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Serotyping & molecular characterization for study of genetic diversity among seafood associated nontyphoidal Salmonella serovars.

Bhowmick PP, Srikumar S, Devegowda D, Shekar M, Darshanee Ruwandeepika HA, Karunasagar I - Indian J. Med. Res. (2012)

Bottom Line: Therefore, this study was attempted to use different phenotypic and molecular fingerprinting methods for investigation of genetic diversity among seafood associated nontyphoidal Salmonella serovars.Fifty eight seafood associated Salmonella isolates were included in this study.Though both PCR based techniques were found to have a good discriminatory index, a better discriminatory ability was observed when the results obtained by the two techniques were combined and taken for composite analysis.

View Article: PubMed Central - PubMed

Affiliation: Department of Fishery Microbiology, Karnataka Veterinary, Animal & Fisheries Sciences University, College of Fisheries, Mangalore, India.

ABSTRACT

Background & objectives: Infections due to seafood associated Salmonella serovars are great risk to public health. Different phenotypic characteristics have been used previously for epidemiological investigation of Salmonella. Beyond the phenotypic characterization, a reliable genetic level discriminatory method is required. Therefore, this study was attempted to use different phenotypic and molecular fingerprinting methods for investigation of genetic diversity among seafood associated nontyphoidal Salmonella serovars.

Methods: Fifty eight seafood associated Salmonella isolates were included in this study. All isolates were serotyped and epidemiological investigation was carried out using molecular fingerprinting methods, random amplified polymorphic DNA (RAPD) and enterobacterial repetitive intergenic consensus sequence based-PCR (ERIC-PCR) along with whole cell protein profiling using sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) in our study.

Results: Among the 58 Salmonella isolates, S. Weltevreden was observed to be the most predominant serovar. Typing of Salmonella serovars using RAPD and ERIC-PCR suggested the existence of a genetic diversity. Though both PCR based techniques were found to have a good discriminatory index, a better discriminatory ability was observed when the results obtained by the two techniques were combined and taken for composite analysis. Protein profiling of whole cells using SDS-PAGE demonstrated the presence of several bands with two bands of sizes 38 kDa and 46 kDa common among all 58 isolates.

Interpretation & conclusions: Our study shows that use of protein profiling in combination with established typing methods such as RAPD and ERIC-PCR may provide useful information in typing of non-typhoidal Salmonella isolates associated with seafood and to develop strategies to protect public from Salmonella infections.

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Related in: MedlinePlus

Dendogram showing the percentages of similarity between typable seafood associated Salmonella generated from random amplified polymorphic DNA-PCR (RAPD-PCR) fingerprinting with the band matching coefficient of Dice and the UPGMA clustering method.
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Figure 2: Dendogram showing the percentages of similarity between typable seafood associated Salmonella generated from random amplified polymorphic DNA-PCR (RAPD-PCR) fingerprinting with the band matching coefficient of Dice and the UPGMA clustering method.

Mentions: Analysis of serovarsby RAPD-PCR: RAPD of the 58 Salmonella serovars yielded different patterns consisting of 5-12 bands ranging approximately from 0.15 to 2.5 kb (Fig. 1). Fig. 2 shows the dendrogram from the RAPD results of the 58 isolates. A common band was found in all 58 isolates at 1 kb. At an average similarity of 54 per cent, 44 of the 58 Salmonella serovars grouped into 13 clusters (R1-R13), while the remaining 14 were unclustered. The unclustered isolates belonged to serovar S. Virchow (SV17), S. Oslo (SO1, SO2, SO9, SO20, and SO77), S. Newport (SN33, SN34 and SN37) and S. Paratyphi C (SU1, SU2, SU6, SU7 and SU12). Heterogeneity was observed within serovars of S. Oslo (6 clusters), S. Weltevreden (5 clusters), S. Newport (6 clusters), S. Paratyphi C (6 clusters) and S. Barielly (2 clusters). S. Weltevreden, the major group with 18 isolates was assigned to RAPD clusters designated R2, R5, R7, R8 and R12. S. Newport isolates grouped in clusters designated R4, R10 and R11. S. Bareilly isolates presented as two groups viz. R9 and R13 of which R13 was further sub-clustered into two where one subgroup belonged to S. Bareilly and the other to S. Infantis at 60 per cent similarity. The single isolate of S. Aba and S. Virchow clustered with S. Infantis and S. Paratyphi C at 72 and 51 per cent, respectively. All the serovars typed in this study were isolated from a particular seafood source. The source of isolates and the serotype results showed commonality. Each serovars was linked to a particular seafood type in most of the isolates. For example, in S. Weltevreden, except for R2 and R5, where the cluster was generated from serovar isolated from fish, the remaining clusters (R7, R8 and R12) were generated from isolates from mixed animal sources of fish, oyster and shrimp.


