Bite lecture

Bites and Stings of all Kinds

Matthew Tucker, DOEmergency Medicine

Objectives

• Discuss the different types of bites you will encounter in practice.

• Discuss the pathophysiology of these bites.• Discuss the treatment of these various bites.• Discuss pitfalls of treatment and lack of

treatment.• Answer questions pertaining to bites.

Overview

• Mammalian bites– Canine/Feline– Other carnivores– Herbivores/Lagomorphs– Human

Mammalian bites

• Canine/Feline– In 2007, est 5 million bites with approx 800,000

requiring medical attention.– Dog bites typically cause crush type injuries

along with lacerations and puncture wounds.– Cat bites typically produce lacerations and

puncture wounds.– Extremity wounds (defensive) are most common

with the majority of these being on the hands.– Several factors significant in evaluating bite:

provoked bite, health of animal, behavior of animal, local of bite, etc.).

Mammalian bites (con’t)

• Canine/Feline– Bites to the hands are considered more prone to infection

and serious trauma due to the relatively poor blood supply and proximity of significant structures to the epidermis (flexor tendon sheath, palmar arterial arcade, etc.)

– Bacteria assoc primarily with canine bites are Staph and Strep species (several others, but these are predominant)

– Bacteria assoc with feline bites is primarily Pasturella.– We need to tailor antibiotic therapy with these in mind.

Mammalian bites (con’t)• Treatment for canine/feline bites fairly straight forward. As will

any tissue trauma, meticulous wound care is paramount. Debridement of devitalized tissue is important to help prevent infection.

• Radiographs necessary if any suspicion of bony involvement or retained tooth from animal.

• Primary closure of lacerations is to be used on a limited, selected basis. Typically, delayed closure is recommended based on infective potential.

• It is generally regarded that laceration closure of the face is acceptable because of the generous blood supply and relatively low incidence of infection. This will also be of benefit from a cosmetic standpoint.

Mammalian bites (con’t)Canine/Feline

-Update tetanus if indicated.-Consider administration of rabies vaccine and rabies immunoglobluins.-Antibiotic selection should be based on presumed organisms (discussed earlier).-Prophylactic antibiotics are generally regarded as appropriate, however, there is no data to suggest they are beneficial ( www.thennt.com ). -Amoxicillin/clavulanate is consider first line. Consult appropriate source (Sanford, etc) if unusual presentation should arise.

Mammalian bites (con’t)• Other carnivores

-Typically rare (unless you jump into a

polar bear enclosure).-Treatment is similar to

canine/feline (domestic) however significant trauma much more likely.

Mammalian bites (con’t)

• Herbivores/Lagomorphs/Rodentia– Extremely rare due to the nature

of the animal involved. Usually either domesticated or very shy animal.

– Incidence of rabies in rodents/lagomorphs rare. Should consider rabies treatment, however, consultation with state epidemiologist is often helpful.

– Rodent bacteria=Streptobacillus and Spirillum (rat bite fever).

Mammalian bites (con’t)

• Human– Nasty… just plain nasty..– Approx 100 million orgs/mL

saliva…all of them bad (hepatitis, HIV, TB, actinomycosis just to name a few)…

– Treatment consists of meticulous wound care (as discussed), careful evaluation for other trauma (assaulted patient) and appropriate antibiotic selection.

Mammalian bites (con’t)

• Human– Eikenella corrodens, Staph (aureus up to 30% of isolates),

Strep, Corynebacterium are predominant aerobic organisms isolated from bites. Peptostreptococcus and Bacteriodes are commonly isolated anaerobes in human saliva. Antibiotic therapy must be selected based on careful consideration of the likely organisms.

– Unfortunately, virus transmission is possible, with Hepatitis B being the most commonly transmitted (approx 75% Hep B pts have the virus detected in saliva).

– HIV considered very low likelihood of transmission.– Fight bites

Mammalian bites (con’t)

• Pitfalls of treatment– Poor wound care.– Inappropriate antibiotic selection (probably the

biggest).– Fight bite evaluation or lack of…– Lack of follow up care.

Arthropod Bites/Stings

• Phylum Arthopoda consists of several members that can envenomate either through biting or stinging.

• Most envenomations are minor, with only localized pain or irritation.

• Epidemiology is difficult to ascertain because of the wide distribution and mostly minor injuries.

Arthopoda (con’t)

• Spiders -epidemiology– Recluse • 5 species of Loxosceles assoc with necrotic

arachnidism.• Difficult to definitively ascribe bite to L. reclusa because

of the increase of MRSA lesions. Vast majority of “spider bites” are in fact not bites at all.• 2010 Poison Control Center reports 612 bites with no

deaths reported and various severity of involvement.

