動物咬傷

衛生署疾病管制局

中區傳染病防治醫療網

王任賢指揮官

Overview l About half of all persons will incur an animal

bite sometime in their life. l Not all bite wounds need medical attention,

but severe bite wounds and those at high risk of infection are frequent reasons for emergency department visits.

Epidemiologyl Dog bites account for majority(80%-

90%) of animal bite wounds treated in the ER, followed by cat bites (10%) and human bites (3%)

Animal Bitesl 3-6 millions animal bites yearl Estimated 300,000 annual ER visits due to

dog bitesl 6,000 yearly hospital admissions and 20

deaths due to dog bitesl Dogs 70-93% of bitesl Cats 3-15% of bitesl Infection rate 2-10% dog bitesl Higher infection rate for cats, up to 30-50%

Epidemiology - Dogl Dogs are responsible for

more than 80% of animal bite wounds

l The peak incidence is between 5 and 9 years of age

l Their own petl Most often on the

extremities. Facial bites

Epidemiology - Dogl 4% to 25% of dog bite wounds become

infectedl The median time from bite to appearance of

first symptoms of infection is 24 hours

Dog Bites:l Crush injury are common and enhances for

infection.l Rarely lethal, but may produce significant

damage.l Fatalities occur at a rate of 10-20 deaths per

year in the US, majority occurring in children.l Tend to occur in the late afternoon and early

morning, more occurring in the summer.

Dog Bites:l Victims are more likely to be male and young,

with a peak incidence with 5- to 9-year-old age group. (Boys >> Girls)

l Location of bites: Adult dog bite victims are more likely to be bitten on their extremities, while children are likely on the head and neck. (upper extremities > lower extremities > head & neck > trunk)

Dog Bites:l Puncture wounds occur in 13%-34%, lacerations

in 31%-45%, and superficial abrasions in 30%-43% of dog bite injuries.

l Victims presenting to the ER can be divided into two groups: l within 8-12 hrs of injury who are primarily concerned

about wound management and rabies l after 12 hrs with signs and symptoms of infection.

Epidemiologyl Cat bites more commonly in women, 30% to

50% of cat bite injuries become infected, appearance of first symptoms of infection is 12 hours

l Human bites occur during fights command become infected

l Other animal bites

Cat Bites:l 5-18% of reported animal bites (US).l Unlike dog bite victims, cat bite victims tend to

be female and older, with a mean age of 19.5 years.

l The majority of cat bites are inflicted by the pet of the victim or victim’s acquaintance.

Cat Bites:l Approximately two-thirds of cat bite injuries

occur on the upper extremity, frequently involving the hand.

l Due to cat’s sharp, slender teeth, which easily penetrate skin and other structures. (Up to 80% of bites become infected)

l Therefore, over half of all cat bite injuries are puncture wounds (57-86%), with lacerations (5-17%) and abrasions (9-25%) occurring less frequently.

Common bacteria- cat & dog

l Aerobic and anaerobic bacteria l Pasteurella species - facultatively anaerobic,

gram-negative coccoobacilli rods, 50% to 75% of cat bites and 20% to 50% of dog bites

l Streptococci, staphylococci, and Moraxella, Corynebacterium, and Neisseria species, Bergeyella zoohelcum, Capnocytophagaspecies

l Fusobacterium, Porphyromonas

Human Bites:l Males are more likely to be victims of human

bites, with a peak incidence in the 10- to 34-year-old age group.

l Tend to occur during the summer months, typically on weekends, and most often involve acts of aggression.

Human Bites:l The hands and upper extremities are the most

commonly bitten location (60%-75%), followed by the head and neck (15%-20%), trunk (10%-20%), and lower extremities (5%).

l For various reasons, including embarrassing circumstances and possible legal repercussions, many adult human bite victims delay seeking medical care until a complication ensues.

Human Bites:l Divided into two categories: occlusional and

clenched-fist injuries (CFIs).l Occlusional bites: closure of the perpetrator’s teeth

onto the victim’s skin.l CFIs (or “fight bites”): injuries to the dorsum of the

metacarpophalangeal region of the fist as it strikes the teeth of an adversary and most occur in young adult males with drinking.

