Eating habits - final Flashcards
Antibiotics (small)
Substance produced naturally in minute quantity by some microbes that has the potency to inhibit growth or kill other microorganisms.
Drug
an agent that affects physiology
Semisynthetic antibiotic
antimicrobial agent part synthesized in lab and part synthesized in microbe.
ex of semisynthetic (DAAM)
doxycycline, methcillin, ampicillin, amoxycillin
Synthetic drug
antimicrobial agent synthesized in laboratory.
ex of synthetic
Isoniazid, sulfa drugs
advantages of synthetic
more effective against gram negative, long lasting, easier to adminster
antibiotics - many available..
targets, some exclusive to microbes.
Inhibition of general metabolic pathways (anti-metabolites)
blocking synthesis of essential metabolites
plasma membrane
injury
targets cell wall
targets peptidoglycan
targets protein synthesis (ribs)
ribosomes (70S vs 80S). Tetracycline
targets nucleic acid (eskimo)
enzymes
Selective toxicity (what bacteria have that we don’t)
peptioglycan and 70s vs. 80s
harm the microbe without significant damage to the host - exploits some key aspects of physiology different from eukaryotes 1. bacterial cell have peptioglycan cell wall but we don’t have it. 2. bacterial cells have 70s we have 80s. - shouldn’t be influenced by food or disease status
Agent should be bio-available (what this bio class is not)
penetrate and non-toxic
- be able to penetrate host tissue and reach microbial colony - must be effective at low, non toxic concentration to host
Antibiotic action should be either…(static - standstill) and ex.
bacteriostatic or cidal (same thing) - these kill bacterial cells. ex. penicillin. these stop bacterial growth, then body defense cells are able to kill not get overwhelmed.
Stability
should be stable in body fluids and exhibit therapeutic effect; not degraded by stomach acids
Spectrum of activity (just spectrum)
drug action on various pathogen - varies, either broad or narrow spectrum
Broad spectrum
agent targets microbes from both taxonomic (gram + and gram -) groups of bacteria
Disadvantage - broad spectrum (super)
they disturb normal microflora - normal flora prevents pathogen colonization (competing for space, nutrients, attachment site) - cause super infection ; opens doors to transient pathogens
Narrow spectrum and ex. (the original)
when antimicrobial action is limited to few microbe sps Ex: Penicillin only affects Gram (+)ve bacterial cells
Tissue distribution differs…
differ re. metabolism and excretion of the drug
Half life
time it takes to eliminate one half of the original antibiotic dose in serum. - some antibiotics ( like penicillin - 6 hrs.) have short half life- additionally liver dysfunction / kidney disease, dose needs to be adjusted accordingly because associated with slow metabolism and excretion of the drug
Combination of antimicrobials…(work)
must exhibit some effect
Synergism and ex. (S)
two drugs given simultaneously, antimicrobial effect is greater than either given alone - given individually works poorly, but well if combined Ex: Streptomycin and penicillin / vancomycin together will weaken cell wall, easier for streptomycin to enter cell.
Antagonism and ex. (tetris)
two drugs when given simultaneously, their action interfere with each other Ex: Tetracycline ( bacteriostatic - slows growth) and penicillin ( bacteriocidal - kills), acts on growing cells, disrupting peptidoglycan)
Additive (add nothing)
drug combination that are neither antagonistic nor synergistic in action
Side effects should be…
minimal
Side effects (chic in class) and ex.
undesirable effects on the host - can limit clinical usefulness of an agent; can manifest as i. trigger of allergic reactions: e.g. penicillin allergy 300 deaths / year; with fever, rash and / or anaphylactic shock
side effects exhibit…
toxic effects, though selective toxicity against bacteria
disruption of the normal flora (think diptheria plus cloistrid)
antibiotic associated pseudomembranous colitis caused by clostridium difficle vaginitis and thrush - yeast overgrowth
lesions (intestines - think diptheria)
colonizes intestines of ppl. whose normal microflora have been reduced or eliminated due to antibiotics. bacteria secretes toxin, that targets intestinal epithelial, kills and forms pseudomembrane. the lesions are dead epithelial cells, inflammatory cells, clotted blood. it causes fever, diarrhea, and abdominal pain. common in nursing homes.
Route of administration
can be via external or internal route. Topical / local application: applied on skin directly
Internal
administered via orally or im or iv A. Orally: simple, no needle or provider’s help. Disadvantage: don’t follow time table - difficult for TB treatment - for long time. DOT - direct observation therapy.
Intramuscularly
slow diffusion via blood vessels Disadvantage: high concentration can’t be achieved
Intravascular (kidneys)
via needle or catheter - can attain high concentration for limited time (?) needs to be continuously infused. liver and kidneys remove rapidly
Antibiotic safety (interactions and neutral) neutral effect ex.
