Presence of Listeria monocytogenes in Ready-to-Eat Meat Products Sold at Retail Stores in Costa Rica and Analysis of Contributing Factors

Abstract

Listeria monocytogenes is a pathogenic bacterium associated with RTE meat products sold at the retail level. The objective of this research was to determine the prevalence of Listeria monocytogenes in RTE meat products sold at retail in Costa Rica and to study the factors associated with the levels of contamination; analyzed factors include hygienic practices within stores (cutting techniques, microbial contamination of products) and the behavior of the isolates (persistence against antimicrobials and transfer potential). A total of 190 samples of RTE meat products were collected and analyzed for the presence of coliforms and Listeria species. Isolates of L. monocytogenes were then evaluated in terms of resistance to disinfectants (quaternary ammonium compounds and chlorine) and their transfer potential from food contact surfaces (knife and cuttingboards). Overall Listeria spp. prevalence was 37,4% (71/190); L. innocua was present in 32,1% (61/190) of the products and L. monocytogenes was found in just 2,6% (5/190) of the samples. Most of the contaminated samples were cut with a knife at the moment of purchase (44,2%). When analyzing practices within the stores, it was observed that L. monocytogenes transfer from inoculated knife to “salchichón” was higher for samples cut right at the beginning of the experiment. Also, L. monocytogenes transfer from inoculated cuttingboards was independent of the number of slices but contamination from plastic was higher than wood. Regarding L. monocytogenes resistance to disinfectants, average reductions of 2,6 ± 1,1 log CFU/mL were detected after 6 minutes of exposure to 200 ppm of chlorine; however, chlorine resistance varied among the strains. Prevalence of L. monocytogenes in RTE meat products sold at retail could be associated with handling practices within the stores; further studies are necessary to estimate the impact of these practices on the overall risk for consumers.

Calidad microbiológica del chorizo crudo expendido en el Gran Área Metropolitana de Costa Rica

“…Los coliformes totales se emplearon como indicador de condiciones higiénicas presentes durante la manipulación y procesamiento de los alimentos (Calvo-Arrieta et al, 2021) y el estándar para determinar el número aceptable de coliformes en alimentos varía según el tipo de producto, la edad de los consumidores y las agencias Cuadro 3. Distribución de frecuencias, promedios y medianas del recuento de coliformes totales (UFC/g) en chorizos crudos expendidos en el Gran Área Metropolitana de Costa Rica entre enero y agosto 2019.…”

“…Un estudio reciente de muestras (32) de chorizo crudo en Costa Rica determinó un nivel de contaminación del 65,60 % con Listeria innocua, pero no se evidenció presencia de L. monocytogenes (Calvo-Arrieta et al, 2021); los autores sugirieron que este es un hallazgo normal, debido a que L. monocytogenes no es buena competidora y puede ser difícil su detección en muestras con alta carga microbiana. Por su parte, Clostridium perfringens no parece representar un peligro para el consumidor, puesto que aun cuando fue aislado de una muestra, en este estudio el recuento evidenciado fue menor que 10 6 -10 7 UFC/g, que corresponde a la dosis infecciosa (Sofos et al, 2013).…”

Modelling the Effect of Salt Concentration on the Fate of Listeria monocytogenes Isolated from Costa Rican Fresh Cheeses

“…As all the samples from our study were obtained from public stores and it could be assumed that contamination of fresh cheese is related to sanitary and handling practices performed at retail level [41]. However, a significant proportion of these Turrialba cheeses are fabricated under artisanal or semi-artisanal conditions where contamination from the processing environment may occur [42].…”

Whole Genome Sequence Analysis of <em>Listeria monocytogenes</em> Isolates Recovered from Cattle Farms, Cattle Abattoirs, and Retail Outlets in Gauteng Province, South Africa

“…Antimicrobial resistance (AMR) genes have been documented in L. monocytogenes isolates are produced to facilitate the development of phenotypic resistance to antimicrobial agents [31]. Variable frequencies of AMR genes have been reported for L. monocytogenes isolated from cattle farms, abattoirs, and retail outlets [32,33,34]. The abuse and overuse of antimicrobial agents in human and animal populations result in developing resistance to antimicrobial agents, which is facilitated by the production of appropriate resistance genes as an adaptive response by the pathogen [35,36].…”