Common bacteria - human

l S aureus, Staphylococcus epidermidis, viridansstreptococci, Eikenella corrodens, Haemophilusinfluenzae, and beta-lactamase-producing anaerobic bacteria

Pathophysiology:l Local wound infections account for approximately

95% of complications following a dog, cat, or human bite.

l Infections caused by Pasteurella species occur shortly after the bite, typically developing within 24 hours.

l Infections presenting more than 24 hrs after the bite are more likely cause by Staphylococcus and Streptococcus species.

Pathophysiology:l Cellulitis and abscess formation are the most

common, although bites may damage deep structures, including arteries, nerves, tendons, joints, and bones. Osteomyelitis, tenosynovitis, and septic arthritis occur, especially with hand bites.

l Sepsis, DIC, meningitis, endocarditis, and tetanus can develop after animal bites, and transmission of HIV and hepatitis B and C is possible from human bites.

Pathophysiology:l Puncture wounds, perhaps because of their deep

inoculation of bacteria into the tissue, are at higher risk for infection as compared with other types of bites.

l One study of mammalian bites found a 30% infection rate for punctures, 15% for lacerations, and 0% for superficial wounds such as abrasions.

Bite wounds at increased risk for infection

l Puncture woundsl Hand and upper-extremity bites l Full-thickness bitesl Bites requiring debridementl Bites in patients over 50l Bites causing damage to deep structures

Cat ZoonosesInfectious Salival Bartonella henselael Pasteurella multocidal Rabiesl Caphocytophagial Tularemial Cowpox

Dog ZoonosesInfectious Salival Rabiesl Pasteurellal Capnocytophaga l Brucella (B. canis)

Wound Culture Bacteriologic analysis of infected dog and cat

bitesl Average 5 organisms per culturel 56% (of 107) were mixed aerobic and

anaerobic infectionsl Pasturella species most common bacteria in

dog and cat bite cultures (50 and 75%)

Bacteria Isolated

19%28%Prevotella30%28%Porphyromous28%35%Bacteroides33%32%Fusobacterium5%6%Pseudomonas

10%8%Bacillus12%10%Enterococcus35%10%Moraxella28%12%Cornyebacterium19%16%Neisseria35%46%Staphylococcus46%46%Streptococcus75%50%Pasteurella speciesCatDog

Pasturella Multocidal Small gram negative,

non-motile, aerobic coccobacilli

l Common commensal in the upper respiratory tract of healthy and diseased fowls and mammals.

l Species include P. multocida, P. septica, P. canis, P. dagmatic, and P. stomatis

History l First isolated from wild

hogs 1878 l Characterized by Louis

Pasteur in 1880 l Human disease 1918

bacterial empyema from influenza A pneumonia

Route of Inoculationl Bitel Scratchl Lickl Inhalation or aspiration l Unknown

Clinical Manifestationsl Local soft tissue infectionsl Respiratory tract infectionsl Other serious or systemic infections

Soft Tissue Infectionsl Most often results in local infectionsl Inflammation, pain, swelling, and erythema within

12-24 hours l Abscess, cellulitis, lymphadenopathy, tenosynovitis.l Often in hand/finger after a cat bite due to direct

inoculationl Septic arthritis associated with chronic disease, Rh

arthritis, DJD, corticosteroid use, or prosthetic joints. l Affects joints distal to the bite

Osteomyelitisl Several reports involving the hand and digits,

acute and subacute presentation l Due to direct inoculation and penetration of

the periosteuml Few reports vertebral osteomyelitis due to

hematogenous spreadl No reported cases of sternal osteomyelitisl Treated with surgical debridement and long-

term antibiotics

Respiratory Infectionsl 2nd most common pasteurella infectionl Upper and lower respiratory tract infectionsl One series 107 patients Pneumonia 47%,

tracheobronchitis 37%, empyema 25%, lung abscess 3%

l Underlying disease present 93% cases. l Smokers, elderly populationl Mortality 29%

Sepsis l Review sited 46 case reports of sepsis due

to Pasteurella 1984-2003 l Often affects patients with underlying illness:

cirrhosis, diabetes mellitus, malignancy, COPD

l Most often due to cellulitis, arthritis, meningitis, peritonitis, pneumonia

Cardiovascular involvement l 15 reported cases endocarditisl Affects both native and prosthetic valvesl Often underlying valvular and chronic diseasel Associated with bacteremial Mortality 30%

Pasteurella Meningitis l 29 documented adult cases in English literaturel Classic presentation including fever, headache,

nuchal rigidity, altered mental status l Animal contact 89%, 15% reported animal bitesl CSF revealed elevated protein, leukocytosis,

decreased glucose, positive gram stain l Associated with bacteremia 63%, otitis media 24%

