M. Fredriksson-Ahomaa - Academia.edu (original) (raw)

Papers by M. Fredriksson-Ahomaa

Letters in Applied Microbiology, 2016

Significance and Impact of the Study: Yersinia enterocolitica strains are currently divided into ... more Significance and Impact of the Study: Yersinia enterocolitica strains are currently divided into six biotypes and two subspecies. Strains of biotype 1A, which are phenotypically and genotypically very heterogeneous, are classified as subspecies palearctica. In this study, European Y. enterocolitica 1A strains isolated from both human and nonhuman sources were characterized using restriction fragment length polymorphism and multilocus sequence analysis. The European biotype 1A strains formed a separate group, which differed from strains belonging to subspecies enterocolitica and palearctica. This may indicate that the current division between the two subspecies is not sufficient considering the strain diversity within Y. enterocolitica.

The Journal of Infectious Diseases, 2004

Background. The vehicles and sources of Yersinia pseudotuberculosis infection are unknown. In Fin... more Background. The vehicles and sources of Yersinia pseudotuberculosis infection are unknown. In Finland, clinical microbiology laboratories routinely report Y. pseudotuberculosis isolations and submit isolates for serotype analysis. In October 1998, the number of serotype O:3 infections increased markedly. Methods. Case patients with culture-confirmed Y. pseudotuberculosis O:3 infection were identified by use of laboratory-based surveillance. We conducted a population-based case-control study. Healthy community control subjects were matched by age, sex, and postal code. Isolates were subtyped by pulsed-field gel electrophoresis (PFGE). Results. Nationwide, 47 case patients were identified (age range, 2-77 years; median, 19 years). One patient with bacteremia died; 5 underwent appendectomies. We enrolled 38 case patients and 76 control subjects in the case-control study. Seventy-one percent of case patients and 42% of control subjects reported having eaten iceberg lettuce (matched odds ratio, 3.8; 95% confidence interval, 1.3-9.4); a dose-response relationship was found for increasing frequency of consumption. Of the 27 isolates obtained from case patients and tested in the analysis, all had indistinguishable PFGE patterns. Four lunch cafeterias that had served iceberg lettuce were associated with clusters of case patients. The lettuce was traced back to originating farms. Conclusions. Iceberg lettuce was implicated as the vehicle of a widespread foodborne Y. pseudotuberculosis outbreak. Ongoing laboratory-based surveillance and serotype analysis were essential in the rapid detection of infection. Cases of yersiniosis, which appear to be sporadic, may be part of unrecognized outbreaks caused by contaminated fresh produce. Yersinia pseudotuberculosis infections are characterized by fever and abdominal pain due to mesenteric lymphadenitis, which, in the clinical setting, is frequently indistinguishable from acute appendicitis [1, 2]. Occasionally, in individual cases, transmission has been reported to have occurred by contact with infected animals [3] or by drinking contaminated water [4]. Reports of community outbreaks are rare. They have mainly occurred in Finland [1, 2], Japan [5, 6], and the former Soviet Union; 1 outbreak in Canada has also

Zoonoses and Public Health, 2016

Backyard poultry has become increasingly popular in industrialized countries. In addition to keep... more Backyard poultry has become increasingly popular in industrialized countries. In addition to keeping chickens for eggs and meat, owners often treat the birds as pets. However, several pathogenic enteric bacteria have the potential for zoonotic transmission from poultry to humans but very little is known about the occurrence of zoonotic pathogens in backyard flocks. The occurrence and the antimicrobial resistance of Salmonella enterica, Campylobacter spp., Listeria monocytogenes and enteropathogenic Yersinia spp. was studied in 51 voluntary backyard chicken farms in Finland during October 2012 and January 2013. Campylobacter isolates were further characterized by pulsed‐field gel electrophoresis (PFGE), and the occurrence of ESBL/AmpC‐producing E. coli was investigated. The findings from this study indicate that backyard chickens are a reservoir of Campylobacter jejuni strains and a potential source of C. jejuni infection for humans. Backyard chickens can also carry L. monocytogenes, although their role as a primary reservoir is questionable. Campylobacter coli, Yersinia pseudotuberculosis and Salmonella enterica were only found sporadically in the faecal and environmental samples of backyard poultry in Finland. No Yersinia enterocolitica carrying the virulence plasmid was isolated. All pathogens were highly susceptible to most of the antimicrobials studied. Only a few AmpC‐ and no ESBL‐producing E. coli were found.

