Keftab (Cephalexin) vs Alternative Antibiotics: Quick Comparison

Quick Takeaways

• Keftab (Cephalexin) is a first‑generation cephalosporin best for skin, bone and urinary infections.
• It shares a beta‑lactam core with penicillins but resists many common beta‑lactamases.
• Alternatives such as amoxicillin, doxycycline, clindamycin and azithromycin cover overlapping but distinct bacterial spectrums.
• Key decision factors: infection site, susceptibility patterns, patient allergies, and dosing convenience.
• For community‑acquired infections without penicillin allergy, Cephalexin often offers a simpler, well‑tolerated option.

What is Keftab (Cephalexin)?

When you see the brand name Keftab is the Australian trade name for the generic antibiotic Cephalexin, think of a white‑pill that belongs to the first‑generation cephalosporin family. Cephalexin was first approved by the U.S. Food and Drug Administration (FDA) in 1979 and has since become a staple for doctors treating mild to moderate bacterial infections.

Cephalexin works by interrupting cell‑wall synthesis in susceptible bacteria, leading to rapid bacterial death. Its beta‑lactam ring is similar to that of penicillins, but chemical tweaks give it extra stability against many beta‑lactamases that would otherwise break down penicillin drugs.

How Cephalexin Works: The Science in Simple Terms

The drug targets the enzyme transpeptidase, which links peptidoglycan strands in the bacterial cell wall. By binding to this enzyme, Cephalexin prevents the final cross‑linking step, leaving the wall weak and leaky. Without a sturdy wall, bacteria cannot survive the osmotic pressure of their environment and burst open.

Because the mechanism relies on a structure common to many Gram‑positive bacteria, Cephalexin is especially potent against Staphylococcus aureus (non‑MRSA), Streptococcus pyogenes, and certain Enterococcus species. Its activity against Gram‑negative organisms is modest, which is why doctors often pair it with other agents when a broader spectrum is needed.

When Doctors Prescribe Keftab

Typical indications include:

• Uncomplicated skin and soft‑tissue infections (e.g., cellulitis, impetigo).
• Bone infections like osteomyelitis caused by susceptible organisms.
• Urinary tract infections (UTIs) where Escherichia coli is known to be sensitive.
• Dental abscesses after dental extraction.
• Prophylaxis before certain surgical procedures.

The usual adult dosage ranges from 250mg to 1g taken 2‑4 times daily, depending on infection severity. Children receive weight‑based dosing, generally 25‑50mg/kg per day divided into multiple doses.

Key Alternatives to Cephalexin

Not every infection fits Cephalexin’s profile. Below are four widely used alternatives, each with distinct strengths and weaknesses.

Amoxicillin

Amoxicillin is a broad‑spectrum penicillin that covers many of the same Gram‑positive bugs as Cephalexin but also hits a few additional Gram‑negative organisms like Haemophilus influenzae. It’s often the first choice for otitis media, sinusitis, and community‑acquired pneumonia.

Doxycycline

Doxycycline is a tetracycline antibiotic prized for its oral convenience (once‑daily dosing) and activity against atypical bacteria, such as Mycoplasma and Chlamydia, plus some MRSA strains. It’s a go‑to for travel‑related diarrhea and certain tick‑borne infections.

Clindamycin

Clindamycin is a lincosamide that penetrates bone and abscesses very well. It’s an excellent fallback for patients allergic to beta‑lactams, but it carries a higher risk of Clostridioides difficile colitis.

Azithromycin

Azithromycin is a macrolide known for its long half‑life, allowing a 5‑day course to replace a typical 7‑10‑day regimen. It works nicely for atypical pneumonia and certain sexually transmitted infections, yet resistance among Streptococcus pneumoniae has risen sharply.

Side‑Effect Profiles at a Glance

All antibiotics can cause gastrointestinal upset, but the frequency and severity differ. Below is a quick reference:

• Keftab (Cephalexin): nausea (10‑15%), mild diarrhea (5‑10%), rare rash.
• Amoxicillin: similar GI upset, higher chance of allergic rash (up to 10%).
• Doxycycline: photosensitivity, esophageal irritation, possible yeast infections.
• Clindamycin: higher incidence of C.difficile infection (up to 5%).
• Azithromycin: generally well‑tolerated, but can cause QT‑prolongation in susceptible patients.

Comparison Table: Cephalexin vs. Common Alternatives

How to Choose the Right Antibiotic

Think of the selection process as a checklist rather than a guess. Ask yourself:

1. What is the likely pathogen? Culture results are gold, but empiric choices rely on common culprits for the infection site.
2. Is the patient allergic to beta‑lactams? A documented penicillin allergy pushes you toward clindamycin or a macrolide.
3. Does the infection involve bone or deep tissue? Drugs that penetrate well (Cephalexin, Clindamycin) are preferred.
4. Are there local resistance patterns? In regions with high macrolide resistance, azithromycin loses appeal.
5. What dosing schedule fits the patient? Once‑daily agents (Doxycycline, Azithromycin) improve adherence for busy adults.
6. Any special populations? Pregnancy, renal impairment, and children each shift the risk‑benefit balance.

When the infection is a straightforward skin infection in a non‑allergic adult, Cephalexin often wins because it’s cheap, well‑tolerated, and hits the usual suspects. If the same patient has a penicillin allergy, clindamycin becomes the next logical step.

Special Considerations for Australian Patients

Australian Therapeutic Guidelines (2024 edition) list Cephalexin as a first‑line oral option for uncomplicated cellulitis and mild osteomyelitis. The government PBS subsidises Cephalexin, Amoxicillin, and Doxycycline, but not clindamycin or azithromycin unless a specialist writes the script. That cost difference can influence prescribing in a public health setting.

The rise of community‑acquired MRSA in parts of Western Australia has prompted clinicians to add coverage with doxycycline or clindamycin when MRSA is suspected. However, susceptibility testing still shows that about 85% of MSSA isolates remain fully sensitive to Cephalexin, keeping it in the frontline toolbox.

Potential Pitfalls & How to Avoid Them

• Cross‑reactivity mistake: Many prescribers assume a 10% cross‑reactivity between penicillins and cephalosporins. Modern data suggest it’s closer to 1‑2% for first‑generation agents like Cephalexin, so an uncomplicated penicillin allergy may not rule it out.
• Skipping the loading dose: For severe skin infections, an initial 1g dose of Cephalexin can achieve therapeutic levels faster.
• Ignoring renal function: Cephalexin is renally cleared; dosing should be halved for eGFR <30mL/min.
• Overlooking drug interactions: Doxycycline chelates with calcium supplements, reducing absorption-take it on an empty stomach.

FAQs

Bottom Line

If you need an oral antibiotic for a typical skin, bone, or urinary infection and you don’t have a severe beta‑lactam allergy, Cephalexin (Keftab) is a solid, affordable choice. When the infection involves atypical bacteria, MRSA, or when the patient can’t tolerate beta‑lactams, alternatives like doxycycline, clindamycin or azithromycin fill the gaps.

Always pair the drug choice with a quick look at local resistance patterns, patient history, and practical dosing considerations - that’s the shortcut to successful treatment without unnecessary side effects.