Chapter 20- Antimicrobial Growth Flashcards
the use of chemical drugs to treat a disease
chemotherapy
interfere with the growth of microbes within a host
antimicrobial drugs
a substance produced by a microbe that, in small amounts, inhibits another microbe
antibiotic
killing harmful microbes without damaging the host
selective toxicity
affect a broad range of Gram positive and Gram negative
broad spectrum
more selective or limited range
narrow spectrum
drugs are selected with limited damage to _____ microbota
normal
most common bacteria
terracycline
kills microbes directly
bactericidal
prevent microbes from growing
bacteriostatic
action of anitmicrobial drugs
- inhibition of cell wall synthesis
- inhibition of protein synthesis
- inhibition of nucleic acid replication and transcription
- injury of plasma membrane
- inhibition of essential metabolite synthesis
penicillins, cephalosporins, bacitracin, vancomycin
inhibition of cell wall synthesis
chloramphenicol, erythryomycin, tetracyclines, streptomycin
inhibition of protein synthesis
quinolones, rifampin
inhibition of nucleic acid replication and transcription
sulfanimide, trimethoprim
inhibition of essential metabolite synthesis
ploymyxin B
injury to plasma membrane
- identified by beta-iactam ring
- susceptible to penicillinase
natural penicillin
penicillin g
requires injection
penicillin v
can be taken orally
identified by beta iactam ring
more resistant to penicillinase
semisynthetic penicillin
narrow spectrum
only gram positive
resistant to penicillins
oxacillin
many gram negatives
extended spectrum
ampicillin
microbes resistant to penicillin have ______ activity that breaks down beta iactam ring structure, making the drug useless.
penicillianse
narrow spectrum
act against gram positive bacteria
first generation cephalosporins
extended spectrum
includes gramnegative bacteria
second generation cephalosporins
includes pseudomonads
injected
third generation cephalosporins
oral
fourth generation cephalosporins
topical application
against gram positives
polypeptide antibiotics-bacitracin
glycopeptide
important last line against antibiotic resistant S. aureus
polypeptide antibiotics-vancomycin
inhibits mycolic acid synthesis
also effective against mycobacterium
antimycobacterial antibiotics-isoniazid
inhibits incorporation of mycolic acid
antimycobacterial antibiotics- ethambutol
broad spectrum
binds 50s subunit
inhibits peptide bond formation
chloraphenicol
– Streptomycin, neomycin, gentamicin
-Broad spectrum
– Change shape of 30S subunit, preventing protein synthesis from
bacterial ribosome
Aminoglycosides
-broad spectrum
-Interfere with tRNA attachment, preventing protein
synthesis from bacterial ribosome
tetracyclines
- Gram-positives
- Bind 50S subunit; inhibit translation
Streptogramins
– Structural changes in the membrane, followed by
arrest of the synthesis of DNA, RNA, and protein
– MRSA
Lipopeptides
-topical
-combined with bacitracin and neomycin in
over-the-counter preparation
Polymyxin B
– Inhibits RNA synthesis
– Antituberculosis
Rifamycin
– Nalidixic acid: urinary infections
– Ciprofloxacin
– Inhibit DNA gyrase
– Urinary tract infections
Quinolones and fluoroquinolones
- Inhibit folic acid synthesis
- Broad spectrum
Sulfonamides (sulfa drugs)
Inhibition of cell wall synthesis.
– Miconazole
– Triazole
antifungal drugs
- Targets Ergosterol (a component of the cell
wall) - Inhibits other glycoproteins in the cell wall
antifungal drugs
– Indinavir: HIV
– Interferes with protein synthesis
antiviral drugs-enzyme inhibitors-protease inhibitors
– HIV
antiviral drugs-enzyme inhibitors-integrase inhibitors
Amantadine: influenza
antiviral drugs-entry inhibitors-
-Zanamivir: influenza
– Block CCR5: HIV
antiviral drugs-entry inhibitors-fusion inhibitors
Prevent spread of viruses to new cells
– Alpha interferon: Viral hepatitis
antiviral drugs-interferons
promotes interferon production
Imiquimod
– Inhibits DNA synthesis
• Malaria
Chloroquine-antiprotozoan drugs
Kills Plasmodium sporozoites
antiprotozoan drugs-artemisin
Interferes with anaerobic metabolism
• Trichomonas and Giardia
antiprotozoan drugs-metronidazole
Interferes with anaerobic metabolism
• Trichomonas and Giardia
Antihelminthic Drugs-niclosamide
Alters membrane permeability
-Flatworms
Antihelminthic Drugs- Praziquantel
Interfere with nutrient absorption
Intestinal roundworms
Antihelminthic Drugs- Mebendazole and albendazole
Paralysis of helminths
Intestinal roundworms
Antihelminthic Drugs- ivermectin
Bacterial resistance to antibiotics
- block entry
- inactivation by enzymes
- alteration of target molecule
- efflux of antibiotic
• A variety of mutations can lead to
antibiotic resistance
Resistance genes are often on _____ or ________ that can be transferred between
bacteria
plasmids, transposons
Misuse of antibiotics selects for
resistance
mutants
Using outdated or weakened antibiotics
misuse of antibiotics
– Using antibiotics for the common cold and other
inappropriate conditions
misuse of antibiotics
Using antibiotics in animal feed
misuse of antibiotics
– Failing to complete the prescribed regimen
OR
using someone’s leftover prescription
misuse of antibiotics
occurs when the effect of two
drugs together is greater than the effect of
either alone
synergism
occurs when the effect of two
drugs together is less than the effect of either
alone
antagonism
A growth of cells of one specific microorganisms
Pure culture
A medium may be a ____ or _____
Solid or liquid
Solid media has
Agar
Must be heated to boiling to dissolve but will solidify at 40C
Agar
Originating or taking place in a hospital
Acquired in a hospital, especially in reference to an infection
Nosocomial Infection
