Best antibiotics for a cat bite

Cat bite and antibiotic
Cat bite and a preferred antibiotic. Photos: Michael.
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These are the best antibiotics for cat bites (my thanks to InFocusL Culture that Infected Cat Bite (and Give Antibiotics):


  • Amoxicillin-clavulanate (Augmentin)


Add metronidazole to each alternative – used for anaerobic activity. It is unclear if metronidazole is always necessary and it is usually added for prophylaxis.

  • Doxycycline
  • Trimethoprim/sulfamethoxazole (Bactrim)
  • Penicillin VK
  • Cipofloxacin/levofloxacin


  • Cephalexin (Keflex)
  • Dicloxacillin
  • Erythromycin
  • Clindamycin
Preferred antibiotics for cat bites
Preferred antibiotics for cat bites

Some Detail

Dr Robert James MD writing in Emergency Medical News provides us with some very useful information about the most effective antibiotics for cat bites. He incorrectly (sorry doctor) says that cats sometimes bite ‘for no good reason’. They always bite for a reason even if some people don’t understand it.

In order to decide the best antibiotics, you have to find out ‘the microbiology of infected cat bites’. In other words, you have to know what species of bacteria are deposited under the skin when the cat bites.

A study enrolled 57 people who’d been bitten. They had bad infections. Most of the bites were puncture wounds. Comment: these typically leave two or four ‘vampire’ holes in the skin. The infections had taken hold very quickly i.e. after 25 hours.

Five organisms were found that had been ‘injected’ into the person. They were aerobes and anaerobes. These are organisms which can survive where there is oxygen and without oxygen respectively.

Most common organism

The most common organism isolated (75% of bites) was of the Pasteurella species, particularly Pasteurella multocida. ‘Streptococcus and Staphylococcus were common aerobic organisms, but a number of anaerobes were also identified’.

Treatment should be directed at ‘Pasteurella, Streptococcus, Staphylococcus, and anaerobes’.

Personal experience

I suffered a nasty cat bite from my beloved cat. It is very rare. It was a case of ‘transferred aggression‘ and not aggression directed at me. It needed almost immediate antibiotics. I was prescribed Doxycycline. They worked by it took ages – about 2 months as I recall. This was the correct antibiotic but the infection was bad. I could not be prescribed penicillin as I am allergic to it.


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