Human bites can become easily infected due to the large amount of bacteria in the human mouth. The most common types of human bites are clenched fist injuries and occlusive bites, which occur on the hands. Human bites often result from aggressive behavior or domestic violence and have high infection rates. Investigation may include blood tests and radiography to check for fractures or infections. Treatment involves thorough wound cleaning, possible closure of selected wounds, antibiotics for infection prevention or treatment, and reconstructive surgery if needed.

1. Human bites
DR MUNTHALI
MODERATOR: DR MITI

2. Definition
 A human bite occurs when a human's teeth make contact with another human's
skin. Approximately 10%-15% of human bite wounds become infected owing to
multiple factors. The bacterial inoculum of human bite wounds contains as many
as 100 million organisms per milliliter and is made up of as many as 190 different
species. Many of these are anaerobes that flourish in the low redox environment of
tartar that lies between human teeth or in areas of gingivitis. Most injuries due to
human bites involve the hands. Hand wounds, regardless of the etiology, have a
higher rate of infection than do those in other a locations

3. Types
1) Clenched fist injury
2) Occlusive bites

4. Types
 Clenched fist injury
They occur as the closed fist strikes the teeth of another individual with sufficient
force to create a small wound, usually 3-8 mm in length. The injury usually occurs
over the dorsal surface of the 3rd and 4th metacarpophalangeal (MCP) or proximal
interphalangeal joints of the dominant hand. potential injuries include joint
penetration, metacarpal fracture, and extensor tendon laceration.
Occlusive bites
Occlusive bites occur when there is sufficient force to break the skin. Such injuries to
the hand have a higher infection rate than similar bites to other parts of the body
because of the thinness of the skin in this area.

5. Etiology
 Aggressive behavior, often in combination with alcohol (the cause of most clenched-fist injuries)
 Rough sexual play or sexual assault
 Domestic violence
 Child abuse
 Occupational injury to dental personnel
 Seizure-related tongue lacerations
 Nose biting (punishment for adultery in several cultures)[8]
 Accidents during sporting events
 Aggressive play of children in daycare centers
 Self-inflicted wounds in persons who are emotionally disturbed or mentally handicapped - Lesch-
Nyhan syndrome is an uncommon disorder that includes self-mutilation through biting

6. Epidermiology
 Human bites are ranked as the third leading cause of all bites seen in hospital
emergency departments (after dog and cat bites), accounting for 3.6-23% of bite
wounds
 approximately 60% occur in an upper extremity (most frequently the dominant
one), while 15% occur in the head and neck region, most commonly the ears, nose,
or lips. The remainder occur on the breasts, genitals, thighs, and other areas.
 Clenched-fist infections are predominantly found in men, presumably owing to
their more aggressive behavior. Occlusive bite wounds occur with equal frequency
in males and females

7. Complications
 Cosmetic deformity resulting from wound contraction
 Permanent hand disability secondary to stiffness and/or chronic pain
 Infectious tenosynovitis
 Septic arthritist,
 Abscess formation
 Amputation (rare)
 Transmission of disease (eg, hepatitis B or C, HIV)
 Osteomyelitis
 Necrotizing fasciitis
 Joint infections

8. Investigations
FBC, Blood cultures, renal and liver function tests if bacteremia or sepsis is suspected.
If indicated, draw appropriate baseline viral titers from the patient and the assailant
Radiography may be useful, particularly in hand injuries or over bone, to reveal
fractures, foreign bodies, or air within a joint

9. Treatment
 Wound cleaning
 wound Closure (selected wounds)
 Tetanus prevention
 Antibiotic use for prophylaxis or treatment of active infections
 Hepatitis and Hiv prevention
 Possible reconstructive surgery

10. Treatment
 Wound cleaning : meticulous wound care is the cornerstone of human bite
wound management. Copious irrigation decreases the incidence of wound
infection. Use isotonic sodium chloride solution, dilute povidone-iodine
(Betadine), or dilute hydrogen peroxide to thoroughly cleanse the wound.
Cleansing is best performed with a 10-mL syringe with an 18-gauge angiocatheter
attached. Take care to avoid injection of the tissues and to prevent additional
trauma.
 Wound Closure: In general, do not close hand wounds, puncture wounds, infected
wounds, or wounds more than 12 hours old.Head and neck wounds, being in a
cosmetically sensitive area, maybe closed if they are less than 12 hours old and are
not obviously infected.Antibiotic prophylaxis is mandatory in these
patients.Perform closure in a simple, interrupted fashion, avoiding layered closure
with buried sutures.The objective is to provide wound edge approximation that is
not watertight and still allow for drainage.

11. Treatment of infected burn wounds
 The current recommendations from the IDSA call for the use of
amoxicillin/clavulanate or ampicillin/sulbactam in patients with an infected human
bite wound. Cephalexin, which is commonly used for skin and soft-tissue
infections, is ineffective against E corrodens, an important pathogen in infected
human bites. Trimethoprim-sulfamethoxazole (TMP-SMZ) or a quinolone such as
levofloxacin or moxifloxacin in addition to clindamycin is an acceptable alternative
in the penicillin-allergic patient

12. References
1. Kennedy SA, Stoll LE, Lauder AS. Human and Other Mammalian Bite Injuries of the
Hand: Evaluation and Management. J Am Acad Orthop Surg. 2015 Jan. 23 (1):47-57
2. Aziz H, Rhee P, Pandit V, Tang A, Gries L, Joseph B. The current concepts in
management of animal (dog, cat, snake, scorpion) and human bite wounds. J Trauma
Acute Care Surg. 2015 Mar. 78 (3):641-8.
3.. Thomas MG, Hopkins CJ, Luey CE. Transmission of HIV infection by severe bites. Int
J STD AIDS. 2019 Aug. 30 (9):927-929