Microbiology: Protozoa flashcards

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Information about Microbiology: Protozoa flashcards

Published on February 25, 2014

Author: ExamMasters

Source: slideshare.net


Microbiology cards covering protozoa! Excellent for medical, nursing, college, and university students!

Unicellular organisms

Intestinal Protozoa  Amoeba: Entamoeba histolytica  Flagellates: Giardia lamblia & Trichomonas parvum/hominis  Ciliates: Balantidum coli  Sporozoa:  Isospora belli  Cyclospora cayetanensis  Cryptosporidium parvum/hominis  Sarcocystis hominis

Entamoeba histolytica Amoebiasis  World wide distribution – 3rd after malaria and     schistosomiasis Hand-mouth; fecal-oral; sexual transmission Increasing in homosexuals Resistant to chlorine Major complications: amoebic abscesses in liver, brain, lung  Amoebic pericarditis (rare) is most dangerous complication of amoebic liver abscess

Clinical Classification of Amoebiasis  Asymptomatic infection  Colonization without invasion  Symptomatic infection  Invasion with mild symptoms  Intestinal disease  Dysentery, colitis, amoeba  Extraintestinal amoebiasis  Liver, skin, lung, pleura, brain

Pathogenesis of Amoebiasis  Ingested cysts  trophozoites in large intestine 75% remain in lumen 15% invasive disease; adherence/digestion of epithelium; formation of flask-shaped ulcers  bacterial superinfection may occur  dissemination  liver abscess  rupture  pericardial disease

Clinical Presentation of Amoebiasis  Asymptomatic  Mild GI discomfort  Diarrhea, pain, blood, mucus  Weight loss  Organ specific symptoms  Dx: history, cysts/trophozoites, ELISA/PCR

Intestinal Flagellates  Giardia lamblia  Giardia intestinalis  Giardia duodenalis  Trichomonas hominis  Epidemiology: worldwide  Traveler’s/backpacker’s diarrhea: hikers/campers  Day care centers  Zoonotic; water, food (fecal-oral)

Life Cycle of Giardia  Ingestion of cysts  trophozoites attach to duodenal brush border causing irritation and obstruction of absorption  cysts in colon; passed in feces  See them moving in stool

Clinical Presentation of Giardia  Watery diarrhea, abdominal cramps  Weight loss  No blood, no pus, no fever  Steatorrhea – fatty and foul-smelling  Lactose intolerance  Antibody deficiency  Dx: fecal cysts/trophozoites; enterotest; ELISA; duodenal aspiration

Comparison of Clinical Presentations Amoebiasis Giardiasis  Asymptomatic  Non-inflammatory watery  Mild GI discomfort   Inflammatory     Diarrhea, pain, blood, mucu s Weight loss, fever Organ specific symptoms Dx: history, cysts/trophozoites, E LISA/PCR History: international travel       diarrhea, abdominal cramps Steatorrhea – fatty and foulsmelling No blood, no pus, no fever Weight loss Lactose intolerance Antibody deficiency Dx: fecal cysts/trophozoites; enterotest; ELISA; duodenal aspiration History: Camping in Northern US wilderness; drink mountain water

Oral Flagellate  Trichomonas tenax

Intestinal Ciliate  Balantidum coli – Balantidiasis  The only ciliated protozoa!  Common parasite of animals  No extraintestinal spread  Easily treated, not very common  Seen in ppl who are around animals all the time  Farmers, zoo workers  Tx: tetracycline

Intestinal Sporozoa      Isospora belli Cyclospora cayetanesis water or produce Cryptosporidium parvum/hominis water and food Non-inflammatory diarrhea Infection by ingestion of oocyst  infection of intestinal epithelium  Sexual & asexual stages – sporogony/schizogony  Self-limiting in immunocompetent; Severe in AIDS or other immunocompromised individuals  Dx: acid-fast oocysts in stool & history

Urogenital Flagellate  Trichomonas vaginalis  Sexual transmission

Amoeboflagellates  Primary CNS pathogens  Naegleria fowleri  Enter thru olfactory neuroepithelium causing primary amoebic meningoencephalitis (PAM) in healthy ppl  Trophozoites in CSF and tissue  Acanthamoeba culbertsoni  Balamuthia mandrillaris  Acanthamoeba and Balamuthia enter thru lower respiratory tract or thru broken skin causing granulomatous amoebic encephalitis (GAE) in immunocompromised individuals  Trophozoites and cysts in tissue

Haemoflagellates  Trypanosoma & Leishmania  Insect borne  Found in blood, tissue, lymph and CSF  Amastigote and trypomastigote most imp forms

Trypanosomiasis  T. Gambiense  Tsetse fly; West Africa  T. Rhodesiense  Tsetse fly; East Africa  T. Cruzi  Reduviid bug, Americas

T. Cruzi – American trypanosomiasis  Chagas disease  Vector: reduviid bug (triatomine bug)  Zoonotic  South/Central America  Infection thru eyes or open cuts, transplacental, at parturition or breastfeeding, blood, uncooked or contaminated food  Patho: bug feces  infection of local tissue  ulceration & inflammation  spread  localization in mesenchymal tissues of heart, GI, esophagus, etc  markedly enlarged heart, esophagus, and megacolon  tachycardia, chest pain, ECG changes, constipation

