Animal bite injuries caused by domestic and wild animals: retrospective analysis and development of a prognostic score

Abstract

The current guidelines on injuries caused by animal bites recommend surgical debridement and antibiotic treatment. Bite wounds generally lead to high-risk infections due to deep skin lesions. However, bite wounds may differ dramatically in terms of depth and involvement of different anatomic structures. A prognostic classification regarding depth or severity is only available for facial injuries in paediatric patients, provided by Lackmann's score. In this study, we assessed prognostic factors and developed a prospective score for general animal bite injuries. We performed a retrospective single-centre analysis in patients sustaining animal bite injuries from 2007 to 2017. Patients were subdivided according to animal species, location of bite(s), type of treatment and medical care, admission, length of stay, need for revision, and spectrum of microorganisms. We established and verified a rating score ranging from grade I (superficial scratch) to grade Va (deep wound with bone involvement) and grade Vb (deep wound with joint involvement). This study included 567 patients with animal bite injuries, of which 51.7 % were caused by dogs, 39.2 % by cats and 4.1 % by wild animals. 75.7 % of injuries were located in the hands, 12.9 % in the arms, 5.1 % in the face and 5.3 % in other body parts. The most common microorganism was pasteurella, followed by staphylococci and other aerobic strains. Antibiotic treatment comprised Sultamicillin in 75 % of cases, cephalosporins in 10.2 %, Clindamycin in 7.6 % and other antibiotics in 5.1 % of cases.There was a significant correlation (p < 0.001) between animal species and presence of an infection, type of medical care, rating score and spectrum of microorganisms as well as between rating score and need for revision, duration of antibiotic treatment, mode of admission, treatment and medical care, and length of hospital stay. The prognostic value of the established rating score was verified. In addition, the study demonstrated that animal species are an important factor influencing treatment. Being effective against most of the identified microorganisms, Sultamicillin should be used as first-line antibiotic treatment.