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28M presents with a laceration over his MCP joint incurred during an altercation 3 days prior. He has associated erythema, edema, purulent discharge and decreased ROM. What is your management plan?

35M presents 3 hours after an altercation with what is determined after your evaluation to be an uncomplicated closed fist injury, and you intend to discharge him home. Should you provide any prophylactic antibiotics, and if so, which one? What if the patient has a penicillin allergy?

45F presents 3 hours after a seizure with a mucocutaneous (through-and-through) lower lip laceration. Should this wound be closed? What is the infection rate of this wound without prophylactic antibiotics?

BACKGROUND

50% of Americans will be injured by the bite of an animal or human during their lifetime

Bites account for 1% of all emergency department visits

The highest incidence of bites occurs in boys 5 to 9 years of age

Lack of well-designed, prospective studies

Soft tissue infection is the most common complication

Centers for Disease Control and Prevention. Nonfatal dog bite-related injuries treated in hospital emergency departments—United States, 2001. MMWR Morb Mortal Wkly Rep. 2003;52(26):605–610.Weiss HB, Friedman DI, Coben JH. Incidence of dog bite injuries treated in emergency departments. JAMA 1998;279:51-53Griego RD, Rosen T, Orengo IF, et al. Dog, cat and human bites: a review. J Am Acad Dermatol 1995;33:1019.

BACKGROUND

Soft tissue infection is the most common complication

Factors determining risk of infection:

Type of bite

BACKGROUND

Soft tissue infection is the most common complication

Factors determining risk of infection:

Type of bite

Site of bite

BACKGROUND

Soft tissue infection is the most common complication

Factors determining risk of infection:

Type of bite

Site of bite

Time elapsed between bite and presentation

BACKGROUND

Soft tissue infection is the most common complication

Factors determining risk of infection:

Type of bite

Site of bite

Time elapsed between bite and presentation

Host factors: Oral flora

BACKGROUND

Soft tissue infection is the most common complication

Factors determining risk of infection:

Type of bite

Site of bite

Time elapsed between bite and presentation

Host factors: Oral flora

Wound management

ANATOMY OF THE BITE

Bite injuries reflect the dental anatomy and jaw strength of the biting animal

DOG: large, broad, sharp teeth and powerful jaws

Lacerations, Crush and avulsion injuries

CAT: sharp, elongated needle-like teeth

Puncture wounds

HUMAN: more closely resemble dog bites than cat bites

Abrasions and lacerations >> Punctures

Tend to be more superficial than animal bites, but with higher infection rate

HUMAN BITES: CATEGORIES (NOT MUTUALLY EXCLUSIVE)

Intentional bite

Unintentional bite

Occlusional bite/Simple

Occlusional bite of the hand

Clenched-fist bite

HUMAN BITES: 2 MAJOR CATEGORIESOcclusional Bite - teeth punctures the skin

Carry same risk of infection as animal bites, except when they occur on the hand

Most simple non-hand human bites are no more significant than ordinary lacerations

Clenched-Fist Bite (“Fight Bite”) - hand is injured by contact with teeth

Usually occurs during a fistfight or accidental sports injury

Opponent’s tooth inoculates deeper tissue planes of fist with oral flora

Typically occurs at the 3rd MCP joint

Associated with a high risk of infectious complications, significant morbidity

Serious complications include septic arthritis, tenosynovitis, and osteomyelitis

Surgical amputation may be required [74, 75]

Rate of infectious complication in hand bites is estimated at 25 to 50% [88]

Compartmentalized anatomy of the hand contributes to increased infection risk

Requires prompt and appropriate identification and management

HUMAN BITES: MICROBIOLOGY

Human mouth carries a high population of resident bacteria

A larger number of bacteria is transferred to the victim compared to dog, cat bites

Eikenella corrodens is characteristic of human bites

(found in >30% of human bites)

