BACTERIOLOGIC
ANALYSIS OF INFECTED DOG AND CAT BITES. EMERGENCY MEDICINE ANIMAL BITE
INFECTION STUDY GROUP.
Talan
DA, et al. N Engl J Med 1999 Jan 14;340(2):85-92.
BACKGROUND
AND METHODS: To define better the bacteria responsible for infections of dog
and cat bites, we conducted a prospective study at 18 emergency departments. To
be eligible for enrollment, patients had to meet one of three major criteria
for infection of a bite wound (fever, abscess, and lymphangitis) or four of
five minor criteria (wound-associated erythema, tenderness at the wound site,
swelling at the site, purulent drainage, and leukocytosis). Wound specimens
were cultured for aerobic and anaerobic bacteria at a research microbiology
laboratory and, in some cases, at local hospital laboratories.
RESULTS:
The infected wounds of 50 patients with dog bites and 57 patients with cat
bites yielded a median of 5 bacterial isolates per culture (range, 0 to 16) at
the reference laboratory. Significantly more isolates grew at the reference
laboratory than at the local laboratories (median, 1; range, 0 to 5;
P<0.001). Aerobes and anaerobes were isolated from 56 percent of the wounds,
aerobes alone from 36 percent, and anaerobes alone from 1 percent; 7 percent of
cultures had no growth. Pasteurella species were the most frequent isolates
from both dog bites (50 percent) and cat bites (75 percent). Pasteurella canis
was the most common isolate of dog bites, and Past. multocida subspecies
multocida and septica were the most common isolates of cat bites. Other common
aerobes included streptococci, staphylococci, moraxella, and neisseria. Common
anaerobes included fusobacterium, bacteroides, porphyromonas, and prevotella.
Isolates not previously identified as human pathogens included Reimerella anatipestifer
from two cat bites and Bacteroides tectum, Prevotella heparinolytica, and
several porphyromonas species from dog and cat bites. Erysipelothrix
rhusiopathiae was isolated from two cat bites. Patients were most often treated
with a combination of a beta-lactam antibiotic and a beta-lactamase inhibitor,
which, on the basis of the microbiologic findings, was appropriate therapy.
CONCLUSIONS:
Infected dog and cat bites have a complex microbiologic mix that usually
includes pasteurella species but may also include many other organisms not
routinely identified by clinical microbiology laboratories and not previously
recognized as bite-wound pathogens.