Chapter 12 -- Drugs, Microbes, Host - The Elements of Chemotherapy Flashcards
Chemotherapy
treating conditions with chemicals
Antibiotics
chemical substances produced by living organisms that have antimicrobial activity usually molds, yeasts and bacteria
Synthetic drugs
made in lab
Semisynthetic drugs
made naturally but altered in lab
Streptomyces sp.
produces most; best sources for ATB
Broad spectrum
kills normal biota, GI issues, yeast infections
Narrow
limited spectrum of activity
Genetic changes
mutations followed by natural selection = chromosomal resistance
Transfer of R plasmids
R= resistance; transformation, conjugation; transduction = extrachromosomal resistance
Non genetic resistance
microbes persist in the tissues “out of reach” of antimicrobial agents; multiply; release progeny which is still susceptible to agent – not really resistant but just never touched by ATB
Prophylaxis
drugs are administered to PREVENT infection in susceptible people
Combined therapy
two or more drugs are given simultaneously, either to prevent the emergence of resistant species or to acheive synergism
Synergism
combining drugs; you can use 1/10 concentration when used together – ex. TMP-SMZ
Antagonism
medications that work against each other – ex. tetracycline and PCN
Penicillin
acts on cell wall – beta-lactam ring; narrow spectrum – PCN G (gram +) requires injection; PCN V (gram +) PO
penicillinase
beta-lactamase; causes development of bacterial resistance to drugs
Cephalosporins
works on cell wall – broader spectrum that PCN - Cephalothin requires injection; has beta-lactam ring –
Vancomycin
cell wall; used life threatening, methicillin resistant Staph infections
Isoniazid
very narrow spectrum; inhibits synthesis of mycolic acid in cell wall of Mycobacterium
Bacitracin
cell membrane; Gram + only – toxic to liver; topical
Polymyxin
cell membrane; Gram - ; topical only
Fluoroquinolones
Affects nucleic acid; levaquin - destroys normal flora - ruins ligament; diarrhea, C. diff, yeast infections
Rifampin
affects nucleic acid; turns body fluids orange; inhibits synthesis on mRNA; used to treat Tb & leprosy
Chloroquine
affects nucleic acid - treatment in malaria
Capsofungin
anti-chitin drugs; inhibits fungal cell wall; echinocandins
Ketoconazole
one of the first available oral treatments for systemic fungal infections - toxic to liver; best absorbed at high acidic level, so antacids cause decrease stomach acid levels and lowers drugs absorption – S/E of med: decrease testosterone and helps treatment post operative erections after penile surgery
Metronidazole
Flagyl; antiparasitic drugs – also used for anaerobic bacteria
Antihelminthic drugs
most effective drugs immobilize, disintegrate or inhibit metabolism of all stages of life cycle
Niclosamide
drug of choice for tapeworms – destoys scolex and adjoining proglottids of tapeworms
Mebendazole
drug of choice of round worms; broad spectrum; work locally in intestines to inhibit microtubule or worms, eggs and larvae
Antiviral drugs
most antiviral drugs have limited spectrum of activity, designed to block a step in viral multiplication
HIV drugs
interfere with action of reverse transcriptase enzyme
Broth dilution tests
bacteria in tubes; ATB added in different concentration – look at 1st tube without growth – take material from MIC tubes and try to grow again – if no growth then its MDC; not MIC
