Emergence of new Salmonella Enteritidis phage types in Europe? Surveillance of infections in returning travellers

BACKGROUND: Among human Salmonella Enteritidis infections, phage type 4 has been the dominant phage type in most countries in Western Europe during the last years. This is reflected in Salmonella infections among Swedish travellers returning from abroad. However, there are differences in phage type distribution between the countries, and this has also changed over time. METHODS: We used data from the Swedish infectious disease register and the national reference laboratory to describe phage type distribution of Salmonella Enteritidis infections in Swedish travellers from 1997 to 2002, and have compared this with national studies conducted in the countries visited. RESULTS: Infections among Swedish travellers correlate well with national studies conducted in the countries visited. In 2001 a change in phage type distribution in S. Enteritidis infections among Swedish travellers returning from some countries in southern Europe was observed, and a previously rare phage type (PT 14b) became one of the most commonly diagnosed that year, continuing into 2002 and 2003. CONCLUSIONS: Surveillance of infections among returning travellers can be helpful in detecting emerging infections and outbreaks in tourist destinations. The information needs to be communicated rapidly to all affected countries in order to expedite the implementation of appropriate investigations and preventive measures

Evaluation of the Widal tube agglutination test for the diagnosis of typhoid fever among children admitted to a rural hdospital in Tanzania and a comparison with previous studies

BACKGROUND: The diagnosis of typhoid fever is confirmed by culture of Salmonella enterica serotype Typhi (S. typhi). However, a more rapid, simpler, and cheaper diagnostic method would be very useful especially in developing countries. The Widal test is widely used in Africa but little information exists about its reliability. METHODS: We assessed the performance of the Widal tube agglutination test among febrile hospitalized Tanzanian children. We calculated the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of various anti-TH and -TO titers using culture-confirmed typhoid fever cases as the "true positives" and all other febrile children with blood culture negative for S. typhi as the "true negatives." RESULTS: We found that 16 (1%) of 1,680 children had culture-proven typhoid fever. A single anti-TH titer of 1:80 and higher was the optimal indicator of typhoid fever. This had a sensitivity of 75%, specificity of 98%, NPV of 100%, but PPV was only 26%. We compared our main findings with those from previous studies. CONCLUSION: Among febrile hospitalized Tanzanian children with a low prevalence of typhoid fever, a Widal titer of > or = 1:80 performed well in terms of sensitivity, specificity, and NPV. However a test with improved PPV that is similarly easy to apply and cost-efficient is desirable

Regional maritime management and security

This monograph includes the discussion papers presented at the Third Meeting of the CSCAP Maritime Cooperation Working Group held in Bangkok 30 May-1 June 1997. It is the third in the series of similar monographs by the CSCAP Maritime Cooperation Working Group. The theme of the meeting was regional ocean management and security. Its objectives were fourfold: - to review progress with the Guidelines for Regional Maritime Cooperation; - to contribute to the development of new ideas about cooperative management of regional sea and ocean areas; - to identify present and planned activities in some area of regional maritime cooperation (such as shipping, resource management, pollution prevention, marine safety, and law and order at sea) which have benefits for regional security (that is, 'value added'); - and to share national and sub-regional perspectives of cooperative oceans and marine management. The overall aim of the meeting was to explore new ideas of preventive diplomacy and confidence building in the general area of regional maritime cooperation, particularly in the enclosed and semi-enclosed regional seas of Southeast and Northeast Asia, where maritime activity is increasing and cooperation so important. The opportunity was also taken to discuss existing arrangements for regional maritime cooperation and the experiences of other regions in the world with similar considerations of maritime cooperation (that is, the Baltic and Mediterranean seas, and the Caribbean)

The anti-bacterial iron-restriction defence mechanisms of egg white; the potential role of three lipocalin-like proteins in resistance against Salmonella

Salmonella enterica serovar Enteritidis (SE) is the most frequently-detected Salmonella in foodborne outbreaks in the European Union. Among such outbreaks, egg and egg products were identified as the most common vehicles of infection. Possibly, the major antibacterial property of egg white is iron restriction, which results from the presence of the iron-binding protein, ovotransferrin. To circumvent iron restriction, SE synthesise catecholate siderophores (i.e. enterobactin and salmochelin) that can chelate iron from host iron-binding proteins. Here, we highlight the role of lipocalin-like proteins found in egg white that could enhance egg-white iron restriction through sequestration of certain siderophores, including enterobactin. Indeed, it is now apparent that the egg-white lipocalin, Ex-FABP, can inhibit bacterial growth via its siderophore-binding capacity in vitro. However, it remains unclear whether ex-FABP performs such a function in egg white or during bird infection. Regarding the two other lipocalins of egg white (Cal-γ and α-1-glycoprotein), there is currently no evidence to indicate that they sequester siderophores