Pasteurella multicoda is absent in human bites

Higher incidence of beta-lactamase producing organisms

CLASSIC SYSTEMIC INFECTIONS TRANSMITTED BY BITESViral: Arbovirus (bat), B herpes virus (macaque), CMV (chimpanzee),

hantavirus (rodent), HBV, HCV, HIV, rabies, Venezuelan equine

encephalitis (bat)

Bacterial: brucellosis (dog), cat-scratch disease (cat, dog, monkey),

leptospirosis (dog, mouse, rat), plague (cat), rat-bite fever (dog, gerbil,

mouse, rat, squirrel, weasel), syphilis, tetanus (dog), tularemia (cat, dog,

other mammals)

Mycobacterial: M. marinum (dolphin), tuberculosis (human)

Fungal: blastomycosis (dog), sporotrichosis (cat)

Parasitic: trypanosomiasis (bat)

RISK FACTORS FOR SOFT TISSUE INFECTION FROM ANIMAL OR HUMAN BITELocation on the hand, foot, or over a major joint 

Location on the scalp or the face of an infant

Infection of cartilaginous (ear, nose) 

Puncture wound (often cat bites)

Immunosuppression 

Chronic alcoholism 

Diabetes mellitus 

Corticosteroid use 

Delay in treatment lasting longer than 12 hours 

Preexisting edema in an affected extremity 

AMONG THOSE WHO SEEK MEDICAL ATTENTION FOR BITE INJURYInfection rates

Dog: 2 to 20%

Cat: 30 to 50%

Human: 10 to 50%

Bite Type

Dog: 80 to 90%

Cat: 3 to 15%

Nondomestic animals: 1 to 2%

ORGANISMS MOST FREQUENTLY ISOLATED FROM DOG AND CAT BITE WOUNDSBite wounds are grossly contaminated

Polymicrobial (mix of aerobes and anaerobes)

Aerobes:

Pasteurella multocida (50 to 80% of cat bites, 25% of dog bites)

Corynebacterium spp, Staph, Strep and (rare) Capnocytophaga canimorsus

Anaerobes:

Bacteroides spp, B. fragilis, Prevotella, Porphyromonas, Peptostreptococci, Fusobacterium, Veillonella parvula

PASTEURELLA MULTOCIDA - MOST COMMON DOMESTIC ANIMAL BITE

PATHOGENGram negative, facultative anaerobe, zoonotic pathogen

Most common pathogen isolated from domestic animal bite

50 to 80% of cat bites, 25% of dog bites

Symptoms classically arise within first 24 hours of bite

Erythema, edema, tenderness, bloody drainage

Typically, localized cellulitis and abscesses

Complications: direct extension, lymphangitis, LAD, bacteremia, OM, arthritis, tenosynovitis, sepsis, meningitis, brain abscess, pneumonia, endocarditis

Risk factors for complicated infection: DM, cirrhosis, rheumatoid arthritis, neoplasms, immunosuppression

Bite wound infection developing after >24hr, less likely Pasteurella

ANTIBIOTICS – FOR HIGH RISK ANIMAL BITESSelect a broad-spectrum antibiotic with anaerobic and aerobic

coverage

Augmentin (amoxicillin-clavulanate) is gold standard

Bactrim (trimethoprim-sulfamethoxazole), Doxycycline, Ciprofloxacin

PATHOGENS OF HUMAN BITES

Also polymicrobial, but usually higher # of isolated organisms compared to animal bites

Average 5 organisms per bite wound

The concentration of bacteria in the human oral cavity is higher compared to animals

Anaerobes:

Similar distribution of anaerobes as in animal bites. Bacteroides spp are more common than animals

-However in human bites these pathogens often produce Beta-lactamases

Aerobes:

Different distribution. Most common Staph aureus, Staph epidermidis, alpha and beta hemolytic strep, Corynebacterium, and E. corrodens

Viral exposures:

Hepatitis B or C, HIV

EIKENELLA CORRODENS - COMMON HUMAN BITE PATHOGENGram negative rod, facultative anaerobe