Prescribing antibiotic often involves assessing risk and benefits. Often, 2nd drug use may have a toxic effect that is not there when the 1st drug is taken alone Also, one drug may neutralize the intended effect of the other Ex : - few antibiotics (includes tetracycline) dampens effectiveness of contraceptive pills - hypersensitivity towards penicillin antibiotic
Pregnant women should be given antibiotics…
that are considered safe as recommended by FDA - there should be no / minimal risk to the developing fetus
Drug susceptibility vs sensitivity
a microbe may be susceptible to drug action but humans can develop allergic sensitivity to the drug
antibiotic - sensitivity and susceptibility. sensitivity of host, susceptibility of microbe.
pencillin - degraded by..(body part)
liver
Penicilloyl (combined w/ dropper)
Major, abundant product penicilloyl by itself will not trigger an immune response. but when combined w/ serum protein it triggers a reaction.
75% of allergic reactions …(happen)
75% of allergic reactions is due to penicilloyl haptens
25% of reactions is due to other breakdown product
haptens (iggy sailing)
Triggers IgE mediated reactions. it triggers mast cells to release histamine mediators
Major and minor determinant…(it happens)
refers to the frequency with which antibodies to these haptens form, rather than the severity of the reactions.
Acute anaphylactic shock reaction…
to penicillins is the most important and immediate
danger connected with use of this antibiotic in some individuals
antibiotics prone to inactivation in gastric environment should be given…
via IV / intra-muscular route
bacterial infection of the CNS or eyes are…
hard to treat bc blood brain barrier.
most antibiotics detoxified by…
the liver and excreted by kidneys. antibiotics quickly removed by kidneys -good choice for bladder infection treatment, but poor choice for heart infection.
ex of toxic effects - ciprofloxacilin (cip cartilage)
limited use in pregnant women and children because it affects cartilage development
ex of toxic effects -chloramphenicol (last resort) (pale flora)
causes aplastic anemia
ex toxic effects - polymyxin B (don’t drink)
toxic to kidneys; so not useful for systemic use. disrupts membrane.
ex toxic effects - tetracycline (soft…)
forms Calcium complex, limits availability. inhibits Ca+ absorption. teeth get soft. that’s why elderly patients must take calcium supplements.
ex toxic effects - metronidazole
black hairy tongue. due to RBC breakdown products accumulation
broad spectrum ex. (amplify)
ampicillin - semi-synthetic
isoniazid targets…
mycolic acid and used as a TB drug
antibiotic modes of action
Plasma membrane, cell wall synthesis, protein synthesis, Nucleic acid, metabolism.
limits availability (limited tetris)
tetracycline: forms Calcium complex, limits availability.
Chloramphenicol action is it…(flora - pep)
attacks protein synthesis. peptidyl transferase inhibitor of the large subunit
Ciprofloxacillin targeting..and treats…(cip chern)
gyrase enzyme of DNA replication ; can withstand chemical composition of urine like the sulfa drugs. nucleic acid and DNA replication.
attacks protein synthesis
Tetracyclines : (tetra -4, cylcine - ring) wedges in between codon and anticodon. codon sequence is in the Mrna. and anticodon (complimentary) is in transfer RNA. reason it doesn’t hurt us (selective toxicity)
Macrolides (big tiger - ACE myocin)
binds reversibly to large subunit of ribosome ( 50S) - specifically inhibits translocation
Ex: erythromycin, clarithromycin, azithromycin (it stops protein synthesis by attacking ribosome. your defense system will get rid of bacteria) etc
antibiotic resistance - extrachromasomal resistance due to…(R - down milk)
R plasmids beta lactamase
Rifamycins (rif raj)
inhibits RNA synthesis. binds and blocks RNA polymerase activity (from DNA to RNA)
rifamycin for tb due to its…
slow mycolic acid synthesis. is associated with slow turnover of proteins like RNA polymerase.
Antimetabolite
a substance that prevents a cell from carrying it’s normal metabolic reaction (anti - against).
2 ways antimetabolites function (anti f compete - - spy)
competing for the same sites on an enzyme, or they are erroneously incorporated into molecules like nucleic acids
the sulfa and trimethoprim have a…
synergistic action. they are available as bactrim or septra. if they escape sulfa, then trimethoprim will stop it.
bacteria has to make folic acid from…
paba
competitive inhibition of enzymes (can’t compete w/ the bomb)
sulfa
sulfa targets (di - bomb)
specific enzyme called dihydropteroate synthase (DHPS). NOT IN HUMANS
bacteria don’t scavange our folic acid (large)
1) folic acid is a big molecule 2) folic acid simply can’t diffuse across the architecture of the cell wall or the membrane.
Isoniazid (INH) and ethambutol (together)
synergistic for TB
attacks plasma membrane
polymixin B
protein synthesis (baseball)
tetracyline, neomycin, chloramfinenicol, eyrthromyocin target.
