Serotype and Phage Type Distribution of
            <i>Salmonella</i>
            Strains Isolated from Humans, Cattle, Pigs, and Chickens in The Netherlands from 1984 to 2001

Duijkeren, Engeline van; Wannet, W J B; Houwers, D.J.; Pelt, Wilfrid van

doi:10.1128/jcm.40.11.3980-3985.2002

Cited by 99 publications

(72 citation statements)

References 13 publications

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“…From 1996, 73.2% of these isolates were resistant to more than one antimicrobial drug, with resistance to ampicillin, trimethoprim-sulfamethoxazole, furazolidone, and flumequine predominating (20). This serovar emerged in The Netherlands in 1996, and its prevalence has since increased, being the predominant serotype found in chickens and chicken products in 2001 (30 and 43% of all Salmonella isolates, respectively), replacing Salmonella serovar Enteritidis (16,18). The increasing frequency of isolation of Salmonella serovar Paratyphi B variation Java from chickens has also been reported from Germany (5) but not from other European countries.…”

Section: Discussionmentioning

confidence: 99%

“…The increasing rates of resistance to ampicillin, tetracycline, and chloramphenicol since 1996 among isolates from humans, pigs, and chickens can be attributed to the emergence of multiresistant serovar Typhimurium pt 506 and pt 401 strains (DT 104 in the English phage typing system), which are resistant to ampicillin, chloramphenicol, streptomycin, sulfamethoxazole, and tetracycline and to ampicillin, streptomycin, sulfamethoxazole, and tetracycline, respectively. Salmonella serovar Typhimurium DT 104 was the most important emerging phage type in humans, pigs, chickens, and cattle in The Netherlands: in 2001, this phage type was responsible for 15, 16, 10, and 3% of all Salmonella infections in humans, pigs, cattle, and chickens, respectively, and 43, 25, 31, and 57% of all serovar Typhimurium infections, respectively (16,17). The rate of resistance to flumequine was low (Ͻ2%) among serovar Typhimurium (including DT 104) strains.…”

Section: Discussionmentioning

confidence: 99%

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Antimicrobial Susceptibilities of Salmonella Strains Isolated from Humans, Cattle, Pigs, and Chickens in The Netherlands from 1984 to 2001

Duijkeren

Wannet²,

Houwers

et al. 2003

J Clin Microbiol

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We monitored antimicrobial susceptibility data for Salmonella strains isolated from humans, cattle, pigs, and chickens in The Netherlands from 1984 to 2001 in order to provide insight into the dynamics of resistance over time. The strains were tested for their susceptibilities to seven antimicrobial agents by the agar diffusion method. Resistance was most common in Salmonella enterica subsp. enterica serovar Typhimurium. Among the strains from humans, pigs, and chickens, it was found that the level of resistance of serovar Typhimurium strains to tetracycline, ampicillin, chloramphenicol, and trimethoprim-sulfamethoxazole increased from 1984 to 2001. This increase could be attributed to the emergence of multidrug-resistant serovar Typhimurium DT 104. Among the strains from cattle, it was found that the level of resistance of serovar Typhimurium strains, which was already very high in the 1980s, declined during the study period to the same levels as those for the strains from the other species from 1996 to 2001. Serovar Enteritidis isolates remained susceptible during the entire survey period. Among serovar Paratyphi B variation Java strains isolated from chickens, resistance to furazolidone, flumequine, trimethoprim-sulfamethoxazole, and ampicillin emerged, although furazolidone was not used after 1990. Together, the data indicate that the levels and patterns of resistance differed considerably between Salmonella serovars isolated from one host species.Nontyphoid salmonellosis is a major zoonotic disease. In The Netherlands, with a population of 15.8 million, it has been estimated that approximately 50,000 cases of salmonellosis occurred in 1999 (19). The emergence of resistance to antimicrobial drugs within the salmonellae is a problem for humans and animals worldwide. The extensive use of antimicrobials in human and veterinary medicine has led to an increase in multidrug-resistant strains. Salmonella strains may acquire resistance in food animals before transmission to humans through the food chain (15). Therefore, surveillance for antimicrobial resistance in humans and food animals is important in order to detect changes in susceptibility, to implement control measures on the use of antimicrobial drugs, and to prevent the further spread of multidrug-resistant strains. We reviewed susceptibility data for Salmonella strains isolated from humans, cattle, pigs, and chickens in The Netherlands for routine surveillance from 1984 to 2001. We analyzed whether the levels of resistance to antimicrobials increased with time and whether changes in susceptibility coincided for the Salmonella strains isolated from the different sources. MATERIALS AND METHODS Bacterial isolates. (i) Human isolates.A total of 45,198 Salmonella isolates tested for antimicrobial resistance were included in this study. The isolates were sent to the Dutch National Institute of Public Health (RIVM) by the Dutch regional public health laboratories. All strains were the first isolates recovered from patients with salmonellosis (clinical isolates). A...

