Cefaclor: Second-Generation Oral Cephalosporin Antibiotic
Cefaclor (Ceclor) is an oral second-generation cephalosporin with activity against both Gram-positive bacteria (including most streptococci and methicillin-susceptible staphylococci) and Gram-negative bacteria (H. influenzae, E. coli, Klebsiella, Moraxella catarrhalis).
Used primarily for respiratory tract infections, otitis media, urinary tract infections, and skin and soft tissue infections in outpatient settings.
Mechanism of Action
Beta-lactam antibiotic: inhibits bacterial cell wall synthesis by binding to and inactivating penicillin-binding proteins (PBPs), preventing peptidoglycan cross-linking. Bactericidal. Susceptible to beta-lactamase destruction (less stable than 3rd-generation cephalosporins).
Indications & Use
Upper respiratory tract infections (pharyngitis, otitis media, sinusitis), lower RTIs (bronchitis, pneumonia — mild community-acquired), UTIs (uncomplicated), skin and soft tissue infections. Oral use — well-absorbed even with food.
Dosage
Adults: 250–500 mg three times daily (standard course 7–10 days). Children: 20–40 mg/kg/day in 3 divided doses (max 1 g/day). Extended-release (ER): 375–500 mg twice daily. Reduce dose in renal impairment.
Side Effects
Common: diarrhoea (most frequent, ~4%), nausea. Hypersensitivity: rash, urticaria (check penicillin allergy — ~1–2% cross-reactivity with 2nd/3rd gen cephalosporins). Serum sickness-like reaction (unique to cefaclor: fever, arthralgia, rash — 0.02%–0.2%, more in children).
Drug Interactions
Anticoagulants (warfarin): may prolong PT — monitor INR. Probenecid: increases cefaclor plasma levels (reduces renal tubular secretion). Oral contraceptives: theoretical reduction of efficacy (not clinically significant per current evidence).
Contraindications
Hypersensitivity to cephalosporins. Previous severe immediate hypersensitivity (anaphylaxis) to penicillin — ~1-2% cross-reactivity risk with second-generation cephalosporins, though lower than often cited.
Frequently Asked Questions
Can cefaclor be given to patients with penicillin allergy?
The cross-reactivity between penicillins and cephalosporins is often overstated. Estimated cross-reactivity is ~1-2% for most cephalosporins. Cefaclor has a different side chain from penicillin. Patients with a mild penicillin allergy (rash) can usually receive cefaclor. Avoid in patients with a history of anaphylaxis to penicillin.
What is the serum sickness-like reaction to cefaclor?
Unique to cefaclor among cephalosporins: a serum sickness-like reaction (SSR) — fever, arthralgia, urticaria — occurring 10–14 days after starting treatment, especially in children. It is not a true serum sickness (immune complex-mediated) and resolves on stopping cefaclor.
Is cefaclor effective against MRSA?
No. Cefaclor, like all cephalosporins, is not effective against MRSA (methicillin-resistant Staphylococcus aureus). For MRSA, vancomycin, linezolid, or daptomycin are used.
References
- EMA Ceclor SPC 2023
- EUCAST Breakpoints for cephalosporins 2023
- Gruchalla RS et al. NEJM 2006 (penicillin allergy)
Medical Disclaimer: This information is for educational purposes only and does not replace professional medical advice.