Antibiotics


Amoxicillin

Rapid Review

  • Mechanism of Action: Beta-lactam antibiotic; inhibits bacterial cell wall synthesis.
  • Indications: Typically used for otitis media, strep pharyngitis, sinusitis, and community acquired pneumonia. 
  • Contraindications: allergy to class/drug
  • Dosage: General: 500 – 1000 mg q12h x 10 days 
  • Half-Life: 30 – 90 minutes
  • Adverse Reactions: Common reactions: nausea, vomiting, diarrhea, rash. Serious reactions: anaphylaxis, SJS/TEN, hypersensitivity vasculitis.
  • Special Considerations: N/A

Pearls

Video Credit: JJ Medicine


Azithromycin

Rapid Review

  • Mechanism of Action: Macrolide antibiotic; 
  • Indications: community-acquired pneumonia, sinusitis, pharyngitis, COPD exacerbations, and genital infections.
  • Contraindications: allergy/hypersensitivity to macrolides
  • Dosage: Typically a tapered dose of 500 mg PO on day 1, then 250 mg PO x 4 days). Often a single 1-2 gram dose for sexually transmitted infections.
  • Half-life: 68 hours
  • Adverse Reactions: vomiting, diarrhea, headache, vision changes. May also cause prolonged QT or hepatic necrosis.
  • Special Considerations: None

Pearls

Video Credit: Medicosis Perfectionales


Cephalexin

Rapid Review

Pearls

Deep Dive



Cefazolin

Rapid Review

  • Mechanism of Action: 1st generation cephalosporin; inhibits cell wall mucopeptide synthesis.
  • Indications: Frequently used for cellulitis, osteomyelitis, and intra-abdominal infections. May also be used for surgical prophylaxis.
  • Contraindications: allergy to class/drug
  • Dosage: generally 500-1000 mg IM/IV q6-8hrs.
  • Half-life: 1.8 hours
  • Adverse Reactions: GI effects (nausea/vomiting/diarrhea). Hypersensitivity reactions.
  • Special Considerations: N/A

Pearls

Video Credit: MED CRAM


Cefepime

Rapid Review

  • Mechanism of Action: 4th-generation cephalosporin antibiotic; inhibits cell wall mucopeptide synthesis.
  • Indications: empiric treatment for severe infections (sepsis, bacteriemia, multi-drug resistant infections, hospital-acquired pneumonia)
  • Contraindications: allergy to class/drug
  • Dosage: Generally 1-2 g IV/IM q12 hours
  • Half-life: 2-19 hours (depending on dose/route)
  • Adverse Reactions: GI effects (nausea/vomiting/diarrhea). Hypersensitivity reactions.

Pearls

Deep Dive

Video Credit: MED CRAM


Cefotaxime

Rapid Review

  • Mechanism of Action: 3rd-generation cephalosporin antibiotic; inhibits bacterial wall synthesis
  • Indications: Commonly used to treat intra-abdominal infections, meningitis, gonorrhea, and pneumonia.
  • Contraindications: allergy/hypersensitivity to drug class
  • Dosage: generally 1-2 g IV/IM q6-12 hrs
  • Half-life: 1-2 hrs
  • Adverse Reactions: local reaction to injection site, GI effects, hypersensitivity

Pearls

Video Credit: MED CRAM


Ciprofloxacin

Rapid Review

  • Mechanism of Action: Fluoroquinoline antibiotic; inhibits DNA gyrase
  • Indications: Commonly used for diverticulitis, colitis, and urinary tract infections.
  • Contraindications: allergy to class/drug, administration with tizanidine
  • Dosage: Generally 250-750mg PO q12h or 200-400mg IV q12hrs.
  • Half-life: 4 hours
  • Adverse Reactions: GI effects (nausea/vomiting/diarrhea), tendon rupture

Pearls

Video Credit: Medical Animations


Ceftriaxone

Rapid Review

  • Mechanism of Action: 3rd generation cephalosporin with broad-spectrum gram-negative activity. Inhibits cell wall synthesis
  • Indications: Bacterial meningitis, gonorrhea, pelvic inflammatory disease, joint infection
  • Contraindications: Allergy to class/drug, age < 1 month
  • Dosage
    • Generally 1-2 grams IM/IV q24hrs
    • Gonorrhea: 500 mg IM (single dose)
  • Half-life: 5.8 – 8.7hrs
  • Adverse Reactions: Anaphylaxis, bronchospasm, SJS, diarrhea, eosinophilia

Pearls

Video Credit: USMLE Pass


Clindamycin

Rapid Review

  • Mechanism of Action: Lincosamide antibiotic; bacteriostatic/bactericidial 
  • Indications: odontogenic infections, MRSA, necrotizing soft tissue infections
  • Contraindications: allergy to class/drug; ulcerative colitis
  • Dosage: generally 150-450mg PO q6 hrs; 1200-2700mg/day IV/IM q6-12 hrs
  • Half-life: 2.5-3 hours
  • Adverse Reactions: GI effects (nausea/vomiting/diarrhea), pruritus, thrombocytopenia.
  • Special Considerations: clindamycin should be used rarely due to high risk of clostridium difficile associated diarrhea.

