Chapter 9 Antibiotics

Comprehensive vocabulary flashcards covering antibiotic classes, mechanisms of action, prototypes, boxed warnings, clinical considerations, and patient teaching from Chapter 9.

Antibiotic

A chemical that inhibits the growth of, or kills, specific bacteria.

Gram Staining

A lab technique that sorts bacteria by cell wall type into gram-positive or gram-negative.

Aerobic Bacteria

Bacteria that require oxygen to survive.

Anaerobic Bacteria

Bacteria that survive without oxygen, often found in chronic wounds and the GI tract.

Synergistic Drugs

Drugs that work together to produce a bigger effect than either would alone.

Gram-Positive Cell Wall

A thick peptidoglycan wall that holds the purple stain; common in respiratory tract and soft tissue infections.

Gram-Negative Cell Wall

A thin bacterial wall that loses the purple stain and decolorizes; common in GU and GI tract infections.

Streptococcus pneumoniae

An example of a gram-positive organism that causes pneumonia and is common in respiratory tract infections.

Escherichia coli (E. coli)

An example of a gram-negative organism commonly associated with cystitis in GU and GI tract infections.

Culture

A diagnostic laboratory test used to identify the specific organism causing an infection.

Sensitivity Testing

A laboratory test that shows which antimicrobial drugs work effectively against an identified organism.

Empiric Treatment

Antibiotic therapy initiated against the most likely pathogens when the causative organism cannot be identified in time.

Goal of Antibiotic Therapy

To reduce the bacterial population enough for the host immune system to finish the job of eliminating the infection.

Four Mechanism Families

The organizational map of antibiotics: cell wall synthesis inhibitors, protein synthesis inhibitors, DNA/RNA synthesis inhibitors, and folic acid synthesis inhibitors.

Cell Wall Synthesis Inhibitors

The family (penicillins, cephalosporins, carbapenems, monobactam, lipoglycopeptides) that weakens the cell wall, causing bacteria to swell and burst.

Protein Synthesis Inhibitors

The family (aminoglycosides, tetracyclines, macrolides, lincosamides, oxazolidinones) that jams the ribosome so bacteria produce no proteins and cannot survive.

DNA/RNA Synthesis Inhibitors

The family (fluoroquinolones, antimycobacterials) that blocks genetic copying, preventing bacterial division.

Folic Acid Synthesis Inhibitors

The antibiotic family (sulfonamides) that starves bacteria of a critical nutrient they must synthesize themselves.

Penicillins Mechanism of Action

Prevents bacteria from building their cell wall during division, weakening the wall until the cell swells and bursts.

Amoxicillin

The most prescribed penicillin antibiotic; an exception that can safely be taken with food.

Penicillin G

An intramuscular (IM) penicillin formulation indicated for severe bacterial infections.

Amoxicillin–Clavulanate (Augmentin)

A combination antibiotic in which clavulanate protects amoxicillin from degradation by bacterial penicillinase.

Clavulanate

An agent that protects penicillin antibiotics against destruction by bacterial penicillinase.

Penicillinase

A bacterial defense enzyme that inactivates penicillin, serving as a classic example of antibiotic resistance.

Penicillin Allergy

A contraindication that can progress to anaphylaxis with repeat exposure; many gram-negative infections fall outside penicillin's natural spectrum.

Penicillin Empty-Stomach Rule

The administration guideline that most penicillins must be taken on an empty stomach with a full glass of water, 1 hour before or 2–3 hours after meals.

Penicillin Dietary Interference

Food, milk, and fruit juices that can all interfere with the gastrointestinal absorption of most penicillins.

Penicillin Food Exceptions

Amoxicillin and penicillin V, which are specific penicillins that CAN be taken with food.

Cephalosporins

A major class of cell wall synthesis inhibitors divided into four generations that provide broader coverage and CNS penetration as generations advance.

Cefazolin

A first-generation cephalosporin commonly utilized for surgical prophylaxis.

Ceftriaxone

A third-generation cephalosporin noted for broad coverage, once-daily dosing, and central nervous system (CNS) penetration.

Cefepime

A fourth-generation cephalosporin that provides the broadest antibacterial coverage within its class.

Cephalosporin Generational Progression

Trends where higher generation numbers provide more gram-negative coverage, better CNS penetration, and greater resistance to bacterial defense enzymes.

Cephalosporin Cross-Sensitivity

The potential for allergic cross-reactivity requiring caution when administering cephalosporins to patients with a history of penicillin allergy.