GI/GU l Spontaneous bacterial peritonitis most often

associated with cirrhosis and found in peritoneal dialysis pateints

l Bacteremia and tubo-ovarian abscessl Chorioamnionitisl Newborn meningitis due to vertical

transmission

Ocular and ENT l One report of acute suppurative thyroiditis

with thyrotoxicosisl Corneal ulceration, orbital and periorbital

cellulitis, and endophthalmitisl Epiglotitis, sinusitis, tonsillitis

Pasteurella and HIV l Increased susceptibility to zoonoses in

immunocompromised patientsl Few reports associated with HIV l Including: pneumonia, meningitis, peritonitis, local

soft-tissue infections, and malakoplakia of the lung

Prehospital care:l With the exception of bites causing only superficial

abrasions, all dog, cat, and human bites should receive medical evaluation.

l A sterile dressing should be applied to all open wounds and direct pressure should be used to control bleeding.

l Intravenous access is suggested when a significant amount of blood loss has occurred.

ER Evaluation Il Bite victims should be evaluated shortly after arrival

to the ER, as time to treatment is one of the main determinants of infection.

l History: the circumstances of the attack, information about the bite source, and information about the bite victim.

l Ask about the timing of the bite. As a general rule, untreated bites more than 6-12 hrs old are at high risk for infectious complications.

ER Evaluation IIl When treating an animal bite, determine whether the

bite was provoked or unprovoked, as this may influence the decision to administer rabies prophylaxis.

l When dealing with dog and cat bites, information about the bite source should include ownership and immunization status, as well as the current locationof the animal.

ER Evaluation IIIl With human bites, attempt to determine the HIV and

hepatitis B status of the bite source, or if they are in a high-risk group for these illnesses.

l Ask about the bite victim’s past medical history, current medications and allergies, as well as his or her tetanus status.

Factors associated with increased risk of bite wound infectionl Chronic illness: cirrhosis, renal failure, SLE and

other immune disorders and diabetes mellitusl Medications: corticosteroids, methotrexate and other

immunosuppressive drugsl Alcoholism, Asplenia, Peripheral vascular disease,

HIV, Conditions causing chronic edema of the bitten part (mastectomy, CHF with pedal edema)

Physical Examination:l Vital signs often give valuable clues to bite-

related pathology.l Hypotension with tachycardia suggests

hemorrhagic shock when significant blood loss has occurred.

l Fever is often associated with systemic infection.

Physical Examination:l Note the location, size, and depth of all wounds and

carefully assess the vascular status distal to all extremity bites.

l Check motor and sensory function of all nerves distal to the wound; specifically, the median, radial, and ulnar nerve in the hand and the tibial and deep and superficial peroneal nerves in the foot.

Diagnostic Studies:l Obtain radiographs if there is a considerable amount

of edema and tenderness around the wound, or if there is any possibility of bony damage or a foreign body.

l Teeth and tooth fragments can be “left behind” in bite wounds, with resultant infectious complications.

Diagnostic Studies:l When reviewing x-rays, look for air in the joint, which

indicates penetration of the capsule. With older infected wounds, assess for osteomyelitis and soft-tissue gas.

l Angiography is indicated if the bite is near a major artery and there is evidence of vascular injury(e.g., expanding hematoma, pulsatile mass or diminished peripheral pulses)

Treatment:l Analgesia: Adequate analgesia is vital to allow for

appropriate examination and wound care of bite wounds. Procedural sedation may be necessary in extremely anxious patients, those with large or complex wounds, and children.

l Wound care: Cleaning, debridement, and irrigation are the most important factors in preventing bite wound infections and optimizing outcomes.

Treatment:

Repair (To close or not to close):Primary closure is recommended for:

l Simple bite wounds of the trunk and extremities (excluding hands and feet) less than six hours old; and

l Simple bite wounds of the head and neck less than 12 hours old.

Treatment:

Primary closure is “not”recommended for:

l CFIs;l puncture wounds; l hand and foot bites;l bites with extensive crush injury; andl bite wounds more than 12 hours old or that are

clinically infected.

Treatment:Repair (The best way to close the wound):

l Use a standard percutaneous closure technique with non-absorbable suture such as monofilament nylon or polypropylene.

l Avoid multiple layer closures if possible and avoid subcutaneous sutures unless they are absolutely necessary.

