We collected serotyped isolates of salmonella from reference laboratories in the United States, tested their susceptibility to antibiotics, and extracted plasmids from isolates that were resistant to a different combination of antibiotics from each of three serotypes. Restriction-endonuclease digestion showed that within each of the three groups, plasmid molecules from animal and human isolates were often identical or nearly identical. One serotype-plasmid combination appeared to be endemic in cattle in 20 states and infected 26 persons in two states. The human cases, which were not recognizably related except for their common plasmids, appeared to be clustered in time but geographically dispersed, like cases in previous outbreaks spread by food products. These findings suggest that resistance plasmids may be extensively shared between animal and human bacteria, and that spread of multiresistant strains of salmonella among animals and human beings, as observed in Britain, may have been undetected in the United States for lack of comparable surveillance.

Dogs have been shown to harbor 53 salmonellae serotypes. Multiple simultaneous infections with 2 to 4 serotypes have been observed. The prevalence of canine salmonellosis may be a high as 27 per cent. Salmonella typhimurium and S. anatum are the most common etiologic agents. Dogs commonly experience a sub-clinical course of salmonellosis. Some investigators state that the dog may serve as a source of human infections. A few reports in the literature have documented this fact. The transmissions of S. enteritidis from dog to child is described in this article.

The Salmonella genus comprises over 1700 serotypes of pathogenic enteric bacteria. These microorganisms colonize in the intestinal tracts and mesenteric lymph nodes of man and lower vertebrates. Intra-and intergenus transfer of the lnfection(s) is common. Salmonellosls is highly contagious, and is frequently a cause of "food poisoning" in man. Estimates of 100,000 to 2 million human cases with 500 deaths occur annually in the U.S. The disease in man and animals has not decreased during the last decade. Fecal contamination, by either symptomatic or occult carriers and shedders, is the primary transmission source of aalmonellosis. The salmonellae problem and its possible resolution are intimately associated with the environment: waste disposal, including water and land use; food and feed processing, transportation and storage; livestock, poultry and dairy production; freeliving and captive wildlife hosts as infection reservoirs; household pets and companion animals; various stress factors affecting man and food-producing animals; wholesale and retail marketing of fresh and frozen foods, and ultimately the consumer, including restaurants, involved in handling, preparation and storage of foods destined for the dinner table. Salmonellosis cannot be eradicated in the U.S. due to the environmental complexities of the problem. We can only hope for better preventive and control measures through greater efforts in research, surveillance and education as well as awareness of the national problem. 755

No abstract

No abstract