Phenotypic and Genotypic Eligible Methods for Salmonella Typhimurium Source Tracking.

Rafaela G Ferrari,Pedro H N Panzenhagen,Carlos A Conte-Junior

doi:10.3389/fmicb.2017.02587

Abstract

Salmonellosis is one of the most common causes of foodborne infection and a leading cause of human gastroenteritis. Throughout the last decade, Salmonella enterica serotype Typhimurium (ST) has shown an increase report with the simultaneous emergence of multidrug-resistant isolates, as phage type DT104. Therefore, to successfully control this microorganism, it is important to attribute salmonellosis to the exact source. Studies of Salmonella source attribution have been performed to determine the main food/food-production animals involved, toward which, control efforts should be correctly directed. Hence, the election of a ST subtyping method depends on the particular problem that efforts must be directed, the resources and the data available. Generally, before choosing a molecular subtyping, phenotyping approaches such as serotyping, phage typing, and antimicrobial resistance profiling are implemented as a screening of an investigation, and the results are computed using frequency-matching models (i.e., Dutch, Hald and Asymmetric Island models). Actually, due to the advancement of molecular tools as PFGE, MLVA, MLST, CRISPR, and WGS more precise results have been obtained, but even with these technologies, there are still gaps to be elucidated. To address this issue, an important question needs to be answered: what are the currently suitable subtyping methods to source attribute ST. This review presents the most frequently applied subtyping methods used to characterize ST, analyses the major available microbial subtyping attribution models and ponders the use of conventional phenotyping methods, as well as, the most applied genotypic tools in the context of their potential applicability to investigates ST source tracking.

Highlights

Salmonellosis is considered one of the most important zoonosis and one of the major worldwide foodborne diseases (Petrovska et al, 2016)
Phenotyping methods based on antimicrobial resistance profiling, phage typing and serotyping have been used as a basis of Salmonella epidemiology in the past and still have its importance
Pulsed-Field Gel Electrophoresis (PFGE) is the most commonly used molecular typing method and still remains as a standard technique for Salmonella spp. subtyping in routine surveillance laboratories worldwide due the good data collections, which have been stored in data bases for a long time

Summary

INTRODUCTION

Salmonellosis is considered one of the most important zoonosis and one of the major worldwide foodborne diseases (Petrovska et al, 2016). Both antimicrobial susceptibility profiling and phage typing are the traditional methods for Salmonella phenotyping (Jeoffreys et al, 2001) Their discriminatory power is sufficient to source attribute ST and are implemented as a screening of an investigation by computing results using frequency-matching models, as above described. Despite useful, these subtyping methods still often require being complemented by molecular DNA analysis, such as ribotyping and pulsed field electrophoresis (PFGE) (Wattiau et al, 2011). A thorough understanding of the advantages and limitations of such typing techniques is crucial in the choice of the appropriate approach to best define a pathogen responsible for an outbreak

PHENOTYPIC METHODS

GENOTYPIC METHODS

Findings

CONCLUSION