Antibiotic Pharmacology (Lectures 40–44)

Comprehensive vocabulary flashcards covering the mechanism of action, key clinical indications, and major cautions or reasons to avoid for all 86 antibacterial and antifolate drug entries across Lectures 40 to 44.

Penicillin G

A natural penicillin that inhibits PBPs and blocks peptidoglycan cross-linking

Parenteral preferred agent for syphilis, susceptible streptococci, and Clostridium spp.

Not active against penicillinase-producing staphylococci.

Penicillin V

An oral natural penicillin that inhibits PBPs and blocks cell-wall cross-linking

Used for oral therapy of susceptible streptococcal infections

Less potent than penicillin G and susceptible to penicillinase.

Nafcillin and Oxacillin

An antistaphylococcal penicillinase-stable PBP inhibitor indicated for MSSA and MSSE infections

Not active against MRSA.

Dicloxacillin and Cloxacillin

An oral antistaphylococcal penicillinase-stable PBP inhibitor indicated for MSSA and MSSE infections

Not active against MRSA.

Cloxacillin

An oral antistaphylococcal penicillinase-stable PBP inhibitor indicated for MSSA and MSSE infections; not active against MRSA.

Ampicillin

An aminopenicillin that inhibits PBPs with extended gram-negative spectrum

Preferred agent for Listeria, susceptible enterococci, and respiratory or enteric infections

Carries rash risk with allopurinol.

Amoxicillin

An oral aminopenicillin that inhibits PBPs with extended gram-negative spectrum

Indicated for susceptible respiratory and other infections

Carries rash risk with allopurinol.

Ampicillin–sulbactam

An aminopenicillin plus beta-lactamase inhibitor combination where ampicillin blocks PBPs and sulbactam inhibits beta-lactamases

Used for broader susceptible polymicrobial and respiratory infections.

Amoxicillin–clavulanate

An aminopenicillin plus beta-lactamase inhibitor combination where amoxicillin blocks PBPs and clavulanate inhibits beta-lactamases

Indicated for beta-lactamase-producing respiratory and other susceptible infections.

Piperacillin

An antipseudomonal penicillin that inhibits PBPs with extended antipseudomonal action

Indicated for susceptible Pseudomonas and serious gram-negative infections

Susceptible to beta-lactamases.

Piperacillin–tazobactam

An antipseudomonal penicillin plus beta-lactamase inhibitor combination providing PBP and beta-lactamase inhibition

Used for serious polymicrobial infections, Pseudomonas, and intra-abdominal, urinary, and burn infections.

Ticarcillin–clavulanate

An antipseudomonal penicillin plus beta-lactamase inhibitor combination providing PBP and beta-lactamase inhibition

Indicated for susceptible gram-negative and Pseudomonas infections.

Clavulanic acid

An irreversible beta-lactamase inhibitor used to protect amoxicillin or ticarcillin in combinations

Not adequate as antibacterial monotherapy.

Sulbactam

An irreversible beta-lactamase inhibitor that binds Acinetobacter baumannii PBPs

Used in ampicillin combinations and with durlobactam for susceptible A. baumannii pneumonia.

Tazobactam

An irreversible beta-lactamase inhibitor that protects piperacillin and ceftolozane

Not adequate as antibacterial monotherapy.

Avibactam

A reversible beta-lactamase inhibitor combined with ceftazidime for resistant gram-negative infections

Does not inhibit all beta-lactamases.

Relebactam

A reversible beta-lactamase inhibitor combined with imipenem–cilastatin for KPC-producing gram-negative bacteria.

Vaborbactam

A reversible beta-lactamase inhibitor combined with meropenem for KPC-producing gram-negative bacteria.

Durlobactam

A reversible beta-lactamase inhibitor combined with sulbactam for susceptible Acinetobacter baumannii–calcoaceticus pneumonia

Not a standalone treatment.

Cefazolin

A first-generation cephalosporin that binds PBPs to inhibit cell-wall cross-linking

Preferred cephalosporin for MSSA, also covers susceptible streptococci and PEcK GNBs

Not active against MRSA or Pseudomonas.

Cephalexin

An oral first-generation cephalosporin that binds PBPs to inhibit cell-wall cross-linking

Used for susceptible MSSA, streptococcal, and PEcK infections

Not active against MRSA or Pseudomonas.