Carbapenems

The broadest beta-lactams, active against both gram-positive and gram-negative bacteria, reserved for serious or resistant infections.

Meropenem and Ertapenem

Two key carbapenem antibiotics reserved for treating serious and drug-resistant bacterial infections.

Carbapenem-Valproic Acid Interaction

An adverse drug interaction that increases the risk of seizures when carbapenems are administered alongside valproic acid.

Monobactams

A cell wall synthesis inhibitor class consisting exclusively of a single drug, aztreonam.

Aztreonam

The only monobactam drug; offers gram-negative coverage only, with no gram-positive or anaerobic coverage.

Aztreonam Allergy Safety

A safe therapeutic alternative for patients with documented allergies to penicillins or cephalosporins.

Lipoglycopeptides

A class of cell wall inhibitors providing gram-positive bacterial coverage, including activity against MRSA.

Vancomycin

The original lipoglycopeptide with gram-positive and MRSA coverage; requires monitoring renal function and slow infusion to avoid red man syndrome.

Telavancin

A lipoglycopeptide antibiotic that provides gram-positive coverage, including against MRSA.

Red Man Syndrome

An adverse reaction to vancomycin that is avoided by infusing the drug slowly.

Vancomycin Renal Monitoring

The clinical requirement to watch kidney function closely during vancomycin therapy to monitor for nephrotoxicity.

Aminoglycosides Mechanism of Action

Irreversibly binds bacterial ribosomes, causing misreading of genetic code and cell death; bactericidal mainly against gram-negative aerobes.

Gentamicin

The prototype aminoglycoside antibiotic used for bactericidal coverage of gram-negative aerobic infections.

Tobramycin and Amikacin

Two key aminoglycoside antibiotics to know alongside the prototype gentamicin.

Aminoglycosides Boxed Warning

FDA boxed warnings highlighting severe risks of nephrotoxicity and potentially irreversible ototoxicity.

Aminoglycoside-Loop Diuretic Interaction

A dangerous drug combination that increases the risk of ototoxicity and should be avoided.

Tetracyclines Mechanism of Action

Inhibits bacterial protein synthesis to exert broad-spectrum bacteriostatic antimicrobial effects.

Doxycycline

The most commonly used tetracycline antibiotic in clinical practice today.

Tetracycline Pediatric Contraindication

Contraindication in children under 8 because tetracyclines bind developing bone and teeth, causing staining and weakened structure.

Tetracycline Pregnancy Contraindication

Contraindication in pregnancy because the drug binds to developing fetal bones and teeth, causing structural weakening and staining.

Tetracycline Bone and Tooth Staining

Adverse binding of tetracyclines to developing skeletal structures, causing permanent tooth discoloration and structural weakening.

Tetracycline Photosensitivity

A hallmark adverse effect requiring sun protection, sunscreen, and protective clothing to prevent severe sunburn-like reactions.

Tetracycline Cation Chelation

Binding that occurs when tetracyclines interact with dairy, calcium, iron, magnesium, and antacids, blocking drug absorption.

Tetracycline Administration Timing

The rule to take tetracyclines on an empty stomach with water, 1 hour before or 2–3 hours after meals, avoiding mineral binding agents.

Macrolides

A class of protein synthesis inhibitors serving as a key alternative for patients with penicillin allergies.

Azithromycin (Z-Pak)

A macrolide antibiotic featuring a long half-life that allows for once-daily dosing regimens.

Clarithromycin and Erythromycin

Two macrolide antibiotics to know that alter bacterial protein synthesis and serve as penicillin alternatives.

Macrolides Mechanism of Action

Binds the ribosome to change protein synthesis; can be bactericidal or bacteriostatic depending on dose.

Macrolide QT Interval Prolongation

An adverse cardiac conduction effect associated with macrolides that clinicians must watch for.

Macrolide-Digoxin Interaction

A pharmacokinetic interaction resulting in increased digoxin levels when combined with a macrolide.

Clindamycin

A lincosamide protein synthesis inhibitor carrying a significant risk of C. difficile and pseudomembranous colitis.

Clindamycin Diarrhea Warning

The critical instruction to stop clindamycin immediately at the first sign of severe diarrhea.

Pseudomembranous Colitis

Severe inflammatory bowel infection caused by C. difficile overgrowth, famously linked to clindamycin therapy.

Oxazolidinones

A class of protein synthesis inhibitors, including linezolid and tedizolid, developed to treat resistant bacterial strains.

Linezolid

An oxazolidinone effective against MRSA and VRE that also acts as a monoamine oxidase inhibitor (MAOI).

