Prevalence and antimicrobial resistance of Listeria species and molecular characterization of Listeria monocytogenes isolated from retail ready-to-eat foods

Abstract

A wide variety of foods can be contaminated with Listeria species, especially L. monocytogenes. Ready-to-eat (RTE) foods are predominantly associated with human listeriosis caused by L. monocytogenes. Therefore, this study aimed to assess the presence of Listeria species in RTE foods and to characterize L. monocytogenes isolates by means of detection of virulence markers, serotypes and genetic relatedness. Of the 300 RTE food samples, 59 (19.7%) were positive for Listeria species: L. innocua (13.3%), L. monocytogenes (5%), L. welshimerii (2.3%), L. grayi subsp. murrayi (1.3%), L. grayi (1%), L. ivanovii (1%) and L. ivanovi subsp. londoniensis (0.3%). All L. monocytogenes isolates identified were positive for the actA, iap, inlA, inlB, inlC, inlJ, plcA and prfA virulence genes and biofilm. The isolates were serotyped as 1/2c (33.3%), 4b (26.7%), 1/2a (26.7%), 1/2b (6.7%) and 3c (6.7%) by the multiplex-PCR and agglutination methods. PCR-restriction fragment length polymorphism with AluI and MluCI resulted in three and two profiles, respectively. Pulsed-field gel electrophoresis differentiated the L. monocytogenes isolates into 15 ApaI and 12 AscI patterns. Antimicrobial resistance of all Listeria isolates was determined by the disk diffusion method. Most L. monocytogenes isolates were sensitive to antimicrobials used in the treatment of listeriosis. This study shows the presence of potential pathogenic and antimicrobial-resistant L. monocytogenes in RTE foods that may lead to consumer health risks.

Genomic analysis of high copy-number sequences for the targeted detection of Listeria species using a flow-through surveillance system

“…To further validate the detection capabilities of the assay, the specificity of the BH1 oligonucleotide set was further expanded by testing for Listeria species other than L. monocytogenes . Other additional tested species were L. innocua, L. ivanovii, L. welshimeri, and L. seeligeri , which have been potentially implicated in causing illness to immunocompromised individuals (Korsak and Szuplewska 2016 ) and have been recovered from ready-to-eat foods or raw/unprocessed foods (Arslan and Özdemir 2020 ; Guerra et al 2001 ; Pesavento et al 2010 ; Soriano et al 2001 ; Zeinali et al 2017 ) as well as in food processing facilities (Huang et al 2007 ; Korsak and Szuplewska 2016 ), and food products (Chen et al 2009 ; Pesavento et al 2010 ). The inclusivity test was conducted using RNA (100 pg) from Listeria species , corresponding to an estimated 100–150 cell equivalents of RNA per amplification reaction (Glaser et al 2001 ; Milner et al 2001 ) (Fig.…”

“…Recently, high profile outbreaks of L. monocytogenes have been associated with deli meats, fresh produce, and ready-to-eat foods (Churchill et al 2019). Other Listeria species have also been found in ready-to-eat, raw or unprocessed foods (Arslan and Özdemir 2020;Guerra et al 2001;Pesavento et al 2010;Soriano et al 2001;Zeinali et al 2017), as well as in food Communicated by Erko Stackebrandt.…”

“…Recently, high profile outbreaks of L. monocytogenes have been associated with deli meats, fresh produce, and ready-to-eat foods (Churchill et al 2019 ). Other Listeria species have also been found in ready-to-eat, raw or unprocessed foods (Arslan and Özdemir 2020 ; Guerra et al 2001 ; Pesavento et al 2010 ; Soriano et al 2001 ; Zeinali et al 2017 ), as well as in food processors (Huang et al 2007 ; Korsak and Szuplewska 2016 ) and other food products (Chen et al 2009 ; Pesavento et al 2010 ). Given that L. monocytogenes is widespread in the environment, food production facilities constantly monitor and control for the presence of Listeria species on surfaces.…”

Diversity and Antibiotic Resistance Profiles of Listeria monocytogenes Serogroups in Different Food Products from the Transylvania Region of Central Romania

“…In this survey, the serogroup 4b-4d-4e (29.4%) from lineage I, was the second most commonly identified across the investigated food types, and the most prevalent in raw meat samples. Recent studies have documented the occurrence of this serogroup members in different food matrices with variable detection rates, from 7.6% to 26.7% (2,16). Differences in geographical region and the investigated type of food may cause variation in serogrouping (2).…”

“…Notably, another member of lineage II, the serogroup 1/2c-3c, was identified in only two sausage samples in this study (11.8%). From this group, the 1/2c member has been the most frequently detected in different food products in Romania [50%; (5)] and in several RTE foods in Turkey [33.3% - (2)]. However, according to some investigations, the frequency of isolation of the members of the serogroup 1/2c-3c in food matrices is considered to be generally moderate or low (6,12).…”