Food Control, 2021

Meat inspection of broiler chickens (broiler) in the European Union is regulated by common legisl... more Meat inspection of broiler chickens (broiler) in the European Union is regulated by common legislation to secure meat safety. However, the legislation is general in nature and proper post-mortem inspection (PMI) of every carcass and visceral organs of broilers is challenging in slaughterhouses (SHs) with a high slaughter line speed. The aim of this study was to investigate the on-site organization and possible differences of the PMI in four Finnish SHs, which slaughter over 99% of broilers in Finland. Our results show that the meat inspector's available inspection time per broiler in the PMI varied between 0.28 and 0.90 s, with the shortest available inspection time in the SH with the highest slaughter line speed and the longest available inspection time in the SH with the slowest line speed. We observed that only part of the total inspection time per broiler could be used for true PMI in most (3/4) SHs, as the meat inspectors also performed other tasks during the PMI. We observed deficiencies in the visual inspection of broiler carcasses; in particular, the proper inspection of all or most of the body cavities was impossible in all SHs during the PMI. Some deficiencies in facilities (e.g. in recording system) were observed. Moreover, lighting properties varied between the SHs and a significant difference between illumination conditions at the first inspection stations in the SHs was observed. This study considered the prerequisites for proper PMI and revealed that the PMI of broilers was not completely uniform in Finland. The results emphasize the need for more precise guidelines and recommendations, especially for inspection time and lighting at inspection stations.

Journal of Food Protection, 2002

A total of 425 pig tonsils, including 210 tonsils from fattening pigs and 215 from sows, from sev... more A total of 425 pig tonsils, including 210 tonsils from fattening pigs and 215 from sows, from seven different abattoirs in Finland were studied for the occurrence of Yersinia pseudotuberculosis from 1999 to 2000. The mean prevalence of Y. pseudotuberculosis in fattening pig tonsils was 4%, varying from 0 to 10% between slaughterhouses. Y. pseudotuberculosis was not recovered from sow tonsils. All 30 Y. pseudotuberculosis isolates from eight pig tonsils were recovered after cold enrichment. Seventeen isolates from seven tonsils were found after cold enrichment for 14 days, followed by alkali treatment. Y. pseudotuberculosis was not isolated after direct plating, overnight enrichment, or selective enrichment. All 30 isolates belonged to bioserotype 2/O:3 and carried the virF gene in the virulence plasmid. The isolates exhibited calcium dependence and Congo red absorption. The pyrazinamidase test gave variable results. All isolates were characterized with pulsed-field gel electrophores...

Food Control, 2019

Small-scale slaughterhouses (SHs) face many challenges, not least due to the requirements of food... more Small-scale slaughterhouses (SHs) face many challenges, not least due to the requirements of food safety legislation. Food business operators' (FBOs') own-check system is very important for food safety, but its proper implementation can be quite difficult and laborious for small-scale SHs. In the European Union, the importance not only of food safety but also facilitation of local food production, including small-scale slaughtering, is highlighted. The aim of our study was to assess compliance with legislation of own-check systems, including six own-check programmes and HACCP, in small-scale SHs. The FBOs' opinions of the implementation of own-check systems were also sought to elucidate possible obstacles in implementation. Our results showed that the best compliance in own-check programmes was achieved in temperature of storage rooms and traceability. FBOs also evaluated these programmes as necessary. However, FBOs' perceived necessity of own-check programmes did not always lead to compliance, as was the case with labelling and HACCP. Instead, in HACCP laboriousness and compliance showed a negative correlation (p < 0.05). In addition to laboriousness, costs of own-check programmes, specifically concerning microbiological sampling requirements, appeared to influence compliance, with many of the small-scale SHs poorly following sampling requirements. FBOs also noted the high costs of the non-edible by-product programme. Moreover, the results show that official veterinarians' assessment of compliance was significantly higher than that of the researcher, which warrants further investigation. This study reveals that many small-scale SHs in Finland struggle with food safety requirements. Amendments of some of the requirements to ease the burden of FBOs are proposed. HACCP in particular is suggested to be simplified. In addition, ways to improve food safety and official control in small-scale SHs are discussed.

