Genomic Characterization of Listeria monocytogenes Isolated From Ready-to-Eat Meat and Meat Processing Environments in Poland

Abstract

Listeria monocytogenes is one of the major foodborne pathogens. Isolates of PCRserogroups IIb (n = 17) and IVb (n = 31) recovered from food (n = 33) and food processing environment (n = 15) in Poland were characterized using whole genome sequencing. Most isolates belonged to Multi-Locus Sequence Type (MLST) ST2 (31.3%) and ST5 (22.9%). Core genome MLST (cgMLST) analysis classified isolates into seven sublineages (SL) and 25 different cgMLST types (CT). Consistent with the MLST results, most sublineages were SL2 and SL5. Eleven isolates harbored aacA4 encoding resistance to aminoglycosides, three isolates harbored emrC (n = 3) and one brcABC (n = 1) encoding tolerance to benzalkonium chloride. Isolates belonging to SL5 CT2323 carried a so far unreported inlB allele with a deletion of 141 nucleotides encoding the β-repeat sheet and partially the GW1 domain of InlB. Comparison with publicly available genome sequences from L. monocytogenes isolated from human listeriosis cases in Poland from 2004 to 2013 revealed five common CTs, suggesting a possible epidemiological link with these strains. The present study contributes to characterize the diversity of L. monocytogenes in ready-to-eat (RTE) meat and meat processing environments in Poland and unravels previously unnoticed links with clinical cases in Europe.

Molecular Typing of Listeria monocytogenes IVb Serogroup Isolated from Food and Food Production Environments in Poland

“…Additionally, 11 strains (IDs: 47080, 47081, 47082, 47083, 47105, 47106, 47111, 47113, 47115, 47119, 47120) from the current study, classified to SL2-ST145-CT375 and mainly recovered from raw meat (10 strains) were identical, based on the cgMLST allelic profile, with strains with ID 27850 and ID 27852 from RTE food previously described in Poland [ 40 ]. Similarly, such a close molecular relatedness was also observed among 10 strains classified to SL2-ST2-CT4325, isolated mainly from RTE food and four strains (IDs: 27816, 27834, 27838, 27842) characterized by Kurpas et al [ 40 ] ( Figure 3 , Tables S1 and S3 ).…”

“…It was found that the current strains classified to clonal complex CC1 did not reveal any genotypic relationship with 59 strains of the corresponding CC, recovered from patients with listeriosis ( n = 38), food ( n = 19), and food production environments ( n = 2) in other countries. Comparison with 20 other L. monocytogenes strains previously isolated in Poland, including 14 isolates from clinical cases, showed that some of these, e.g., the current isolates of cgMLST type SL1-ST1-CT322 (IDs 47065, 47070, 47071, 47100, and 47122) and one strain previously described by Kurpas et al [ 40 ] (ID 27929) displayed a very close molecular relationship with up to 7 allelic differences, although they had been isolated in different regions of Poland and in different years. A similar genetic relationship was noted for L. monocytogenes ID 47098 and the previously isolated strain ID 27845, both classified to CT4326 and recovered from RTE food, which showed 7 allelic difference in the cgMLST analysis ( Figure 2 , Tables S1 and S3 ).…”

“…However, some strains of the current study displayed a genetic similarity with the sequences of other Polish L. monocytogenes recovered from food or from clinical cases. For example, four strains of cgMLST type SL1-ST1-CT4382 of RTE food origin revealed a close genetic relationship with the strains of the same origin with IDs 27830, 27800, 27801, 27833, isolated in 2015 and 2016 [ 40 ] and with one isolate (ID 34354) responsible for human listeriosis isolated in 2011 [ 26 ]. Additionally, 11 strains (IDs: 47080, 47081, 47082, 47083, 47105, 47106, 47111, 47113, 47115, 47119, 47120) from the current study, classified to SL2-ST145-CT375 and mainly recovered from raw meat (10 strains) were identical, based on the cgMLST allelic profile, with strains with ID 27850 and ID 27852 from RTE food previously described in Poland [ 40 ].…”

“…For example, four strains of cgMLST type SL1-ST1-CT4382 of RTE food origin revealed a close genetic relationship with the strains of the same origin with IDs 27830, 27800, 27801, 27833, isolated in 2015 and 2016 [ 40 ] and with one isolate (ID 34354) responsible for human listeriosis isolated in 2011 [ 26 ]. Additionally, 11 strains (IDs: 47080, 47081, 47082, 47083, 47105, 47106, 47111, 47113, 47115, 47119, 47120) from the current study, classified to SL2-ST145-CT375 and mainly recovered from raw meat (10 strains) were identical, based on the cgMLST allelic profile, with strains with ID 27850 and ID 27852 from RTE food previously described in Poland [ 40 ]. Similarly, such a close molecular relatedness was also observed among 10 strains classified to SL2-ST2-CT4325, isolated mainly from RTE food and four strains (IDs: 27816, 27834, 27838, 27842) characterized by Kurpas et al [ 40 ] ( Figure 3 , Tables S1 and S3 ).…”

Whole Genome Sequence Analysis of Phage-Resistant Listeria monocytogenes Serotype 1/2a Strains from Turkey Processing Plants

“…In a previous study, we characterized L. monocytogenes from different turkey processing plants in the United States for their resistance to a panel of phages [ 12 ]. The majority of the phage-resistant strains were of serotype 1/2a, followed by 1/2b and 1/2c, i.e., serotypes which are commonly encountered in food and food processing ecosystems [ 12 , 28 , 29 , 30 , 31 ]. In the current study, our objective was to integrate whole genome sequence analysis, phage adsorption assays and phenotypic characterization of WTA decorations in order to elucidate mechanisms mediating phage resistance in FPE-derived serotype 1/2a strains.…”