CHAPTER 10 Flashcards
are chemicals used to treat diseases.
Chemotherapeutic agents
kind of chemotherapeutic agents
Antimicrobial agent or antimicrobials
Antimicrobials include
Antibiotics, semisynthetic antimicrobials, and synthetic drugs
Biologically produced agents
Antibiotics
Chemically modified antibiotics
Semisynthetic antimicrobials
Successful chemotherapy against microbes is based on ___, that is, using antimicrobial agents that are more toxic to pathogens than to the patient.
selective toxicity
penicillins, carbapenems, cephalosporins—have a functional lactam ring. They prevent bacteria from cross-linking NAM subunits of peptidoglycan in the bacterial cell wall during growth
Beta-lactams
also disrupt cell wall formation in many Gram- positive bacteria.
Lipoglycopeptides and cycloserine
blocks NAG and NAM transport from the cytoplasm
Bacitracin
Block mycolic acid synthesis in the walls of mycobacteria
Isoniazid (INH) and ethambutol
block synthesis of fungal cell walls.
Echinocandins
Antimicrobial agents that inhibit protein synthesis
by interfering with 70S ribosomes include __ which inhibit
functions of the 30S ribosomal subunit,
Aminoglycosides and tetracyclines
which inhibit 50S subunits.
chloramphenicol, lincosamides, streptogram-
ins, and macrolides,
block initiation of translation.
Oxazolidinones
molecules inhibit protein synthesis by preventing ribosomes from assembling on mRNA.
Antisense nucleic acid
binds to isoleucine aminoacyl-tRNA synthetase—the enzyme that loads isoleucine onto the tRNA.
Mopirocin
disrupt the cytoplasmic membranes of fungi.
Polyenes, azoles, and allylamines
are structural analogs of para-aminobenzoic acid (PABA), a chemical needed by some microorganisms but not by humans.
Sulfonamides
Drugs that inhibit nucleic acid replication in pathogens include
actinomycin, nucleotide analogs and nucleoside analogs, quino- lones, and rifampin.
Chemotherapeutic agents have a
Spectrum of action
Types of spectrum of action
Narrow and broad
such as the Kirby-Bauer test, reveal which drug is most effective against a particular pathogen;
Diffusion susceptibility tests
the larger the __ around a drug- soaked disk on a Petri plate, the more effective the drug.
zone of inhibition
usually deter- mined by either a broth dilution test or an Etest, is the smallest amount of a drug that will inhibit a pathogen.
Minimum inhibitory concentration
ascertains whether a drug is bacteriostatic and the lowest concentration of a drug that is bactericidal.
Minimum bactericidal concentration
is essentially a ratio of the drug’s tolerated dose to its effective dose. The higher the TI, the safer the drug.
Therapeutic index
Clinicians use the term __ to indicate the range of concentrations of a drug that are effective without being exces- sively toxic.
therapeutic window
Some members of a pathogenic population may develop resis- tance to a drug because of extra DNA pieces called
R plasmids or the mutation of genes
Microorganisms may resist a drug by producing enzymes such as
Beta-lactamases
by removing the drug from the cell with ___ or by protecting the drug’s target by binding another molecule to it
efflux pumps,
occurs when resistance to one chemotherapeutic agent confers resistance to similar drugs
Cross resistance
are resistant to three or more types of antimicrobial drugs.
Multiple drug resistant pathogens
describes the interplay between drugs that results in efficacy that exceeds the efficacy of either drug alone. Some drug combinations are antagonistic.
Synergism
