MAUI, HAWAII Cat-scratch disease should be consided in any patient with fever of an unknown origin who has had contact with catsespecially kittens, according to Dr. Jay M. Lieberman.
He presented several cases of children with prolonged fevers who remained without a diagnosis, despite extensive evaluations, until the possibility of cat-scratch disease was entertained and a history of contact with kittens was obtained.
The diagnosis of cat-scratch disease often can be made from the history and physical examination, and serologies may not be reliable, Dr. Lieberman said at a meeting sponsored by the University Childrens Medical Group and the American Academy of Pediatrics.
Kittens are more likely to cause cat-scratch disease than are older cats.
The disease is caused by Bartonella henselae, and approximately 40% of cats are bacteremic with the organism, explained Dr. Lieberman, who is professor of clinical pediatrics at the University of California, Irvine.
Cat-scratch disease is transmitted to humans through scratches, licks, or bites from kittens, less often from older cats, and sometimes from dogs.
A primary papule may be seen 3-12 days after inoculation time, followed 7-60 days (average 12-14 days) later by regional lymphadenopathy that may suppurate or regress over 2-4 months.
Lymphadenopathy usually involves the nodes that drain the site of inoculation. Fever occurs in half of patients, and malaise, anorexia, and headache also may occur.
The area around the nodes may be noninflamed but can be warm, tender, and erythematous, Dr. Lieberman said at the meeting, which also was sponsored by California Chapter 2 of the AAP. As many as 30% of nodes will suppurate spontaneously.
Atypical presentations of cat-scratch disease included prolonged fever/fever of unknown origin, granulomatous hepatitis, conjunctivitis with preauricular adenopathy (Parinaud's oculoglandular syndrome), encephalopathy/encephalitis, osteomyelitis, and ocular disease.
Although patients may be treated with rifampin or gentamicin or trimethoprim-sulfamethoxazole (TMP/SMZ), or a combination of anti-infectives, Dr. Lieberman does not routinely recommend their use.
"In general, we have not treated our patients with antimicrobial therapy," he said. "Most patients do not require specific therapy, and the illness resolves on its own."
One prospective randomized trial of azithromycin vs. placebo found a significantly greater decrease in lymph node size in azithromycin-treated patients at 30 days, but there was no significant difference thereafter (Pediatr. Infect. Dis. J. 1998;17:447-52).
Dr. Lieberman then discussed other infections that can be acquired from pets:
▸ Dog and cat bite wound infections. Approximately 5%-15% of dog bites lead to infections, as do 20%-50% of cat bites.
Pasteurella species, short gram-negative coccobacilli that are part of the normal flora of cats and dogs, are isolated from 75% of infections from cat bites and 50% of infections from dog bites.
Pasteurella organisms are not susceptible to cephalexin or dicloxacillin, Dr. Lieberman said.
To help prevent infection from bites, wounds should be cleaned, debrided, and closed. Bite wounds should be reevaluated in 1-2 days. When indicated, there may be a need for tetanus and/or rabies prophylaxis.
Antibiotic prophylaxis is indicated for puncture wounds (including all cat bites), bites over tendons, joints, and bone; bites on the face and/or genitals; bites involving an immunocompromised person; and bites that cannot be well cleaned and debrided. Antibiotic prophylaxis, when indicated, may be used for 48-72 hours.
Amoxicillin-clavulanate is the antibiotic of choice for prevention or treatment of animal bite wound infections, he said. Alternatives include a combination of cephalexin or dicloxacillin and penicillin V or a combination of clindamycin and trimethoprim-sulfamethoxazole.
▸ Rat-bite fever. This is "caused by Streptobacillus moniliformis, an unusual gram-negative pleomorphic rod. It is normal oral flora in rats and can be excreted in rat urine. Humans are infected after a bite or scratchor kissfrom an infected rat, or after handling a rat or ingesting food or water contaminated with rat excreta," explained Dr. Lieberman.
There is an incubation period of 2-10 days, followed by rapid onset of fever, chills, headache, and myalgia.
Rash may develop 2-4 days after the onset of fever. The rash usually is maculopapular, often including the palms of hands and soles of feet, and it may evolve into petechiae, purpura, and vesicles. About half of patients develop an asymmetric septic polyarthritis.
Dr. Lieberman described three children with rat-bite fever seen at his hospital over the past several years, all of whom presented with fevers, polyarthritis, and the characteristic rash, which was most prominent on the soles of the feet.
The treatment of choice is penicillin G. "These patients get better quickly," he said.
▸ Salmonellosis. About 3% of U.S. households have reptiles, most commonly lizards, snakes, turtles. Tortoises are chronic, intermittent shedders of Salmonella, and the Centers for Disease Control and Prevention estimates that more than 70,000 reptile-associated U.S. cases of salmonellosis occur each year, Dr. Lieberman said.