Evolution of Salmonella enterica Virulence via Point Mutations in the Fimbrial Adhesin

Whereas the majority of pathogenic Salmonella serovars are capable of infecting many different animal species, typically producing a self-limited gastroenteritis, serovars with narrow host-specificity exhibit increased virulence and their infections frequently result in fatal systemic diseases. In our study, a genetic and functional analysis of the mannose-specific type 1 fimbrial adhesin FimH from a variety of serovars of Salmonella enterica revealed that specific mutant variants of FimH are common in host-adapted (systemically invasive) serovars. We have found that while the low-binding shear-dependent phenotype of the adhesin is preserved in broad host-range (usually systemically non-invasive) Salmonella, the majority of host-adapted serovars express FimH variants with one of two alternative phenotypes: a significantly increased binding to mannose (as in S. Typhi, S. Paratyphi C, S. Dublin and some isolates of S. Choleraesuis), or complete loss of the mannose-binding activity (as in S. Paratyphi B, S. Choleraesuis and S. Gallinarum). The functional diversification of FimH in host-adapted Salmonella results from recently acquired structural mutations. Many of the mutations are of a convergent nature indicative of strong positive selection. The high-binding phenotype of FimH that leads to increased bacterial adhesiveness to and invasiveness of epithelial cells and macrophages usually precedes acquisition of the non-binding phenotype. Collectively these observations suggest that activation or inactivation of mannose-specific adhesive properties in different systemically invasive serovars of Salmonella reflects their dynamic trajectories of adaptation to a life style in specific hosts. In conclusion, our study demonstrates that point mutations are the target of positive selection and, in addition to horizontal gene transfer and genome degradation events, can contribute to the differential pathoadaptive evolution of Salmonella

Genome-scale metabolic reconstructions of multiple <i>Salmonella</i> strains reveal serovar-specific metabolic traits

Salmonella serovars colonize a wide range of hosts but the underlying genetic determinants remain poorly understood. Here, Seif et al. use a network-based computational analysis to link specific metabolic capabilities with host range and nutritional niche

The serodiagnosis of infection with Salmonella typhi

Background/Aims—The serodiagnosis of infection with Salmonella typhi,using the Widal agglutination assay, relies on patients' antibodies to the O=9,12 lipopolysaccharide (LPS) antigens, H=d flagellar antigens, and the Vi capsular antigens. A Vi agglutination titre of > 1/40 has traditionally been regarded as indicative of recent infection withS typhi. In this study, 91 sera were used to assess the reliability of the Widal agglutination assay based on antibodies to the Vi antigens. Methods—The Widal agglutination assay was carried out using protocols established by the Central Public Health Laboratory, Colindale. Antibodies to the Vi capsular antigen were detected using a standard preparation of S typhi,ViI Bhatnagar variant strain (S typhi, ViI). Sera used in the study comprised 73 from patients who were culture positive for S typhi, 10 from patients who were culture positive for other species of Salmonella not expressing a Vi antigen (namely, S javiana, S enteritidis, S typhimurium, S stanley, S saint paul, S bareilly,or S mbandaka), and eight from healthy blood donors. Results—Agglutination titres of ≥ 1/40 were detected to S typhi ViI in 69 of 73 sera from patients with typhoid, although 27 of these also agglutinated an unrelated control antigen. The Widal assay also detected significant amounts of agglutinating antibodies to S. typhi ViI in all eight control sera and seven sera from patients infected with S bareilly, S enteritidis, S javiana, S mbandaka, S saint paul, and S stanley. Conclusions—Agglutinating antibodies to the Vi antigen can be detected by the Widal assay, but even with the appropriate control antigens the results were unreliable. The serodiagnosis of infections with S typhi should be based on the detection of antibodies to both the O=9,12 LPS antigen and the H=d flagellar antigen by immunoblotting, and should not use the Vi antigen-based Widal assay. Conclusions should be made in the light of patients' clinical details and any knowledge of previous immunisation for typhoid. Key Words: Salmonella typhi • Widal assay • O=9,12 lipopolysaccharide antigen • H=d flagellar antige