A child comes to an emergency room because of an infected dog bite. The wound is found to contain small Gram-negative rods. The most likely cause of infection is

Pasteurella multocida, a coccobacillary Gram-negative rod, is pa of the normal mouth flora of dogs and cats. Consequently, many animal bites become infected with this microorganism. It is susceptible to penicillin, although multiresistant strains have been recovered from pigs and sheep. P. multocida has four different capsular types--designated A, B, D, and E--that correlate with disease production and host predilection; however, serotyping of these isolates is beyond the resources of most laboratories. Reference: Ananthanarayan and Paniker&;s Textbook of Microbiology Tenth edition