Pearls

Video Credit: Medical Animations


Doxycycline

Rapid Review

  • Mechanism of Action: Tetracycline; inhibits bacterial protein synthesis after specific ribosomal binding
  • Indications: Community-acquired pneumonia, cellulitis, bacterial sinusitis, chlamydia/gonorrhea, PID, lyme disease
  • Contraindications: Allergy to drug/class, pregnancy, Age < 8 years old (due to teeth staining, although short courses are permissible)
  • Dosage: Generally 100mg PO/IV daily or q12 hours x 7 days
  • Onset: Peak concentration after 2-4 hours
  • Duration: Half life of 18 hours
  • Adverse Reactions: Headache, nausea, dyspepsia, tooth discoloration (controversial), C. Diff diarrhea
  • Special Considerations: None

Pearls

Video Credit: Pharmacist Conversations


Gentamicin

Rapid Review

  • Mechanism of Action: Aminoglycoside; bactericidal antibiotic with broad coverage against aerobic gram-negative bacteria, including Pseudomonas. Binds to the 16s rRNA at the 30s ribosomal subunit, disrupting mRNA translation.
  • Indications: PID, sepsis, meningitis, endocarditis, blepharitis
  • Contraindications: Allergy to drug/class
  • Dosage: Generally 5-7 mg/kg IV q24 hours
  • Onset: Reaches peak concentrations after 30-90 minutes
  • Duration: 2-3 hours
  • Adverse Reactions: Ototoxicity, renal toxicity, abnormal LFTs, rashes 

Pearls

Video Credit: Drug Talk


Levofloxacin

Rapid Review

  • Mechanism of Action: 3rd generation Fluoroquinolone; inhibits bacterial DNA synthesis. Broad spectrum antibiotic with good coverage against both gram positive and gram negative organisms.
  • Indications: Pneumonia (community or nosocomial), pyelonephritis, UTI, sinusitis, prostatitis.
  • Contraindications: QT prolongation, hypersensitivity, myasthenia gravis
  • Dosage:
    • Pyelonephritis: 250 mg PO daily X 10 days
    • Prostatitis: 500 mg PO X 28 days
    • Pneumonia: 750 mg PO/IV q24 hours X 7-14  days 
  • Half-life: 6-8 hours (27-35 hours in adults with renal impairment)
  • Adverse Reactions: Tendon rupture, photosensitivity, nausea, prolonged QT
  • Special Considerations: Has limited coverage against pseudomonas compared to ciprofloxacin
  • Levofloxacin is a fluoroquinolone antibiotic that is commonly used to treat pneumonia and COPD exacerbation

Pearls

Video Credit: Medical Animations


Metronidazole

Rapid Review

  • Mechanism of Action: Nitroimidazole antibiotic/anti-protozoan. Inhibits protein synthesis by interacting with DNA. 
  • Indications: Intra-abdominal infections (colitis, diverticulitis), genital infections (pelvic inflammatory disease, bacterial vaginosis, trichomoniasis) C. difficile, amebiasis
  • Contraindications: Hypersensitivity, 1st trimester pregnancy
  • Dosage:
    • Intra-abdominal infections: 500 mg IV q8 hours
    • Genital infections (PID, BV, Trich): Generally 500 mg PO q12 hours X 7 days
  • Half-life: 8 hours
  • Adverse Reactions: Headache, vaginitis, nausea, confusion, neuropathy
  • Special Considerations: Patient should avoid alcohol consumption while on this medication and at least 2-3 days after last dose (creates a disulfiram-like effect)

Pearls

Video Credit: Medical Animations


Piperacillin-Tazobactam

Rapid Review

  • Mechanism of Action: Antipseudomonal penicillin. Piperacillin inhibits cell wall mucopeptide synthesis, tazobactam inhibits the beta lactamase enzyme to prevent bacteria from destroying the piperacillin.
  • Indications: Pneumonia, sepsis, pelvic inflammatory disease, intra-abdominal infections.
  • Contraindications: Hypersensitivity
  • Dosage
  • Half-life: 0.7-1.2 hours
  • Adverse Reactions: Anaphylaxis, SJS, nausea/vomiting, headache

Pearls

Video Credit: Drug Talk


Vancomycin

Rapid Review

  • Mechanism of Action: Glycopeptide antibiotic; inhibits cell wall synthesis, exhibiting a bactericidal action. Very potent against gram-positive bacteria. 
  • Indications: Sepsis, MRSA skin and soft tissue infections, endocarditis, meningitis, C difficile colitis
  • Contraindications: Allergy to class/drug
  • Dosage: Initial loading dose generally 15-20mg/kg IV. Maintenance dose is 500-1000 IV q12 hours.
  • Onset: Rapid
  • Duration: Half life of 4-6 hrs
  • Adverse Reactions: Hypotension (with rapid IV use), “red man syndrome”,  nausea
  • Special Considerations: None

Pearls

Video Credit: Simple Nursing

Brandon Simpson, PA-C
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