For epidemiologic investigations, the primary subdivision of Salmonella Typhi is vi-phage typing; 106 Vi-phage types are defined. For multidrug-resistant strains the most common types have been M1 (Pakistan) and E1 (India, Pakistan, Bangladesh, and the Arabian Gulf); a strain untypable with the Vi phages has been responsible for a major epidemic in Tajikistan. Most often, isolates from the Indi...

The assay for serum antibody to the Salmonella typhi capsular polysaccharide (Vi) antigen has recently been revised because of the availability of a purified, highly polymerized Vi antigen. We compared this revised Vi antibody assay to the traditional one for potential usefulness in the surveillance of chronic enteric carriers of S. typhi. The purified Vi antigen of Citrobacter freundii was inc...

Invasiveness of Salmonella typhi was investigated. At first, we introduced Tn5 into the chromosome of a wild-type S. typhi strain, GIFU 10007, and screened the independent Tn5 insertion mutants for noninvasive (Inv-) strains. During the first half of this work, we obtained 4 Inv- strains from 1,338 independent Tn5 mutants. The four were either nonflagellate (Fla-), nonmotile (Mot-), or nonchemo...

A simple passive haemmagglutination assay (PHA) was developed to detect Vi antibodies, to improve the diagnosis of typhoid fever by small laboratories. The Vi capsular antigen of Salmonella typhi was extracted by alternate alcohol and acetone precipitation. Formalin fixed, sheep red blood cells treated with chromium chloride were sensitised with this Vi antigen and antibodies detected and measu...

Introduction: Typhoidal Salmonella causes an invasive infection resulting in 200 000 deaths among 20 million patients annually. Typhoid remains a public health problem in Southeast Asia, the Indian subcontinent, Africa, and South America. Traveler’s diarrhea caused by Salmonella is common in Asia. Outbreaks of typhoidal Salmonella resistant to ampicillin, chloramphenicol, and t...

objective(s):typhoid fever is a dreadful disease of a major threat to public health in developing countries. vaccination with bacterial immunodominant components such as surface proteins may prove as a potent alternative to live attenuated vaccines. invh, an important part of needle complex in type three secretion system (ttss) plays important role in efficient bacterial adherence and entry int...

The propagation of Vi-phage I1 on ‘degraded Vi strains ’ of Salmonella typhi did not yield phage preparations bearing any trace of the specificity of the original Vi type from which the degraded strains had sprung. Ten different standard Vi-typing phages were grown on a selection of degraded Vi strains. The phages could be separated into two groups: six underwent a change which appeared to be a...

OBJECTIVES To investigate the association between the presence of a genetic island inserted within the sapABCDF operon of Salmonella Typhi and the susceptibility to antimicrobial peptides. METHODS Genetics and bioinformatics approaches were used to study the genomic organization of the sap operon of Salmonella Typhi and several serovars of Salmonella enterica. PCR was used to confirm the info...

The Vi capsular polysaccharide (CPS) of Salmonella enterica serovar Typhi, the cause of human typhoid, is important for infectivity and virulence. The Vi biosynthetic machinery is encoded within the viaB locus composed of 10 genes involved in regulation of expression (tviA), polymer synthesis (tviB-tviE), and cell surface localization of the CPS (vexA-vexE). We cloned the viaB locus from S. Typ...