have cutting plates allowing attachment to host's small intestine causing hemorrhages, blood loss, anmeia -diagnosis through eggs in feces -penetrate through the skin -nematodes

Schistosoma spp.

-many species infecting about 200 million persons resulting in about 1 million deaths per year -Cercariae penetrate human skin (causing itching) and travel through bloodstream and end up in the veins near the small intestine or urinary bladder where they lay eggs which can be excreted -eggs become encapsulated in liver, lungs, or brain or block portal venous system (complications due to inflammatory response to eggs) -adult worms display molecular mimicry: incorporate host antigens on their surface which fools the immune system into believing that they are not foreign -diagnoses through eggs in urine or feces

Allylamines

-mechiansm of action is inhibition of squalene epoxidase, an essential step in ergosterol synthesis (squalene + Iansterol=ergosterol) -Naftifine (topical) and terbinafine (topical and oral) -used to treat dermatophyte infection such as chronic tinea pedis, tine corporis

Acanthamoeba

-microscopic, free-living amoeba -lives in fresh water lakes, soil, air, sewers, drinking water, -Acanthamoeba keratitis=a local infection of the eye that typically occurs in healthy persons and can results in visual impairment or blindness -Granumlomatous Amebic Enchephalitis (GAE)=a serious infection of the brain and spinal cord that typically occurs in persons with a compromise immune system -disseminated infection=a widespread infection that can affect the skin, sinuses, lungs, and other organs independently or in combination; more common with immune compromised

protozoa

-microscopic, unicellular organisms -lack photosynthetic capability -usually motile at some stage in their life cycle -reproduce by asexual fission -protists -traditionally grouped according to their mode of locomotion (flagella, pseudopodia, cilia, polar filament)

algae structure

-multicellular -holdfast anchors organisms to substrate -stipe is the stalk of the algae -bladder is gas filled to help algae to float on water surface to maximize the exposure of blades to sunlight -blades are leaf-like structures attached to stipe (sites of photosynthesis) -cell wall composed of cellulose

Fungi: saprophytes

acquire nutrients from dead or dying material (soil, rotten vegetation, wood)

fungi structure

-non-motile (non-flagellated) eukaryotic cell that have definite cell walls composed of chitin -insensitive to antibiotics like penicillin that inhibit peptidoglycan synthesis -are devoid of chlorophyll -reproduce by means of spores (either sexually or asexually) -fungal cell cell membrane contains ergosterol and zymosterol (not cholesterol) -Amphotericin B active against ergosterol synthesis

Protozoan Reproduction

-often require more than one habitat or host -can be found in morphologically distinct stages of the life cycle (polymorphic) -can exist as trophozoite (vegetative or feeding form) or as a cyst (resting, infectious form found when protozoa encounter certain conditions such as lack of nutrients, moisture, oxygen)

Candida albicans

-oral thrust (mouth) -diaper rash (groin) -Candida vaginitis (vagina)

Phylum Microspora

-polar filament ex. Microscporidium are intracellular protozoan infection of immune compromised individuals that cause diarrhea

Algae

-primitive photosynthetic eukaryotic organisms -contain chlorophyll and other pigments -differ form other photosynthetic eukaryotic organisms due to lac of vascular system and simple reproductive system -do no directly infect humans -may produce toxins (paralytic shellfish poisoning) -identified by principal photosynthetic pigment, cell wall structure, type of storage products, mechanisms of motility, and mode of reproduction -classified by color displayed: Chlorophytes (green algae), Rhodophyta (red algae), Chrysophyta (golden brown algae and diatoms) Phaeophyta (Brown algae)

fungi

-require organic compounds for energy and as a carbon source -mainly terrestrial organisms -prefer slightly moist environments and a temperature range of 20˚C- 35˚C -most are aerobic but some are facultative anaerobes and carry out alcoholic fermentation (S. cerevisiae)

lichens

-result from symbiotic relationship between fungi and photosynthetic organisms (algae or cyanobacteria) -fungus provides protections while photosynthetic organisms supplies nutrients

Leishmaniasis

-sandfly takes a blood meal (inject eggs into the skin) -zoonotic protozoa carried by rodents, dogs, and foxes and is transmitted to humans by the bite of the sandfly -promastigote (flagellated motile form) invades phagocytic cells (macrophages) ad transforms into nonmotile amastigote -amastigotes multiplies w/n phagocytic cells in the lymph node, spleen, liver, and bone marrow (reticuloendothelial system) -severity of disease depends on invasiveness of the species as well as the host's immune response

toxin production (red tides)

-several dinoflagellates in group Pyrrophyta cause algal blooms -Karenia brevis -produces brevetoxin -kills fish that feed on phytoplankton -persons eating fish that have ingested G. breve suffer a tingling sensation in mouths and fingers; reversal of hot and cold perceptions, reduced pulse rate, and diarrhea, rarely deadly, recovery in 2-3 days -Gonyaulax species (Alexandrium fundyense) produces neurotoxins -accumulaste in tissues of shellfish that feed on these dinoflagellates w/o causing harm to themselves -humans eating shellfish suffer -cause paralytic shellfish poisoning that causes general numbness, dizziness, muscle weakness, impaired respiration (can result in death from respiratory failure)

Trichomonas vaginalis

-sexually transmitted in the female vagina and male urethra -transmission via trophozoite (no cyst stage) -most males are asymptomatic -often asymptomatic in women but heavy infection may result in itching (pruritus), burning on urination, white, frothy, malodorous discharge from genital tract -highly motile trophozoites visible in discharge -males are also treated to prevent re-infection of female partner

microscopic algae

-singel cells propelled by flagella or free floating or growth in long chains or filaments -unicellular algae include diatoms, some green algae, dinoflagellates, euglenids, a few red algae -some (ex. Volvox) form colonies of 500 to 60K biflagellate cells -diatoms incorporate silicon dioxide into cell walls;deposits mined for diatomaceous earth

