Supplement 1989 (n. 33) to the Kauffmann-White scheme.

This supplement reports the characters of 18 new Salmonella serovars recognized in 1989 by the WHO Collaborating Centre for Reference and Research on Salmonella: 11 were assigned to S. enterica subsp. enterica, 3 to subspecies salamae, 1 to subspecies arizonae, 2 to subspecies houtenae and 1 to S. bongori.

Supplement 1997 (no. 41) to the Kauffmann-White scheme.

This supplement reports the characterization of 15 new Salmonella serovars recognized in 1997 by the WHO Collaborating Centre for Reference and Research on Salmonella: 8 were assigned to S. enterica subsp. enterica, 4 to subspecies salamae, 2 to subspecies diarizonae, and 1 to subsp. houtenae. In addition, the antigenic factors H:z85 and H:z87 are described and one modification to the Kauffmann-White scheme is reported.

Supplement 1998 (no. 42) to the Kauffmann-White scheme.

This supplement reports the characterization of 14 new Salmonella serovars recognized in 1998 by the WHO Collaborating Centre for Reference and Research on Salmonella: 11 were assigned to S. enterica subsp. enterica, one to subspecies salamae, one to subspecies diarizonae, and one to subsp. indica. In addition, the antigenic factor H:z88 is described.

Supplement 1999 (no. 43) to the Kauffmann-White scheme.

This supplement reports the characterization of 26 new Salmonella serovars recognized in 1999 by the WHO Collaborating Centre for Reference and Research on Salmonella: 15 were assigned to S. enterica subsp. enterica, seven to subspecies salamae, two to subspecies diarizonae, and one to subsp. houtenae; and one to S. bongori. In addition, the antigenic factor H:z89 is described.

Supplement 1994 (no. 38) to the Kauffmann-White scheme.

This supplement reports the characterization of 24 new Salmonella serovars recognized in 1994 by the WHO Collaborating Centre for Reference and Research on Salmonella: 11 were assigned to S. enterica subsp. enterica, 6 to subspecies salamae, 6 to subspecies diarizonae and 1 to subspecies houtenae. In addition, the antigenic factor H:z83 is described.

Supplement 2000 (no. 44) to the Kauffmann-White scheme.

This supplement reports the characterization of 12 new Salmonella serovars recognized in 2000 by the WHO Collaborating Centre for Reference and Research on Salmonella: nine were assigned to S. enterica subsp. enterica, two to subspecies salamae, and one to subspecies diarizonae.

Supplement 1996 (no. 40) to the Kauffmann-White scheme.

This supplement reports the characterization of 13 new Salmonella serovars recognized in 1996 by the WHO Collaborating Centre for Reference and Research on Salmonella: 8 were assigned to S. enterica subsp. enterica, 3 to subspecies salamae and 2 to subspecies diarizonae.

Molecular characterization of the Salmonella typhi StpA protein that is related to both Yersinia YopE cytotoxin and YopH tyrosine phosphatase.

Analysis of the nucleotide sequence of a 4-kb DNA fragment located between the sip and iag loci on Salmonella typhi chromosome revealed three open reading frames, termed sipF, ctpA and stpA. The 82-amino-acid (aa) sipF product showed extensive similarity to the lacP protein from S. typhimurium. The StpA protein (535 aa) exhibited significant similarity to both Yersinia enterocolitica YopE cytotoxin and YopH tyrosine phosphatase. The CtpA polypeptide (130 aa) might be the molecular chaperone of the StpA protein.

Salmonella typhimurium TnphoA mutants with increased sensitivity to biological and chemical detergents.

Salmonella typhimurium is a ubiquitous pathogenic bacterium able to sustain the environmental conditions of the gastrointestinal tract, including biliary salts. To understand the mechanisms involved in bile salt resistance and, more generally, detergent resistance, we investigated S. typhimurium mutants produced with the random mutagenic TnphoA transposon. A total of 3,000 transpositional mutants were isolated. Three strains among the 1,432 first mutants lost the ability to grow in the presence of biological and chemical detergents. They were prototrophic and exhibited normal lipopolysaccharide and outer membrane protein profiles after SDS-PAGE. They did not show sensitivity to dyes but showed very different sensitivities to antibiotics. For each mutant strain, Southern blotting analysis revealed a unique TnphoA insertion at different chromosomal locations. These observations were confirmed by transduction experiments.

The putative sigma factor KatF (RpoS) is required for the transcription of the Salmonella typhimurium virulence gene spvB in Escherichia coli.

The virulence of Salmonella typhimurium for mice is dependent on a plasmid-borne gene cluster termed spv. We previously determined that both S. typhimurium and Escherichia coli bacteria grown in a rich medium preferentially express the spv genes during the stationary phase of growth. In this study we evaluated the role of KatF, a putative sigma factor for starvation- and stationary phase-induced genes, in the expression of the spvB gene. The transcription of spvB in E. coli was compared in katF and wild-type backgrounds, using cloned spvB-lacZ and spvB-cat fusions. Expression of spvB was found to be greatly affected in katF mutants. Complementation experiments performed with the cloned katF gene confirmed that KatF is required for the expression of the S. typhimurium virulence gene spvB in E. coli.