Journal of Food Protection, 2000

This study was carried out in order to evaluate the contamination of the pig-slaughtering line wi... more This study was carried out in order to evaluate the contamination of the pig-slaughtering line with pathogenic Yersinia enterocolitica carrying the yadA gene. A total of 292 samples were collected from the slaughterhouse; 131 swab samples from pig carcasses, ears, livers, kidneys, and hearts; 89 swab samples from the environment; and 72 sedimentation samples from the air. All surface samples were studied with both the polymerase chain reaction (PCR) and culture methods. The contamination rate of edible pig offals was high with both methods. Using PCR, the detection rates of yadA-positive Y. enterocolitica for livers, kidneys, and hearts were 38, 86, and 63%, respectively, and using the culture method, the detection rates were 31, 69, and 50%, respectively. Pathogenic Y. enterocolitica was also detected from different environmental sites in the slaughterhouse. Using PCR, 13% of the surface samples from the environment were contaminated with yadA-positive Y. enterocolitica. PCR-positi...

INTERNATIONAL JOURNAL OF SYSTEMATIC AND EVOLUTIONARY MICROBIOLOGY, 2010

The taxonomic position of three strains from water, soil and lettuce samples was studied by using... more The taxonomic position of three strains from water, soil and lettuce samples was studied by using a polyphasic taxonomic approach. The strains were reported to lack the virulence-encoding genes inv and virF in a previous study. Controversially, API 20 E and some other phenotypic tests suggested that the strains belong to Yersinia pseudotuberculosis, which prompted this polyphasic taxonomic study. In both the phylogenetic analyses of four housekeeping genes (glnA, gyrB, recA and HSP60) and numerical analyses of HindIII and EcoRI ribopatterns, the strains formed a separate group within the genus Yersinia. Analysis of the 16S rRNA gene sequences showed that the strains were related to Yersinia aldovae and Yersinia mollaretii, but DNA–DNA hybridization analysis differentiated them from these species. Based on the results of the phylogenetic and DNA–DNA hybridization analyses, a novel species, Yersinia pekkanenii sp. nov., is proposed. The type strain is ÅYV7.1KOH2T ( = DSM 22769T = LMG...

Foodborne Pathogens and Disease, 2012

Hepatitis E virus (HEV) is an emerging foodborne pathogen with domestic and wild pigs (and likely... more Hepatitis E virus (HEV) is an emerging foodborne pathogen with domestic and wild pigs (and likely other species such as deer or rabbits) recognized as reservoir. Pathogenesis in pigs usually leads to an asymptomatic course of disease. Since there is no enzyme-linked immunosorbent assay (ELISA) kit for the detection of anti-HEV antibodies in pigs commercially available, the objective of this study was to assess the seroprevalence in fattening pigs at slaughter and at herd level using a newly developed ELISA based on genotype (GT) 1 and GT 3 in Bavaria, Germany. Based on 516 serum and 198 meat juice samples collected from different herds at four different Bavarian slaughterhouses, the overall seroprevalence of anti-HEV IgG in serum and meat juice samples was 68.6% and 67.6%, respectively. Analyzing the serum for the presence of anti-HEV IgM, 36/516 (7%) were positive for anti-HEV IgM. At herd level, most of the herds were seropositive for anti-HEV antibodies. The present study shows that HEV is widespread among the Bavarian pig population and that some pigs might test positive for anti-HEV IgM even at the age of slaughter. Also, meat juice serves as an equivalent matrix to serum to test for anti-HEV antibodies in pigs.