Cutaneous Leishmaniasis (L. tropical and L. mexicana)

-skin ulcer develops at site of bite due to skin destruction following activation of intact CMI (ulcer takes about a year to heal) -diffuse -nodular lesions diffuse across body due to inactive CMI response -untreated infections can last for years

arthropods: lice

-small , wingless insects; suck blood through skin -appendages adapted for attachment -Pediculus humans easily spreads by direct contact or contact with personal items -survives on a few days away from hosts -body lice can transmit bacterial diseases: trench fever (Bartonella quintana); epidemic typhus (Rickettsia prowazekii); relapsing fever (Borrelia recurrent) -head lice do not transmit disease

Sarcomastigophra (Phylum)

-subphylum Mastigophra that include flagellated protozoa ex. Giardia, Leishmania, Trichomonas, Trypanosoma -sybphylum Sarcodine that move by means of pseudopodia ex. Entamoeba histolitica produces disease in humans

mycorrhizae

-symbiosis with fungi and roots of plants -increase absorptive property of roots -allows plant to grow in direr climate

Helminths

-three classes: Nematodes (Roundworms), Cestodes (Tapeworms), and Trematodes (Flukes) -multiple routes of entry into body -causes disease by invading host tissues or robbing the body by nutrients -complex life cycles include an intermediate hosts (one or more) during the early stages of development and definitive host when they are sexually mature

arthropods: mites

-tiny, fast moving arachnids -lives on outer surface of plants, animals -microscopic Demodex mites live unnoticed in hair follicles or oil producing glands -large numbers often live indoors, feed on shed skin cells -do not transmit disease but an trigger ashtma -chiggers (mite larvae) may attach, feed on fluids within skin cells cause intense itching -Sarcoptes scabiei transmitted by personal contact, causes scabies

Cryptosporidium parvum/hominis

-transmission via ingestion of oocysts in fecally contaminated water (agricultural runoff-zoonosis) -short term, mild diarrhea -chronic watery diarrhea in immune compromised individuals (AIDS patients) -important opportunistic infection -common occurrence in the US

Wuchereria bancrofti and W. (Brugia) malayi (elephantiasis)

-transmitted through the bite of an infected mosquito -microfilarie mature into adults in lymphatics and lymph nodes of genitals and lower extremities, mate, and their offspring enter nearby blood vessels -symptoms: fever, swollen lymph, and elephantiasis (due to formation of fibrous tissue around dead filariae that plugs up the lymphatic system resulting in swelling of the legs and genitals -nematode

African sleeping sickness drugs

-treatment depends on stage -Suramin does not cross CNS thus not effective once organisms has crossed into CNS -Melarsoprol is an arsenical compounds with CNS involvement that is extremely toxic

Chaga's disease drugs

-two clinical stages -Nifurtimox and Benzonidaxole treat the acute stage -no treatment against chronic stage

Phylum Apicomplexa (Sporozoa)

-use flagella to move -includes Plasmodium species that cause malaria, Toxoplasma gondii that use Toxoplasmosis, and Cryptosporidium parvum that cause Cryptosporidiosis

Metronidazole

-used for intestinal/urogenital protozoa -activated by anaerobic metabolism, interferes with electron transport and alters DNA -trade name Flagyl -used for Entamoeba histolytica, Giardia lamblia, Trichomonas vaginalis infections

ergosterol

-vital part of the cell membrane of fungi but is not found in humans -most anti fungal agents bind more avidly to ergosterol than to cholesterol thus damaging cell membranes f fungi -drugs targeting ergosterol synthesis increase the permeability of the fungal membrane, causing cell lysis ex. Polyenes, Azoles, Allylamines

arthropods: fleas

-wingless insects, can jump up to 30 cm -usually a nuisance but can transmit some pathogens -causative agent of plague, Yersenia pestis -fleas pick up when biting infected host; bacterium multiplies, blocks digestive tract -can live in vacant building dormant for months -mature quickly and jump to greet new hosts

Trichuris spp. (whipworms)

-worms liven large intestine with their anterior ends embedded into the cells that line the large intestine -worms can live a long time resulting in constant re-infections and heavy worms burdens -symptoms: diarrhea, dysentery, anemia -heavy worm infestations in children can lead to mental and physical retardation -diagnoses eggs in feces -nematodes

fungal forms

-yeast -molds

superficial cutaneous mycoses

Dermatophytosis -normal skin generally resistant to dermatophytes -excessive moisture allows invasion of keratinized layers of tissue -infection of the hair, skin, and nails caused by keratinophilic fungi of three specific specific genera termed dermatophytes (Trichophyton, Epidermophyton, Microsporum) -prodcue keratinase that allows the destruction of keratin

cell wall synthesis

Ehcinocnadins (Caspofungin approved) -inhibits betal-1,3 glucan synthesis component of the cell wall -used to treat Candida and Aspergillus infections

nucleic acid synthesis

Flucytosine -inhibits fungal protein synthesis by replacing uracil with 5-flurouracil in fungal RNA -effective against candidiasis and cryptococcosis (used synergistically with amphotericin B)

cell division

Griseofluvin -produeced by penicillium species -disrupts spindle formation, thus preventing mitosis -drug taken orally for months becomes concentrated into dead keratinized layers of the skin where it's taken up by the fungi thereby inhibiting fungal growth -active against ringworm of the skin, nails, or hair due to Trichophyton, Epidermophytin, and Microsporum species (not against superficial candidiasis, tinea versicolor)