40 terms

Chapter 7

antimicrobial compounds
used to inhibit or kill microorganisms
what makes an appropriate microbial compound
easily administered
selective toxicity
needs to remain in the system long enough to be effective
must be broken down and secreted by the host
selective toxicity
kill or inhibit the microorganism without simultaneously damaging the host tissue
goal of selective toxicity
to target specific function or structure in the pathogen that is not present in the host
-cell wall (not present in humans)
70S ribosome (some toxicity to mitochondria)
harder to have selective toxicity with some pathogens (fungi, helminths, and viruses)
chemotherapeutic agent
chemical that is used in the treatment, relief, or prophylaxis of disease
use of a drug to prevent imminent infection of a person at risk
compound produced by one microorganism that inhibits or kills another microorganism
synthetic drugs
drugs that are synthesized in a laboratory
drugs that are naturally produced but chemically altered in the laboratory
narrow spectrum
chemotherapeutic agent that is effective against a narrow range of microorganisms
broad spectrum
chemotherapeutic agent that is effective against a wide variety of microorganisms
Paul Ehrlich
worked into antimicrobial compounds
-used an arsenic based drug that was toxic to cause syphilis
origins of antimicrobial drugs
antibiotics are common metabolic products of aerobic spore-forming bacteria and fungi
Targets of antimicrobial drugs
-inhibition of cell wall synthesis
-inhibition of nucleic acid synthesis, structure or function
-inhibition of protein synthesis
-disruption of cell membrane structure or function
Penicillin and cephalosporins
react with one or more nzymes that synthesize/complete the cell wall, causing the cell to lyse
blocks the peptidase enzymes that link the cross bridges between the glycans in peptidoglycan
Drugs that inhibit nucleic acid synthesis
may block synthesis of nucleotides, inhibit replication, or stop transcription
sulfonamides and trimethoprim
block enzymes required for tetrahydrofolate synthesis needed for DNA and RNA synthesis.
-these drugs are competitive inhibitors called metabolic analogs
synergistic effect
an additive effect, achieved by multiple drugs working together, requiring a lower dose of each
streptomycin, gentamicin
insert on sites on the 30S subunit and cause misreading of mRNA
block attachment of tRNA to stop protein synthesis
Drugs that disrupt cell membrane function
-cell with a damaged membrane dies from disruption in metabolism or lysis
-these drugs have specificty for a particular microbial group, based on differences in types of lipids in their cell membranes
Penicillin consist of 3 parts
-thiazolidine ring
-beta-lactam ring
-variable sidechain dictates microbial activity
Penicillin is the drug of choice for
gram-positive cocci
and some gram-negative bacteria
Primary problems with penicillin
allergies and resistant strains of bacteria
-account for majority of all antibitics administered
-beta-lactam ring that can be altered
1st generation of cephalosporins
most effective against gram-positive cocci
2nd generation of cephalosporins
more effective against gram-negative bacteria
3rd generation
broad-spectrum activity against enteric bacteria with beta-lactamase
chromobacterium violaceum
may be used by people allergic to penicillin
impair ribosome function
-comosed of 2 or more amino sugarsand an aminocyclitol (6C ring)
broad spectrum
inhibit protein synthesis especially useful against gram-negtive rods and certain gram-positive bacteria
examples of aminoglycosides
side effects of aminoglycosides
hearing loss
loss of appetite
nausea, vomiting
blocks protein synthsis
-prevents the binding of aminoacyl tRNA to the ribosome
Tetracycline antibiotics
taken orally
needs to be taken 2 hours after eating to prevent binding with food
-also inactivated by antacids
side effects tetracycline antibiotics
-potential damage to developing bones of a fetus
-discoloration of teeth in children
-sensitivity to light
blocks peptie bond formation
inhibits protein synthesis
typhoid fever
brain abscesses
rickettsial & chlamydial infections
reserved for serious infections
chloroamphenicol-mode of action
-irreversibly binds with 50s subunit
prevents the formation of peptide bond
-can interact with mitochondrial ribosomes