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Clinician’s Corner: Cephalosporins


Mechanism:  like their closest cousins the penicillins, cephalosporins bind to proteins in the cell wall, enabling it to inhibit cell wall synthesis of the bacteria, causing cell wall lysis and cell death. Are bactericidal.

Indications for use:

Differs between 1st, 2nd, and 3rd generation cephalosporins.


Gram positive activity, staph aureus, S.epidermidis, Strep pyogenes, Strep pneumoniae.

Not active against MRSA/ MRSE.

Some strains of Klebsiella, P.mirabilis, E.coli, Shigella (Gram Negatives)

Primarily cover gram positive organisms:  methicillin-sensitive S. aureus, group A strep

Some gram-negative coverage: E. coli, Klebsiella species, P. mirabilis

Poor anaerobic coverage

Most Common 1st Generation Cephalosporins

Cephalexin (Keflex)

Cefadroxil (Duricef®)

Most Common use: Methicillin Sensitive Staph Aureus (MSSA) skin/soft tissue. Urinary Tract Infection. Surgical infection prevention

2nd Generation

Cefuroxime (Ceftin®)

Common use: Cefuroxime: Upper Respiratory Infection, Urinary Tract Infections, Lyme early stage, Otitis media, sinusitis.

3rd Generation: broad spectrum, most resistant breakdown by bacteria.

Third-generation agents have enhanced activity against both gram-positive and gram-negative bacteria compared to 1st and 2nd generation.

3rd Generation Cephalosporins

Cefdinir (Omnicef®)

Major Counseling point: Will turn stools red!  Occurs when cefdinir combines with iron to form a precipitate that gives stool a characteristic discoloration

Cefpodoxime (Vantin®)- available as oral tablets

Ceftriaxone (Rocephin®)-Available only as injection

COMMON USES: Third Generation Cephalosporins

  • Cefdinir: ear infections; upper respiratory infection.
  • Ceftriaxone: Lyme’s, ear infections, gonorrhea, upper and lower respiratory infections. skin infections

Warnings/Precaution: Crossover Allergy

Cross-reactivity between penicillins and cephalosporins is less than 1%, (instead of 10% as previously thought) which is less likely with second- and third generation cephalosporins than first-generation cephalosporins.

  • Cefdinir (Omnicef®), cefuroxime (Ceftin®), cefpodoxime (Vantin®) or ceftriaxone (Rocephin®), are a safe choice for people with penicillin allergy because they do not have the “penicillin-like” side chains.

Patient Education:

Watch for severe penicillin allergy patients

Take with food or milk

Complete course of therapy

Your Thompson Pharmacist can help your physician come up with the best choice for infections that are treated with cephalosporins.  From skin infections to Lyme disease treatment your Thompson Pharmacist can help you get the most from antibiotic therapy with cephalosporins.

Go Ahead and ASK… at Thompson Pharmacy it’s All for YOU!!