Chagas’ Disease  Chagoma, Romana’s sign  Hepatosplenomegaly, lymphadenopathy  Myocarditis w/ CHF; Meningoencephalitis  Tx: nifurtimox, benznidazole

Leishmaniasis sand fly  Vector – Phlebotomine  3 forms  Leishmania tropica: dermal/cutaneous form  Leishmania brasiliensis: mucocutaneous form  Leishmania donovanii: visceral form     Most severe form (KALA AZAR) – 100% fatality if untreated Hypoalbuminemia; hypergammaglobulinemia Irregular fever, marked weight loss, anemia, hepatosplenomegaly Amastigotes in deep tissue – liver, spleen, bone marrow  Drug: Sodium stibogluconate

Visceral leishmaniasis  Patho: Parasite localization in macro of RES  PANCYTOPENIA  high output heart failure  myocarditis/pericarditis  Leishmania – HIV coinfection on the rise

Tissue Sporozoa  Plasmodium (blood & tissue)  Malaria; Vector: female anopheles mosquito  Babesia (blood)  Babesiosis; Vector: Ixodes scapularis  Ixodes also carries lyme disease and human granulocytic anaplasmosis  Toxoplasma gondii (tissue)  Toxoplasmosis; Vector: cat  Most commonly reported parasitic disease following heart transplantation  Two life cycles, two hosts: sexual (sporogony) – definitive host; Asexual (schizogony) – intermediate host


Plasmodium  P. falciparum, ovale, vivax, malariae

Parasite detection: HRP2 detection, parasite LDH ... Dipstick tests

Complications of Malaria  Parasitized RBCs adhere  fibrin thrombi  microinfarcts in brain, heart  CHF, encephalopathy  death  Phagocytosis by macro  macro hyperplasia  hepatosplenomegaly  nephrosis  death

Pathology of Malaria  Fever, anemia, jaundice  Hepatosplenomegaly, hepatorenal syndrome  Pulmonary edema, CHF  Blackwater fever – dark urine  Encephalopathy – cerebral malaria

Protection against Malaria  Absence of receptor (“duffy antigen” FyaFyb)  G6PD deficiency  HbS  Thal

Malaria hypnozoites  P. vivax & P. Ovale  Use primaquin against hypnozoites  Chloroquine against severe malaria  Quinine in severe parasitemia and resistant malaria  Metronidazole for amoebic liver abscesses  Also for giardiasis, trichomoniasis, dracunculis medinensis

Babesiosis  Similar to malaria; co-infection w/ Lyme disease; Ixodes scapularis  Fever, chills, sweating, myalgias, fatigue, hepatospleno megaly, hemolytic anemia

Toxoplasmosis  Infection  flu-like  latency  reactivation if pt becomes immunocompromised  myocarditis, pericarditis, CHF

Helminthology  Platyhelminthes  Cestodes – tapeworms Tx: Praziquantel, Niclosamide  Trematodes – flukes Tx: Praziquantel  Nemathelminthes (Nematodes)  Intestinal worms Tx: Mebendazole  Tissue worms - filaria

Trematodes  Hermaphroditic flukes  Mammals – definitive hosts  Snails – 1st intermediate hosts  Fish, crustacea, vegetable – 2nd intermediate hosts  Schistosomes  Mammals – definitive hosts  Snails intermediate hosts

Clinical Classification  Lung fluke  Paragonimus westermanii CRAB  Liver fluke  Clonorchis sinensis FISH  Fasciola hepatica PLANT/VEGETABLE  Intestinal fluke  Heterophyes heterophyes FISH  Fasciolopsis buski PLANT/VEGETBALE  Tx: Praziquantel for all trematodes

Schistosomiasis (blood fluke)  Direct skin penetration by cecariae  S. Mansoni – intestinal (side spine)  S. Japonicum – intestinal (no spine)  S. Hematobium – urinary (terminal spine)  Tx: Praziquantel  Picture:  Left, S. mansoni  Middle, S. Haematobium  Right, S. japonicum

Diphylobothrium Latum  Broad or fish tapeworm  Very big  From ingestion of larvae in RAW fish  Clinical:  Low serum B12, eosinophilia  Atrophic gastritis  Megaloblastic anemia  Dx: history, presentation, eggs in stool  Tx: Praziquantel, Niclosamide

Taeniasis  Beef tapeworm – T. Saginata  Ingestion of larvae in undercooked/raw beef  Pork tapeworm – T. Solium  Ingestion of eggs in undercooked/raw pork  Associated w/ heart problems  Dx – eggs/proglottids in human feces; adult in intestines  Tx: Praziquantel, Niclosamide

Nemathelminthes  Intestinal nematodes  Ascaris lumbricoides – Roundworm  Strongyloides stercoralis – Threadworm  Ancylostoma duodenale – Hookworm  Necator americanus – Hookworm  Enterobius vermicularis – Pinworm  Trichuris trichiura – Whipworm  Trichinella spiralis – Porkworm  Infections characterized by eosinophilia and high IgE levels; hygiene and lifestyle is important

