Diarrhoeagenic Escherichia coli (DEC) cause serious foodborne infections in humans. Total of 450 Shigatoxigenic E. coli (STEC) strains isolated from humans, animals and environment in Finland were examined by multiplex PCR targeting the virulence genes of various DEC pathogroups simultaneously. One per cent (3/291) of the human STEC and 14% (22/159) of the animal and environmental STEC had genes typically present in enterotoxigenic E. coli (ETEC). The strains possessed genes encoding both Shiga toxin 1 and/or 2 (stx1 and/or stx2 ) and ETEC-specific heat-stable (ST) enterotoxin Ia (estIa). The identified stx subtypes were stx1a, stx1c, stx2a, stx2d and stx2g. The three human STEC/ETEC strains were isolated from the patients with haemolytic uraemic syndrome and diarrhoea and from an asymptomatic carrier. The animal STEC/ETEC strains were isolated from cattle and moose. The human and animal STEC/ETEC strains belonged to 11 serotypes, of which O2:H27, O15:H16, O101:H-, O128:H8 and O141:H8 have previously been described to be associated with human disease. Identification of multiple virulence genes offers further information for assessing the virulence potential of STEC and other DEC. The emergence of novel hybrid pathogens should be taken into account in the patient care and epidemiological surveillance.
The crayfish plague agent Aphanomyces astaci was isolated from 69 noble crayfish Astacus astacus samples in Finland between 1996 and 2006. All isolates were genotyped using randomly amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR). Altogether, 43 isolates belonged to the genotype group of Astacus strains (As), which is assumed to represent the genotype originally introduced into Europe around 1860 and into Finland in 1893. There were 26 crayfish plague isolates belonging to the group of Pacifastacus strain I (Ps1), which appeared in Europe after the stocking of the North American species signal crayfish Pacifastacus leniusculus. The geographical distribution of the 2 genotypes in Finland corresponded with the stocking strategies of signal crayfish. The majority of Ps1-strains (83%) were associated with a classical crayfish plague episode involving acute mortality, compared with only 33% of the As-strains. Asstrains were found more often by searching for reasons for population declines or permanently weak populations, or through cage experiments in connection with reintroduction programmes. In some water bodies, isolations of the As-strains were made in successive years. This study shows that persistent crayfish plague infection is not uncommon in noble crayfish populations. The described epidemiological features suggest a difference in virulence between these 2 genotypes. KEY WORDS: Crayfish plague · Aphanomyces astaci · RAPD-PCR · Oomycete · VirulenceResale or republication not permitted without written consent of the publisher Dis Aquat Org 103: 199-208, 2013 Although some introductions of signal crayfish were made previously in the middle, eastern and northern parts of Finland, there was later a proposal (Kirjavainen 1989) that signal crayfish stocking should be restricted to a distinct region of southern Finland. This area, with some minor changes, was approved by the fisheries authorities in a national crayfish strategy agreement (Mannonen & Halonen 2000). As the carrier of crayfish plague, the signal crayfish has been shown or suspected to be the source of native crayfish mortalities in numerous reports. There are also numerous reports that invading North American crayfish species have been shown or suspected to be the source of native crayfish mortalities (e.g. Huang et al. 1994, Vennerström et al. 1998, Lilley et al. 1997, Oidtmann et al. 1999a, Pöckl & Pekny 2002, Bohman et al. 2006.In spite of the long history of crayfish plague in Europe, relatively little is known about the behaviour of Aphanomyces astaci in natural epidemics involving the highly susceptible European species. It took over 50 yr before the oomycete was accepted as the etiological agent for crayfish plague, illustrating the difficulties in the isolation and identification of the organism (Schäperclaus 1935, Nybelin 1936, Rennerfelt 1936. Subsequent research has provided improved methods for isolation (Alderman & Polglase 1986, Cerenius et al. 1988, Oidtmann et al. 1999b, Viljamaa-Dirks & Heinikainen 2006, and...
Clostridium perfringens is an important bacterial pathogen, especially in poultry, where it can lead to both subclinical and clinical disease. The aim of this study was to present data on pathological findings at outbreaks of necrotic enteritis (NE) in turkey production in Finland during the period from 1998 to 2012. Furthermore, C. perfringens isolates from healthy and diseased turkeys were characterized and their genetic diversity was investigated using pulsed-field gel electrophoresis (PFGE). Isolates (n = 212) from birds with necrotic gut lesions and from healthy flocks of 30 commercial turkey farms were characterized for the presence of cpa, cpb, iA, etx, cpb2, and cpe and netB genes. A total of 93 C. perfringens isolates, including 55 from birds with necrotic gut lesions and 38 from healthy birds from 13 different farms, were analyzed with PFGE. All contract turkey farmers (n = 48) of a turkey company that produces 99% of domestic turkey meat in Finland were interviewed about background information, management at the farm, and stress factors related to NE outbreaks. Pulsed-field gel electrophoresis analysis with SmaI restriction enzyme resulted in 30 PFGE patterns among the 92 C. perfringens isolates of high diversity. Out of all isolates, 212 (100%) were α-toxin-positive and one isolate (0.5%) was both α- and β2 toxin-positive. Fourteen isolates (6.6%) were necrotic enteritis toxin B (NetB) positive; all were recovered from turkeys with NE. In none of the isolates obtained from healthy turkeys was the netB toxin identified. In conclusion, a high diversity of C. perfringens isolates from turkeys with different health status was shown. All isolates produced α toxin, whereas only low percentages of isolates carried the netB toxin gene. The role of the netB toxin in NE in turkeys needs to be further investigated.
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