Treatment:When to call for specialty consultation?l If there is a significant amount of tissue missing and

skin grafting may be indicatedl If there is known or potential damage to important

underlying structures (e.g., tendons, arteries, nerves, bones, or joints)

l If general anesthesia will be required to allow for appropriate wound care

l Patient or family request

Treatment:Antimicrobial Prophylaxis:

l The value of prophylactic antibiotics given for dog, cat, and human bites remains highly controversial.Consider prophylactic antibiotics in the following situations:

l Bites requiring repair in the operating rooml Human and cat bites that extend through the dermis

Management - antibioticl Moderate to severe wounds l High risk of infection –l on the hand, head, neck, or genital regionl puncture wounds, crush injuriesl injuries in which a deeper structure -bone or jointl patients with specific conditions (eg, diabetes, liver

disease)l bite wounds that require surgical repairl from a human or cat.

Management - antibiotic

l Cat/dog should be directed against Pasteurella, Streptococcus, Staphylococcusand anaerobes

l For human bites, antibiotic coverage should be directed against Streptococcus and Staphylococcus species, anaerobes, and E corrodens.

Management - antibiotic

l Augmentin 875/125 mg PO bid or 500/125 mg PO tid

l Doxycycline in patients allergic to penicillin

Indications for admission after a bite injuryStructural:l Injury to deep structures (bones, joints, tendons,

arteries, or nerves)l Injuries requiring reconstructive surgeryl Injuries requiring general anesthesia for appropriate

wound care

Indications for admission after a bite injuryInfectious:l Rapidly spreading cellulitisl Significant lymphangitis, lymphadenitis or evidence

of sepsisl Infection in patient at high risk for complications (e.g.,

diabetic, immunocompromised, noncompliant)l Infections involving bones, joints, or tendonsl Infection with failed outpatient therapy

Management Rabies and tetanusl consideration of tetanus and rabies

prophylaxis l Rabies - eradicated in Taiwanl Tetanus - dependent on the wound

classification and immunization status of the patient

Dog or cat bite in U.S. to human (continuation of animal bite algorithm)╬

Is animal available for testing or quarantine? YesNo

Dog/cat is not located; risk assessment provided by public health officials provided to patient and/or physician, based on a combinations of factors:

• most important factor: geographic area of state (e.g. metro area is considered low risk, PEP usually not recommended unless animal exhibited neurological signs vs. stray animals from rural areas with known rabies epizootics is considered as increased risk)

• healthy acting is low risk vs. acute neurological symptoms is high risk

• provoked vs. unprovoked (provoked: PEP is usually not recommended)

• known animal vs. stray (Animal with a collar indicates a level of care which is likely to include previous rabies vaccination and thus a lower risk. Stray cats routinely seen within bite victim’s neighborhood can be observed from a distance for 10 days for health status)

Withhold PEP & Quarantine animal for 10 days (Ferret = 14 days)

If animal dies or develops signs of rabies, test brain

tissue

If animal remains healthy, PEP not

indicated

╬ Examples of factors considered within risk assessment by public health officials are provided within the text above. Patients are advised to combine risk assessment with discussion with a physician.

For a risk assessment, call your local health department or Arizona Department of Health Services (ADHS), Vector-Borne & Zoonotic Disease Section at (602) 364-4562 or 1-800-496-9660

Negative result, no

further action needed; PEP not indicated

Positive result,

initiate PEP

Attempt to locate animal; report to animal control (or observe patient calling animal control, as details provided directly from bite victim will increase chances of locating animal)

•educate patient on how rare rabies is in dogs & cats in Arizona (e.g. last rabid dog in Arizona: stray puppy in 2002 from Graham County; last rabid dog in Maricopa County was over 30 years ago; rabid cats have been confirmed in 2005 & 2006 from Santa Cruz & Coconino counties)

• advise patient to wait to hear back from animal control

• if animal is not located, encourage patient to discuss with local health department; provide local health and state health department phone numbers

If risk is low, public health will not

encourage vaccination

If risk is increased, public health will

encourage vaccination

If risk is high, public health will track patient, may assist in

coordinating PEP & document completion of rabies PEP

Summary l Animal and human bites are common.l Basic bite wound care should be performed,

including cleansing and irrigation of the wound.l A good understanding of bite wound bacteriology

and the situations in which antibiotics may be indicated is important.

l Rabies and tetanus prophylaxis should be considered and appropriate follow-up care ensured.

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