Antibiotic Overview

By no means an exhaustive list, but this compilation may serve as a reference for basic antibiotic classifications, indications, and side effects.

Inhibitors of Cell Wall Synthesis (ICWS)

• Beta-lactams
  • Penicillins: Major side effect profile = rash, anaphylaxis
    • 1st Generation: Target Gram-positive cocci
      • Pencillin G (oral/parenteral)
      • Penicillin V (oral)
    • 2nd Generation: Antistaphylococcal (Beta-lactamase resistant)
      • Nafcillin (“Naf for staph”)
      • Oxacillin
      • Cloxacillin
      • Dicloxacillin
    • 3rd Generation: Additional anti-pseudomonal coverage
      • Piperacillin (option of adding beta-lactamase inhibitor tazobactam)
      • Ticarcillin
      • Mezlocillin
    • 4th Generation: Extended spectrum (targets Gram-positive AND Gram-negative)
      • Ampicillin (option of adding beta-lactamase inhibitor sulbactam)
      • Amoxicillin (option of adding beta-lactamase inhibitor clavulanic acid)
  • Cephalosporins: Cross reaction with penicillins <3% ₍₁₎
    • 1st Generation: Mostly Gram-positive coverage
      • Cephalexin
      • Cefazolin
    • 2nd Generation: Increased Gram-negative coverage, less Gram-positive coverage
      • Cefuroxime
      • Cefotetan
      • Cefaclor
    • 3rd Generation: Increased Gram-negative coverage, less Gram-positive coverage
      • Ceftriaxone
      • Cefdinir
      • Cefotaxime
    • 4th Generation: Additional antipseudomonal coverage
      • Cefepime
  • Monobactams: Beta-lactamase resistant. NO cross-reaction with penicillin allergy. GNR and pseudomonas coverage. No Gram-positive coverage or anaerobic coverage
    • Aztreonam
  • Carbapenems
    • Imipenem: Gram-positive, Gram-negative, anaerobic coverage
    • Ertapenem: Gram-positive, Gram-negative, anaerobic coverage
    • Meropenem: Gram-positive, Gram-negative, anaerobic pseudomonal coverage
• “Other” ICWS
  • Vancomycin: Inhibits transglycosylation of cell wall (step before transpeptidation)
    • Targets Gram-positive organisms
    • Use PO for C. diff colitis, IV for everything else (Not absorbed orally)
    • Major side effects: Nephrotoxicity, ototoxicity, “red man” syndrome
  • Fosfomycin: Treats Gram-negative UTIs
  • Bacitracin: Topical only (very nephrotoxic if absorbed systemically)
  • Polymyxins (B & E): Gram negative and anti-pseudomonal salvage therapy

Inhibitors of Protein Synthesis

• Aminoglycosides: Inhibit 30S ribosome. Major side effects: nephrotoxicity, ototoxicity. Can be used to treat Yersinia pestis (plague)
  • Streptomycin
  • Gentamicin
  • Tobramycin
  • Amikacin
• Tetracyclines: Inhibit 30S ribosome. Poor absorption with elemental metals. Major side effects: teeth discoloration, bone growth retardation, photosensitization. Target atypical bacteria as well tick-borne diseases.
  • Tetracycline
  • Doxycycline: May be used to cover MRSA but has poor streptococcal coverage
  • Tigecycline: Resistant to drug efflux pumps
• Macrolides: Inhibit 50S ribosome. Major side effects: QT prolongation
  • Erythromycin
  • Clarithromycin
  • Azithromycin
• Nitroimidazole
  • Metronidazole: Targets anaerobes and parasites
• Other
  • Chloramphenicol: inhibits 50S ribosome. Treats typhoid fever, rocky mountain spotted fever in children. Major side effects: Aplastic anemia, gray baby syndrome.
  • Clindamycin: Can treat MRSA, anaerobes. Major side effect: C. diff colitis
  • Streptogramins: Inhibit 50S ribosome
    • Quinupristin and Dalfopristin: Treat VRE, MRSA
  • Oxazalidones: Prevents 70S ribosome formation
    • Linezolid: Treats VRE, MRSA. Good oral absorption. Bacteriostatic.

Folate Pathway Inhibitors

• p-Aminobenzoic Acid (PABA) analogues: pteridine synthetase inhibitors
  • Silver sulfadiazine: Used topically for burns, not for use on face – concern for application to eye
  • Sodium sulfacetamide: Ophthalmic solution
  • Sulfasalazine: Used to treat ulcerative colitis
• Dihydrofolate Reductase (DHFR) inhibitors: prevents USE of folate
  • Trimethoprim: Used in conjunction with sulfamethoxazole to treat MRSA, pneumocystis, UTIs, etc.
    • Studies have shown an increased resistance by S. pneumoniae ₍₂₎, however, it does appear to still be efficacious in the treatment of S. pyogenes ₍₃₎.
    • Trimethoprim/sulfamethoxazole (TMP-Sulfa) has potential side effects that include elevation in creatine as well as drug-induced liver injury (typically in a cholestatic or mixed pattern). It also reduces the ability of acetaminophen to undergo glucuronidation, leading to increased NAPQI formation and injury to hepatocytes.

DNA Gyrase Inhibitors

• Quinolones
  • Nalidixic Acid
• Fluoroquinolones: Good for intra-abdominal gram-negative coverage as well as UTIs. Can also treat Bacillus anthracis. Major side effects = QT prolongation, CNS toxicity, tendinopathy, C. diff colitis
  • Ciprofloxacin: Best pseudomonal coverage of fluoroquinolones
  • Levofloxacin: Additional anti-streptococcal pneumonia coverage. Also covers stenotrophomonas
  • Ofloxacin
  • Moxifloxacin: Additional anaerobe coverage. Does not cover pseudomonas except for ocular application

Urinary Tract Antiseptics

• Nitrofurantoin: Causes oxidative stress to bacteria
  • May also cause anorexia, hemolytic anemia in individuals with G6PDH deficiency

LIPOPEPTIDES

• Daptomycin: Bactericidal. Covers gram-positive including MRSA, VRE. Inactivated by surfactant, so not a recommended choice for lung infections

References:

1. Solensky, R., MD. (2012, December 1). Allergy to beta-lactam antibiotics. Retrieved November 6, 2020, from https://www.jacionline.org/article/S0091-6749(12)01383-8/fulltext
2. Jacobs MR;Good CE;Windau AR;Bajaksouzian S;Biek D;Critchley IA;Sader HS;Jones RN;. (n.d.). Activity of ceftaroline against recent emerging serotypes of Streptococcus pneumoniae in the United States. Retrieved December 30, 2020, from https://pubmed.ncbi.nlm.nih.gov/20308374/
3. Imöhl, M., & Linden, M. (n.d.). Antimicrobial Susceptibility of Invasive Streptococcus pyogenes Isolates in Germany during 2003-2013. Retrieved December 30, 2020, from https://journals.plos.org/plosone/article?id=10.1371%2Fjournal.pone.0137313