Cefuroxime

A second-generation cephalosporin that binds PBPs to inhibit cell-wall cross-linking

Used for respiratory infections with expanded coverage against Haemophilus influenzae and Moraxella.

Cefoxitin

A cephamycin that binds PBPs to inhibit cell-wall cross-linking

Indicated for infections involving Bacteroides fragilis and anaerobes

Lacks MRSA and Pseudomonas coverage.

Ceftriaxone

A third-generation cephalosporin that binds PBPs

Indicated for meningitis, uncomplicated gonorrhea (single IM dose), and serious infections

Avoid in neonates due to risks of bilirubin displacement and calcium precipitation.

Cefotaxime

A third-generation cephalosporin that binds PBPs

Indicated for meningitis and preferred over ceftriaxone for neonates.

Cefdinir

An oral third-generation cephalosporin PBP inhibitor used for susceptible respiratory and other gram-negative infections

Not active against Pseudomonas.

Ceftazidime

A third-generation antipseudomonal cephalosporin that binds PBPs

Active against Pseudomonas and other susceptible gram-negative infections, with weaker gram-positive activity.

Ceftazidime–avibactam

A third-generation antipseudomonal cephalosporin and beta-lactamase inhibitor combination

Indicated for resistant gram-negative and Pseudomonas infections.

Ceftolozane–tazobactam

A cephalosporin and beta-lactamase inhibitor combination

Indicated for resistant Pseudomonas and ESBL-producing gram-negative infections.

Cefepime

A fourth-generation cephalosporin that binds PBPs and inhibits cell-wall cross-linking

Indicated for severe hospital infections, Pseudomonas, and Enterobacterales.

Ceftaroline

An advanced cephalosporin that binds PBPs including MRSA PBP2a

Indicated for susceptible MRSA infections

Not antipseudomonal.

Cefiderocol

An advanced cephalosporin that utilizes siderophore iron uptake followed by PBP inhibition

Indicated for MDR aerobic gram-negative pneumonia and complicated UTI, including Pseudomonas

Lacks gram-positive and most anaerobic coverage.

Imipenem–cilastatin

A carbapenem combination where imipenem inhibits PBPs and cilastatin prevents renal degradation

Indicated for severe complicated mixed infections including Pseudomonas and Bacteroides fragilis.

Meropenem

A broad-spectrum carbapenem PBP inhibitor indicated for severe complicated infections, Pseudomonas, and anaerobes.

Ertapenem

A broad-spectrum carbapenem PBP inhibitor indicated for severe complicated susceptible mixed and enteric infections

Lacks activity against Pseudomonas.

Imipenem–cilastatin–relebactam

A carbapenem plus beta-lactamase inhibitor combination providing PBP inhibition plus renal enzyme and KPC inhibition

Indicated for KPC-producing resistant gram-negative infections.

Meropenem–vaborbactam

A carbapenem plus beta-lactamase inhibitor combination providing PBP and KPC beta-lactamase inhibition

Indicated for KPC-producing Enterobacterales infections.

Aztreonam

A monobactam PBP inhibitor active against aerobic gram-negative infections and inhaled for CF Pseudomonas

Lacks gram-positive or anaerobic activity and carries cross-reactivity concerns with ceftazidime.

Vancomycin

A glycopeptide that binds D-Ala–D-Ala to block peptidoglycan synthesis

Indicated for serious MRSA and enterococcal infections, and administered orally for Clostridioides difficile

IV form does not treat luminal C. difficile.

Daptomycin

A lipopeptide that inserts into and depolarizes the gram-positive cell membrane

Used for MRSA/VRE bacteremia, endocarditis, and deep infections

Contraindicated in pneumonia due to inactivation by surfactant.

Polymyxin B

A polymyxin that disrupts gram-negative cell membranes via phospholipid binding

Indicated for serious MDR gram-negative infections

Associated with nephrotoxicity and neurotoxicity.

Colistimethate / colistin

A polymyxin prodrug releasing colistin that causes detergent-like membrane disruption

Used for serious MDR gram-negative infections

Carries risks of nephrotoxicity, neurotoxicity, and bronchoconstriction.

