Cell Wall Inhibitor Antibiotics – Vocabulary Flashcards

Vocabulary flashcards summarizing key antibiotics, mechanisms, pharmacology, resistance and clinical uses for drugs that inhibit bacterial cell-wall synthesis.

β-Lactam Antibiotics

Large family of cell-wall–active drugs that contain a four-membered β-lactam ring and include penicillins, cephalosporins, monobactams and carbapenems.

β-Lactam Ring

Four-atom cyclic amide essential for the antibacterial activity of β-lactam drugs and target of many β-lactamases.

Penicillin-Binding Proteins (PBPs)

Bacterial enzymes that catalyze transpeptidation and are the molecular targets of β-lactam antibiotics.

Transpeptidation

Cross-linking step in peptidoglycan synthesis inhibited by β-lactam antibiotics.

Cell-Wall Synthesis Inhibition

Mechanism by which β-lactams block peptidoglycan cross-linking, leading to osmotic lysis of growing bacteria.

Penicillin G

Natural narrow-spectrum penicillin used IV/IM for streptococci, meningococci, syphilis and anaerobes that do not make β-lactamase.

Benzathine Penicillin G

Long-acting IM depot of penicillin G that maintains low serum levels for weeks; used for streptococcal pharyngitis and syphilis.

Procaine Penicillin G

IM depot formulation of penicillin G with 12-24 h duration; painful but prolongs exposure.

Anti-Staphylococcal Penicillins

Semisynthetic penicillins (methicillin, nafcillin, oxacillin, dicloxacillin) resistant to staphylococcal β-lactamase.

Methicillin

First anti-staphylococcal penicillin; no longer used clinically due to high nephrotoxicity and interstitial nephritis.

Nafcillin

IV anti-staphylococcal penicillin eliminated mainly by bile; drug of choice for severe MSSA infections such as endocarditis.

Dicloxacillin

Oral isoxazolyl penicillin used for mild-to-moderate MSSA skin and soft-tissue infections; absorption reduced by food.

Oxacillin

Parenteral anti-staphylococcal penicillin associated with reversible hepatitis; active against MSSA.

Ampicillin

Prototype aminopenicillin active against enterococci, Listeria, many gram-negatives; IV/PO; susceptible to β-lactamases.

Amoxicillin

Orally better-absorbed aminopenicillin used for otitis, sinusitis, prophylaxis of endocarditis; food does not impair absorption.

Aminopenicillins

Broad-spectrum penicillins (ampicillin, amoxicillin) that retain gram-positive activity and gain coverage of many gram-negatives.

Carboxypenicillins

Extended-spectrum penicillins (carbenicillin, ticarcillin) developed for Pseudomonas coverage; not available in the USA.

Ureidopenicillins

Extended-spectrum penicillins (piperacillin) active against P. aeruginosa and Klebsiella; given with β-lactamase inhibitor.

Piperacillin

Parenteral ureidopenicillin formulated with tazobactam; covers many gram-negatives including Pseudomonas.

β-Lactamase

Bacterial enzyme that hydrolyzes the β-lactam ring, inactivating susceptible antibiotics.

β-Lactamase Inhibitors

Molecules with weak antibacterial activity that protect β-lactams from hydrolysis (clavulanate, sulbactam, tazobactam, avibactam, vaborbactam).

Clavulanic Acid

Classical suicide inhibitor of many plasmid-encoded β-lactamases; combined with amoxicillin or ticarcillin.

Sulbactam

β-lactamase inhibitor combined with ampicillin or cefoperazone to expand spectrum.

Tazobactam

β-Lactamase inhibitor co-formulated with piperacillin or ceftolozane.

Avibactam

Non-β-lactam β-lactamase inhibitor paired with ceftazidime; active against some carbapenemases.

Resistance Mechanisms (β-Lactams)

Include β-lactamase production, altered PBPs, decreased drug entry (porin mutation) and active efflux pumps.

Altered PBP

Target modification that lowers affinity for β-lactams; classic cause of MRSA and penicillin-resistant pneumococci.

Efflux Pump

Transport protein that exports antibiotics from the bacterial cell, lowering intracellular concentration and efficacy.

Porin Mutation

Change in outer-membrane channel that reduces β-lactam entry into gram-negative bacteria.

Penicillin Pharmacokinetics

Most agents eliminated rapidly by renal tubular secretion; probenecid prolongs serum levels; adjust dose in renal failure.

Probenecid

Uricosuric drug that blocks renal tubular secretion of weak acids, increasing serum levels of penicillins and some cephalosporins.

Penicillin Hypersensitivity

IgE-mediated allergy ranging from rash to anaphylactic shock; occurs in 0.05 % of courses.

Interstitial Nephritis

Renal hypersensitivity reaction classically associated with methicillin and, less commonly, nafcillin.

