Outbreaks of multidrug-resistant Salmonella Typhimurium reported at veterinary facilities in 1999

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Three state health departments in 1999 reported outbreaks of multidrug-resistant Salmonella Typhimurium infections in employees and clients of small animal clinics and an animal shelter, according to a report in the Aug. 24 Morbidity and Mortality Weekly Report.

Salmonella infections are usually acquired by eating contaminated food. Direct contact with infected animals, including dogs and cats, also can result in exposure and infection, however.

Between September and October 1999, the Idaho Department of Health and Welfare identified an outbreak of Salmonella infections among employees of a small animal clinic. Ten of 20 persons had abdominal cramps and diarrhea, and two had bloody diarrhea. Four persons sought medical care.

One patient reported caring for several kittens with diarrhea one or two days before illness onset. The ill employees ate meals in the clinic and had no common exposures outside the clinic. Fecal specimens from five ill employees yielded S Typhimurium. All isolates were resistant to ampicillin, ceftriaxone, cephalothin, chloramphenicol, clavulanic acid/amoxicillin, gentamicin, kanamycin, streptomycin, sulfamethoxazole, and tetracycline.

That same year, the Minnesota Department of Health tested S Typhimurium isolates from nine cats and seven humans that were indistinguishable by pulsed-field gel electrophoresis. All isolates were resistant to ampicillin, chloramphenicol, streptomycin, sulfamethoxazole, and tetracycline. Three cat and two human isolates tested were definitive type 104. The cats had died in an animal shelter between September and October as a result of infection. All persons sought medical care, and one was hospitalized for four days. An adult treated with ciprofloxacin shed S Typhimurium in feces at least 214 days after illness onset.

A connection with the animal shelter was established for six of the seven human patients; four purchased cats from the shelter between August and October and two attended the same daycare center as an ill child who owned a cat from the shelter. One cat developed bloody diarrhea one day after adoption and onset of illness in the patient began four days later. Two cats had no signs, but the owner became ill 77 days after adopting the cats. Salmonella Typhimurium was recovered from one cat 115 days after adoption.

Through laboratory-based surveillance and patient interviews, the Washington State Department of Health detected in late 1999 an outbreak of Salmonella infections associated with a small animal clinic. Fecal specimens from three ill persons yielded S Typhimurium; all three sought medical care, but none was hospitalized. One ill person was a clinic employee, and the two others recently had brought their cats to the clinic. The cats developed diarrhea after their discharge from the clinic, and the owners subsequently became ill. Salmonella Typhimurium was isolated from 14 cats associated with this clinic. Isolates from the ill persons and cats were indistinguishable by pulsed-field gel electrophoresis.