Listeria monocytogenes Serotype Identification by PCR

Abstract

Serotyping is a universally accepted subtyping method for Listeria monocytogenes. Identification of the strain serotype permits differentiation between important food-borne strains (1/2a, 1/2b, and 4b) and provides a "gold standard" for comparing isolates analyzed in different labs and with different techniques. Although an efficient enzyme-linked immunosorbent assay serotyping protocol was described recently, identification of PCR serotyping primers would further increase the ease and accessibility of this classification system. Serotyping PCR primers were designed from variable regions of the L. monocytogenes genome. Three primer sets were used in conjunction with a previously described Division III primer set in order to classify 122 L. monocytogenes strains into five serotype groups [1/2a(3a), 1/2b, 1/2c(3c), 4b(d,e), and 4a/c]. Results of the PCR method agreed with those of the conventional slide agglutination method for 97, 100, 94, and 91% of strains belonging to serotypes 1/2a, 1/2b, 1/2c, and 4b, respectively.

Gene Scanning of an Internalin B Gene Fragment Using High-Resolution Melting Curve Analysis as a Tool for Rapid Typing of Listeria monocytogenes

“…In contrast to several recently described molecular serotyping approaches, which separate L. monocytogenes isolates of diverse serotypes into four groups, 12,13,28 the inlB HRM curve profiling separated the 11 investigated L. monocytogenes serotypes into at least 15 specific HRM curve profiles comprising 18 different sequence types. Nonetheless, as described for other PCR-based typing methods, 12,13,28 HRM curve profiling does not allow differentiation of serotype 3a isolates from serotype 1/2a inlB ST-7, inlB ST-9, and inlB ST-12 isolates, of serotype 1/2c from serotype 3c isolates, of some serotype 1/2b isolates from serotype 3b and from serotype 7 isolates, of some 2a, 1/2b, 1/2c, 3a, 3b, 3c, 4a, 4b, 4d, 4e, and 7. The baseline is represented by an inlB ST-2 curve profile.…”

“…8 -11 Recently developed multiplex PCR serotyping methods allow a differentiation of isolates on the PG level. 12,13 Phylogenetic groups have been correlated with serotypes: PG I.1 with serotype 1/2a, 3a; I.2 with 1/2c, 3c; II.1 with 4b, 4d, 4e; II.2 with 1/2b, 3b, 7; and III with 4a, 4c. 10 In cases of outbreak, the discriminatory power of multiplex PCR serotyping methods is insufficient, and it is necessary to type isolates by pulsed-field gel electrophoresis (PFGE), which is the current gold standard for L. monocytogenes typing.…”

Prevalence of Listeria monocytogenes, E. coli, Salmonella Spp. and Staphylococcus aureus Bacteria Contamination on Meat at Public Market in the North of Vietnam

“…However, they were lower than those of with 100% on enterotoxin Stn production and 100% invA invasion [4] ( Figure 2). Table 23 presented the results of determination of the number of strains possessing the encoded gene LLO (hlyA) of Listeria monocytogenes isolates; It was found that with Listeria monocytogenes on beef, 7/32 strains possessed gene hlyA, accounting for 21.8%; on pork, there were 9/40 strains, accounting for 22.5%; on chicken meat, there were 11/32 strains, accounting for 34.3% [20,25,38] (Figure 3). There were 21/27 strains of Listeria monocytogenes resisting to amoxicilline, accounting for 77.77%; 1/27 strains resisting to nitrofurantoin, ceftazidime, oxytetracycline, accounting for 3.70%; 3/27 strains resisting to erythromycin, accounting for 11.11%; None of the strains (0%) were resistant to vancomycin and oxacillin; 2/27 strains resisting to rifampicin, accounting for 7.40%; 5/27 strains resisting to gentamicin, accounting for 18.51%; 3/27 strains resisting to bacitracin, accounting for 11.11%; 4/27 strains resisting to nalidixic acid (14.81%).…”

Phylogenetic Charaterization of Listeria Monocytogenes Isolated From Different Sources in Iraq

“…The PCR was used to detect the virulence factor genes of bacteria L. monocytogenes isolated from clinical and food samples, according to the steps described by Borucki and Call [16].…”