3.6: Cephalosporins

Cephalosporins are a slightly modified chemical “twin” to penicillins due to their beta lactam chemical structure. (See Figure 3.8 for a comparison of the beta-lactam ring structure, spectrum of activity, and route of administration across different classes of medications.) Because of these similarities, some patients who have allergies to penicillins may experience cross-sensitivity to cephalosporins.

Figure 3.8 Comparison of beta-lactam ring structure across different classes of medications, spectrum of activity and routes of administration^{[footnote]"OSC Microbio 14 02 BetaLactam.jpg" by CNX Openstax is licensed under CC BY 4.0 Access for free at https://openstax.org/books/microbiology/pages/14-3-mechanisms-of-antibacterial-drugs[/footnote]}

Indications: Cephalosporins are used to treat skin and skin-structure infections, bone infections, genitourinary infections, otitis media, and community-acquired respiratory tract infections.

Mechanism of Action: Cephalosporins are typically bactericidal and are similar to penicillin in their action within the cell wall. Cephalosporins are sometimes grouped into “generations” by their antimicrobial properties. The 1st-generation drugs are effective mainly against gram-positive organisms. Higher generations generally have expanded spectra against aerobic gram-negative bacilli. The 5th-generation cephalosporins are active against methicillin-resistant Staphylococcus aureus (MRSA) or other complicated infections. ^[1]

Specific Administration Considerations: Patients who are allergic to pencillins may also be allergic to cephalosporins. Patients who consume cephalosporins while drinking alcoholic beverages may experience disulfiram-like reactions including severe headache, flushing, nausea, vomiting, etc.^[2] Additionally, like penicillins, cephalosporins may interfere with coagulability and increase a patient’s risk of bleeding. Cephalosporin dosing may require adjustment for patients experiencing renal impairment. Blood urea nitrogen (BUN) and creatinine should be monitored carefully to identify signs of nephrotoxicity.

Patient Teaching & Education: Patients who are prescribed cephalosporins should be specifically cautioned about a disulfiram reaction, which can occur when alcohol is ingested while taking the medication. Additionally, individuals should be instructed to monitor for rash and signs of superinfection (such as black, furry overgrowth on tongue; vaginal itching or discharge; loose or foul-smelling stool) and report to the prescribing provider.

It is also important to note that cephalosporin can enter breastmilk and may alter bowel flora of the infant. Thus, use during breastfeeding is often discouraged.^[3] Now let’s take a closer look at the cephalosporin medication grid in Table 3.6.^[4]

Table 3:6 Cephalosporin Medication Grid

Class/Subclass	Prototype/Generics	Administration Considerations	Therapeutic Effects	Side/Adverse Effects
Cephalosporins	1st generation: cephalexin Cefazolin 2nd generation: cefprozil 3rd generation: ceftriaxone 4th generation: cefepime 5th generation: ceftolozane	Check for allergies, including if allergic to penicillin Dosage adjustment if renal impairment Use with caution with seizure disorder PO: Administer without regard to food; if GI distress, give with food IV: Reconstitute drug with sterile water or normal saline; shake well until dissolved. Inject into large vein or free-flowing IV solution over 3-5 minutes Drug interaction: anticoagulants	Monitor for systemic signs of infection: -WBCs – Fever Monitor actual site of infection Monitor culture results, if obtained	Common side effects: -Nausea -Vomiting -Epigastric distress -Diarrhea Monitor for: -Rash -C-diff Nephrotoxicity if pre-existing renal disease Elevated INR and bleeding risk Development of hemolytic anemia

Critical Thinking Activity 3.6a

Using the above grid information, consider the following clinical scenario question:

Mrs. Jenkins is an 89-year-old patient admitted to the medical surgical floor for treatment of a skin infection. The admitting provider prescribes Cefazolin 1 gram every 8 hours IV.

Mrs. Jenkins’ admission laboratory tests include renal laboratory studies reflecting:

• Creatinine: 1.3 mg/dL (Normal range: 1.2 mg/dL^[5]
• Blood urea nitrogen (BUN): 25 mg/dL (Normal: 8-20 mg/dL)
• Glomerular Filtration Rate: 55 ml/min (Normal: 90-120 ml/min)^[6]

On Day 3 Mrs. Jenkins has renal laboratory studies performed again. The results are:

• Creatinine: 1.6 mg/dL
• Blood urea nitrogen (BUN): 57 mg/dL
• Glomerular Filtration Rate: 20 ml/min

Are Day 3 findings expected or not? What course of action should the nurse take?

Note: Answers to the Critical Thinking activities can be found in the “Answer Key” sections at the end of the book.

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1. Werth, B.J. (2018, August). Cephalosporins. Merck Manual Professional Version. https://www.merckmanuals.com/professional/infectious-diseases/bacteria-and-antibacterial-drugs/cephalosporins↵
2. Ren, S., Cao, Y., Zhang, X., Jiao, S., Qian, S., & Liu, P. (2014). Cephalosporin induced disulfiram-like reaction: a retrospective review of 78 cases. International Surgery, 99(2), 142–146. https://www.internationalsurgery.org/doi/full/10.9738/INTSURG-D-13-00086.1↵
3. uCentral from Unbound Medicine. https://www.unboundmedicine.com/ucentral↵
4. Daily Med, dailymed.nlm.nih.gov/dailymed/index.cfm, used for hyperlinked medications in this module. Retrieved June 27, 2019. ↵
5. U.S. National Library of Medicine, Medline Plus. (2020, February 13). Basic metabolic panel. https://medlineplus.gov/ency/article/003462.htm↵
6. U.S. National Library of Medicine, Medline Plus. (2020, February 13). Glomerular filtration rate.https://medlineplus.gov/ency/article/007305.htm↵