Antibiotics

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

Deep Dive

• Amoxicillin (Drugs.com)

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

Deep Dive

• Should we Stop Prescribing Azithromycin in the ED? (REBEL EM)

Rapid Review

Pearls

Deep Dive

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

Deep Dive

• Cefazoline (Drugs.com)

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

• Cefepime (PubMed)

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

Deep Dive

• Cefotaxime (PubMed)

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

Deep Dive

• US Based Emergency Department Visits for Fluoroquinolone-Associated Hypersensitivity Reactions (PubMed)

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

Deep Dive

• Appropriate Use of Ceftriaxone in the Emergency Department of a Veteran’s Health Care System (PubMed)

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

Deep Dive

• Clindamycin (PubMed)

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

Deep Dive

• Doxycycline (Drugs.com)

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

Deep Dive

• Gentamicin (PubMed)

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

Deep Dive

• Levofloxacin (PubMed)

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

Deep Dive

• Metronidazole (PubMed)

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

Deep Dive

• Piperacillin-Tazobactam (Drugs.com)

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

Deep Dive

• Is vancomycin/zosyn the answer for everything? (emDocs)