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Antimicrobial Susceptibilities of Salmonella Strains Isolated from Humans, Cattle, Pigs, and Chickens in The Netherlands from 1984 to 2001

Duijkeren

Wannet²,

Houwers

et al. 2003

J Clin Microbiol

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“…For diversifying selection to provide an explanation for serovar-host specificity, both bacterial prey and their protozoan predators must be stably and differentially distributed between host species. Differential distribution of bacteria among hosts, i.e., the nonuniform abundance of different genotypes among different environments, has been convincingly demonstrated for Salmonella (36,57), E. coli (58)(59)(60), Enterococcus (61,62), and Bacteroides (62). Our preliminary data suggest similar results for protozoa, i.e., Naegleria polyphaga was found preferentially in carnivorous metamorphosing Rana catasbiena, whereas Hartmanella was found in herbivorous tadpoles (randomization test, P Ͻ 0.023).…”

Section: Discussionmentioning

confidence: 99%

Protozoan predation, diversifying selection, and the evolution of antigenic diversity in Salmonella

Wildschutte

Wolfe

Tamewitz

et al. 2004

Proc. Natl. Acad. Sci. U.S.A.

145

140

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Extensive population-level genetic variability at the Salmonella rfb locus, which encodes enzymes responsible for synthesis of the O-antigen polysaccharide, is thought to have arisen through frequency-dependent selection (FDS) by means of exposure of this pathogen to host immune systems. The FDS hypothesis works well for pathogens such as Haemophilus influenzae and Neisseria meningitis, which alter the composition of their O-antigens during the course of bloodborne infections. In contrast, Salmonella remains resident in epithelial cells or macrophages during infection and does not have phase variability in its O-antigen. More importantly, Salmonella shows host-serovar specificity, whereby strains bearing certain O-antigens cause disease primarily in specific hosts; this behavior is inconsistent with FDS providing selection for the origin or maintenance of extensive polymorphism at the rfb locus. Alternatively, selective pressure may originate from the host intestinal environment itself, wherein diversifying selection mediated by protozoan predation allows for the continued existence of Salmonella able to avoid consumption by host-specific protozoa. This selective pressure would result in high population-level diversity at the Salmonella rfb locus without phase variation. We show here that intestinal protozoa recognize antigenically diverse Salmonella with different efficiencies and demonstrate that differences solely in the O-antigen are sufficient to allow for prey discrimination. Combined with observations of the differential distributions of both serotypes of bacterial species and their protozoan predators among environments, our data provides a framework for the evolution of high genetic diversity at the rfb locus and host-specific pathogenicity in Salmonella.T he enteric pathogen Salmonella enterica presents at least 70 different O-antigens [the outermost structure of the Gramnegative lipopolysaccharide (LPS)] to mammalian immune systems (1); this polysaccharide decorates the outer surface of the cell. Historically, extensive genetic diversity at the rfb locus, which encodes enzymes directing O-antigen synthesis (2-6), has been attributed to frequency-dependent selection (FDS) (7,8) imposed by the host immune system (5, 9, 10). Novel rfb loci would have an advantage because their cognate O-antigens would be unrecognized by immune systems (Fig. 1A); strains carrying rare loci would have higher fitness and would avoid rapid stochastic loss, rising to higher frequency. Yet selective advantages decrease with abundance; as a result, strains with common rfb loci cannot dominate the population or elicit a selective sweep (7) because their fitnesses become lower as they become more abundant. In concert, FDS prevents the loss of rare alleles or the dominance of common alleles, thus maintaining diversity (8).According to the FDS model, expression of different LPS molecules through gene regulation allows invading bacteria to escape host immunity, survive, and proceed throughout its life cycle; this hypothesis explains...