Tedizolid

An oxazolidinone antibiotic indicated for resistant bacterial strains like MRSA and VRE.

Linezolid MAOI Activity

The drug's monoamine oxidase inhibition, creating risks of serotonin syndrome and hypertension when interacting with tyramine or serotonergic drugs.

Linezolid Dietary and Drug Restrictions

The required avoidance of tyramine-rich foods and serotonergic medications to prevent hypertensive crisis and serotonin syndrome.

Fluoroquinolones Mechanism of Action

Interferes with DNA enzymes bacteria need to grow and reproduce; bactericidal with broad gram-positive and gram-negative coverage.

Ciprofloxacin, Levofloxacin, and Moxifloxacin

The 2–3 prototype fluoroquinolones to know, providing broad gram-positive and gram-negative coverage.

Fluoroquinolones Boxed Warning

Black-box warnings for tendinitis, tendon rupture, peripheral neuropathy, CNS effects, and worsening of myasthenia gravis.

Fluoroquinolones Pediatric Restriction

Contraindication in patients under 18 years of age due to the risk of cartilage damage.

Fluoroquinolones Myasthenia Gravis Warning

Contraindication in patients with myasthenia gravis due to the risk of worsening muscle weakness symptoms.

Fluoroquinolones Mineral Separation

The requirement to separate dosing from iron, calcium, magnesium, and antacids by at least 4 hours to prevent blocked absorption.

Fluoroquinolone Warfarin Interaction

A drug interaction in which fluoroquinolones increase circulating warfarin levels and raise INR.

Fluoroquinolone Theophylline Interaction

A pharmacokinetic interaction in which fluoroquinolones increase serum theophylline levels.

Fluoroquinolones QT Prolongation Risk

An adverse cardiac risk warning clinicians to avoid combining fluoroquinolones with other drugs that prolong the QT interval.

Mycobacteria

Slow-growing pathogens with a protective mycolic acid coat that cause tuberculosis (TB) and leprosy.

Mycolic Acid Coat

The waxy protective coat of mycobacteria that impairs drug penetration and causes them to grow very slowly.

Antimycobacterial Combination Therapy

Using multiple drugs at once hitting bacteria in different ways, which dramatically slows the emergence of resistant TB strains.

Antimycobacterial Treatment Duration

Prolonged therapeutic regimens running 6 months to 2 years, necessary because mycobacteria grow very slowly.

Isoniazid (INH)

An anchor antimycobacterial drug for TB that carries an increased risk of liver damage when combined with alcohol.

Rifampin

An anchor antimycobacterial drug that turns body fluids orange and accelerates the metabolism of warfarin and oral contraceptives.

Pyrazinamide and Ethambutol

Companion antimycobacterial medications routinely combined with isoniazid and rifampin to treat tuberculosis.

Directly Observed Therapy (DOT)

An adherence strategy where a trained health worker directly watches the patient take every single antibiotic dose.

Rifamycin Body Fluid Discoloration

The turning of body fluids orange (urine, sweat, tears) by rifampin, rifabutin, and rifapentine, which can stain contact lenses.

Isoniazid and Alcohol Interaction

A combination that increases the risk of liver damage, requiring regular monitoring of hepatic function.

Rifampin and Oral Contraceptives

Accelerated hepatic metabolism of hormonal birth control by rifampin, requiring patients to use a backup contraceptive method.

Sulfonamides Mechanism of Action

Blocks bacteria from synthesizing their own folic acid required for RNA and DNA, leaving human cells unaffected because humans obtain folate from diet.

Trimethoprim–Sulfamethoxazole (Bactrim/Septra)

The prototype sulfonamide combination antibiotic to know cold, acting as a folic acid synthesis inhibitor.

Sulfadiazine

A sulfonamide antibiotic that starves bacteria of necessary folic acid.

Kernicterus

A severe neurological risk to the fetus that contraindicates the use of sulfonamides during pregnancy.

Sulfonamide Cross-Sensitivity

Potential allergic cross-reactivity between sulfonamides, sulfonylureas, and thiazide or loop diuretics.

Universal Pre-Administration Screening

The nursing safety check of screening allergy history, organ function (renal/hepatic), age, and pregnancy status before any antibiotic reaches the patient.

Finish the Full Course

Universal patient teaching to finish the entire prescribed course even after feeling better, as early cessation is the biggest driver of bacterial resistance.

Superinfections

Secondary infections (such as oral thrush, vaginal yeast infections, or C. diff diarrhea) caused when broad-spectrum antibiotics eliminate normal flora.