Serotyping & molecular characterization for study of genetic diversity among seafood associated nontyphoidal Salmonella serovars.

Bhowmick PP, Srikumar S, Devegowda D, Shekar M, Darshanee Ruwandeepika HA, Karunasagar I - Indian J. Med. Res. (2012)

Dendogram showing the percentages of similarity between typable seafood associated Salmonella generated from random amplified polymorphic DNA-PCR (RAPD-PCR) fingerprinting with the band matching coefficient of Dice and the UPGMA clustering method.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3361875&req=5

Figure 2: Dendogram showing the percentages of similarity between typable seafood associated Salmonella generated from random amplified polymorphic DNA-PCR (RAPD-PCR) fingerprinting with the band matching coefficient of Dice and the UPGMA clustering method.
Mentions: Analysis of serovarsby RAPD-PCR: RAPD of the 58 Salmonella serovars yielded different patterns consisting of 5-12 bands ranging approximately from 0.15 to 2.5 kb (Fig. 1). Fig. 2 shows the dendrogram from the RAPD results of the 58 isolates. A common band was found in all 58 isolates at 1 kb. At an average similarity of 54 per cent, 44 of the 58 Salmonella serovars grouped into 13 clusters (R1-R13), while the remaining 14 were unclustered. The unclustered isolates belonged to serovar S. Virchow (SV17), S. Oslo (SO1, SO2, SO9, SO20, and SO77), S. Newport (SN33, SN34 and SN37) and S. Paratyphi C (SU1, SU2, SU6, SU7 and SU12). Heterogeneity was observed within serovars of S. Oslo (6 clusters), S. Weltevreden (5 clusters), S. Newport (6 clusters), S. Paratyphi C (6 clusters) and S. Barielly (2 clusters). S. Weltevreden, the major group with 18 isolates was assigned to RAPD clusters designated R2, R5, R7, R8 and R12. S. Newport isolates grouped in clusters designated R4, R10 and R11. S. Bareilly isolates presented as two groups viz. R9 and R13 of which R13 was further sub-clustered into two where one subgroup belonged to S. Bareilly and the other to S. Infantis at 60 per cent similarity. The single isolate of S. Aba and S. Virchow clustered with S. Infantis and S. Paratyphi C at 72 and 51 per cent, respectively. All the serovars typed in this study were isolated from a particular seafood source. The source of isolates and the serotype results showed commonality. Each serovars was linked to a particular seafood type in most of the isolates. For example, in S. Weltevreden, except for R2 and R5, where the cluster was generated from serovar isolated from fish, the remaining clusters (R7, R8 and R12) were generated from isolates from mixed animal sources of fish, oyster and shrimp.

Bottom Line: Therefore, this study was attempted to use different phenotypic and molecular fingerprinting methods for investigation of genetic diversity among seafood associated nontyphoidal Salmonella serovars.Fifty eight seafood associated Salmonella isolates were included in this study.Though both PCR based techniques were found to have a good discriminatory index, a better discriminatory ability was observed when the results obtained by the two techniques were combined and taken for composite analysis.

View Article: PubMed Central - PubMed

Affiliation: Department of Fishery Microbiology, Karnataka Veterinary, Animal & Fisheries Sciences University, College of Fisheries, Mangalore, India.

ABSTRACT

Background & objectives: Infections due to seafood associated Salmonella serovars are great risk to public health. Different phenotypic characteristics have been used previously for epidemiological investigation of Salmonella. Beyond the phenotypic characterization, a reliable genetic level discriminatory method is required. Therefore, this study was attempted to use different phenotypic and molecular fingerprinting methods for investigation of genetic diversity among seafood associated nontyphoidal Salmonella serovars.

Methods: Fifty eight seafood associated Salmonella isolates were included in this study. All isolates were serotyped and epidemiological investigation was carried out using molecular fingerprinting methods, random amplified polymorphic DNA (RAPD) and enterobacterial repetitive intergenic consensus sequence based-PCR (ERIC-PCR) along with whole cell protein profiling using sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) in our study.

Results: Among the 58 Salmonella isolates, S. Weltevreden was observed to be the most predominant serovar. Typing of Salmonella serovars using RAPD and ERIC-PCR suggested the existence of a genetic diversity. Though both PCR based techniques were found to have a good discriminatory index, a better discriminatory ability was observed when the results obtained by the two techniques were combined and taken for composite analysis. Protein profiling of whole cells using SDS-PAGE demonstrated the presence of several bands with two bands of sizes 38 kDa and 46 kDa common among all 58 isolates.

Interpretation & conclusions: Our study shows that use of protein profiling in combination with established typing methods such as RAPD and ERIC-PCR may provide useful information in typing of non-typhoidal Salmonella isolates associated with seafood and to develop strategies to protect public from Salmonella infections.

Show MeSH
Related in: MedlinePlus