Arthopoda (con’t)

• Spiders-epidemiology– Latrodectus-• Small, shiny- not always black. Typical red spot or

“hour glass” pattern on abdomen.• Very secretive and typically not easily encountered.• Alpha-latrotoxin involved in opening the cation

channels resulting in over-stimulation of ANS. Effects of widow bite are predominately neurologic as compared to tissue destruction in recluse bites.

Arthropoda (con’t)

• Spiders –symptoms and treatment– Recluse• Initial “bite” sensation, followed by increasing pain as

venom produces vasospasm and ischemia. Typically the necrosis is worse over “fatty” areas of the body.• Systemic loxoscelism severity is not related to the

severity of the localized tissue reaction.

Arthropoda (con’t)

• Spiders-symptoms and treatment– Recluse (Loxoscelism)• Symptoms Loxoscelism of bite include:

– Morbilliform rash– Fever/Chills– Nausea/Vomiting– Joint pain– Hemolysis/Disseminated intravascular coagulation (DIC)– Renal failure– Seizures/Coma

Arthropoda (con’t)

• Spiders- symptoms and treatment– Recluse bite treatment• No definitive treatment per se.• “Watchful waiting” is employed and the patient hates

that.• To date, the use of antibiotics, dapsone, steroids,

hyperbaric therapy, etc., has not been established to provide any benefit to outcome.• Evaluation for loxoscelism. If noted, immediate

hospitalization is indicated.

Arthropoda (con’t)

• Spiders-symptoms and treatment– Latrodectus• Symptoms

– Bite itself is usually not noticed– Systemic sx will typically begin within 1-2 hours– These include:

» Muscle cramping (can be severe)» Nausea/vomiting» Headaches» Hypertension/tachycardia/diaphoresis

Arthropoda (con’t)

• Spiders-symptoms and treatments– Latrodectus

• Treatment– Envenomation graded by significance of symptoms– Grade 1 – Mild: Local pain at bite site. Normal vital signs– Grade 2 – Moderate: Muscular pain in the bitten extremity.

Extension of pain to the abdomen if bitten on a lower extremity or to the chest. Local diaphoresis of bite site. Normal vital signs

– Grade 3 – Severe: Generalized muscular pain in the back, abdomen, and chest. Diaphoresis remote from bite site. Abnormal vital signs (blood pressure >140/90 mm Hg, pulse >100). Nausea, vomiting, headache.

Arthropoda (con’t)

• Spiders-symptoms and treatments– Latrodectus• Consultation of Poison Control important (BIGGEST

PITFALL).• Most bites managed with pain meds, sedatives, etc• Antivenom is recommended when there is a limb/life

threat (Grade II, III), or threat to pregnancy. • Historically, Calcium gluconate has been recommended

for widow bites, however, this is no longer the case.• Admission considered for: anaphylaxis, severely

symptomatic children, intractable pain, hx HTN or CAD.

Arthopoda (con’t)

• Scorpions– Scorpions of the US are relatively harmless.– Localized pain (can be intense) and mild swelling is

typical. Usually self limited and requiring NSAIDs and cool packs.

– The Centruoides (Bark scorpion) from Arizona is an exception. This can deliver a fatal sting, especially to children and elderly/debilitated.

Hymenoptera

• Won’t say much about this except it is exceedingly common. Major significant issue is anaphylaxis (different lecture) or being overwhelmed by Africanized bees (different lecture).

Snake (Pit Viper) Envenomation

• In Oklahoma, the two subfamilies of venomous snakes are: Crotalidae and Elapidae, with no documented sightings of coral snake in years.

• The practice of keeping reptiles, including venomous snakes is increasingly popular in the US. Many of these species are not native to the US.

• Approx 2000 venomous bites per year. National average is 4 bites per 100,000 persons. Deaths very rare and have been reported at 4 deaths per year (national average.)

• White males 76% of bites. 3T’s and a D.

Snake Identification

Snake Identification

• www.oksnakes.org very good reference!!

Pit Viper Envenomation• Overview

– All venomous snakes posses modified teeth through which they inject venom into the victim.

– The amount of venom injected varies widely.– The size of the victim and overall health of the victim plays an

important role in morbidity and mortality.– The venom itself is a hugely complex mixture of peptides, kinins,

proteins and the like with the singular task or rendering living tissue into dead/destroyed tissue.

– The vast majority of venom that we encounter is hemotoxic. However, several species of rattlesnakes do have neurotoxic components to varying degrees.

– With the increase in popularity of nonnative species being kept as pets, the possibility of encountering an exotic bite is rising.

Pit Viper Envenomation(Price list from importer)

• EASTERN CORAL Micrurus fulvius fulvius WC, AD, $125.00 • TEXAS CORAL Micrurus fulvius tener WC $55.00 • 3.0 MONOCLE COBRA Naja kaouthia CB, 3 - 4 foot, Great display!