Gentamicin

An aminoglycoside that causes irreversible 30S/16S rRNA binding and mRNA misreading

Used for serious aerobic gram-negative infections and synergistic endocarditis therapy

Carries nephrotoxicity, ototoxicity, and neuromuscular blockade risks.

Tobramycin

An aminoglycoside that irreversibly binds 30S/16S rRNA causing mRNA misreading

Indicated for serious aerobic gram-negative infections including Pseudomonas

Ineffective in anaerobic sites.

Amikacin

An aminoglycoside that irreversibly binds 30S rRNA causing mRNA misreading

Indicated for resistant aerobic gram-negative bacteria and MDR TB

Lacks anaerobic action.

Plazomicin

An aminoglycoside that irreversibly binds 30S rRNA causing mRNA misreading

Indicated for complicated UTIs resistant to other antibiotics.

Streptomycin

An aminoglycoside that irreversibly binds 30S rRNA causing mRNA misreading

Indicated for tularemia, plague, and resistant TB

Toxicities include ototoxicity, nephrotoxicity, and optic or peripheral neuritis.

Neomycin

An aminoglycoside that irreversibly binds 30S rRNA

Formulated topically and given orally for bowel decontamination or hepatic encephalopathy

Too toxic for systemic parenteral administration.

Paromomycin

A poorly absorbed oral aminoglycoside that irreversibly binds 30S rRNA

Indicated for luminal amebiasis and leishmaniasis.

Spectinomycin

An aminocyclitol that binds 30S rRNA and inhibits protein synthesis without mRNA misreading

Rare alternative for resistant gonorrhea

Not effective for pharyngeal gonorrhea and unavailable in the US.

Tetracycline

A tetracycline that reversibly binds the 30S A site to block aminoacyl-tRNA

Used for susceptible atypical, spirochetal, and bacterial infections

Chelates polyvalent cations and affects teeth and bones in pregnancy and young children.

Doxycycline

A tetracycline that reversibly binds the 30S A site to block aminoacyl-tRNA

Used for Lyme disease, Rocky Mountain spotted fever, chlamydia, and zoonoses

Associated with photosensitivity and esophagitis.

Minocycline

A tetracycline that reversibly binds the 30S A site to block aminoacyl-tRNA

Used for susceptible bacterial/atypical infections and acne

Associated with vestibular adverse effects.

Demeclocycline

A tetracycline that reversibly binds the 30S A site to block aminoacyl-tRNA

Previously used for SIADH and not used as an antibacterial agent.

Tigecycline

A glycylcycline that binds the 30S A site and overcomes several tetracycline efflux and protection mechanisms

Carries an increased all-cause mortality warning and risk of pancreatitis.

Eravacycline

A new tetracycline that binds the 30S A site to block aminoacyl-tRNA

Indicated for susceptible resistant bacterial infections

Subject to class pregnancy and cation chelation cautions.

Omadacycline

A new tetracycline that binds the 30S A site to block aminoacyl-tRNA

Indicated for susceptible bacterial infections

Subject to class pregnancy and cation chelation cautions.

Sarecycline

A new narrow-spectrum tetracycline that binds the 30S A site to block aminoacyl-tRNA

Indicated for the treatment of acne.

Erythromycin

A macrolide that binds 50S/23S rRNA to inhibit translocation

Used for susceptible respiratory and atypical infections

Causes GI effects, QT prolongation, CYP3A4 interactions, and estolate hepatotoxicity.

Clarithromycin

A macrolide that binds 50S/23S rRNA to inhibit translocation

Indicated for respiratory/atypical infections and Helicobacter pylori regimens

Causes QT prolongation, strong CYP3A4 interactions, and is avoided in pregnancy.

Azithromycin

A macrolide that binds 50S/23S rRNA to inhibit translocation

Indicated for atypical respiratory infections, chlamydia, and Campylobacter

Causes QT prolongation and is not routinely used for gonorrhea alone.

Clindamycin

A lincosamide that binds 50S to block protein elongation

Active against susceptible anaerobes and gram-positive skin/soft tissue infections

Carries a high risk of Clostridioides difficile colitis and lacks aerobic gram-negative coverage.