Ascaris lumbricoides - Roundworm  One of the most common human infections worldwide  Patho:  Stage 1: “infective” eggs ingested  larval migration  cough, hemoptysis (bloody sputum), dyspnea, hemorrhagic pneumonia, asthma attacks, pulmonary infiltration, urticaria  Stage 2: adult in intestine  dependent on worm load  pain, distension, nausea, anorexia, malnutrition (growth stunting in children), intestinal obstruction  Stage 3: adult migration  acute pancreatitis or obstruction, biliary obstruction, jaundice, appendicitis, peritonitis  Dx: larvae in sputum; ova & parasites in stool  Tx: Mebendazole

Strongyloides stercoralis Threadworm  Direct skin penetration  2 distinct adult forms  Filariform (infective form): larvae penetrate intact skin initiating infection  enter circulatory system  lungs  penetrate alveolar spaces  reach small intestine  mature to adult female (not male)  produce uninfective larvae  autoinfection   Uninfective  infective in intestine and stool Uninfective  adults in soil or become infective  Rhabditiform (uninfective form)

Strongyloides Clinical Features  Acute disease:  Ground itch, cough, dyspnea, wheezing, fever, epigastric pain  Chronic disease:  Abdominal cramping, diarrhea, pain  Severe disease  Hyperinfection syndrome  Extraintestinal spread (CNS, etc)  **dissemination in AIDS pts**  Dx: larvae in stool, urine, duodenum, enterotest  Tx: Ivermectin

Enterobius Vermicularis - Pinworm  Common in US; children  Eggs on perianal folds  perianal itching  Pricking anal pain, restlessness, sleeplessness  Dx: see them around anus, eggs on scotch tape  Tx: pyrantel pamoate or mebendazole Enterobius vermicularis

Necator Americanus & Ancylostoma Duodenale – Hookworms  Worldwide distribution; Enter thru FEET  Clinical stages:  Cutaneous Stage: ground itch  Pulmonary Stage: pulmonary hemorrhage  Cough, wheezing, pneumonitis  Intestinal Stage: GI discomfort, blood loss

Hookworm Infection Complications  Protein losing enteropathy  Fe deficiency anemia  Tachycardia  Stillbirth  Poor physical development  Dx: history and eggs in stool  Tx: mebendazole + dietary supplements  Wear shoes!!

Trichuris Trichura - Whipworm  Fecal-oral transmission; rare  Clinical:  Light infection: asymptomatic  Moderate infection:  Discomfort, gas, diarrhea/constipation  Heavy infection   Distension, vomiting, diarrhea, weight loss **RECTAL PROLAPSE**  Dx: history & eggs in stool  Tx: mebendazole

Trichinella Spiralis - Porkworm  No eggs  No external phase  Dead end transmission! – ingestion of undercooked meat  larvae turn to adults in intestinal cells  migrate to muscle  encyst

Clinical Presentation of Trichinella Spiralis     Diarrhea, constipation Fever, myalgia, fatigue Macular or petechial rash Periorbital edema, conjunctivitis/retinal hemmorrhage  Splinter hemmorhage; heart problems  Dx: muscle biopsy, positive serology, presentation symptoms  Tx: Thiabendazole – before tissue invasion  Rest + analgesics for after invasion

Tissue Nematodes = Filaria  Adults in tissue  Eggs not produced; microfilaria produced  Wuchereria bancrofti – mosquito  Brugia malayi/timori – mosquito  Loa loa – deer fly  Onchocerca volvulus – simulium black fly  Dracunculus medinensis – Cyclops (water flea)

Elephantiasis/Lymphatic filariasis  Wuchereria bancrofti  Brugia malayi & Brugia timori  Patho: microfilaria  adult worms in lymphatics  more microfilariae  lymphoedema  inflammatory reaction  elephantiasis  Early: acute inflammation, hypereosinophilia, massive lymphatic dilatation, bacterial and fungal infections, infection by wolbachia bacteria (tx: tetracycline)  Late: lymphoedema/elephantiasis; chyluria (lymph in urine)  Tx: DEC + Albendazole or Albendazole + Ivermectin

Elephantiasis  Dx: presentation, very high increase in eosinophils, IgE, IgG4, and specific antifilarial Ab; microfilariae in blood (nocturnal periodicity)  Sheath = pathogenic; no sheath = nonpathogenic

Onchocerca Volvulus  River blindness/onchocerciasis  Vector: Simulium Black Fly  Larvae in subcutaneous tissue  Patho: adult in onchocercoma  millions of migrating microfilariae  death due to immune response  onchodermatitis/keratitis  Dx: Skin biopsy nodules  tons of little worms  Tx: DEC or Ivermection (single dose)

Dracunculiasis  Dog, horse, cow, monkey  Vector: Cyclops (Water Flea)  Debilitatin skin eruptions  worms come out of them!!  Tx: metronidazole/thiabendazole Dracunculus medinensis

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