Management of Dog Scratch Infections

Microbiology and Epidemiology

Dog scratches can introduce multiple bacteria into the wound, with an average of 5 different bacterial species per wound, including Pasteurella species, Staphylococcus aureus, and Streptococcus species, as well as anaerobic bacteria like Bacteroides and Fusobacterium 2
Pasteurella species are found in 50% of dog bite/scratch wounds, while Staphylococcus aureus and Streptococcus species are found in approximately 40% of wounds 2, 3
Anaerobic bacteria, including Bacteroides, Fusobacterium, and Peptostreptococci, are also common in dog scratch infections 4, 1

The Infectious Diseases Society of America recommends amoxicillin-clavulanate as the first-line antibiotic treatment for dog scratches due to its broad coverage against both aerobic and anaerobic bacteria 1
Alternative oral options include doxycycline, which has excellent activity against Pasteurella multocida, and penicillin VK plus dicloxacillin 1, 6
For severe infections, intravenous options such as ampicillin-sulbactam, piperacillin-tazobactam, and second-generation cephalosporins like cefoxitin may be considered 1, 6

For minor dog scratches, prophylactic antibiotics may be considered for 3-5 days in high-risk patients, such as those who are immunocompromised or have advanced liver disease 1, 6
For established infections, empiric therapy with amoxicillin-clavulanate should be started, and treatment should be continued for 7-14 days depending on severity 1
Tetanus prophylaxis should be administered if vaccination is not current, and rabies prophylaxis should be considered based on consultation with local health officials 7, 1

Hand wounds are at higher risk for complications and should be treated more aggressively 2, 1
Failure to recognize the polymicrobial nature of dog scratch infections can lead to inadequate treatment, and using antibiotics with inadequate coverage against Pasteurella species can also lead to treatment failure 2, 4