Normal human oropharyngeal flora

Often causes serious, chronic infections

[you may remember it as implicated in culture-negative endocarditis “HACEK”

and Needle-licker’s osteomyelitis]

Typically indolent infections, requiring incubation period of 1 week or more

Foul-smelling

Common isolate of human bite infections

Especially in Clenched-Fist injuries (25%)

Augmentin or Unasyn are first-line due to broad coverage and E. corrodens sensitivity

MANAGEMENT OF BITE WOUNDS

ABCs. History. Neurovascular assessment (distal pulses, sensory/motor exam, ROM)

Evaluate for signs of infection and involvement of deeper structures (joint, tendon, bone)

Gram stain and culture (aerobic and anaerobic) wounds that appear infected

* Meticulous wound care is of utmost importance *

High-pressure irrigation

Debridement

Always leave HUMAN BITE wounds OPEN

Immobilize and elevate injured extremities

Determine tetanus status and vaccinate prn

MANAGEMENT OF BITE WOUNDS

X-rays may be indicated to rule out osseous injury, gas formation, foreign bodies

CT, MRI or even open exploration/surgical debridement may be indicated in rare instances

Antimicrobial therapy? Empiric treatment if evidence of wound infection. Or consider prophylaxis for wounds without evidence of infection.

Critical attacks may require collaboration of multiple services: Plastics, Vascular, Ortho, etc.

The majority of cases can be treated as outpatient

With oral antibiotics and site elevation at home

WOUND MANAGEMENT: TO CLOSE OR NOT TO CLOSEControversial topic

Options for closure include primary closure, healing by secondary intention, delayed direct closure, skin grafts, composite grafts, and local flaps

When to close: All CLOSED wounds require prophylactic abx

DOG BITE If seen early (<12h) and not involving the hand Avoid any buried sutures or layered closures

Many facial bite wounds Goal: approximate edges yet allow for drainage

When to leave open:

Most DOG BITES After 12h

ALL CAT BITES

ALL HUMAN BITES

ALL bites involving the victim’s HAND

Most puncture wounds

Infected wounds

SPECIAL CONSIDERATIONS IN CLENCHED-FIST BITE MANAGEMENTImportant to recognize the potential severity of the injury in a clenched-fist bite

The compartmentalized anatomy of the hand can contribute to the development of an infection.

If an infection is not appropriately diagnosed and treated, significant morbidity can result.

Often delay in seeking care, late presentation

Classically a small 3 to 5mm laceration on the dorsum of the hand, overlying an MCP joint

Must assess extensor tendon function in clenched-fist injuries

Puncture wounds should be extended proximally & distally while looking for extensor tendon injury

Early surgical intervention may be warranted, especially in setting of risk factors/comorbidities (DM, PVD, immune compr)

Some MDs believe that all CFIs warrant inpatient admission and surgical consultation

OTHER SPECIAL CONSIDERATIONS

For infants and small children (up to 2 years old) who sustain substantial bite wounds to the scalp, should obtain skull films or CT.

Evidence of skull perforation neurosurgical c/s and admit patient

Facial bite wounds: infectious complications create challenges in restoring esthetic appearance

Care of avulsed body parts:

Wrap in sterile gauze soaked with normal saline and place in plastic bag

Place that bag in a container of ice water

For bites violating cartilaginous tissue, should consult plastics and/or ENT

Inform your patients and involve them in decisions

SPECIAL CONSIDERATIONS FOR ANIMAL BITESIn most states, physicians are required by law to report animal

bites

Address potential need for Rabies prophylaxis

Immune-globulin on day of presentation. Vaccination on days 0, 3, 7, 14

MANAGEMENT OF EARLY HUMAN BITES OF THE HAND: A PROSPECTIVE RANDOMIZED STUDYZubowicz VN, Gravier M. Plast Reconstr Surg. 1991;88:111–4

N=45 bite wounds to the hand

All seen within 24 hours

All without e/o infection, tendon injury or joint capsule penetration

Of those subjects who did NOT receive antibiotics, 47% developed an infection

Of those subjects who Did receive prophylactic antibiotics, 0% developed an infection

Study was terminated early d/t high infection rate in control group

CONCLUSION: ALL hand bites should be managed with ppx antibiotics

Zubowicz VN, Gravier M. Management of early human bites of the hand: a prospective randomized study. Plast Reconstr Surg. 1991;88:111–4

ANTIMICROBIAL THERAPYProphylaxis is still controversial. Should at least be considered

with every bite wound.