$225.00 • 2.5 MONOCLE COBRA Naja kaouthia CB'12, Cute babies! $95.00 • 4.0 MONOCLE COBRA Naja kaouthia CB'12, het.$125.00 • 1.0 ALBINO MONOCLE COBRA Naja kaouthia CB, 5’, $500.00 • 1.0 CAPE COBRA Naja niveaCB'12, NICE! $300.00 • 4.2 SAMAR COBRA Naja samarensis CB'13, Awesome cobras,

$600.00 9.0 BLACK AND WHITE SPITTING COBRA Naja siamensis CB'12,

colorful babies, $95.00

Pit Viper Envenomation

• Evaluation and Treatment– History and physical important. Chronic issues,

important meds, allergies, etc.– Presence (or absence) of fang marks, location, etc.– Timing of bite and symptoms at time of

presentation. Proximal swelling, systemic sx, etc.– ABC’s!!!!!, 2 large bore IV’s, ALS stuff!!! Just be

ready.

Pit Viper Envenomation

• Evaluation and Treatment– On presentation, labs should be drawn. CBC,

PT/aPTT/INR, Fibrinogen, T&C, CMP, UA (myoglobinuria). Consider lactate (venous or ABGs) with patients exhibiting systemic s/sx.

– Contact Poison Control!!! (Again, they have a toxicologist on staff, no reason not to consult them).

Pit Viper Envenomation

• Evaluation and Treatment– Grading envenomation (pitfall..envenomation is a

DYNAMIC process and may change RAPIDLY!!)• Evenomation grading determines the need for antivenom.

Grades are defined as mild, moderate, or severe.– Grade I-Mild: is characterized by local pain, edema, no signs of systemic

toxicity, and normal labs.– Grade II- Moderate: is characterized by severe local pain; edema larger

than 12 inches surrounding the wound; and systemic toxicity including nausea, vomiting, and alterations in laboratory values.

– Grade III-Severe: is characterized by generalized petechiae, ecchymosis, blood-tinged sputum, hypotension, hypoperfusion, renal dysfunction, changes in prothrombin time and activated partial thromboplastin time, or DIC.

Pit Viper Envenomation

• Evaluation and Treatment– There is a fairly significant number of “dry bites”,

has been estimated at 7-15% of all venomous bites.

– When evaluating grade of bite, the Snakebite Severity Score should be utilized.

Pit Viper Envenomation

• SSS

Pit Viper Envenomation

• Treatment– The use of antivenom is indicated in all bites moderate

or above (Grade II or higher). (Pitfall-failure to use antivenom in a timely fashion)

– CroFab is a purified Fab fragment from an ovine source comprised of venoms from Eastern and Western diamondback, Mojave rattlesnake and cottonmouth.

– This is a much “cleaner” product than what was available prior to CroFab’s development. The risk of allergic reaction/anaphylaxis is significantly reduced.

Pit Viper Envenomation

• Treatment– CroFab should (ideally) be administered within 6 hours of bite. – Initial (loading) dose is 4 to 6 vials. See package insert for

reconstitution and rate.– Maintenance dosing is 2 vials Q 6 hrs over next 18 hrs. – Monitor labs for changes and frequent VS checks.– Liberal use of analgesics…..LIBERAL…– There is no indication for steroids, antibiotics, poultices, electric

shocks, cut-and-suck or the like…EVER.– I would include surgeons in the above statement (mostly)…unless

you suspect compartment syndrome. Consult ortho/gen surg for eval. Have high index of suspicion (though it is not common with appropriate CroFab use).

Pit Viper Envenomation Case Study

• Aug 3, 22:30, Ms. M (patient) was bitten twice on the left foot by a rattlesnake (as ID’d by the sound of a rattle and puncture marks). 911 called and EMS dispatched to meet patient en route. Estimated time elapsed from bite to ED arrival was 1 hour.

• • While en route, the patient stated the EMS crew told her that “the snakes around here are not that

poisonous so anti venom is not used”. Patient at this time reported increasing pain. Patient also states she was experiencing diaphoresis and vomiting.

• • At 23:30, charting reports pt in ED and given medication for pain and dT booster Swelling at this

time reported to be past ankle. • • As the ED stay progressed, the chart data indicate a tachycardic patient with nausea and vomiting

and diaphoresis. The dictated report indicates the patient had severe anxiety. During the ED stay, it was reported that pain persisted, and that the swelling and discoloration continued to be observed. The attending ED physician stated that patient did not meet criteria for CroFab (anti venom). It was determined that because of intractable pain, the patient would be admitted to hospital.

• •

Pit Viper EnvenomationCase Study

• What went wrong?

• What was outcome?

Bites and Stings

• Questions?