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“…The human strains (n = 59 168) were clinical isolates, and the animal strains (n = 65 567) were from clinical and non-clinical infections. The most prevalent serovars were as follows: in humans, serovars Typhimurium and Enteritidis; in cattle, serovars Typhimurium and Dublin; in pigs, serovar Typhimurium; and in chickens, serovars Enteritidis, Infantis, and Typhimurium (van Duijkeren et al, 2002). In the EU, approximately 9 % of turkey carcasses are Salmonella-positive and the top six serovars that contribute to human cases are S. Enteritidis, S. Kentucky, S. Typhimurium, S. Newport, S. Virchow and S. Saintpaul (EFSA BIOHAZ Panel, 2012).…”

Section: Salmonella Sppmentioning

confidence: 99%

Scientific Opinion on the public health risks related to the maintenance of the cold chain during storage and transport of meat. Part 2 (minced meat from all species)

Publication¹

2014

EFSA Journal

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Fresh meat intended for the production of minced meat may be contaminated by a range of pathogens including Salmonella spp. and verocytotoxigenic Escherichia coli (VTEC). These may grow if the temperatures are not maintained below 5 °C along the continuum from carcass chilling to mincing. Moreover Listeria monocytogenes and Yersinia enterocolitica will grow at chill temperatures, albeit slowly, but significant growth may occur during prolonged storage. Current legislation (Regulation (EC) 853/2004) requires that red meat carcasses are immediately chilled after post‐mortem inspection to not more than 7 °C throughout and that this temperature be maintained until mincing which must take place not more than 6 or 15 (vacuum‐packed meat) days after slaughter. The corresponding figures for poultry are 4 °C and 3 days. The impact of storage time between slaughter and mincing on bacterial pathogen growth was investigated using predictive modelling. Storage time‐temperature combinations that allow growth of Salmonella, VTEC, L. monocytogenes and Y. enterocolitica equivalent to those obtained under the conditions defined by Regulation (EC) 853/2004 were identified. As the modelling assumed favourable pH and aw for bacterial growth, no microbial competition and no lag phase, the equivalent times reported are based on worst‐case scenarios. This analysis suggested, for example, that red meat, vacuum packed beef and poultry could be stored at 2 °C for up to 14, 39 and 5 days, respectively, without more bacterial pathogen growth occurring than that which would be achieved under current legislative conditions. It was therefore concluded that alternative time‐temperature combinations for the storage of fresh meat between slaughter and mincing are possible without increasing bacterial pathogen growth, and maximum times for the storage of fresh meat intended for minced meat preparation are provided for different storage temperatures. The impact of spoilage on maximum storage times was not considered.

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Serotype and Phage Type Distribution of Salmonella Strains Isolated from Humans, Cattle, Pigs, and Chickens in The Netherlands from 1984 to 2001

Cited by 99 publications

References 13 publications

Antimicrobial Susceptibilities of Salmonella Strains Isolated from Humans, Cattle, Pigs, and Chickens in The Netherlands from 1984 to 2001

Antimicrobial Susceptibilities of Salmonella Strains Isolated from Humans, Cattle, Pigs, and Chickens in The Netherlands from 1984 to 2001

Protozoan predation, diversifying selection, and the evolution of antigenic diversity in Salmonella

Scientific Opinion on the public health risks related to the maintenance of the cold chain during storage and transport of meat. Part 2 (minced meat from all species)

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