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ARS Home » Northeast Area » Wyndmoor, Pennsylvania » Eastern Regional Research Center » Characterization and Interventions for Foodborne Pathogens » Research » Publications at this Location » Publication #276857
Title: Genetic diversity demonstrated by pulsed field gel electrophoresis of Salmonella enterica isolates obtained from diverse sources in Mexico

Author
item GALLEGOS-ROBLES, MIGUEL - Juarez University Of The State Of Durango
item MORALES-LOREDO, ALBERTO - Autonomous National University Of Mexico
item ALVAREZ-OJEDA, GENOVEVA - Instituto Nacional De Investigaciones Forestales Y Agropecuarias (INIFAP)
item VAZQUEZ-NAVARRETE, JESUS - Instituto Nacional De Investigaciones Forestales Y Agropecuarias (INIFAP)
item VELARDE-FELIX, SIXTO - Instituto Nacional De Investigaciones Forestales Y Agropecuarias (INIFAP)
item Fratamico, Pina
item GARCIA-HERNANDEZ, JOSE - Juarez University Of The State Of Durango

Submitted to: Journal of Pure and Applied Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/26/2014
Publication Date: 9/18/2014
Citation: Gallegos-Robles, M.A., Morales-Loredo, A., Alvarez-Ojeda, G., Vazquez-Navarrete, J., Velarde-Felix, S., Fratamico, P.M., Garcia-Hernandez, J.L. 2014. Genetic diversity demonstrated by pulsed field gel electrophoresis of Salmonella enterica isolates obtained from diverse sources in Mexico. Journal of Pure and Applied Microbiology. 8(5):3589-3597.

Interpretive Summary: Bacteria belonging to the genus Salmonella are important foodborne pathogens associated with foods of animal origin such as poultry, eggs, meat, and dairy products, and also fruits and vegetables such as tomatoes, cantaloupes, alfalfa sprouts, and peppers. Outbreaks of foodborne illness have also been associated with imported food, including tomatoes and peppers. This study was conducted to determine the prevalence of Salmonella in peppers grown in Mexico, to determine if irrigation water was a potential source of contamination of peppers. A technique known as pulsed field gel electrophoresis (PFGE) was used to determine the source of contamination and to determine the diversity of Salmonella strains isolated from various sources. Salmonella was isolated from more than half of the samples tested, including pepper rinses and irrigation water, and irrigation water was identified as a potential source of contamination of peppers. Since most of the Salmonella strains could be grouped according to their origin, it can be concluded that PFGE is a technique that has the ability to discriminate between Salmonella strains of different origin. Identifying potential sources of contamination of peppers and other produce could permit a science based design of control strategies for use growing and packing of fruits and vegetables, as part of the multiple efforts that need to be applied for controlling pathogens in produce.

Technical Abstract: This study was conducted to determine the genetic diversity of Salmonella isolates recovered from a variety of sources using pulsed-field gel electrophoresis (PFGE) to assess their possible relatedness. Salmonella was isolated from ca. 52% of samples from a pepper var. Bell production system. A total of 54 isolates of Salmonella enterica isolated from the Bell pepper production system, the animal environment (poultry and swine), meat (bovine and chicken), humans (diarrhea and blood), and from unknown sources were examined. The isolates belonged to serotypes S. Enteritidis, S. Typhimurium, S. Choleraesuis, S. Arizonae, S. Gallinarum, S. Newport, and S. Typhi. Pulsotypes generated by PFGE for the various isolates were compared, and the similarities of the fragment length patterns between strains were scored by the Dice coefficient of similarity. Restriction analysis of the 54 isolates with XbaI yielded 30 pulsotypes. S. Enteriditis yielded 16 pulsotypes, with pulsotype 4 as the most common comprising 34.3% (11/32) of the isolates. Isolates of S. Typhimurium yielded 9 pulsotypes, and the remaining serotypes each yielded one pulsotype. Strains obtained from poultry showed more variation in their PFGE patterns and belonged to serotypes S. Enteritidis, S. Typhimurium, and S. Gallinarum. Likewise, the strains obtained from the Bell pepper production system belonged to serotypes S. Enteritidis and S. Typhimurium and were obtained at the field and at the packing plant. This study showed that Salmonella was present in a high number of samples in a Bell pepper production system that did not employ Good Agricultural Practices. Furthermore, since most isolates were grouped based on their origin, it may be concluded that PFGE has the ability to discriminate among Salmonella isolates of different origin.