Chapter 14: Antimicrobial Drugs

Comprehensive vocabulary flashcards covering the historical concepts, drug mechanisms of action, spectrums, eukaryotic treatment challenges, and resistance pathways from Chapter 14 Antimicrobial Drugs.

Chemotherapy

The use of chemical agents to treat disease.

Antimicrobial drugs

Chemical agents that act against microorganisms to treat infectious diseases.

Natural antibiotic

An antimicrobial substance naturally produced by a microorganism, such as a fungus or bacterium.

Semisynthetic antimicrobial

A natural antimicrobial product that has been chemically modified in the laboratory to enhance its activity, stability, absorption, or resistance to breakdown.

Synthetic antimicrobial

An antimicrobial drug produced entirely through laboratory chemical synthesis rather than biological sources.

Penicillin

A natural antibiotic discovered through Alexander Fleming's observation of mold inhibiting bacterial growth, which blocks cell-wall synthesis.

Bacteriostatic

Property of an antimicrobial that stops bacterial multiplication and growth without necessarily killing the cells, requiring host immune defenses for clearance.

Bactericidal

Property of an antimicrobial that directly kills bacterial cells.

Narrow-spectrum antimicrobial

An antimicrobial agent that targets a limited group of microorganisms, preserving host microbiota and minimizing selective pressure when the pathogen is known.

Broad-spectrum antimicrobial

An antimicrobial agent that targets a wide variety of bacterial groups, useful for empiric therapy but capable of disrupting protective microbiota.

Superinfection

A secondary infection resulting from broad-spectrum antimicrobial use that disrupts protective normal microbiota, allowing resistant or opportunistic pathogens to overgrow.

Dosage

The amount and scheduling of medication necessary to sustain therapeutic levels at the infection site while minimizing host toxicity, tailored to factors such as half-life, age, and organ function.

Route of administration

The path by which a drug enters the body (e.g., oral, intravenous, intramuscular, or topical), influencing absorption speed and systemic concentration.

Selective toxicity

The core principle that an antimicrobial drug should exploit specific microbial features absent or significantly different in human cells to damage the pathogen without harming the host.

Therapeutic index

A comparison between the toxic dose and the effective therapeutic dose of a drug; a larger ratio generally denotes a safer treatment window.

Synergy

A positive drug interaction where the combined effect of two antimicrobials is greater than expected from the sum of each drug administered alone.

Antagonism

A negative drug interaction where one antimicrobial reduces the efficacy or interferes with the action of another.

Mode of action

The specific cellular or biochemical mechanism through which an antimicrobial drug damages or inhibits a target pathogen.

Peptidoglycan

The mesh-like macromolecule forming the structural backbone of bacterial cell walls, assembled by cross-linking enzymes that are targeted by various wall-active drugs.

β-lactam

A class of antibacterial cell-wall inhibitors that contain a specific ring structure, binding penicillin-binding proteins (PBPs) to block peptidoglycan cross-linking (transpeptidation).

Penicillin-binding proteins (PBPs)

Bacterial enzymes responsible for catalyzing the cross-linking of peptidoglycan chains during cell-wall synthesis, which act as targets for beta-lactams.

Glycopeptides

A class of cell-wall synthesis inhibitors, such as vancomycin, that block peptidoglycan construction in bacteria.

Bacitracin

An antibacterial agent that interferes with cell-wall synthesis by preventing the assembly and transport of peptidoglycan precursors.

Aminoglycosides

A class of antibacterial protein-synthesis inhibitors that bind the 30S ribosomal subunit, causing misreading of mRNA and generating faulty proteins.

Tetracyclines

A class of antibacterial protein-synthesis inhibitors that bind the 30S ribosomal subunit, blocking aminoacyl-tRNA from attaching to the ribosomal acceptor site.

Macrolides

A class of antibacterial protein-synthesis inhibitors that bind the 50S ribosomal subunit to block peptide elongation and translocation.

Lincosamides

A class of antibacterial protein-synthesis inhibitors that target the 50S ribosomal subunit to inhibit translation.

Chloramphenicol

An antibacterial protein-synthesis inhibitor class that binds the 50S ribosomal subunit and prevents peptide-bond formation.

Oxazolidinones

A class of antibacterial protein-synthesis inhibitors that interact with the 50S ribosomal subunit to prevent the formation of the ribosomal initiation complex.

Polymyxins

A class of antibacterial drugs that target bacterial membranes, disrupting their physical integrity and permeability.

Lipopeptides

A class of membrane-targeting antibacterial agents, such as daptomycin, that depolarize and impair bacterial cell membrane function.

Fluoroquinolones

A class of antibacterial agents that block nucleic-acid synthesis by inhibiting bacterial DNA gyrase and topoisomerase.

Rifamycins

A class of antibacterial agents that target bacterial RNA polymerase to inhibit RNA transcription.

Sulfonamides

Antimetabolite antimicrobials that structurally mimic PABA to inhibit the enzymatic synthesis of folic acid in bacteria.

Trimethoprim

An antimetabolite drug that inhibits a sequential step in bacterial folic-acid synthesis, frequently combined with sulfonamides to achieve synergistic activity.

Ergosterol

A principal sterol found in fungal cell membranes that serves as a primary target for selective antifungal drugs.

Polyenes

A class of antifungal agents that bind directly to fungal membrane ergosterol, forming pores that compromise membrane integrity.

Azoles

A class of antifungal agents that selectively inhibit the enzymatic biosynthesis of ergosterol in fungal membranes.

Echinocandins

A class of antifungal agents that inhibit the synthesis of beta-glucan, a major structural component of the fungal cell wall.

Drug resistance

The ability of a microorganism to survive and reproduce despite exposure to concentrations of an antimicrobial that would normally inhibit or kill it.

Resistance genes

Genetic determinants that encode biochemical defenses against antimicrobials, acquired via spontaneous mutation or horizontal gene transfer.

Drug modification or inactivation

A resistance mechanism in which microbial enzymes chemically alter or degrade an antibiotic, exemplified by beta-lactamase degradation of beta-lactam rings.

Reduced uptake

A mechanism of resistance where changes in cell-envelope composition or the loss of outer-membrane porin proteins prevent antimicrobial drugs from entering the cell.

Efflux pump

A transport protein system that actively exports antimicrobial drugs out of the microbial cell to keep intracellular levels below toxic thresholds.

Target modification

A resistance mechanism in which mutations or alterations change the molecular structure of the drug's binding target, preventing effective drug binding.

Target overproduction

A resistance mechanism wherein a microbe synthesizes an excess of the targeted enzyme or component to overwhelm and dilute the drug's inhibitory effect.

Metabolic bypass

A resistance mechanism in which the pathogen develops or utilizes an alternate metabolic pathway that skirts around the reaction inhibited by an antimicrobial drug.

Multidrug resistance

A condition in which a microbial strain demonstrates resistance to multiple distinct classes of antimicrobials, often via multiple genes or broad efflux systems.

Cross-resistance

A phenomenon where a single resistance mechanism provides protection against several chemically related drugs that share a target or pathway.

MRSA

Methicillin-resistant Staphylococcus aureus; a pathogen that expresses an altered penicillin-binding protein with low affinity for many beta-lactams, making it resistant to standard beta-lactam therapies.

Stewardship

A coordinated clinical approach to optimize antimicrobial use by selecting appropriate drugs, dosages, routes, and durations to treat bacterial disease while curbing resistance.