Article

Rapid detection of Salmonella enterica serovar Typhi from Humans

Journal of Pure and Applied Microbiology (Impact Factor: 0.07). 05/2010; 04(02):837-841.

ABSTRACT Present study was carried out to investigate Salmonella enterica serovar Typhi associated with Typhoid fever in humans. A total of six blood samples were collected from six patients (4 males and 2 females) and processed for the isolation and identification of the causative agents and their virulence determinants. Microbial investigation revealed the causative agents Salmonella enterica Serovar Typhi in all the six clinical cases. In polymerase chain reaction (PCR) assay, all the six isolates were found positive for the Invasion gene (invA; 244bp fragment), Tyvelose epimerase gene (tyv; 615bp fragment), phage-1 flagellin gene for d-antigen (fliC-d; 750bp fragment) and Vi antigen genes (viaB; 439bp fragment). This study confirms the association of virulent strains of Salmonella enterica Typhi in occurrence of the Typhoid fever in humans. Present study suggested that PCR can be a useful, high throughput diagnostic tool for the rapid detection of Salmonella enterica Serovar Typhi.

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    ABSTRACT: Aims: Salmonella enterica serovar Typhi is the major causative agent for typhoidial fever around the globe among human population reported till date. Present research work was carried out for detection and molecular characterisation of Salmonella enterica serovar Typhi isolated from humans with Typhoidial fever by biochemical, phenotypical and virulence gene based polymerase chain reaction (PCR) techniques. The isolated strains were also investigated for antibiotic susceptibility patterns as a control measure. Methodology and Results: A total of 16 clinical samples were collected from the same numbers of patients (7 males and 9 females) from Coimbatore, Erode and Salem districts of Tamil Nadu and were processed via broth enrichment methods for isolation and identification of the causative agent S. enterica serovar Typhi. Microbiological and biochemical investigations revealed the presence of S. Typhi from 16 samples. The biotyping of the isolates showed that all the isolates belonged to biotype IV. The PCR analysis confirmed the presence of invA (Invasion gene, 244bp), tyv (Tyvelose epimerase gene, 615 bp), fliC-d (Phage-1 flagellin gene for d-antigen, 750 bp) and viaB (Vi antigen gene, 439bp) in all 16 clinical samples. The antibiotic susceptibility test that was carried out among the isolates against 12 antimicrobial agents, showed 100 % resistance to only ampicillin and 100 % sensitivity to carbenicillin, chloramphenicol, clindamycin, gentamycin, kanamycin and tetracycline. Conclusion, significance and impact of study: This study confirmed the association of virulent strains of S. enterica serovar Typhi from Typhoidial fever among human population and suggested that PCR based diagnostic could be very useful for the rapid detection of S. Typhi isolates. Present study emphasized the use of antibiotic like chloramphenicol or in combination with other antibiotics for the effective control of S. Typhi.
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