Microorganisms CH 10 Flashcards
Medically important microorganisms
- Medically important microorganisms include: bateria, fungi, viruses, and protozoa.
- Bacteria: small, single celled organism.
- Shapes include:
1.) cocci (subshapes: diplococci, staphylococci, streptococci).
2.) Rod shapes are bacilli.
3.) Spirochetes are corkscrew shaped. - Gram stain is another way of classification: gram positive are blue and have a teichoic acid in their cell wall.
- Acid fast stains also allow for another classification
Important to classify
- Pathogenic cocci
- S. aureus, S. pneumoniae, N. gonorrhoeae, N. meninigitis
- Pathogenic bacilli
- C. tetani, C. botulinum, B. anthracis
- Klebsiella granulomatis (Granuloma inguinale – Donovan bodies)
- Pathogenic Spirochetes
- T. pallidum, B. bugdorferi
- Acid Fast
- M. tuberculosis, M. leprae, M. avium intercellulare N. asteroides
- Others
- Chlamydia trachomatis, richettsiae
Fungi
- unicellular or multicellular, similar to plants.
- No chlorophyll and don’t carry out photosynthesis.
- Filamentous fungi are also called molds. Basic structure of these is the hypha. Collectively, the hyphae form the mycelium and sometimes divide
into septa. - Yeast are single round
budding fungi. Cryptococcus
neoformans is an example. - Psuedohyphae do not detach, an example is Candida albicans.
- Filamentous fungi
- Yeasts
- Psuedohyphae
4, Dimorphic Fungi
Filamentous fungi
- Aspergillus fumigatus
Yeasts
- Cryptococcus neoformans
Psuedohyphae
- Candida albicans*
- One of the most widespread mycotic diseases
Dimorphic Fungi
- Blastomyces dermatitidis, Coccidiodes immitis, Histoplasma capsulatum
- Viruses
- Protozoans
Viruses
- DNA or RNA and small proteins that require a host to infect.
- Most cannot be seen in light microscopy, but the cytomegalovirus and Negri bodies can be seen
Protozoans
- single celled but functionally complex organisms.
- Locomotion determines this classification.
- Flagella, cilia, and pseudopods help them move. P. carinii?? (jirovecii)
Kinyoun
- Detects acid fast mycobacteria
- Detects acid fast mycobacteria
- Lipoid capsule of acid fast organisms takes up carbol fuchsin but can resist decolorization
- NO Carnoy for fixative
- Cut at 4-5um
- Control must have mycobacteria
◦ Results:
- Acid fast bacteria: bright red
- Background: light blue
Stains for microorganisms
- Kinyoun
- Ziehl-Neelsen
- Fite
- Auramine-rhodamine
- Gram
- Giemsa
- Alcian yellow-toluidine blue
- PAS
- CAS
- Gridley fungal stain
- Grocott modification of Gomori
- Mayer mucicarmine
- Warthin-Starry
- Dieterle
- Steiner and Steiner
Protozoans
- Entamoeba histolytica
- Giardia lamblia
- Toxoplasm gondii
- Leishmania
- Plasmodium
Ziehl Neelsen
- Demonstrates acid fast bacteria
- Demonstrates acid fast bacteria
- NO Carnoy fixative
- Cut at 4-5um
- Control with acid fast bacteria required
- Microwave Modification also available!
◦ Results:
- Acid fast bacteria: bright red
- Background: light blue
Fite acid-fast stain
- Demonstrates Mycobacterium leprae
- Demonstrates Mycobacterium leprae
- NO Carnoy fixative
- Cut at 4-5um
- Leprosy tissue must be used as control
- Xylene-penut oil deparaffin step
- Must avoid alcohol
◦ Results:
- M leprae: bright red
- Background: light blue
Brown-Hopps Gram stain modification
- Demonstrates gram pos and gram neg bacteria
- Demonstrates gram pos and gram neg bacteria
- 10% NBF preferred fixative
- Cut at 4-5um
- Control tissue should contain both gram + and gram –
◦ Results:
- Gram pos: blue
- Gram neg: red
- Nuclei: light red
- Background: yellowish
Microwave auramine -rhodamine
- Detects mycobacteria or other acid-fast bacteria
- Detects mycobacteria or other acid-fast bacteria
- 10% NBF preferred fixative
- Cut at 4-5um
- Control must have acid fast mycobacteria
◦ Results:
- Acid-Fast bacteria: reddish-yellow fluorescence
- Background: black
Diff-Quick Giemsa for H.P
- Demonstrates H pylori
- Demonstrates H pylori
- Romanowsky stains combine basic methylene blue and acidic eosin in one dye.
- 10% NBF preferred fixative
- Cut at 4-5um
- Control should contain H pylori
◦ Results:
- H pylori – dark blue
- Other bacteria – blue
- Nuclei – dark blue
- Cytoplasm - pink
Alcian Yellow- Toluidine Blue
- Detects H. pylori
- Detects H. pylori
- 10% NBF fixative
- Cut at 4-5um
- Control must contain organism
- Toluidine blue is metachromatic
◦ Results
- Mucin – Yellow
- H. pylori - Blue
Chromic Acid Schiff fungal stain
- Demonstrates fungi in tissue
- Demonstrates fungi in tissue
- Chromic acid is stronger oxidizer and can eliminate reactive aldehydes in other tissues
- 10% NBF preferred fixative
- Cut at 4-5um
- Control tissue must contain fungus
◦ Results:
- Fungi: deep rose
- Nuclei if hematoxylin is used: blue
- Background: green (if light green is used)
