Human bites are important for their propensity to result in a possibly severe infection of the skin, as numerous pathogenic bacterial species reside in the human oral cavity. The hands and fingers are the most commonly reported as the site of bites. The presence of localized erythema, swelling, and purulent discharge suggest an infection. A properly obtained patient history and a physical examination are the mandatory steps in making the diagnosis.
The clinical presentation of human bites depends on several factors, and two main types of bites are described in the literature  :
Virtually any site of the body is a target of a human bite, but the principal locations are the hands and fingers, the extremities, and the head and neck area   . Human bites are much more frequent among males, with a median age of presentation established at 28 years of age . Although human bites do not cause profound destruction of the affected tissues directly, the reason why early recognition is necessary is the risk for wound infection from the bacteria that were introduced from the oral cavity, especially because they are able to descend into deeper tissues once the integrity of the skin is disrupted     . Studies have shown that 10-25% of human bite victims will develop a wound infection, and principal causative agents are Streptococcus angiosus, Staphylococcus aureus, Fusobacterium, Prevotella melaninogenica, and Eikenella corrodens, whereas Peptostreptococcus, but also Candida sp. are described as well   . More importantly, the infection can often be polymicrobial, which often complicates the therapeutic approach . The clinical presentation of human bites is not always evident, particularly in the absence of a clear bite mark on the skin. If localized swelling, purulent and foul-smelling discharge, and erythema are present, a strong suspicion of a wound infection must be made  . These signs appear within the first few days after the bite and may be accompanied by a fever and proximal lymphadenopathy . Patients suffering from an underlying immunosuppressive disease, liver failure, or systemic lupus erythematosus (SLE) have shown to be at an increased risk for infection .
Because secondary infections of the wounds caused by human bites potentially lead to significant local tissue destruction, physicians must make a prompt diagnosis. They can only do so, however, by obtaining a detailed patient history and performing a meticulous physical examination. Patients must be asked about the setting and the time of injury, as well as the exact location, which could be identified during the inspection . A detailed personal history, including identification of immunosuppressive disorders or diabetes mellitus, is also important . If possible, a detailed patient history of the individual who bit the patient should be obtained as well, as numerous infections, both bacterial and viral (hepatitis B, hepatitis C, and theoretically HIV) can be transmitted through a human bite   . The physical exam needs to cover the presence of localized symptoms, the extent of soft-tissue injury and depth of the bite, but also if any foreign bodies are present in the wound  . One of the typical findings of a human bite is the distance between the teeth marks in adults. Namely, the average distance of maxillary canine teeth in adults is about 3 cm, which may be a useful tool for making the diagnosis if data during history taking are inconclusive . Imaging studies, in the form of plain radiography, computed tomography (CT), or ultrasonography, might be performed to assess the extent of the soft-tissue injury, while microbiological studies of the samples obtained from the wound are necessary to reveal the underlying pathogen responsible for the infection  .