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Human listeriosis: Grouping of human Listeria monocytogenes isolates with PFGE and AscI restriction enzyme
Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland.
2019 (English)Doctoral thesis, comprehensive summary (Other academic)
Place, publisher, year, edition, pages
Helsingfors, Finland: University of Helsinki, 2019. , p. 121
National Category
Medical and Health Sciences Microbiology in the medical area
Research subject
Medicine
Identifiers
URN: urn:nbn:se:oru:diva-79427ISBN: 978-951-51-5090-5 (print)OAI: oai:DiVA.org:oru-79427DiVA, id: diva2:1388930
Public defence
2019-05-24, Auditorium B4, room 107, Metsätieteiden talo, Viikki campus, Helsinki University, Helsinki, 12:00 (English)
Opponent
Supervisors
Available from: 2020-03-05 Created: 2020-01-28 Last updated: 2020-03-05Bibliographically approved
List of papers
1. Division of Human Listeria monocytogenes Pulsed-Field Gel Electrophoresis (PFGE) Types Belonging to Lineage I (Serovar 4b, 1/2b, and 3b) into PFGE Groups
Open this publication in new window or tab >>Division of Human Listeria monocytogenes Pulsed-Field Gel Electrophoresis (PFGE) Types Belonging to Lineage I (Serovar 4b, 1/2b, and 3b) into PFGE Groups
2015 (English)In: Foodborne pathogens and disease, ISSN 1535-3141, E-ISSN 1556-7125, Vol. 12, no 5, p. 447-453Article in journal (Refereed) Published
Abstract [en]

The 63 pulsed-field gel electrophoresis (PFGE) types identified among 427 clinical isolates of Listeria monocytogenes that were characterized in a previous study by serotyping and PFGE (AscI) could be further divided into 17 PFGE groups. While the 63 PFGE types, all part of lineage I, were established based on the number and distribution of all bands in each DNA profile, the 17 PFGE groups were based on the configuration of small bands with sizes L. monocytogenes serovar 4b isolates (n=334) were divided into 8 PFGE groups; the 32 PFGE types of serovar 1/2b isolates (n=90) and the serovar 3b isolates (n=3, 1 PFGE type) were divided into 9 PFGE groups. An association was observed between PFGE groups and serovars. L. monocytogenes isolates belonging to PFGE groups I, J, Q, R, X, Z, o-4, and o-5 all shared serovar 4b, whereas isolates from PFGE groups D, G, O, P, T, U, o-1, o-2, and o-3 shared serovar 1/2b. Small fragments L. monocytogenes isolates. From the results of the present study, a procedure for accelerating the identification of PFGE types when analyzing new PFGE profiles can be suggested. Therefore, we propose a stepwise procedure to PFGE profiling by first identifying the PFGE group using the smaller band patterns <145.5 kb, and then determining PFGE types based on the band patterns >145.5 kb.

Place, publisher, year, edition, pages
Mary Ann Liebert, 2015
National Category
Other Social Sciences not elsewhere specified
Research subject
Culinary Arts and Meal Science
Identifiers
urn:nbn:se:oru:diva-44674 (URN)10.1089/fpd.2014.1880 (DOI)000353777800010 ()25803595 (PubMedID)
Note

Funding Agency:

Stiftelsen Grythytte Akademi Stipendiefond

Available from: 2015-05-22 Created: 2015-05-22 Last updated: 2020-01-28Bibliographically approved
2. Lineage II (Serovar 1/2a and 1/2c) Human Listeria monocytogenes Pulsed-Field Gel Electrophoresis Types Divided into PFGE Groups Using the Band Patterns Below 145.5 kb
Open this publication in new window or tab >>Lineage II (Serovar 1/2a and 1/2c) Human Listeria monocytogenes Pulsed-Field Gel Electrophoresis Types Divided into PFGE Groups Using the Band Patterns Below 145.5 kb
2017 (English)In: Foodborne pathogens and disease, ISSN 1535-3141, E-ISSN 1556-7125, Vol. 14, no 1, p. 8-16Article in journal (Refereed) Published
Abstract [en]

Among 504 clinical lineage II isolates of Listeria monocytogenes isolated during 1958-2010 in Sweden, 119 pulsed-field gel electrophoresis (PFGE) types (AscI) have been identified based on the number and distribution of all banding patterns in each DNA profile. In this study, these types were further divided into PFGE groups based on the configuration of small bands with sizes <145.5 kb. The 504 isolates included 483 serovar 1/2a isolates distributed into 114 PFGE types and 21 serovar 1/2c isolates distributed into 9 PFGE types; these were further divided into 21 PFGE groups. PFGE group, that is, configuration of small bands below 145.5 kb, and serovars were correlated. L. monocytogenes isolates belonging to PFGE groups A, B, C, E, F, H, K, L, M, S, V, W, Y, and Ö-6 to Ö-12 shared serovar 1/2a, with one exception. PFGE group E also included two PFGE types sharing serovar 1/2c and four PFGE types belonging to either serovar 1/2a or 1/2c. Isolates belonging to PFGE group N shared serovar 1/2c. In contrast to lineage I isolates, small fragments <33.3 kb were visible in all L. monocytogenes isolates belonging to lineage II. In the results from both the present and previous studies, the genomic region of small bands was genetically more conservative than in large bands. The distribution of these small bands established the relatedness of strains and defined a genetic marker for both lineages I and II, while also establishing their serogroup. The division of L. monocytogenes PFGE types into PFGE groups is advantageous as the profile of every new isolate can be identified easily and quickly through first studying the PFGE group affiliation of the isolate based on the smaller band patterns <145.5 kb, and then identifying the PFGE type based on the band patterns >145.5 kb.

