Microbiology:
Gram +: thick peptidoglycan cell wall (w. lipotechoic acid) > imp for determining serotypes.
Gram -: outmem has LPS endotoxin (> + mac to rel TNF a > septic shock).
Mycoplasma has no cell wall, mycobacterium has mycolic acid, thus both are hard to stain.
Gram staining: CV > iodine > decolorizer (gram + retains, - washes out) > saphonin (- turns red).
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Mycobacterium: acid fast carbol fusin ZN stain.
Treponema: dark micro/fluroscence ab stain.
Ricketssia, legionella, chlamydia: immunofluor stain.
Cryptococcus neo: india ink stain.
Fungi, legionella: silver stain.
Sepecial culture: selective (abx; Thayer Martin: vanco, polymyxin, nystatin for N gonn), differential
(Mackonkey agar turns lactose fermenter pink for E. coli).
Obligate aerobes: likes lungs; nocardia, pseudomonas, m. tub, bacillus.
Obligate anaerobes: has no superoxide dismutase (neutralizes superoxide) > cant grow in O2. +/catalase (neutralizes H2O2 which combines w O2 > free rad). Aminoglyco resistant (requires O2 to enter
cell). Clostridium, actinomyces, bacteriodes.
Intracellular bugs: obligate intracellular (cant make ATP; ricketssia, chlamydia), facultative (can live both;
salmonella, Neisseria, brucella, listeria, legionella, yersinia).
Encapsulated organisms: in asplenics/B cell def pt, vaccinate. Hib, S pneu, N meng, salmonella, K pneu,
GBS.
Catalase +: staph, serratia, pseudomonas, actinomyces, candida, E. coli.
Vaccines: polysaccharide alone isn’t very immunogenic so conjugate w protein to elicit T cell binding >
presents protein to B cell to class switch and produce ab.
Urease +: hydrolyzes urea to ammonia and CO2 (brth test). H pylori, ureaplasma, nocardia, proteus,
cryptococcus, klebsiella.
Pigment producing bugs: actinomyces isrealli (yellow sulfur granules), serratia marcesens (red).
Bacteria virulence factors. S. aureaus (protein A > binda Fc og Ig > prevents phago), GAS (M protein >
prevents phag), IgA protease (cleaves IgA to colonize resp tract; S pneu, Hib, niesseria).
Exotoxins: both grams can prod; mechanisms:
Inhibits protein syn: ADP ribosylating