Identification, subtyping and virulence determination of Listeria monocytogenes, an important foodborne pathogen

Abstract

Listeria monocytogenes is an opportunistic intracellular pathogen that has become an important cause of human foodborne infections worldwide. Given its close relationship to other Listeria species and its tendency to produce non-specific clinical symptoms, the availability of rapid, sensitive and specific diagnostic tests for the differentiation of L. monocytogenes from other Listeria species is helpful for selecting appropriate treatment regimens. In addition, with L. monocytogenes comprising a diversity of strains of varying pathogenicity, the ability to precisely track the strains involved in listeriosis outbreaks and speedily determine their pathogenic potential is critical for the control and prevention of further occurrences of this deadly disease. Extensive research in recent decades has revealed significant insights regarding the molecular mechanisms of L. monocytogenes infection. This in turn has facilitated the development of laboratory procedures for enhanced detection and identification of L. monocytogenes, and has also contributed to the implementation of improved control and prevention strategies against listeriosis. The purpose of this review is to summarize recent progress in the species-specific identification, subtyping and virulence determination of L. monocytogenes strains, and to discuss future research needs pertaining to these important areas of listeriosis.

Detection and enumeration of viable Listeria monocytogenes cells from ready-to-eat and processed vegetable foods by culture and DVC-FISH

“…Many authors have studied the target proteins and genes in virulent and avirulent strains in order to establish differences in L. monocytogenes pathogenesis. lmo 2821 gene product (internalin J) seems to be present in all virulent strains of L. monocytogenes (Liu, 2006). In all the isolates identified in this study, the band of 611 bp, resulting from the amplification of a fragment of lmo 2821 gene was observed (Figure 1).…”

“…Both are the most common serotypes isolated in human listeriosis cases (Liu, 2006) and have been previously detected in foods (Vitas, Aguado & García-Jalón, 2004;Kiss, Tirczka, Szita, Bernath & Csiko, 2006).…”

“…A PCR for amplification of the gene encoding lmo 2821 internalin protein J (Sabet, Lecuit, Cabanes, Cossart & Bierne, 2005;Liu, 2006) was performed, using the primers described by Liu, Ainsworth, Austin & Lawrence (2003) which amplify a fragment of 611pb of the gene. Strain CECT 4032, that has often been associated with cases of meningitis was used as a positive control.…”

“…Listeria species are present in a variety of environments, including soil, water, effluents and foods. With manufactured ready-to-eat foods being consumed in increasing quantities, it is not surprising that L. monocytogenes has become recognized as an important opportunistic human foodborne pathogen (Liu, 2006). Freeze injury reversibility of L. monocytogenes transforms contaminated frozen foods into a potential source of infection (Flanders & Donnelly, 1994).…”

Potentials and limitations of molecular diagnostic methods in food safety

“…For instance, Shigella sp. and Escherichia coli received a lot of attention and much effort has been put into the development of a test able to detect and determine the serotype of pathogenic strains [29,31,32]. The identification of a specific serotype is particularly important with E. coli, as pathogenicity varies among different strains, ranging from the harmless K-12 to the life threatening O157:H7.…”