Journal of Medical Microbiology, 2006

Yersinia enterocolitica 4/O : 3 is the most frequent cause of sporadic human yersiniosis in Finla... more Yersinia enterocolitica 4/O : 3 is the most frequent cause of sporadic human yersiniosis in Finland and Germany. To investigate the possible link between pigs and humans, 282 human and 534 porcine strains from Finland and Germany were characterized with PFGE using NotI, ApaI and XhoI enzymes. Most of the human strains (>80 %) were indistinguishable from the porcine strains in both countries and most of the genotypes (178/182) were different in Finland and Germany. The indistinguishable genotypes among human and porcine strains together with different genotypes in Finland and Germany indicate that pigs are an important source of sporadic yersiniosis in both countries.

Encyclopedia of Food and Health, 2016

Yersinia enterocolitica is a heterogeneous species both phenotypically and genotypically. Y . ent... more Yersinia enterocolitica is a heterogeneous species both phenotypically and genotypically. Y . enterocolitica is nutritionally very unfastidious. It is a psychrotrophic bacterium that can grow at refrigeration temperatures. Yersinia strains can also grow well in modified atmosphere with higher levels of CO 2 and in the presence of high number of lactic acid bacteria. Pathogenic strains are genetically homogeneous and carry a 70-kb virulence plasmid (pYV) unlike nonpathogenic strains. The most common and widely distributed human pathogenic Y . enterocolitica strains belong to the bioserotype 4/O:3. Occurrence of this pathogenic bioserotype is high in tonsils of finishing pigs. Nonpathogenic strains, which miss the pYV and the most important chromosomal virulence genes, are ubiquitous in the environment. It is important to confirm the pathogenicity of the isolated strains to assess their significance for human and animal health.

Rapid Detection, Characterization, and Enumeration of Foodborne Pathogens, 2011

INTERNATIONAL JOURNAL OF SYSTEMATIC AND EVOLUTIONARY MICROBIOLOGY, 2011

This study was set up to identify three Gram-negative, rod-shaped strains originating from broile... more This study was set up to identify three Gram-negative, rod-shaped strains originating from broiler meat packaged under a modified atmosphere. A polyphasic taxonomic approach, including multilocus sequence analysis (MLSA) of five genes (16S rRNA, glnA, gyrB, recA and HSP60), DNA–DNA reassociation between the closest phylogenetic neighbours and determination of relevant phenotypic properties, was applied. Phylogenetic analysis of the 16S rRNA gene sequences grouped these strains together and within the genus Yersinia. MLSA of the 16S rRNA gene and four housekeeping genes showed that the strains formed a monophyletic group separate from other Yersinia species in all phylogenetic trees constructed. The strains had a phenotypic profile different from those of other representatives of the genus Yersinia, but most similar to that of Yersinia ruckeri. Typical virulence markers for pathogenic Yersinia were not detected. Based on phylogenetic, phenotypic and DNA–DNA reassociation data, a nove...

BMC Veterinary Research, 2021

Background Between February and April 2016, a slight increase in mortality was observed in a colo... more Background Between February and April 2016, a slight increase in mortality was observed in a colony consisting of 400 captive Seba’s short-tailed bats ( Carollia perspicillata ). These animals cohabited with other nocturnal animal species in a dome of a private zoo in Switzerland. Results Gross and histological analysis of two (14.3%) out of the 13 animals submitted for necropsy within this period revealed a necrosuppurative pneumonia, hepatitis, splenitis, enterocolitis, and endometritis, with abundant intralesional colonies of Gram-negative rods. Yersinia ( Y. ) pseudotuberculosis serotype O:1 and biotype 1 belonging to the sequence type ST90 was isolated from the affected organs in both animals. Following this diagnosis, ¼ of the colony (99 animals) was culled and submitted for gross and histopathological analysis, and a bacterial culture selective for Yersinia spp. of lung, liver, and spleen was performed. From these 99 animals, one gravid female was tested and found to be posit...

International Journal of Food Microbiology

International Journal of Food Microbiology, 2016