Cephalosporins

β-lactam subclass more resistant to many β-lactamases; grouped into generations with progressively broader gram-negative coverage.

First-Generation Cephalosporins

Agents like cefazolin and cephalexin; active against MSSA, streptococci, Proteus, E. coli and Klebsiella.

Cefazolin

Parenteral first-generation cephalosporin of choice for surgical prophylaxis and many MSSA infections.

Cephalexin

Oral first-generation cephalosporin given 250-500 mg q6h for skin and urinary infections.

Second-Generation Cephalosporins

Include cefuroxime, cefaclor, cefoxitin, cefotetan; add H. influenzae and some anaerobe coverage.

Cefuroxime

Second-generation cephalosporin used PO/IV for sinusitis, otitis, COPD exacerbations; crosses BBB but suboptimal for meningitis.

Cefoxitin

Cephamycin with good anaerobic activity used for mixed intra-abdominal or pelvic infections.

Cefotetan

Second-generation parenteral cephalosporin active against Bacteroides; used in surgical prophylaxis of colorectal procedures.

Third-Generation Cephalosporins

Drugs such as ceftriaxone, cefotaxime, ceftazidime; penetrate CSF and broaden gram-negative activity.

Ceftriaxone

Long half-life third-generation cephalosporin given once daily; first-line for community meningitis, gonorrhea, severe sepsis.

Cefotaxime

IV third-generation cephalosporin interchangeable with ceftriaxone but renal elimination.

Ceftazidime

Third-generation cephalosporin uniquely active against Pseudomonas; available with avibactam.

Cefixime

Oral third-generation cephalosporin; no longer first-line for uncomplicated gonorrhea due to resistance.

Fourth-Generation Cephalosporins

Represented by cefepime; highly resistant to many β-lactamases, active vs. Pseudomonas and penetrates CSF.

Cefepime

Broad-spectrum parenteral cephalosporin dosed 1–2 g q12h (q8h for Pseudomonas) for severe hospital infections.

Fifth (Advanced) Generation Cephalosporins

Agents with MRSA activity, mainly ceftaroline (and ceftobiprole where available).

Ceftaroline

Prodrug ceftaroline fosamil; only β-lactam active versus MRSA; used IV 600 mg q12h for CAP and cSSTI.

Ceftolozane-Tazobactam

Combination cephalosporin/inhibitor active against multidrug-resistant Pseudomonas and ESBL producers.

Cefiderocol

Siderophore cephalosporin that hijacks bacterial iron transport to enter cells; active against carbapenem-resistant gram-negatives.

Monobactam

Single-ring β-lactam subclass; aztreonam is only agent, active solely against aerobic gram-negatives.

Aztreonam

IV/IM monobactam 1–2 g q8h; alternative for gram-negative sepsis in severe β-lactam allergy.

Carbapenems

Potent synthetic β-lactams (imipenem, meropenem, doripenem, ertapenem) with broadest antibacterial spectrum.

Imipenem

First carbapenem, degraded by renal dehydropeptidase; co-given with cilastatin and may cause seizures at high levels.

Cilastatin

Renal dehydropeptidase inhibitor administered with imipenem to prevent drug degradation and nephrotoxicity.

Meropenem

Carbapenem with lower seizure risk, active versus Pseudomonas; dosed 1 g q8h IV.

Doripenem

Carbapenem similar to meropenem with enhanced activity against resistant gram-negatives.

Ertapenem

Once-daily carbapenem lacking Pseudomonas and Acinetobacter coverage; convenient for outpatient therapy.

Glycopeptide Antibiotics

Large molecules (vancomycin, teicoplanin) that inhibit cell-wall synthesis by binding D-Ala-D-Ala termini.

Vancomycin

IV glycopeptide for MRSA, enterococcal, C. difficile (PO) infections; eliminated renally; monitor troughs.

Red Man Syndrome

Histamine-mediated flushing, pruritus and hypotension caused by too-rapid vancomycin infusion.

Daptomycin

Lipopeptide that depolarizes bacterial membranes; active against VRE and MRSA; not for pneumonia (inactivated by surfactant).

Fosfomycin

Broad-spectrum phosphoenolpyruvate analogue given as single 3 g oral dose for uncomplicated cystitis.

Bacitracin

Topical polypeptide antibiotic active against gram-positives; systemic use limited by nephrotoxicity.

Cycloserine

Oral analogue of D-alanine used as second-line agent for multidrug-resistant tuberculosis.

Listeria monocytogenes

Gram-positive rod intrinsically resistant to cephalosporins; treated with ampicillin or meropenem.

Pseudomonas aeruginosa

Non-fermenting gram-negative rod often requiring antipseudomonal β-lactams (piperacillin-tazobactam, cefepime, ceftazidime, carbapenems).