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Updated: Jul 25, 2026
An Allelotyping PCR for Identifying Salmonella enterica serovars Enteritidis, Hadar, Heidelberg, and Typhimurium
Published on: July 22, 2011
Effective characterization of Salmonella Enteritidis by most probable number (MPN) followed by multiplex polymerase
Lincohn Zappelini1, Solange Martone-Rocha2, Milena Dropa2
1Department of Environmental Health, School of Public Health, University of São Paulo, São Paulo, SP, Brazil. lincohn.zappelini@gmail.com.
Abstract:
Nontyphoidal Salmonella (NTS) is a relevant pathogen involved in gastroenteritis outbreaks worldwide. In this study, we determined the capacity to combine the most probable number (MPN) and multiplex polymerase chain reaction (PCR) methods to characterize the most important Salmonella serotypes in raw sewage. A total of 499 isolates were recovered from 27 raw sewage samples and screened using two previously described multiplex PCR methods. From those, 123 isolates were selected based on PCR banding pattern-identical or similar to Salmonella Enteritidis and Salmonella Typhimurium-and submitted to conventional serotyping. Results showed that both PCR assays correctly serotyped Salmonella Enteritidis, however, they presented ambiguous results for Salmonella Typhimurium identification. These data highlight that MPN and multiplex PCR can be useful methods to describe microbial quality in raw sewage and suggest two new PCR patterns for Salmonella Enteritidis identification.
Insights
This study combined Most Probable Number (MPN) and multiplex PCR to identify Nontyphoidal Salmonella (NTS) in raw sewage. While effective for Salmonella Enteritidis, PCR showed ambiguous results for Salmonella Typhimurium.
Area of Science:
- Environmental microbiology
- Molecular diagnostics
- Food safety and public health
Background:
- Nontyphoidal Salmonella (NTS) is a significant cause of global gastroenteritis outbreaks.
- Effective methods are needed to track Salmonella serotypes in environmental samples like raw sewage.
- Raw sewage can serve as an indicator of pathogen circulation in a community.
Purpose of the Study:
- To evaluate the combined efficacy of Most Probable Number (MPN) and multiplex polymerase chain reaction (PCR) for characterizing Salmonella serotypes in raw sewage.
- To identify the predominant Salmonella serotypes present in raw sewage samples.
- To assess the accuracy of multiplex PCR methods for differentiating key Salmonella serotypes.
Main Methods:
- Collected 27 raw sewage samples and isolated 499 bacterial colonies.
- Screened isolates using two established multiplex PCR assays.
- Selected 123 isolates with PCR patterns resembling Salmonella Enteritidis or Salmonella Typhimurium for conventional serotyping.
Main Results:
- Multiplex PCR assays accurately identified Salmonella Enteritidis.
- The PCR methods yielded ambiguous results for Salmonella Typhimurium identification.
- Two novel PCR patterns potentially indicative of Salmonella Enteritidis were suggested.
Conclusions:
- The combination of MPN and multiplex PCR is a valuable tool for assessing microbial quality in raw sewage.
- Current multiplex PCR methods require refinement for reliable Salmonella Typhimurium identification.
- Further research could validate the new PCR patterns for Salmonella Enteritidis detection.
