Morning Report: Mammal Bites

Welcome back to Morning Report! Today’s edition is presented by Dr. Alsup!

Mammal bites

Cat bites

Deep puncture wounds, difficult to irrigate
10-40% rate of infections
Staph, step and pasteurella multocida
P. multocida, a highly virulent, facultatively anaerobic, gram-negative rod found in the oral cavity or nasopharynx of 70 to 90% of healthy cats.
Abx required—dicloxacilin, cephalexin,. Augmentin- recommended
Clindamycin-resistant pasteurella is out there

Dog bites

4.5 million dog bites occur per year, affecting nearly 1.5% of the population, but only 20% (885,000) of victims seek medical attention. 1% of all ed visits
crush injury often with avulsions
Dog bites in patients who delay care by as little as 6 hours have an increased risk of becoming infected
Aerobes
- Staphylococcus aureus, alpha-hemolytic and beta-hemolytic streptococci, Klebsiella, Bacillus subtilis, Pseudomonas, Enterobacteriaceae, Capnocytophaga canimorsus

Anaerobic organisms
- Bacteroides, Fusobacterium, Peptostreptococcus, Porphyromonas, and Prevotella

C. canimorsus is a fastidious gram-negative rod that can cause overwhelming sepsis. It is part of the normal oral flora of both dogs and cats. More than 100 cases reports
- Usually begins within 3 days of exposure (range 1-10 days).
- fever, chills, myalgias, and vomiting
- clinical picture on presentation is often that of sepsis, with hypotension, renal insufficiency, and disseminated intravascular coagulation (DIC).
- Purpura, particularly on the face, and petechiae are frequent findings and may progress to symmetrical peripheral gangrene.
- Cutaneous gangrene at the site of the bite strongly suggests C. canimorsus.
- The mortality rate is 30%, with 70% of deaths occurring in immunocompromised patients.

Rosen’s: “it may be logical to limit the use of abx to high risk wounds, such as hand injuries, deep puncture wounds, or wounds in older and immunocompromised pts”

Human bites

Hand bites (fight bites)

Streptococcus and Staphylococcus species are common, but Eikenella corrodens and Bacteroides species are also typical pathogens. Because Eikenella is often resistant to clindamycin, first-generation cephalosporins, and erythromycin, patients with early infection are treated with amoxicillin with clavulanate.

Specifically ask about comorbidities with risk of poor wound healing (i.e. diabetes, peripheral vascular disease); use of immunosuppressive medications or steroids; history of splenectomy; chronic alcoholism, particularly with malnutrition; and parenteral recreational drug use.

SPECIES	SUTURING	PROPHYLACTIC ANTIBIOTICS
Dog	All (except hands)	High-risk wounds only* (all hand wounds)
Cat	Face only	All
Human	Face (as needed)	Hand, especially CFI

High-risk wounds: hand wounds, deep structure involvement (tendon, joint, bone), delayed presentation (>12 hours), contaminated wounds with foreign bodies or devitalized tissue, deep puncture wounds, high-risk patients.

FACTOR

HIGH RISK

LOW RISK

Species

Cat

Human

Primate

Pig, camel

Dog (excluding hand)

Rodent

Location of wound

Hand

Over joint or superficial tendon (CFI)

Through-and-through oral

Below the knee

Face

Scalp

Mucosa

Wound type

Puncture

Extensive tissue damage

Contaminated or devitalized tissue

Old (delayed presentation) or sutured

Large

Superficial

Clean

Recent

High-risk patients

Immunosuppressed, HIV positive

Transplant patient, steroid dependent

Diabetes, cancer chemotherapy

Prosthetic valve patients

Peripheral vascular disease

Elderly, alcoholic, cirrhosis

Social and compliance problems

CFI: closed-fist injury; HIV: human immunodeficiency virus.

CONCLUSIONS

	▪	Prophylactic antibiotics are recommended for dog bites of the hand and for high-risk patients. They are not indicated for routine dog bite wounds.
	▪	Patients at high risk should receive prophylactic antibiotics for C. canimorsus after a dog bite.
	▪	Cat bites and scratches have a high rate of infection, and prophylactic antibiotics are recommended for cat bites of the hand and for cat bites in high-risk patients.
	▪	Prophylactic antibiotics are recommended for human bites of the hand as well as for high-risk patients. They are also recommended for high-risk wounds, including deep punctures and contaminated wounds.
	▪	Ordinary human bite wounds, such as those exchanged among children (superficial, partial thickness, minimal tissue trauma), do not represent a high risk for infection or complication and do not require prophylaxis.
	▪	Wounds at high risk for infection should generally not be sutured.
	▪	All bites are considered tetanus-prone wounds.