Antibiotics

First-generation cephalosporin

β-lactam — inhibits bacterial cell wall PBPs.

Glycopeptide antibiotic

Inhibits cell wall synthesis (binds D-Ala-D-Ala). Active against MRSA + gram-positives.

Lincosamide protein-synthesis inhibitor

Binds 50S ribosomal subunit, blocks peptide-bond formation. Bacteriostatic against most organisms; bactericidal against susceptible streptococci. Excellent activity against anaerobes and gram-positive cocci including community-acquired MRSA.

Aminoglycoside protein-synthesis inhibitor

Binds 30S ribosomal subunit, causes misreading of mRNA → defective bacterial protein synthesis. Bactericidal, concentration-dependent killing. Synergy with cell-wall agents (β-lactams, vancomycin) for gram-positive endocarditis.

2nd-generation cephalosporin

β-lactam — inhibits cell-wall synthesis (PBP binding). 2nd-gen: gram-positive + expanded gram-negative.

4th-generation cephalosporin

β-lactam cell-wall inhibitor. Broad gram-negative (incl. Pseudomonas) + gram-positive coverage.

2nd-generation cephalosporin (cephamycin) with anaerobic coverage

β-lactam; adds anaerobic (B. fragilis) coverage → colorectal/gynecologic prophylaxis.

3rd-generation cephalosporin

β-lactam cell-wall inhibitor. Broad gram-negative + CNS penetration.

2nd-generation cephalosporin (cephamycin) with anaerobic coverage

β-lactam with anaerobic (B. fragilis) activity → colorectal/GYN prophylaxis.

3rd-generation cephalosporin

β-lactam cell-wall inhibitor; broad gram-negative + good CSF penetration. Long half-life → once-daily.

5th-generation cephalosporin (anti-MRSA)

β-lactam that binds PBP2a → the only cephalosporin with reliable MRSA activity.

Fluoroquinolone antibiotic

Inhibits DNA gyrase/topoisomerase IV → blocks DNA replication. Gram-negative (incl. Pseudomonas) focus.

Respiratory fluoroquinolone

DNA gyrase/topoisomerase IV inhibitor; broader gram-positive/atypical ('respiratory') coverage than cipro.

Carbapenem β-lactam (broadest-spectrum)

β-lactam cell-wall inhibitor with very broad gram-positive/negative/anaerobic coverage. Cilastatin blocks renal dehydropeptidase (prevents imipenem degradation + nephrotoxic metabolite).

Carbapenem β-lactam (once-daily, NO pseudomonal coverage)

Broad-spectrum carbapenem; long half-life → once-daily. Does NOT cover Pseudomonas or Acinetobacter (unlike imipenem/meropenem).

Monobactam β-lactam (gram-negative only)

Monobactam that inhibits gram-negative PBP3. No gram-positive or anaerobic activity.

Nitroimidazole antibiotic (anaerobic + antiprotozoal)

Reduced intracellularly to reactive radicals → DNA damage in anaerobes/protozoa.

Tetracycline antibiotic (bacteriostatic)

Binds 30S ribosomal subunit → blocks protein synthesis. Broad atypical/intracellular coverage. Also used for chemical pleurodesis.

Aminopenicillin + β-lactamase inhibitor

Ampicillin (cell-wall inhibitor) + sulbactam (β-lactamase inhibitor) → restores activity vs β-lactamase producers; gram-positive, some gram-negative, anaerobes.

Antipseudomonal penicillin + β-lactamase inhibitor

Piperacillin (broad, antipseudomonal) + tazobactam (β-lactamase inhibitor) → very broad gram-positive/negative/anaerobic + Pseudomonas.

Folate-synthesis inhibitor combination antibiotic

Sequential blockade of folate synthesis (TMP inhibits dihydrofolate reductase; SMX inhibits dihydropteroate synthase).

Triazole antifungal

Inhibits fungal CYP450 14-α-demethylase → blocks ergosterol synthesis. Also a potent human CYP2C9/3A4 inhibitor.

Carbapenem β-lactam (broad-spectrum, antipseudomonal)

Broad gram-positive/negative/anaerobic + Pseudomonas coverage. LOWER seizure potential than imipenem.

Oxazolidinone antibiotic (Gram-positive/MRSA/VRE)

Binds the 23S rRNA of the 50S subunit → blocks protein-synthesis initiation. Also a REVERSIBLE nonselective MAO inhibitor.

Cyclic lipopeptide antibiotic (Gram-positive/MRSA/VRE)

Inserts into the gram-positive cell membrane (calcium-dependent) → depolarization → cell death. Bactericidal.