Generally 5 to 7 days of oral broad-coverage antibiotic: Augmentin is first-line

Prophylactic abx for all bite wounds that are closed to heal by primary intention

Empiric therapy with broad coverage for infected wounds

Narrow to culture/sensitivities

Lack of well-designed, prospective, randomized controlled studies

A meta-analysis of randomized trials found that prophylactic antibiotics reduced the rate of infection in dog bite wounds

A Cochrane review found there is evidence that the use of ppx abx reduced infection rates in bites of the hand, and that there is no evidence for ppx abx in dog and cat bites

INDICATIONS FOR INTRAVENOUS ANTIBIOTICSPatients with systemic signs/symptoms of infection

Severe or extensive cellulitis

Compromised immune status

Diabetics

Significant bites to the hand

Joint, nerve, bone or tendon involvement

Infection refractory to oral antibiotic therapy

(DEBATABLE) INDICATIONS FOR PROPHYLACTIC ANTIBIOTICS

All hand bites

Dog bites more than 8-12 hours old

Moderate to severe dog bites less than 8-12 hours (edema, crush injuries)

Puncture wounds, particularly if bone or joints were penetrated

Severe facial wounds

Wounds in the genital area

Wounds in immunocompromised or asplenic patients

Moderate to severe cat or human bites

HUMAN BITE WOUNDS TO THE HAND

= Indication for antibacterial therapy

Broad spectrum ie Augmentin recommended COURSE?

For Penicillin allergy, Clindamycin + CIPRO or BACTRIM or DOXYCYCLINE

For prophylaxis: 5 to 7 day course

Longer course for infected wounds [44]

REFERENCESAgency for Healthcare Research and Quality National Guideline Clearinghouse. Management of human bite

wounds. Available at: http://www.guideline.gov/content.aspx?

Dellinger EP, Wertz MJ, Miller SD, Coyle MB. Hand infections. Bacteriology and treatment: a prospective study. Arch Surg. 1988;123:745–50.

Goldstein EJC. Bite wounds and infections. Clin Infect Dis 1992;14:633.

Griego RD, Rosen T, Orengo IF, et al. Dog, cat and human bites: a review. J Am Acad Dermatol 1995;33:1019.

Gurunluoglu R1, Glasgow M, Arton J, Bronsert M. Trauma Acute Care Surg. 2014 May;76(5):1294-300. Retrospective analysis of facial dog bite injuries at a Level I trauma center in the Denver metro area.

Patzakis MJ, Wilkins J, Bassett RL. Surgical findings in clenched-fist injuries. Clin Orthop. 1987;220:237–40.

Presutti RJ. Bite wounds: early treatment and prophylaxis against infectious complications. Postgrad Med 1997;101:243.

Smith PF, Meadowcroft AM, May DB. Treating mammalian bite wounds. J Clin Pharm Ther 2000;25:85-

Tan JS. Human zoonotic infections transmitted by dogs and cats. Arch Intern Med 1997;157:1933.

Weber DJ, Hansen AR. Infections resulting from animal bites. Infect Dis Clin North Am 1991;5:663.

Weiss HB, Friedman DI, Coben JH. Incidence of dog bite injuries treated in emergency departments. JAMA 1998;279:51-53

Zubowicz VN, Gravier M. Management of early human bites of the hand: a prospective randomized study. Plast Reconstr Surg. 1991;88:111–4