When Your Two-Legged "Friend" Bites

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WHEN YOUR TWO-LEGGED "FRIEND" BITES

A new study from Texas offers new guidance for treatment for human bites of the heck and neck region.

Alexandria, VA -- The risks associated by too close contact with the animal kingdom are well known. Consequently, there is no question regarding the proper treatment regimen required when an adult or child is bit by a dog, cat, or member of the wild.

But oddly enough there remains controversy regarding the medical and surgical treatment for bites from the most dangerous of all animals -- man. Although human bites are less common than dog or cat bites, they make up two to 23 percent of all bite wounds. Fifteen to 20 percent of human bites are in the head and neck. Other common sites include the hands, arms, and shoulders in men, and the breasts, genitalia, legs, and arms in women. It is estimated that half of all the people in the US will be bitten by an animal or person at some time in their life. Of these, only 20 percent will require medical attention, with most others being minor in nature. Other victims may avoid medical treatment because of embarrassment, resolution of injury, or fear of legal ramifications. Most bites occur during fights, but sports accidents and sexual activity are other sources of injury. Human bites are seasonal, increasing during the spring and summer and on weekends.

Treatment options for human bites have long been a subject of controversy. Early reports from the 1920's and 1930's describe severe infections after human bites. Historical treatments include radical wound excision, wound edge electrocautery, nitric acid cleansing, or radiotherapy. Other suggestions include treating human bites of sites other than the hand with the same wound management principles as lacerations and abrasions. Later research offered that the generous vascularity of the face might account for decreased wound infections compared with other body sites. Further research efforts advocated antibiotic treatment and primary repair, or secondary reconstruction for bites to the face. Some 23 years ago, a new study demonstrated infection prevention with early debridement, antibiotics, and kanamycin soaks.

There have been few recent studies on the treatment and outcome of human bites in the head and neck region. Now, the experience of treating such bites at a major medical center is recorded in a new study. The authors of "Treatment and Outcome of Human Bites in the Head and Neck," are Karen L. Stierman MD, from Austin, TX; Danielle M. DeLuca-Pytell MD, Linda G. Phillips MD, and Karen H. Calhoun MD, all from the University of Texas Medical Branch, Galveston, TX, and Kristen M. Lloyd from the University of Florida, Gainesville, FL. Their findings are appearing in the June 2003 edition of Otolaryngology--Head and Neck Surgery, the medical journal of the American Academy of Otolaryngology--Head and Neck Surgery.

Methodology and results: A retrospective chart review was carried out examining all adult and pediatric head and neck human bites treated at the University of Texas Medical Branch, Galveston, TX, over the past 10 years. These patients were treated by otolaryngology, plastic surgery, or oral and maxillofacial surgery (OMFS) specialists.

Forty human bite cases occurred over the 10-year period 1990-2000. Follow-up ranged from one day to approximately 4.5 years (average 139 days). The average victim was 29 years old. African Americans were most commonly involved (53 percent), followed by Caucasians (30 percent) and Latin Americans (17 percent). Males made up the majority of patients (93 percent). Twenty-five bites (63 percent) occurred among patients who were inmates in the Texas Department of Criminal Justice at the time of injury.

Bites were classified as avulsion, laceration, or abrasion injury. Avulsion, a tearing-away injury, was most frequent (79 percent). The ear was the most common site involved in the head and neck (67 percent). Twenty-eight of the 40 patients presented with exposed cartilage (67 percent), most commonly in those patients with auricular avulsion injuries. All but one patient was involved in an altercation.

Medical and surgical treatments were considered separately. Medical treatment included tetanus vaccination, wound care, and antibiotic treatment. All patients received a tetanus booster if their tetanus vaccine was not known to be up to date. When ear cartilage was exposed and the wound was treated in a delayed fashion, Sulfamylon(r) or Silvadene(r) dressings were most commonly used.

Once the wound was closed, the most common topical antimicrobial treatment was Bacitracin(r). Ticarcillin/Clavulanate acid (Timentin(r)) was the most commonly used systemic antibiotic (15 of 40 cases), and penicillin and ampicillin/sulbactam (Unasyn(r)) were also frequently used. In the majority of non-infected patients (25 out of 30), antibiotics were administered intravenously for at least 48 hours. Only one patient developed post-operative infection after 48 hours of IV antibiotics, and that patient's wound was primarily surgically closed 21 hours after injury. The other five out of the six post-operatively infected patients received less than 48 hours of IV antibiotics prior to development of infection, and all of these patients' wounds were closed primarily (within 24 hours of injury). Surgical treatment was primary closure (within 24 hours of injury) in 15of the 40 patients (37.5 percent), delayed closure in 17 patients (42.5 percent), and eight wounds were never closed surgically.

Ten out of 40 (25 percent) bite injuries resulted in wound infection, defined as erythema or frank purulence documented in the medical record. Four patients were infected prior to initial medical evaluation. The other six developed infection after primary (within 24 hours of injury) surgical wound closure. Five of these six infected wounds were closed within five hours of injury. Of the 15 patients treated with primary closure, six developed post-operative infection (40 percent). None of the 17 patients treated with delayed closure (more than 24 hours after injury) became infected.

Failure to receive at least 48 hours of IV antibiotics was associated with an increased risk of infection in the group whose wounds were closed primarily. The majority of patients (21 of 33, with seven unknown) sought medical treatment within 5 hours of the injury. However, three of the four immediately infected patients had a significant delay prior to seeking treatment after injury, with an average of 18 hours from the time of injury. Although wound cultures were taken in five cases, none resulted in antibiotic therapy changes.

A total of 28 wounds had exposed cartilage (23 in the ear and five in the nose). Nine of the ten infections occurred among these patients, for a 32.1 percent infection rate. Only one infection occurred in a bite wound without exposed cartilage, for a 7.1 percent infection rate.

Conclusions: The study found that timing of treatment and medical and surgical management of human bite injury significantly impacts wound infection. Based on the experience at UTMB, the following management protocol is recommended:

1. Human bite injury should be evaluated and treated expeditiously to prevent infection. Initial treatment includes tetanus prophylaxis and copious high-pressure irrigation. 2. Once the wound is cleansed, intravenous antibiotic treatment is initiated, targeting common organisms associated with human bite injury (Timentin(r), penicillin or a quinolone is appropriate). Intravenous antibiotic treatment for at least 48 hours is recommended, followed by oral antibiotics (Augmentin, or in penicillin-allergic patients, Clindamycin, plus either Bactrim(r) or a quinolone for a total 10 days of antimicrobial treatment. 3. After initiation of antibiotic treatment, obviously devitalized tissue is debrided, and questionable areas left intact. The wound is dressed with a topical antimicrobial dressing (Sulfamylon(r) and Silvadene(r) for ear wounds, Bactroban,(r) or Dakins(r) moist-to-moist dressings). 4. Delayed primary closure (greater than 24 hours from the time of injury) minimizes infection risk, especially when cartilage is exposed. When there is avulsion injury with extensive tissue loss, locoregional flaps offer good cosmetic outcome.

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