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Z - Micro 01
Micro 01
Question | Answer |
---|---|
beta-lactam abx | penicillins because they have a beta-lactam ring |
penicillins bactericidal or bacteristatic? | bactericidal |
difference between bacterial cytoplasmic membrane and animal cytoplasmic membrane | bacterial cytoplasmic membrane doesn't contain cholesterol or other sterols (except for mycoplasma pneumoniae, which has cholesterol) |
what is the antigenic determinant of gram + bacteria? | teichoic acid (in peptidoglycan layer) |
what is the antigenic determinant of gram - bacteria? | Endotoxin/Lipid A |
Do gram + cells have endotoxin? | No, except for Listeria monocytogenes |
For which organisms would you use an acid fast stain? | mycobacteria (TB or leprae), nocardia (partially acid fast), Cryptosporidium parvum (its oocysts are partially acid fast), Isospora belli (oocysts are acid fast) |
Explain acid fast stain | 1. red stain (carbolfuchsin) 2. heat to help dye penetrate, 3.acid poured (but the mycolic acid of acid fast orgs don't dissolve in the acid - hold on to the red color), 4.methylene blue stain. Acid-fast orgs stay red, while non-acid fast stains blue. |
What does the acid fast stain bind to? | mycolic acid in the cell wall of mycobacteria and nocardia |
For which organism would you have to use a darkfield microscope? | Spirochetes (Treponema pallidum, Borrelia, Leptospira) |
What's special about cell wall of chlamydia? | Cell wall doesn't have muramic acid |
What's special about mycoplasma? | No cell wall, and cholesterol in its cytoplasmic membrane |
Bacterial DNA | double stranded, circular |
Bacteria are prokayotes or eukaryotes? | prokaryotes |
Bacterial ribosome | 70S - two subunits: 50 S (targeted by erythromycin) and 30 S (targeted by tetracycline) -- protein synthesis blocked |
Which bacteria must use host cell's machinery to acquire ATP? | Chlamydia and Rickettsia |
Which bacterial enzyme breaks down hydrogen peroxide? | Catalase and Peroxidase |
Which bacterial enzyme breaks down super oxide radicals? | Superoxide dismutase |
Budding yeast, narrow based buds | Cryptococcus neoformans (fungus) -- the halo surrounding is the capsule made up of sugars |
Yeast, broad based buds | Blastomyces dermatitidis |
Fruiting body, narrow angled, branching septate hyphae | Aspergillus fumigatus |
Wide-angled hyphae, non-septate | Mucor |
Likes to inhabit abandoned TB cavities | Aspergillus fumigatus |
Spherules with endospores | Coccidioides immitis |
Southwestern US | Coccidioides immitis |
Ohio/central Mississippi River Valley | Histoplasma capsulatum |
Great Lakes | Blastomyces dermatitidis |
Earthquakes --> dust | Coccidioides immitis |
chicken farmers | Histoplasma capsulatum |
Starlings (birds) | Histoplasma capsulatum |
fungus whose yeast is phagocytosed by alveolar macrophages | Histoplasma capsulatum |
fungus whose yeast looks like Mickey Mouse | Cryptococcus neoformans (fungus) |
How to treat Cryptococcus? | Actinomycin |
How to treat Histoplasma? | Actinomycin |
Mechanism of actinomycin? | inhibit transcription. It does this by binding DNA at the transcription initiation complex and preventing elongation by RNA polymerase (also called Dactinomycin) |
Fungus with a crown, septate, narrow angles | Aspergillus fumigatus |
Allergies to molds -- what kind of hypersensitivity? | Type I |
India ink stain | Cryptococcus (fungus) -- the halo surrounding is the capsule made up of sugars |
Quellung reaction | ID bacteria with capsules. Abs bind to the capsule (opsonization) --> capsule swells with water --> can see the swelling through a microscope. |
Obligate anaerobes (2) | Clostridium and Bacterioides |
What conditions can destroy an endospore | Spores only by Bacillus and Clostridium. Autoclave conditions: 121 C for 15 minutes. |
Facultative INTRACELLULAR organisms | MY LIST for YOUR INTRAmural party includes LEGIONs of SALMON, BRUssel sprouts and FRENCH fries. Mycobacterium, Listeria monocytogenes, Yersinia, Legionella, Salmonella typhi, Brucella, Francisella tularensis. |
Exotoxins - A (damage, toxic) and B (binding, delivery) subunits | The 2 SUBwoofers (A and B) playing ANTHRAX music is VIBRating DEEP in the CLOSet. Bacillus anthracis, Vibrio cholera, Corynebacteria diptheria, Clostridium tetani and botulinum. |