Chloramphenicol

An amphenicol that binds the 50S peptidyl-transferase center

Restricted to life-threatening infections lacking safer options

Causes aplastic anemia, bone marrow suppression, and gray baby syndrome.

Linezolid

An oxazolidinone that binds 50S 23S rRNA to prevent formation of the initiation complex

Indicated for MDR gram-positive infections (MRSA/VRE)

Causes myelosuppression, neuropathy, and MAOI-related serotonin syndrome.

Tedizolid

An oxazolidinone that binds 50S 23S rRNA to block formation of the initiation complex.

Quinupristin–dalfopristin

A streptogramin combination where two agents bind the 50S subunit to inhibit protein synthesis

Historically used for resistant gram-positive infections (marketing discontinued).

Lefamulin

A pleuromutilin that binds the 50S peptidyl transferase A and P sites

Indicated for community-acquired bacterial pneumonia.

Sulfisoxazole

A sulfonamide PABA competitor that inhibits DHPS in folate synthesis

Associated with sulfa hypersensitivity, G6PD hemolysis, crystalluria, and kernicterus risk.

Sulfamethoxazole

A sulfonamide PABA competitor that inhibits DHPS

Combined with trimethoprim

Adverse risks include Stevens-Johnson syndrome, G6PD hemolysis, crystalluria, and kernicterus in late pregnancy and neonates.

Sulfadiazine

A sulfonamide PABA competitor that inhibits DHPS

Administered with pyrimethamine for toxoplasmosis

Associated with G6PD hemolysis, crystalluria, and kernicterus.

Sulfadoxine

A long-acting sulfonamide PABA competitor that inhibits DHPS

Administered with pyrimethamine for malaria; associated with severe skin reactions.

Sulfasalazine

An intestinal sulfonamide-containing prodrug indicated for ulcerative colitis and rheumatoid arthritis.

Sulfacetamide

A topical sulfonamide PABA competitor that inhibits DHPS

Formulated as ophthalmic antibacterial drops.

Silver sulfadiazine

A topical antibacterial sulfonamide agent with folate-related action

Formulated as an antimicrobial cream for burn wounds.

Mafenide acetate

A topical antibacterial sulfonamide used for burn wound management.

Trimethoprim

A folate inhibitor that targets bacterial dihydrofolate reductase (DHFR)

Used for UTI treatment and prophylaxis, or with dapsone for PCP

Adverse effects include folate-associated megaloblastic anemia and leukopenia.

Trimethoprim–sulfamethoxazole (TMP–SMX)

An antifolate combination providing sequential DHPS and DHFR inhibition

Drug of choice for Pneumocystis jirovecii pneumonia (PCP) and nocardiosis, and used for UTIs and MRSA.

Pyrimethamine

A protozoal DHFR inhibitor used with sulfadiazine for toxoplasmosis and with sulfadoxine for malaria

Causes folate-related bone marrow toxicity.

Dapsone

A sulfone agent that inhibits folate synthesis

Used in combination with trimethoprim as an alternative regimen for PCP.

Ciprofloxacin

A bactericidal fluoroquinolone that inhibits DNA gyrase and topoisomerase IV

Indicated for gram-negative/Pseudomonas infections and complicated UTIs

Carries tendon rupture, neuropathy, aortic, and QT risks, and inhibits CYP1A2.

Levofloxacin

A respiratory fluoroquinolone that inhibits DNA gyrase and topoisomerase IV

Covers Streptococcus pneumoniae and gram-negative UTIs

Carries tendon, neuropathy, aortic, QT, and dysglycemia warnings.

Moxifloxacin

A respiratory fluoroquinolone that inhibits DNA gyrase and topoisomerase IV

Used for respiratory infections including S. pneumoniae

Not suitable for UTIs due to poor urine drug levels.

Delafloxacin

A respiratory fluoroquinolone that inhibits DNA gyrase and topoisomerase IV

Indicated for susceptible respiratory and skin infections

Carries class tendon, neuropathy, aortic, and dysglycemia warnings.

Ofloxacin

A fluoroquinolone that inhibits DNA gyrase and topoisomerase IV

Exhibits similar pharmacokinetic and activity profiles to levofloxacin.

Nalidixic acid

An older quinolone that inhibits bacterial DNA gyrase

Historical first quinolone agent.