Cephalosporins

Question 1

Example of Cephalosporin’s

Answer 1

Cephradine (not in book but done generally)

Question 2

How do Cephalosporin’s work?

Answer 2

Cephalosporins and carbapenems are derived from naturally occurring antimicrobials produced by fungi and bacteria. Like penicillins, their antimicrobial effect is due to their β-lactam ring. During bacterial cell growth, cephalosporins and carbapenems inhibit enzymes responsible for cross-linking peptidoglycans in bacterial cell walls. This weakens cell walls, preventing them from maintaining an osmotic gradient, resulting in bacterial cell swelling, lysis and death. Both types of antibiotic have a broad spectrum of action. For cephalosporins, progressive structural modification has led to successive ‘generations’ (first to fifth), with increasing activity against Gram-negative bacteria and less oral activity. Cephalosporins and carbapenems are naturally more resistant to β-lactamases than penicillins due to fusion of the β-lactam ring with a dihydrothiazine ring (cephalosporins) or a unique hydroxyethyl side chain (carbapenems).

Question 3

Indications for Cephalosporin’s

Answer 3

Oral cephalosporins are second- and third-line treatment options for urinary and respiratory tract infections.

Intravenous cephalosporins and carbapenems are reserved for the treatment of infections that are very severe or complicated, or caused by antibiotic-resistant organisms. Due to their broad antimicrobial spectrum they can be used for most indications (with these caveats).

Question 4

Contraindications for Cephalosporin’s

Answer 4

Cephalosporins and carbapenems should be used with caution in people at risk of C. difficile infection, particularly those in hospital and the elderly. The main contraindication is history of allergy to a penicillin, cephalosporin or carbapenem, particularly if there was an anaphylactic reaction.

Question 5

Side effects of Cephalosporin’s

Answer 5

Common:Gastrointestinal upset, such as nausea and diarrhoea

Less frequent: antibiotic-associated colitis occurs when broad-spectrum antibiotics kill normal gut flora, allowing overgrowth of toxin-producing Clostridium difficile. This is debilitating and can be complicated by colonic perforation and death. Hypersensitivity, including immediate and delayed reactions may occur (see Penicillins).

As cephalosporins and carbapenem share structural similarities to penicillins, cross-reactivity may occur with some penicillin-allergic patients.

Risk of CNS toxicity including seizures

Question 6

Interactions of Cephalosporin’s

Answer 6

As broad-spectrum antibiotics, cephalosporins and carbapenems can enhance the anticoagulant effect of warfarin by killing normal gut flora that synthesise vitamin K. Cephalosporins may increase nephrotoxicity of aminoglycosides. Carbapenems reduce plasma concentration and efficacy of valproate.

Question 7

Elimination of Cephalosporin’s

Answer 7

Renal

Question 8

Patient information on Cephalosporin’s

Answer 8

Cephalosporins can be administered orally, as tablets, capsules or oral suspension, or by injection, which can be IV, as bolus injection or infusion, or IM.

Explain that the aim of treatment is to get rid of infection and improve symptoms. For oral treatment, encourage the patient to complete the prescribed course. Before prescribing, always check with your patient personally or get collateral history to ensure they do not have an allergy to any form of penicillin or other β-lactam antibiotics. Warn them to seek medical advice if a rash or other unexpected symptoms develop. If an allergy develops during treatment, give the patient written and verbal advice not to take this antibiotic in the future and make sure that the allergy is clearly documented in their medical records.