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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 Salmonellagenerated from enterobacterial repetitive intergenic consensus-PCR (ERIC-PCR) fingerprinting with the band matching coefficient of Dice and the UPGMA clustering method.
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Figure 4: Dendogram showing the percentages of similarity between typable seafood associated Salmonellagenerated from enterobacterial repetitive intergenic consensus-PCR (ERIC-PCR) fingerprinting with the band matching coefficient of Dice and the UPGMA clustering method.

Mentions: Analysis of serovars by ERIC-PCR: ERIC-PCR fingerprints generated for the 58 isolates comprised 5-15 bands ranging from 0.15 to 4.5 kb (Fig. 3) with a discriminatory index of 0.96. A common band was found in all 58 isolates at 1.5 kb. All the serovars were grouped into 17 clusters (E1-E17) at an average similarity of 51 per cent (Fig. 4). Unlike RAPD where 14 isolates failed to cluster, ERIC analysis resulted in only six which could not be grouped. These included two isolates of S. Paratyphi C and one isolate each of S. Newport, S. Weltevreden, S. Infantis and S. Virchow. It was also observed that except for a few S. Weltevreden isolates which grouped with clusters of other serotypes (S. Oslo in E10, S. Bareilly in E6, and with S. Aba in E1) almost all the isolates within a cluster belonged to the same serotype. Genetic heterogeneity was also observed among the various serovars. Major cluster differentiation was observed for S. Weltevreden which grouped into six clusters designated E1, E2, E12, E14, E15 and E16. Similarly three clusters were observed for S. Bareilly (E5, E6 and E9), two each for S. Paratyphi C (E13 and E17), S. Newport (E7 and E11) and S. Oslo (E8 and E10). Sixteen isolates obtained from clam included nine S. Newport that grouped in two clusters (E7 and E11) and only two of the four S. Paratyphi C grouping as a single cluster (E17). Sixteen fish isolates included 10 S. Weltevreden that grouped in three clusters (E1, E12 and E14), two S. Anatum present in a single cluster and two of the four S. Paratyphi C isolates grouped in one cluster (Table).


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 Salmonellagenerated from enterobacterial repetitive intergenic consensus-PCR (ERIC-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 4: Dendogram showing the percentages of similarity between typable seafood associated Salmonellagenerated from enterobacterial repetitive intergenic consensus-PCR (ERIC-PCR) fingerprinting with the band matching coefficient of Dice and the UPGMA clustering method.
Mentions: Analysis of serovars by ERIC-PCR: ERIC-PCR fingerprints generated for the 58 isolates comprised 5-15 bands ranging from 0.15 to 4.5 kb (Fig. 3) with a discriminatory index of 0.96. A common band was found in all 58 isolates at 1.5 kb. All the serovars were grouped into 17 clusters (E1-E17) at an average similarity of 51 per cent (Fig. 4). Unlike RAPD where 14 isolates failed to cluster, ERIC analysis resulted in only six which could not be grouped. These included two isolates of S. Paratyphi C and one isolate each of S. Newport, S. Weltevreden, S. Infantis and S. Virchow. It was also observed that except for a few S. Weltevreden isolates which grouped with clusters of other serotypes (S. Oslo in E10, S. Bareilly in E6, and with S. Aba in E1) almost all the isolates within a cluster belonged to the same serotype. Genetic heterogeneity was also observed among the various serovars. Major cluster differentiation was observed for S. Weltevreden which grouped into six clusters designated E1, E2, E12, E14, E15 and E16. Similarly three clusters were observed for S. Bareilly (E5, E6 and E9), two each for S. Paratyphi C (E13 and E17), S. Newport (E7 and E11) and S. Oslo (E8 and E10). Sixteen isolates obtained from clam included nine S. Newport that grouped in two clusters (E7 and E11) and only two of the four S. Paratyphi C grouping as a single cluster (E17). Sixteen fish isolates included 10 S. Weltevreden that grouped in three clusters (E1, E12 and E14), two S. Anatum present in a single cluster and two of the four S. Paratyphi C isolates grouped in one cluster (Table).

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