Plasmid profiles as an epidemiological marker in Salmonella enterica serovar berta infections

Abstract

Plasmid profiles of 674 Salmonella berta strains isolated in the period 1985–1989 from 674 cases of human infections were recorded. Five hundred and eighty‐nine of the strains examined (87.4%) contained plasmids and the mean number of plasmids was 1.8 per strain. Sixteen different plasmid sizes were recognized, 13 of which had also been reported from S. berta of poultry origin. The plasmids formed 90 different profiles. Forty‐five of these profiles, comprising 90.7% of isolates, had previously been recorded among poultry strains. Only 12 human isolates (1.8%) carried plasmids which were not demonstrated among isolates obtained from broilers. The prevalences of the 20 most commonly demonstrated profiles were not significantly different among isolates obtained from humans and broilers. The average difference between the prevalences of individual plasmid profiles was 2.1, with a standard deviation of 4.2. Based on the results, indications are that broilers represent the main reservoir for human S. berta infections in Denmark.

Virulence and genotype stability ofSalmonella entericaserovar Berta during a natural outbreak

“…shown that a clear succession in plasmid profile types occurred during the outbreak [1,3]. In a search for more stable markers, we [6] and others [7], have further shown that geographically diverse strains of Berta showed surprisingly little chromosomal restriction fragment variation, and suggested that the serotype consists of a single clone of bacteria.…”

“…The origin and year of isolation of Berta strains used (Table 1) have previously been reported [1,3,6]; strains investigated originated from poultry, humans, cattle, pigs and slurry during the outbreak in Denmark. The collection also contained control strains obtained from poultry and humans in six other countries.…”

“…The collection also contained control strains obtained from poultry and humans in six other countries. Media and growth conditions used were as previously reported [3].…”

“…Salmonella enterica serotype Berta (Berta) (0: 1,9,12; f,g,t:-) is mainly associated with poultry [1,2] but has been reported in relation to large outbreaks of salmonellosis among humans, presumably due to consumption of poultry products [3,4]. It is included among the salmonella serotypes that can be invasive in poultry [5] but it has not been reported to cause disease in these animals.…”

Interaction of Salmonella enterica with basil and other salad leaves

“…Salmonella enterica has long been recognized as an important source of food-borne infections and has commonly been associated with the consumption of contaminated poultry and poultry products (Olsen et al, 1992;Baggesen and Wegener, 1994). The global increase in human infections with serovar Enteritidis observed in the late 1980s and early 1990s (Rodrigue et al, 1990) was almost entirely attributable to the presence of this organism within the poultry production industry.…”