multiphasic: uses both phenotype and genotype to classify

phenotypic classification more likely to relate to disease

polymer of n-acetyl muramic acid (NAM) and n-acetyl glucosamine (NAG), peptide side chain

NAG and NAM are linked by glysosidic bond

adjacent peptidoglycan polymers are crosslinked by peptide side chains

makes up 80% of cell mass

retains cell shape

gives cell staining qualities (GRAM)

provides osmotic stability to cell wall

interpeptide bridge made of amino acids

attach to penultimate (second to last) amino acid on NAM peptide chain

The terminal (last) amino acid is cleaved

this provides high energy to the bond, making peptidoglycan very strong

in Gram + there are 5 Gly connecting 2 NAM chains

in Gram -,  lysine connects directly to alanine on the chains

cleave subunits of peptidoglycan to lyse the cell wall

can attack at different locations

example: lysozyme cleaves glycosidic linkage b/w NAG and NAM

Gram + withstands more osmotic pressure b/c of the larger peptidoglycan layer

teichoic acids are covalently linked to PG layer

cation regulation (important for gram staining)

antigenic and unique to the organism

core oligosaccharide is highly conserved among bacterial species (not unique)

terminal polysaccharide is extermely unique (varies from strain to strain) and produces antigenic response (O antigen)

aid in identification of organisms

consists of particles like nutrients, metabolic products

can be seen as uneven staining (beaded filaments)

avoid recognition by PHAGOCYTES

poor immunogens

when capsular antibodies are present in an animal they act as OPSONINS that facilitate phagocytic recognition of encapsulated organisms 

turbidometric: measures turbidity of solution. will count both dead and live cells

CFU (colony forming units) uses a culture, so only live bacteria are counted

agar is only a support medium, it does not provide nutrients

agarose is agar with added sugar (nutrients)

superoxide: superoxide dismutase

hydrogen peroxide (or other peroxides): peroxidase, catalase

prefer live animals if possible

select a site most likely to contain the pathogen

minimize contamination

want to limit growth

move it quickly

use non nutritive media

control environmental conditions (most and cool)

safety: no splashy

antibiotic: produced by a living organism

antimicrobial: any substance that inhibits microbes including man made / synthetic

chemotherapeutic agent: antimicrobial used to treat a disease

hapten like: can't create an immune response on its own, if response is produced then antibody recognises it

binds to another molecule to create response?

attack folic acid producing cells

mammals can't synthesize folic acid 

selective toxicity

MIC minimum inhibitory concentration: minimum conc that inhibits all growth (original organisms may still be alive)

MBC minimum bacteriocidal concentration: minimum conc where bacteria are killed

anitbiotics are bactericidal if MBC is no more than 4x MIC (don't have to kill at same point as growth inhibition to be bactericidal)

The fluids in the kidney are about isotonic to the bacterial cells

the only reason cell wall break down works is because it makes the cell vulnerable to osmotic pressure

if there is not enough osmotic pressure to lyse the cell then it will not die

there is a bell curve that represents concentration of drug in the body over time: the drug will be expelled from the body after reaching a peak concentration / distribution

the peak concentration must be above MIC for drug therapy to be successful

for concentration dependent drugs: must dose to reach certain cmx; time may not be important

for time dependent drugs: dosages must overlap to keep CMAX over MIC for required period

use AUC (area under conc curve) to MIC ratio to determine dose adjustment

conjugative: encode the F factor (sex pilus) and can transfer itself

mobilizable: does not encode F factor but can be transferred by another plasmid that does; hitch a ride

non conjugative: is not transferred horizontally. might be replicated when cell does binary fission 

Phenotypic change

transcriptional: substrate alteration

post transcritional: proteolysis, covalent modifications

Genotypic change

modify existing DNA: mutations and mobile elements (selective pressure favors good genes)

acquire new DNA: horizontal transfer

the inside of the body is an ecological niche

many organisms occupy the outside but few are viable inside

these few can have a large share of the nutrients found in the body as long as they can avoid immunity

blocks of DNA with signatures of mobile genetic elements

mobile genes can inactivate genes located at their target location

resistance is always present in some subset of the population

it only becomes an issue if these bacteria get in the right situation and get positive selective pressure so that they become prevalent

the antigen is located on the terminal polysaccharide

the immune system does not target Lipid A

Lipid A is the toxic part

A: catalytic domain: alters the target with enzymes

B: binding domain / receptor

AB proteins must be activated by "nicking" after they leave the bacterial cell

If they become active inside the bacterial cell it will attack the cell

it's like a grenade - the pin has to be pulled first to work otherwise it blows up on you

locally non invasive: skin, some diarrheal

locally invasive: cellulitis, pharyngitis

deeply invasive: septicemia, meningitis, osteomyelitis

intoxication and toxemia

shock: toxic/septic/endotoxic (LPS)

death or recovery

post infection: sequelae

sensitive tests are broader spectrum, used for screening

specific tests are narrower spectrum, could be used to verify a positive from the more sensitive test