Salmonella typhimurium acrB-like gene: identification and role in resistance to biliary salts and detergents and in murine infection.

Salmonella serotype typhimurium transpositional mutants altered in resistance to biliary salts and detergents were isolated previously. We have characterized further the LX1054 mutant strain, the most sensitive of them. The chromosomal DNA segment flanking transposon insertion was cloned and sequenced. The highest level of identity was found for the acrB (formerly acrE) gene of Escherichia coli, a gene encoding a drug efflux pump of the Acr family. LX1054 exhibited a reduced capacity to colonize the intestinal tract. After passages in mice, the mutant strain lost the sensitive phenotype. In vitro, a resumption of growth appeared after 17 h of culture in medium with cholate or other tested biological or chemical detergents. Then, the acquired resistant phenotype seemed stable. The data suggested a role of S. typhimurium acrB-like gene in resistance to biliary salts and detergents and in mice intestinal colonization. However, the local and transient sensitivity observed in vivo, and the in vitro adaptations suggest that several detergent-resistance mechanisms operate in S. typhimurium.

Rapid detection of Salmonella subspecies I by PCR combined with non-radioactive hybridisation using covalently immobilised oligonucleotide on a microplate.

A polymerase chain reaction (PCR)-based test was developed for the detection of Salmonella. One pair of oligonucleotide primers was designed to amplify a 93-bp fragment of a gene required for the invasion of HeLa cells by Salmonella ser Typhi strain Ty2. The amplified product was analysed by non-radioactive sandwich hybridisation in microtiter plates using two oligonucleotides. The capture oligonucleotide was covalently linked onto animated wells of microtiter plates. The detection oligonucleotide was labelled with biotine. The hybrid molecules were detected by avidine conjugated with alkaline phosphatase and chromogenic substrate. The described combination of microplate sandwich hybridisation and PCR seems to be a suitable method for rapid detection of Salmonella subspecies I. It only requires a thermal cycler and a conventional microtiter reader, and can be readily done on a large scale.

[Virulence factors of Salmonella: from molecular genetics to diagnostic applications]. / Facteurs de virulence des Salmonella: de la génétique moléculaire à l'application diagnostique.

Salmonella serotype Typhimurium is a facultative intracellular pathogen that causes a systemic infection in naturally, or experimentally, infected mice. After oral contamination, Typhimurium colonizes the ileal mucosa and Peyer's patches and invades draining mesenteric lymph nodes. From these primary sites of infection, bacteria dissiminate to the reticuloendothelial system and proliferate rapidly in spleen and liver. Several virulence factors are encoded by chromosomal genes. The ability of Typhimurium to adhere to and invade epithelial cells has been associated with flagella, pili of type I and mannose-resistant haemagglutinating activity. By comparing the virulence of isogenic strains, it appeared that these traits played a marginal role and were not essential for full virulence expression. It is now clear that other surface structures are important for the invasiness capacity of Typhimurium. To multiply in the reticuloendothelial system, a complete lipopolysaccharide is necessary for the bacteria in resisting serum bactericidal activity and producing tissue damage. Salmonella have evolved a specialized iron-binding ligand, termed enterobactin, to acquire iron necessary for their multiplication. Enterobactin competes with the host iron-binding proteins (transferrin or lactoferrin) to secure the iron required by the bacteria. Though the presence of an enterotoxin in Salmonella is still controversial, there is now substantial evidence to support this concept. Recently, a gene encoding an enterotoxin has been cloned from Typhimurium and expressed in E. coli. Typhimurium strains harbour a 90 kilobases (kb) plasmid which is essential for virulence. This plasmid encodes virulence factors required for replication of Salmonella in liver and spleen. It was postulated that the plasmid allowed Typhimurium to multiply in Kupffer cells and in splenic macrophages. The virulence-associated region of the plasmid restored full virulence to plasmidless strains. Transposon insertion mutagenesis demonstrated the existence of two DNA sequences, designated Vir A and Vir B, which are essential for virulence expression. The Vir A region has been sequenced; it encodes four polypeptides with apparent molecular mass of 27,000, 28,000, 33,000 and 70,000. The Vir B region encodes two polypeptides of 38,000 and 43,000. In an attempt to identify bacterial components contributing to invasion of HeLa cells by Salmonella serovar Typhi, we cloned a 30 kb DNA sequence necessary for entry of bacteria into epithelial cells. However, this sequence is not sufficient for conferring an invasive phenotype to E. coli strains. From this DNA fragment, a short segment of 487 bp was subcloned, sequenced and used as probe to detect Salmonella.(ABSTRACT TRUNCATED AT 400 WORDS)