Things to memorize for BioMed Midterm Flashcards
Lactobacillus species and Candida albicans importance
Lactobacillus maintains low pH of vagina and absence of this can have overgrowth of Candida albicans (yeast infection)
Erythema migrans
Causes lyme disease
Bacteremia
Chills, fever, cardiovascular instability
Gram stain
Crystal violet, iodine (fixer/mordant), acetone (decolorize), safranin
Gram positive (purple)- CV stains thick peptidoglycan wall
Gram negative (pink)- CV washed out and stained pink with safranin
Acid-fast stain
Acid fast organisms like Mycobacterium contain large amount of mycolic acids within their cell walls (Fatty Acids)
Carbolfuschin (stains acid fast organism pink/red), heat fix, acid alcohol (decolorize), methylene blue (stains non acid fast organism blue)
Acid fast= pink/red
Indica Ink
Useful in detecting microbes with capsule
Cryptococcus is identified by their large, transparent capsules that displace the India ink particles
Does not stain the organism, stains the background- negative stain
Potassium Hydroxide Preparation
Treatment with KOH dissolves host cells and bacteria, sparing fungi
Fungi are recognized under the microscope by their filamentous (hyphae) or round (oval) structures
Penicillin and Cephalosporins
inhibit the enzymes responsible for transpeptidation and other enzymatic reactions necessary for the final 3D structure of rigid microbial cell wall
Polymixins - Neomycin and Bacitracin
Alteration of cytoplasmic membrane integrity
Cationic surface membrane action to displace Mg and Ca from
membrane lipids thus allowing for loss of vital intracellular proteins and nucleic acids
Erythromycin and Clindamycin and Tetracycline
Erythromycin: bind to 50S ribosomal subunit to inhibit peptidyl
transferase
Clindamycin: bind to 50S ribosomal subunit to inhibit RNA-dependent protein synthesis
Tetracycline: binds 30S ribosomal subunit to inhibit binding of
tRNA to mRNA
Metronidazole and Quinolones
Metronidazole: microbial reduction of 5’ nitro group by nitroreductase to cell toxic metabolites that damage the DNA and therefore interfere with DNA synthesis
Quinolones: inhibit DNA supercoiling by DNA gyrase -abnormal DNA growth
Sulfonamides
Sulfonamides: block the conversion of PABA to dihydrofolic acid
10 Nutrients required for bacterial growth
Cytoplasm: carbon, hydrogen, oxygen, nitrogen
Nucleic acids and amino acids: sulfur, phosphorous
Proteins and cofactors of enzymes: potassium, magnesium,
calcium and iron
Fermentation pathway end products
i. Lactic acid: lactobacillus, E. faecalis
ii. Ethanol: yeasts
iii. Butyric acid: clostridium, eubacterium, fusobacterium
iv. Mixed acid: e.coli, salmonella
v. Proprionic acid: peptostreptococcus, porphoramonas, prevetella
vi. Formic acid: esterobacter, pseudomonas
Conjugation, Transduction, Transformation
Conjugation - Cell to cell contact with F pilus
Transduction - transfer of gene via phage vector without cell to cell contact
Transformation - Transfer by naked DNA floating after lysis
Griffith’s transformation experiment
Streptococcus pneumoniae (Griffith):
have capsules SMOOTH mucoid colonies (lethal) vs mutants without capsules ROUGH (nonlethal)
(Transformation)
Diseases caused by staphylococcus aureus
Impetigo
Cellulitis
Folliculitis
Furuncle
Carbuncle
Toxic Shock Syndrome (TSS) - Exotoxin TSST-1
Gastroenteritis - Food poisoning
Scalded Skin Syndrome - Exfoliative toxin A and B