Place, publisher, year, edition, pages
New Rochelle, USA: Mary Ann Liebert, 2017
Keywords
PFGE type, PFGE group, Listeria monocytogenes, serovar, lineage II
National Category
Genetics Food Science
Identifiers
urn:nbn:se:oru:diva-53597 (URN)10.1089/fpd.2016.2173 (DOI)000391818800002 ()27860487 (PubMedID)2-s2.0-85009260194 (Scopus ID)
Note

Funding Agency:

Stiftelsen Grythytte Akademi Stipendiefond

Available from: 2016-11-21 Created: 2016-11-21 Last updated: 2020-01-28Bibliographically approved
3. Human isolates of Listeria monocytogenes in Sweden during half a century (1958-2010)
Open this publication in new window or tab >>Human isolates of Listeria monocytogenes in Sweden during half a century (1958-2010)
Show others...
2014 (English)In: Epidemiology and Infection, ISSN 0950-2688, E-ISSN 1469-4409, Vol. 142, p. 2251-2260Article in journal (Refereed) Published
Abstract [en]

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.

Keywords
Cheese, Listeria monocytogenes, PFGE, serotyping, salmon
National Category
Occupational Health and Environmental Health
Research subject
Culinary Arts and Meal Science
Identifiers
urn:nbn:se:oru:diva-40067 (URN)10.1017/S0950268813003385 (DOI)000344921000003 ()24480252 (PubMedID)2-s2.0-84909991349 (Scopus ID)
Note

Funding Agency:

Research Foundation of Ivar and Elsa Sandberg 

Available from: 2014-12-30 Created: 2014-12-30 Last updated: 2020-01-28Bibliographically approved
4. Gravad (Gravlax) and cold-smoked salmon, still a potential source of listeriosis
Open this publication in new window or tab >>Gravad (Gravlax) and cold-smoked salmon, still a potential source of listeriosis
Show others...
2009 (English)In: Journal of Foodservice, ISSN 1748-0140, Vol. 20, no 1, p. 15-20Article in journal (Refereed) Published
Abstract [en]

Gravad (Gravlax) and cold-smoked salmon are associated with human listeriosis in Sweden. The present investigation of Listeria monocytogenes in salmon was a follow-up of a similar study in the middle of the 1990s. Since our first study, there has been an increasing focus on food hygiene in general and specially on self-inspection and Hazard Analysis and Critical Control Points from the authorities and food producers. L. monocytogenes was isolated from 11 (three manufacturers) of the 56 products analyzed. The highest level of L. monocytogenes was 1500 cfu/g from a cold-smoked salmon product; however, the level was low (<100 cfu/g) in most products. Serovar 1/2a was predominant, followed by 4b. restriction enzyme analysis/ pulsed-field gel electrophoresis typing of the 56 salmon isolates identified five types of L. monocytogenes. One type was identical to a human type, whereas two other were closely related. These findings suggest that gravad and coldsmoked salmon are still possible sources of listeriosis in Sweden.

Place, publisher, year, edition, pages
Oxford: Blackwell Publishing, 2009
National Category
Medical and Health Sciences
Research subject
Culinary Arts and Meal Science; Biomedicine
Identifiers
urn:nbn:se:oru:diva-2999 (URN)10.1111/j.1748-0159.2008.00118.x (DOI)
Available from: 2008-09-05 Created: 2008-09-05 Last updated: 2020-01-28Bibliographically approved
5. More than one variant of Listeria monocytogenes isolated from each of two human cases of invasive listeriosis
Open this publication in new window or tab >>More than one variant of Listeria monocytogenes isolated from each of two human cases of invasive listeriosis
Show others...
2007 (English)In: Epidemiology and Infection, ISSN 0950-2688, E-ISSN 1469-4409, Vol. 135, no 5, p. 854-856Article in journal (Refereed) Published
Abstract [en]

Two variants of Listeria monocytogenes were isolated from blood cultures from each of two patients with listeriosis. Each variant displayed a two-band difference in DNA profile from the other by pulsed-field gel electrophoresis. Although this difference in profile is insufficient to distinguish clearly between the variants, the possibility of co-infection with different strains of L. monocytogenes needs to be considered. We suggest that more than one colony should be selected for molecular typing to aid interpretation during investigation of the sources and routes of Listeria infection.

National Category
Nutrition and Dietetics Other Medical Sciences not elsewhere specified
Research subject
Culinary Arts and Meal Science; Household Science
Identifiers
urn:nbn:se:oru:diva-6162 (URN)10.1017/S0950268806007503 (DOI)17109771 (PubMedID)
Available from: 2009-03-30 Created: 2009-03-30 Last updated: 2020-01-28Bibliographically approved

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