| 1. |
- Tham, Wilhem, 1951-, et al.
(author)
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Occurrence of Genetic Variants of Listeria monocytogenes Strains
- 2013
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In: Foodborne pathogens and disease. - : Mary Ann Liebert. - 1535-3141 .- 1556-7125. ; 10:9, s. 825-826
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Journal article (peer-reviewed)abstract
- Isolates of Listeria monocytogenes saved from outbreaks of listeriosis, cases of sporadic listeriosis, and similar events do not always belong to a solitary genetic variant. Variants of the same strain may have evolved from a unique clone, and plasmid loss or gain and phage-mediated genetic changes are suggested as the main mechanism. Some of these reports are summarized in this short communication.
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| 2. |
- Lopez-Valladares, Gloria, 1963-, et al.
(author)
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Human isolates of Listeria monocytogenes in Sweden during half a century (1958-2010)
- 2014
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In: Epidemiology and Infection. - 0950-2688 .- 1469-4409. ; 142, s. 2251-2260
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Journal article (peer-reviewed)abstract
- Isolates of Listeria monocytogenes (n=932) isolated in Sweden during 1958–2010 from human patients with invasive listeriosis were characterized by serotyping and pulsed-field gel electrophoresis (PFGE) (AscI). Of the 932 isolates, 183 different PFGE types were identified, of which 83 were each represented by only one isolate. In all, 483 serovar 1/2a isolates were distributed over 114 PFGE types; 90 serovar 1/2b isolates gave 32 PFGE types; 21 serovar 1/2c isolates gave nine PFGE types; three serovar 3b isolates gave one PFGE type; and, 335 serovar 4b isolates gave 31 PFGE types. During the 1980s in Sweden, several serovar 4b cases were associated with the consumption of European raw soft cheese. However, as cheese-production hygiene has improved, the number of 4b cases has decreased. Since 1996, serovar 1/2a has been the dominant L. monocytogenes serovar in human listeriosis in Sweden. Therefore, based on current serovars and PFGE types, an association between human cases of listeriosis and the consumption of vacuum-packed gravad and cold-smoked salmon is suggested.
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| 3. |
- Lopez-Valladares, Gloria, 1963-, et al.
(author)
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Listeriosis in South American camelids : a review
- 2013
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In: Journal of Camel Practice and Research. - : Camel Publ House. - 0971-6777 .- 2277-8934. ; 20:1, s. 129-132
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Research review (peer-reviewed)abstract
- The main aim of the present study was to review the general aspects of Listeria and the clinical manifestation of the disease listeriosis in humans and domestic ruminants, with emphasis on clinical signs in South American camelids. Camelids are susceptible to infection by Listeria; however, it appears that the prevalence of listeriosis in camelids is low, given that few cases have been reported. The species Listeria monocytogenes is associated with all reported cases. To our knowledge, there are no reported cases of listeriosis in vicunas (Vicugna vicugna) and guanacos (Lama guanicoe).The clinical manifestations of listeriosis in llamas and alpacas are similar to in domestic ruminants and humans, namely meningoencephalitis, encephalitis, septicaemia, abortion, otitis media/interna and polyarthritis. Listerial mastitis and gastroenteritis has not yet been described in camelids. Despite reported cases, there is no specific mention of listeriosis associated with shedding of bacteria in faeces or milk. The occurrence of listeriosis in camelids needs to be confirmed and clinical signs defined.
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| 4. |
- Thisted Lambertz, Susanne, et al.
(author)
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Subtyping of Listeria monocytogenes isolates recovered from retail ready-to-eat foods, processing plants and listeriosis patients in Sweden 2010
- 2013
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In: International Journal of Food Microbiology. - Amsterdam, Netherlands : Elsevier. - 0168-1605 .- 1879-3460. ; 166, s. 186-192
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Journal article (peer-reviewed)abstract
- Identification and prioritisation of food safety interventions requires an understanding of the relationship be- tween food, pathogens and cases. Such understanding can be gained through different approaches, e.g. microbial subtyping to attribute cases of foodborne disease to food vehicles or other sources of illness. In this study, Listeria monocytogenes isolates (n = 166) from (i) three categories of ready-to-eat (RTE) foods, (ii) food processing plant environments, and (iii) human listeriosis cases, all sampled during 2010 in Sweden, were subtyped. In addition, 121 isolates from human listeriosis cases, collected 2005–2009, were subtyped. Subtyping consisted of both serotyping (conventional method and PCR) and genotyping using pulsed-field gel electrophoresis (PFGE). Serotype 1/2a dominated in all three groups of isolates (range 73–96%). Eighteen percent of the human isolates (2010) belonged to serotype 4b, but only 1.4% of the food isolates. The food isolates differentiated into 19 pulsotypes (ID = 0.843), the human isolates collected 2010 into 31 pulsotypes (ID = 0.950) and the processing plant isolates into 22 pulsotypes (ID = 0.991). Six of the pulsotypes were shared between the food and human isolates. These pulsotypes comprised 42% of the human isolates and 59% of the food isolates. For some processing plants, there was suggested persistence of one or more specific L. monocytogenes strains, as indicated by repetitive isolation of the same pulsotype from food. This study indicated the presence of L. monocytogenes in the processing plant environment as a likely source of contamination of gravad and cold-smoked fish, and this food category as an important source of human exposure to the pathogen
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