Title | Examination of food chain-derived Listeria monocytogenes strains of different serotypes reveals considerable diversity in inlA genotypes, mutability, and adaptation to cold temperatures. |
Publication Type | Journal Article |
Year of Publication | 2013 |
Authors | Kovacevic, J, Arguedas-Villa, C, Wozniak, A, Tasara, T, Allen, KJ |
Journal | Appl Environ Microbiol |
Volume | 79 |
Issue | 6 |
Pagination | 1915-22 |
Date Published | 2013 Mar |
ISSN | 1098-5336 |
Keywords | Adaptation, Biological, Bacterial Proteins, British Columbia, Caco-2 Cells, Cold Temperature, DNA, Bacterial, Epithelial Cells, Food Microbiology, Genetic Variation, Humans, Listeria monocytogenes, Molecular Sequence Data, Sequence Analysis, DNA |
Abstract | Listeria monocytogenes strains belonging to serotypes 1/2a and 4b are frequently linked to listeriosis. While inlA mutations leading to premature stop codons (PMSCs) and attenuated virulence are common in 1/2a, they are rare in serotype 4b. We observed PMSCs in 35% of L. monocytogenes isolates (n = 54) recovered from the British Columbia food supply, including serotypes 1/2a (30%), 1/2c (100%), and 3a (100%), and a 3-codon deletion (amino acid positions 738 to 740) seen in 57% of 4b isolates from fish-processing facilities. Caco-2 invasion assays showed that two isolates with the deletion were significantly more invasive than EGD-SmR (P < 0.0001) and were either as (FF19-1) or more (FE13-1) invasive than a clinical control strain (08-5578) (P = 0.006). To examine whether serotype 1/2a was more likely to acquire mutations than other serotypes, strains were plated on agar with rifampin, revealing 4b isolates to be significantly more mutable than 1/2a, 1/2c, and 3a serotypes (P = 0.0002). We also examined the ability of 33 strains to adapt to cold temperature following a downshift from 37°C to 4°C. Overall, three distinct cold-adapting groups (CAG) were observed: 46% were fast (<70 h), 39% were intermediate (70 to 200 h), and 15% were slow (>200 h) adaptors. Intermediate CAG strains (70%) more frequently possessed inlA PMSCs than did fast (20%) and slow (10%) CAGs; in contrast, 87% of fast adaptors lacked inlA PMSCs. In conclusion, we report food chain-derived 1/2a and 4b serotypes with a 3-codon deletion possessing invasive behavior and the novel association of inlA genotypes encoding a full-length InlA with fast cold-adaptation phenotypes. |
DOI | 10.1128/AEM.03341-12 |
Alternate Journal | Appl. Environ. Microbiol. |
PubMed ID | 23315746 |
PubMed Central ID | PMC3592241 |