Molecular Characterization ofListeria monocytogenesof the Serotype 4b Complex (4b, 4d, 4e) from Two Turkey Processing Plants

Abstract

Most foodborne outbreaks of listeriosis have been found to involve a small number of closely related strains of Listeria monocytogenes serotype 4b. The ecology of these organisms and their reservoirs in nature or in the processing plant environment, however, remain poorly understood. Surveys of environmental samples from two turkey processing plants in the United States indicated presence of L. monocytogenes of the serotype 4b complex (serotype 4b and the closely related serotypes 4d and 4e). In addition, environmental and raw product samples from one plant repeatedly yielded isolates with genetic markers typical of two major serotype 4b epidemic clonal groups, ECI and ECII. The pulsed field gel electrophoresis (PFGE) profiles of these isolates, however, were clearly distinct from those of confirmed epidemic-associated strains. Furthermore, we observed minor but consistent differences in PFGE profiles of isolates that harbored ECI- or ECII-specific genetic markers, and that were obtained at different sampling times from the same plant. The findings suggest processing plant persistence (or repeated introductions) and genomic diversification of L. monocytogenes serotype 4b isolates that harbor ECI- or ECII-specific genetic markers. Such diversification would need to be taken into consideration in further efforts to elucidate the evolution and epidemiology of these organisms.

Characterization of epidemic clones of Listeria monocytogenes serotype 4b isolated from humans and meat products in Brazil

“…These findings are reinforced by other studies, which describe the frequency and distribution of epidemic clones [25][26][27][28][29], indicating their wide distribution and importance in the epidemiology of L. monocytogenes in the world.…”

Diverse Geno- and Phenotypes of Persistent Listeria monocytogenes Isolates from Fermented Meat Sausage Production Facilities in Portugal

“…Persistence may indicate deficiencies in sanitation procedures or potential niches in the processing environment where L. monocytogenes is protected from sanitation. While persistence of L. monocytogenes in meat processing plants (15,37,38,61) and in other plants (44,47,73) has previously been reported, identification of different PFGE types (as well as different molecular serotypes and lineages) associated with persistence in different plants (except for one PFGE type associated with persistence in two plants) clearly suggests that many different L. monocytogenes strains have the ability to establish persistent populations in processing plants.…”

Role of Growth Temperature in Freeze-Thaw Tolerance of Listeria spp

“…They included 14 strains of L. monocytogenes (10 of serotype 4b and two each of serotype 1/2a and serotype 1/2b) and two strains each of L. welshimeri and L. innocua (Table 1). Six of the serotype 4b strains were confirmed to be ECI, including five (F2365, F2381, G3982, G4011, and G4030) implicated in outbreaks of listeriosis (37) and one isolated from a turkey processing plant environmental sample (12). Two serotype 4b strains were members of ECII, including strain H7550, implicated in the 1998 to 1999 hot dog outbreak of listeriosis (37) and strain L0226, isolated from a turkey processing plant environmental sample (12).…”

“…Six of the serotype 4b strains were confirmed to be ECI, including five (F2365, F2381, G3982, G4011, and G4030) implicated in outbreaks of listeriosis (37) and one isolated from a turkey processing plant environmental sample (12). Two serotype 4b strains were members of ECII, including strain H7550, implicated in the 1998 to 1999 hot dog outbreak of listeriosis (37) and strain L0226, isolated from a turkey processing plant environmental sample (12). Strain WS1 represented ECV, implicated in an outbreak of listeriosis in Winston-Salem, NC, in 2000 (5, 37), and strain 171A was isolated from a turkey processing plant and did not harbor markers specific to known epidemic clones (12).…”

“…Two serotype 4b strains were members of ECII, including strain H7550, implicated in the 1998 to 1999 hot dog outbreak of listeriosis (37) and strain L0226, isolated from a turkey processing plant environmental sample (12). Strain WS1 represented ECV, implicated in an outbreak of listeriosis in Winston-Salem, NC, in 2000 (5, 37), and strain 171A was isolated from a turkey processing plant and did not harbor markers specific to known epidemic clones (12). The serotype 1/2a strain J0161 represented ECIII, implicated in an outbreak of listeriosis traced to turkey deli meats in 2000 (37).…”