Exam 2: Ch 14 Flashcards
Penicillin
the first mass produced antibiotic in 1940s
* recognized as the “wonder drug”
* discovered in 1928 by Alexander Fleming in the Fortunate Accident
* He observed that contaminating mold growth (subsequently identified as a strain of Penicillium notatum) inhibited staphylococcal growth on one plate. penicillin from the mold was antibacterial against streptococci, meningococci, and Corynebacterium diphtheriae, the causative agent of diphtheria
Importance of Streptomyces
- produced during beer making process
- used to treat a variety of ailments in both adults and children, including gum disease and wounds
Tu Youyou:
found a cure for malaria, utilizing Artemisia, a plant
Who discovered the magic bullet?
- Paul Ehlrich
- compound 606 which targeted the bacterium Treponema pallidum, the causative agent of syphilis. Compound 606 was found to successfully cure syphilis in rabbits
- arsenic based microbial drug
Howard Florey and Ernest Chain:
first to conduct human trials with a chemical (penicillin)
Dorothy Hodgkin
determine the structure of penicillin
Selman Waksman
soil microbiologist who studied fungi and actinobacteria, including soil bacteria in the genus streptomyces
* discovered several antimicrobials, including actinomycin, streptomycin, neomycin
Actinomycetes
are the source of more than half of all natural antibiotic
Factors important for choosing the most appropriate antimicrobial drug therapy:
- bacteriostatic vs bactericidal mechanisms
- spectrum of activity
- dosage and route of administration
- potential side effects
- potential interactions between drugs
Bacteriostatic drugs
prevents microbes from growing, makes them sluggish
* examples: tetracyclines, chloramphenicol, trimethoprim
Bactericidal drugs
kill target bacteria
* used for life threatening infections
* examples: penicillin, cephalosporins, Ciprofloxacin, vancomycin
Spectrum of activity
the spectrum of activity of an antibacterial drug relates to diversity of targeted bacteria
Narrow spectrum antimicrobial
target’s only specific subset of bacterial pathogens
- For example, some narrow spectrum drugs, only target gram-positive bacteria, while others only target gram-negative bacteria
Broad spectrum antimicrobial:
target pathogens, including both gram-positive and gram-negative species
* often used for polymicrobial infections a.k.a. multiple bacterial species
* will also be used if narrow Spectrum antimicrobial fails
* prophylactic prevention
* there is a risk of it targeting normal microbiota, increasing the possibility of a superinfection (for example yeast infections)
Dosage
amount of medication given during a certain time interval
Route of administration
method used to introduce a drug into the body (oral, intramuscular, intravenous)
Oral route of administration
- generally preferred because patients can more conveniently take these drugs at home
- drugs may not be absorbed easily from the G.I. tract into the bloodstream therefore they’re not useful when treating diseases of the intestinal tract such as tapeworm
Intravenous routes of administration
- are parenteral
- most effective
- when a drug is administered intravenously, the concentration peaks very quickly and then gradually decreases
- performed in healthcare settings
- through IV, goes directly into bloodstream
- plasma levels achieved by intravenous administration is substantially higher than levels achieved by oral or intramuscular administration
Intramuscular routes of administration
- drug is shot straight into the muscle
- also parenteral
Topical preparations
used to treat superficial skin infections (drug is absorbed through the skin)
Selective toxicity
important quality for an antimicrobial drug, its selectively kills or inhibits the growth of microbial targets while causing minimal or no harm to the host
Mode of action
the way in which a drug affects microbes at the cellular level, each class of antibacterial drugs has a unique mode of action
5 modes of action
- inhibitors of cell wall biosynthesis
- inhibitors of protein biosynthesis
- inhibitors of membrane function
- inhibitors of nucleic acid synthesis
- inhibitors of metabolic pathways
- inhibitors of ATP synthesis
Inhibitors of cell wall biosynthesis
- Beta-lactams: penicillin, cephalosporins, monobactams, carbapenems, (block the crossing linking of peptide chains)
- Glycopeptides: vancomycin
- Bacitracin
