T05 Mycobacteria, Fungi and Parasites Flashcards
Mycobacteria are non-motile, non-sporing rods.
What is used to stain them?
Carbol fushin - acid fast bacilli
not readily stained by Gram’s stain
Pathogenic mycobacteria requires 2-6 weeks of growth on special media such as?
Lowenstein Jensen medium
**M.leprae fails to grow in vitro.
What can be seen on gram’s stain if the organism is Candida albicans?
*It also goes white colonies of 2-3mm diameter, smooth edge and smooth surface on Sabouraud dextrose agar.
G+ with budding yeast and pseudohyphae at 20 degrees true hyphae (germ tube formation) at 37 degrees
(dimorphic fungi)
Pneumocystis jirovecii shows what in Toluidine O stain?
- cup shaped/collapsed basketball shaped
2. in clusters
Pathogenic effects of Entamoeba histolytica?
Liver abscess;
Amoebic Dysentery
Which causative protozoa will cause vaginitis?
Trichomonas vaginalis
Which genus of Protozoa stays in RBCs as a habitat?
How to distinguish the 4 different species?
Plasmodium
- Vivax - Benign tertian malaria (2 days)
- Falciparum - Malignant tertian malaria (2 days)
- Ovale - Benign tertian malaria (2 days)
- Malariae - Quartan malaria (3 days)
Pathogenic effects of Toxoplasma gondii? (4)
1. Encephalitis Congenital toxoplasmosis: 2. Chorioretinitis 3. Hydrocephalus 4. Intracranial calcifications
What can be seen in fresh specimens for Entamoeba histolytica infection?
Trophozoite: Ingestion of red blood cells (only in fresh specimen!)
- Mature cyst has 4 nuclei. (may not be able to see all)
Which organism has a characteristic falling leaf movement?
Trichomonas vaginalis (trophozoite)
Which organism’s trophozoites have a clown face appearance and move like a falling leaf? (Not Trichomonas vaglinalis)
What disease does it cause?
Giarda lamblia
- causes traveller’s diarrhoea
What shape does Toxoplasma gondii trophozoite has?
Crescent shape
What is the diagnostic sampling of Plasmodium falciparum?
What specific disease does it cause?
- Blood smear for Giemsa stain > rings inside RBC
- Causes cerebral malaria
Trematodes are classified based on their habitats.
Name the organisms that are blood trematodes. (3)
Schistosoma mansoni
Schistosoma japonicum
Schistosoma haematobium
Name the lung trematode you know.
Paragonimus westermani
Name the hepatic trematode you know.
Chinese liver fluke - Clonorchis sinensis
For all trematodes (flukes), common way to diagnose them?
Microscopy: stool OCP for eggs
How can we differentiate Schistosoma haematobium from the other 2 species by morphology of the eggs?
S. haematobium has a terminal spine.
S.mansoni: large lateral spine
S. japonicum: small lateral spine
What are the characteristic morphological features the eggs of Clonorchis sinensis? (2)
- Pear-shaped
- with an operculum at the narrower end
Proglottid is the segment of tapeworms containing both male and female reproductive organs.
Which organisms has proglottids that are passed out in the faecies? (2)
How to differentiate them? (2)
- Taenia solium - <13 lateral branches on one side of main stem of the uterus
- Taenia saginata - >15 lateral branches on one side of main stem of the uterus
***Eggs of them are indistinguishable!
What causes cysticercus?
Taenia solium
Name all the intestinal nematodes that can be found in the small intestines. (5)
- Ascaris lumbricoides (common roundworm)
- Ancylostoma duodenale
- Necator americanus
- Strongyloides stercoralis
- Trichenella spiralis
Name the 2 intestinal nematodes that can be found at the caecum and appendix.
- Enterobius vermicularis (pinworm)
2. Trichuris trichiura (whipworm)
Name the nematode that infects the lymphatic system.
Wuchereria bancrofti
Name the nematodes that infect the subcutaneous tissues. (2)
- Onchocerca volvulus (river blindness, onchodermatitis)
2. Dracunculus medinensis (chronic cutaneous ulcer from which the worm protrudes)
Name the nematode that infects muscles.
Trichinella spiralis
Characteristics of eggs of Ascaris lumbricoides?
Fertilized eg has thick shell with lumps
Egg is spindle-shaped with a plug at each end. What organism?
Trichuris trichiura (whip worm)
Stronglyloides stercoralis
shape of larva and eggs?
Filariform larve
NO EGGS!
