Diversity of Salmonella serotypes from humans, food, domestic animals and wildlife in New South Wales, Australia

Abstract

BackgroundSalmonella is an important human pathogen in Australia and annual case rates continue to increase. In addition to foodborne exposures, cases have been associated with animal and contaminated environment contact. However, routine surveillance in Australia has tended to focus on humans and food, with no reported attempts to collate and compare Salmonella data from a wider range of potential sources of exposure.MethodsSalmonella data from humans, food, animals and environments were collated from a range of surveillance and diagnostic sources in New South Wales (NSW). Data were categorised to reflect one of 29 sample origins. Serotype diversity was described for each category, and the distribution of serotypes commonly isolated from humans was examined for each sample origin. The distribution of serotypes along the livestock-food-human continuum and at the companion animal-wildlife interface was also examined.ResultsIn total, 49,872 Salmonella isolates were included in this analysis, comprising 325 serotypes. The vast majority of these isolates were from humans (n = 38,106). Overall S. Typhimurium was the most frequently isolated serotype and was isolated from all sample categories except natural environment and game meat. S. Enteriditis was not isolated from any livestock animal, however sporadic cases were documented in food, companion animals and a reptile. Many serotypes that were frequently isolated from livestock animals and associated food products were only rarely isolated from humans. In addition, a number of key human serotypes were only sporadically isolated from livestock and food products, suggesting alternative sources of infection. In particular, S. Paratyphi B Java and S. Wangata were more often isolated from wild animals. Finally, there was some overlap between serotypes in companion animals and wildlife, with cats in particular having a large number of serotypes in common with wild birds.ConclusionsThis is the most comprehensive description of Salmonella data from humans, food, livestock, wildlife, companion animals and various environments in Australia reported to date. Results confirm that livestock and food are important sources of salmonellosis in humans but that alternative sources - such as contact with wildlife and environments - warrant further investigation. Surveillance in NSW is largely human-focussed: major knowledge gaps exist regarding the diversity and frequency of serotypes in animals. More systematic surveillance of domestic animals and wildlife is needed to inform targeted control strategies and quantitative source attribution modelling in this state.Electronic supplementary materialThe online version of this article (10.1186/s12879-018-3563-1) contains supplementary material, which is available to authorized users.

Distribution of Salmonella Serovars in Humans, Foods, Farm Animals and Environment, Companion and Wildlife Animals in Singapore

“…S. Typhimurium was less frequent in chicken and egg products, but the predominant serovar in other foods, i.e., duck, pork and pork products, and other poultry where the serovar accounted for 43.9%, 35.2%, and 21.0% of the isolates, respectively. These findings are in agreement with other studies which reported S. Typhimurium as the principal serovar detected in dairy, pork, beef and mutton [16,19]. Detection of S. Typhimurium in chicken meat was low (9.4%) however relatively more frequent in fresh than frozen chicken meat.…”

Dogs as a source of Salmonella spp. in apparently healthy dogs in the Valencia Region. Could it be related with intestinal lactic acid bacteria?

“…Different studies have recorded that serovars found more frequently in dog faeces are similar to those found in humans [10,12,22,32,36,37]. In the present study, three serotypes were isolated, monophasic Salmonella Typhimurium (16.7%), S. Havana (50%) and S. Mikawasima (33.3%), which have also been implicated in human salmonellosis [38][39][40].…”

“…Different studies have recorded that serovars found more frequently in dog faeces are similar to those found in humans [ 10 , 12 , 22 , 32 , 36 , 37 ]. In the present study, three serotypes were isolated, monophasic Salmonella Typhimurium (16.7%), S .…”

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“…Salmonella is a food-borne disease-causing zoonotic pathogen ( 1 ), and its occurrence has frequently been reported in recent years ( 2 , 3 ). More than 2,600 Salmonella serotypes have been identified and recorded ( 4 ).…”