Salmonella enterica serovar Enteritidis, England and Wales, 1945-2011.

In England and Wales, the emergence of Salmonella enterica serovar Enteritidis resulted in the largest and most persistent epidemic of foodborne infection attributable to a single subtype of any pathogen since systematic national microbiological surveillance was established. We reviewed 67 years of surveillance data to examine the features, underlying causes, and overall effects of S. enterica ser. Enteritidis. The epidemic was associated with the consumption of contaminated chicken meat and eggs, and a decline in the number of infections began after the adoption of vaccination and other measures in production and distribution of chicken meat and eggs. We estimate that >525,000 persons became ill during the course of the epidemic, which caused a total of 6,750,000 days of illness, 27,000 hospitalizations, and 2,000 deaths. Measures undertaken to control the epidemic have resulted in a major reduction in foodborne disease in England and Wales.

Human infections due to Salmonella Napoli: a multicountry, emerging enigma recognized by the Enter-net international surveillance network.

Human infections caused by Salmonella enterica serovar Napoli are relatively uncommon in Europe. Napoli was ranked 22nd in the Enter-net Salmonella database for 2006 with 295 cases (0.28%) of the 105,635 from 29 European countries. For the 18 countries that provided data for all the years 2000-2006, the number of cases rose from 122 out of 116,915 (0.10%) in 2000 to 293 out of 80,318 (0.36%) in 2006-an increase of 140.2%. Over 87% of cases came from three countries, France, Italy, and Switzerland. The epidemiology of the human cases showed an increased frequency in those aged under 5 or over 64, and both sexes were equally represented. Napoli isolates were also reported from nonhuman sources, mainly environmental samples and poultry. Strains compared by pulsed-field gel electrophoresis exhibited high levels of diversity between human, animal, and environmental sources. No single factor has been recognized as causing this rise, hence no public health interventions can be made or advice given to ensure that it does not persist. A 140% rise in 7 years indicates that the public health problem will continue, and further multidisciplinary investigations are needed to solve this enigma.

Antimicrobial drug resistance in human nontyphoidal Salmonella isolates in Europe 2000-2004: a report from the Enter-net International Surveillance Network.

A 5-year survey, from 2000 to 2004, of results of antimicrobial susceptibility testing for 11 antimicrobials for 134,310 isolates of nontyphoidal salmonellas from cases of human infection in 10 European countries has demonstrated an overall increase in the occurrence of resistance, from 57% to 66% over the period of study. In contrast, multiple resistance (to four or more antimicrobial drugs) has declined from 18% to 15%. The most significant increase in resistance has been to nalidixic acid (14% to 20%), particularly in Salmonella enterica serovar Enteritidis (10% to 26%), the most common serovar. For England and Wales this increase has for the most part been attributed to infections linked to contaminated eggs originating outside the United Kingdom. For Salmonella Typhimurium, the second most prevalent serovar, there has been an overall decline in the occurrence of resistance to ampicillin, chloramphenicol, and tetracyclines, attributed to a decline in the occurrence of multiresistant Salmonella Typhimurium DT 104. For Salmonella Virchow, a serotype with a predilection for invasive disease, there has been a substantive increase in resistance to most antimicrobials, attributed to the spread of drug-resistant strains associated with poultry. Because of the widespread importation of foods, it is important that controls to reduce the emergence and spread of drug-resistant strains of Salmonella are internationally implemented.

International outbreak of Salmonella Oranienburg due to German chocolate.

BACKGROUND: This report describes a large international chocolate-associated Salmonella outbreak originating from Germany. METHODS: We conducted epidemiologic investigations including a case-control study, and food safety investigations. Salmonella (S.) Oranienburg isolates were subtyped by the use of pulsed-field gel electrophoresis (PFGE). RESULTS: From 1 October 2001 through 24 March 2002, an estimated excess of 439 S. Oranienburg notifications was registered in Germany. Simultaneously, an increase in S. Oranienburg infections was noted in other European countries in the Enter-net surveillance network. In a multistate matched case-control study in Germany, daily consumption of chocolate (matched odds ratio [MOR]: 4.8; 95% confidence interval [CI]: 1.3-26.5), having shopped at a large chain of discount grocery stores (MOR: 4.2; CI: 1.2-23.0), and consumption of chocolate purchased there (MOR: 5.0; CI: 1.1-47.0) were associated with illness. Subsequently, two brands from the same company, one exclusively produced for that chain, tested positive for S. Oranienburg. In two other European countries and in Canada chocolate from company A was ascertained that also contained S. Oranienburg. Isolates from humans and from chocolates had indistinguishable PFGE profiles. No source or point of contamination was identified. Epidemiological identification of chocolate as a vehicle of infections required two months, and was facilitated by proxy measures. CONCLUSIONS: Despite the use of improved production technologies, the chocolate industry continues to carry a small risk of manufacturing Salmonella-containing products. Particularly in diffuse outbreak-settings, clear associations with surrogates of exposure should suffice to trigger public health action. Networks such as Enter-net have become invaluable for facilitating rapid and appropriate management of international outbreaks.

International trends in salmonella serotypes 1998-2003--a surveillance report from the Enter-net international surveillance network.

One of the objectives of any surveillance activity is to monitor trends in infections. The international surveillance network for human enteric infections, Enter-net, has been collecting and reporting data on laboratory-confirmed human salmonella infections since 1993. The number of cases identified rose in the mid-1990s, with the peak being in 1997. This paper describes the subsequent decline in salmonella serotypes being reported by the national reference laboratories participating in the Enter-net surveillance network between 1998-2003. The total number of human cases of salmonellosis reported by the Enter-net participating countries has fallen from 22,698 to 142,891 during this period. Even at these reported levels salmonellosis remains a major cause of morbidity in humans.

Dramatic shift in the epidemiology of Salmonella enterica serotype Enteritidis phage types in western Europe, 1998-2003--results from the Enter-net international salmonella database.

Salmonella enterica serotype Enteritidis is the predominant salmonella serovar identified by the Enter-net national reference laboratories in western Europe. As it is the most commonly recognised serotype, it is important that phage typing is carried out so that outbreaks can be recognised and confirmed, and trends in infections identified. Data from the Enter-net salmonella database show that there has been a dramatic shift between phage types identified in Europe from 1998-2003. In 1998, the proportion of phage type (PT) 4 was 61.8%, making it the most frequently identified phage type in humans (21,630 cases), whereas by 2003 the proportion of PT4 had fallen to 32.1% (8794 cases) with other strains increasing, both in proportion and numbers. This paper identifies the emerging strains that are becoming more relevant in public health terms.

Role of electronic data exchange in an international outbreak caused by Salmonella enterica serotype Typhimurium DT204b.

From July through September 2000, patients in five European countries were infected with a multidrug-resistant strain of Salmonella Typhimurium DT204b. Epidemiologic investigations were facilitated by the transmission of electronic images (Tagged Image Files) of pulsed-field gel electrophoresis profiles. This investigation highlights the importance of standardized protocols for molecular typing in international outbreaks of foodborne disease.