Chapter 5


Eukaryotic Microorganisms



Eukaryotic cells (Eukaryotes)

   More complex than prokaryotes

   Possess a true nucleus and membrane-bound organelles

   May be single-celled or multicellular

   May or may not have cell walls

   Include members of Domain Eukarya




   Saprobic organisms - live off of dead organic matter

   Live mostly on land and are nonmotile

   Have rigid cell walls made of chitin

   Diverse group ranging from single-celled yeasts to multicellular molds & mushrooms

   Colonies of filamentous molds have hairlike texture due to hyphae

   Asexual Reproduction - budding, fragmentation, or spore formation

  sporangiospores and conidiospores

   Sexual Reproduction - spore formation



Fungi in Medicine and Industry

   Many cause food spoilage and disease in plants

   Used to produce antibiotics, alcohol, and vitamins

  Saccharomyces bakers yeast used to make bread, beer, and wine

  Penicillium - produces penicillin

   Mycoses - Fungi that grow in or on the human body and cause a disease

  Immunocompromised individuals are the most vulnerable

  cause skin infections, lung infections, allergies or produce toxins

  Aspergillis liver and thyroid cancer

  Candida oral and skin infections




   Plant-like organisms that contain chlorophyll and a cell wall of cellulose

   Divided into groups based on photosynthetic pigments

   One of the primary producers of carbohydrates and oxygen

   Found near the surface of salt or fresh water

   Can be microscopic or macroscopic, unicellular or multicellular

   Reproduce by binary fission, fragmentation, or sexual reproduction

   Can cause skin infections and red tides

  toxins induce paralytic shellfish  




   Diverse group of single-celled eukaryotes, larger than prokaryotes

   Found on land and in water

   Lack rigid cell walls

   Reproduce by binary fission and sexual reproduction

   Exist in active trophozoite or dormant cyst forms



Classification of Protozoans

   Mastigophora motile by flagella





   Sarcodina motile by pseudopodia



   Ciliophora motile by cilia


   Apicomplexa non-motile except for a few that have motile reproductive stages






Parasitic Helminths

   Multicellular parasites that enter the body through contaminated food, insect bites, or direct skin penetration

  Most are not microscopic but they are included among microorganisms because of their importance in human diseases

   Diagnosis often requires microscopic examination of eggs and larvae in feces and tissue



Chapter 22



Parasitic Helminth Diseases



Nematodes (roundworms)

   Have elongated, cylindrical bodies

   Inhabit the gastrointestinal tract, blood, or other tissues                                  

   Enterobius vermicularis pinworm

  causes anal itching, nausea, abdominal discomfort, and diarrhea

  human to human transmission by ingesting eggs from contaminated food, drink, fingers

   Ascaris lumbricoides ascariasis

  Human to human spread via contaminated food, drink, or objects placed in the mouth

  Can invade the liver and gall bladder and  cause allergic reactions

   Trichinella sp.- trichinosis

  Transmitted by eating raw pork containing cysts

  Causes muscle and joint pain and can involve the heart and brain

   Necator americanus hookworm

  has cutting teeth on the mouth that anchor it to the intestinal villi

  burrow into the skin from soil contaminated with human feces           

  Causes nausea, vomiting, cramps, diarrhea, and anemia

   Strongyloides stercoralis threadworm

  burrow into the skin from soil contaminated with human feces           

  causes pneumonitis, bloody diarrhea, liver enlargement, and malabsorption

   Trichuris trichiura whipworm

  Ingest eggs from soil contaminated with human feces

  Causes bowel hemorrhage, dysentery, and rectal prolapse



Cestodes (tapeworms)

   Have long flat, ribbon-like bodies

   Infections often go unnoticed, but it can be serious if tapeworm obstructs the GI tract

   Taenia solium pork tapeworm

  have hooklets and suckers to attach to the intestine

  acquired from eating undercooked pork

   Diphyllobothrium latum fish tapeworm

  acquired from eating raw fish

  may have mild abdominal discomfort or anemia



Trematodes (flukes)

   Have flat, ovoid bodies and suckers that hold organism in place and suck fluids from the host

   Clonorchis sinensis Chinese liver fluke

  ingested from undercooked freshwater fish

  causes thickening of bile duct and granuloma formation in the liver

   Schistosoma mansoni shistosomiasis

  blood fluke that causes liver swelling or malfunction

  can invade intact skin

  acquired by swimming in water contaminated with infected human feces