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Chemotherapy
The use of drugs to treat a disease (any chem treatment)
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Prophylaxis
use of a drug to prevent imminent infection of person at risk
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Antimicrobial chemotherapy
use of chemotherapeutic drugs to control infection
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antimicrobials
any antimicrobial drug
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antibiotics
naturally made by a living organism
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semi synthetics drugs
chemically modified in lab after being isolated from natural sources
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synthetic drug
drug produced entirely by chemical reactions
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narrow spectrum
(limited spectrum) better, kills only limited array of bacteria
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broad spectrum
(extended spectrum) kill all, even good bacteria
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Fleming
1928, antibiotic penicillin
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Ehrlich
1910, concept of selective toxicity
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Selective toxicity
drugs should harm pathogens but not the host
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toxic dose
harm to the host
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therapeutic dose
eliminates pathogens in the host
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Domagk
1935, Prontosil was a red dye found to inhibit some gram positive bacterial species, synthetic
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Broad spectrum drugs affect many
taxonomic groups
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Narrow spectrum drugs affect only a few
pathogens
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Testing for Drug susceptibility disc diffusion test (kirby Bauer test)
- plate bacteria on muller- media
- bacteria diffuses through called muller hinton
- smaller diameter of zone of inhibition- resistant to antibiotic
- bigger is better look at chart, measure and see if resistant susceptible
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E-test
tell us susceptible/resistant understand MIC
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Testing for drug susceptibility
tube dilution tests
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tube dilution tests
- more sensitive and quantitative than the kirby bauer test
- antimicrobial is diluted serially in tubes of broth
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minimum inhibitory concentration (MIC)
- the smallest concentration (highest dilution) of drug that visibly inhibits growth
- NOT KILL
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Action of Antimicrobial Drugs (mode of action)
- 1. inhibition of cell wall synthesis
- 2. inhibition of protein synthesis
- 3. inhibition of nucleic acid and transcription
- 4. injury to plasma membrane
- 5. inhibition of synthesis of essential metabolites
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the beta-lactam family
antibiotic
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ampicillin inhibits
peptidoglycan biosynthesis
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Allergy issues with
natural penicillin
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Penicillin resistant bacteria effective against some
gram negative
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Antibiotics killing by
halting translation (RNA to protein)
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tetracyclines
selectively and action based on ribosomal differences between prokaryotes and eukaryotes
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disease cause by toxicity
chlamydial
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interferes with RNA synthesis
Rifampin
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Rifampin
- effective against tb, leprosy, and meningitis
- can cause liver damage
- has acid fast cell wall- waxy michollic acid
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Mechanism of antibiotic resistance:
- 1. Altered metabolic pathway
- 2. Antibiotic inactivation
- 3. active export of antibiotic
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Example of altered metabolic pathway
- Sulfonamides- inhibit folic acid so they make folic acid in another way
- Streptoccus
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Example antibiotic inactivation
Neissera gonorrhera- break down penicillin
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Example of active export of antibiotic
Staphylococcus export of tetracyclines- spit out antibiotic
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Antifungal drugs cause
membrane damage, causing content to leak out
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Used against Candida albicans (yeast infection) in intestines or vagina
Nystatin
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Amphotericin B
used against serious systemic fungal infections (entire body- lung migrate through blood stream)
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Goal of Antiprotozoal Agent
eradicate the parasite
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antimalarial drugs that accumulate in parasitized red blood cells
Aminoquinolines
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Aminoquinolines interfere with
parasites ability to break down and digest hemoglobin
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interfere with DNA synthesis of protozoans
Nitroimidazoles
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Nitroimidazoles used to treat
- amebiasis- amoeba
- giardiasis- intestinal, ingest
- trichomoniasis- sexually transmitted
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used against African trypanosomiasis- protozoa damage red blood cells
Arsenic
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Antihelminthic agents
worms
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Praziqyantel
changes membrane permeability in cestodes and trematodes
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praziqyantel cause
contractions and paralysis in the parasite- paralyze then dislodge them by pooping out (pass)
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Mebendazole
inhibits nutrients uptake in worms
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avermectins
cause paralysis in roundworms
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Drugs to treat protozoa and helminthic infections
synthetic, made in lab to treat both kinds of parasites
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Action of antiviral drugs (mode of action)
- 1. inhibition of virus entry- receptor, fusion, uncoating, inhibitors
- 2. inhibition of nucleic acid synthesis
- 3. inhibition of viral assembly/release
- Virus goes in cell so have to actually kill cells to get rid of them
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Antibiotic resistance
improper or excessive use of antibiotics causes antibiotic resistance
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Unnecessarily large antibiotic doses allow
resistant strains to overgrow susceptible ones
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Superinfection occurs
when resistant strains spread to other patients
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antibiotics are available over the counter in developing countries allowing incorrect use and overuse
true
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Antibiotics used in
livestock feeds
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Antiobiotics transmitted to humans in livestock through
meat consumption
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bacterial cells can pass resistance genes to other bacterial cells
true
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Example of Superinfection
- UTI
- Candida albicans
- antibiotics associated colitis
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Urinary tract infection
caused by E. coli, treated with antibiotics
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Lactobacilli
in female vagina are killed by the broad spectrum cephalosporin used to treat the UTI
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overgrowth of _____ _____ occurs causing vaginal yeast infection or oral thrush, opportunistic infection
candida albicans
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Oral therapy with ______ _____ ________ in antibiotics associated colitis
tetracyclines, clindamycin, and broad spectrum penicillin
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Oral therapy with tetracycline, clindamycin and broad spectrum penicillin kill off
normal biota of the colon
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Clostridium difficile
invades the intestinal lining and releases toxins that cause diarrhea, fever, and abdominal pain
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