Diagnosis and epidemiological association of Listeria monocytogenes strains in two outbreaks of listerial encephalitis in small ruminants

Wiedmann, Martin; Czajka, John; Bsat, Nada; Bodis, Mary; Smith, Margaret Caroline MacHin; Divers, Thomas J.; Batt, Carl A.

doi:10.1128/jcm.32.4.991-996.1994

Cited by 50 publications

(28 citation statements)

References 21 publications

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“…1. Initially, nine L. monocytogenes isolates from two previous listerial encephalitis outbreaks (26) were ribotyped (Table 1), and these results were compared with their RAPD types (described in reference 26). The ribotypes and RAPD types of all isolates corresponded, with the exception of those of silage isolate CU-SIK17/93.…”

Section: Resultsmentioning

confidence: 99%

“…and weekly subculturing on Columbia colistin nalidixic acid agar plates with 5% sheep blood (BBL). Listeriae were isolated from the feed samples by direct plating of 10-fold dilutions of the blended samples on modified Listeria selective agar medium as described previously (8), without a blood agar overlay (26). Between 8 and 12 esculin-positive Listeria-suspected colonies were picked and confirmed as L. monocytogenes by a nested PCR assay (6).…”

Section: Methodsmentioning

confidence: 99%

“…A variety of previous reports have indicated that improperly fermented silage (i.e., that with a pH of Ͼ5.0) is the predominant source for listeriosis outbreaks in ruminants (14,26). In this investigation, L. monocytogenes isolates obtained from different silos, as well as from different locations within a silo, during or after confirmed listeriosis outbreaks in ruminants were used to determine the diversity of L. monocytogenes strains in silage and clinical samples to further understand the epidemiology and pathogenesis of animal listeriosis (14).…”

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confidence: 99%

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Ribotype diversity of Listeria monocytogenes strains associated with outbreaks of listeriosis in ruminants

et al. 1996

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Ribotyping is a molecular method for the characterization, identification, and typing of bacterial isolates that has value in epidemiological studies. To demonstrate the utility of this technique for typing of Listeria monocytogenes, four outbreaks of epizootic listeriosis in ruminants were investigated through coordinated detection and characterization methods utilizing classical microbiology and nucleic acid-based techniques. L. monocytogenes strains isolated from clinical samples and the silage consumed by the affected animals were ribotyped to establish the causal relationship between feed and the disease outbreak. For all but one outbreak, we were able to isolate L. monocytogenes strains represented by the same ribotype from both clinical and silage samples. Additional L. monocytogenes strains with ribotypes different from those of the respective clinical samples were isolated from all silage samples. This indicates that a diverse population of L. monocytogenes strains exists in farm environments, of which some may be more likely than others to cause disease.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Ribotype diversity of Listeria monocytogenes strains associated with outbreaks of listeriosis in ruminants

et al. 1996

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“…Listeriosis is a disease in humans, domestic and wild animals. Thirty‐seven mammals and 20 bird species including cold blooded animals and ticks have been listed as carriers (Gray and Killinger, 1966; Brackett, 1988) and outbreaks in small ruminants such as sheep and goat were repeatedly reported (Chand and Sadana, 1999; du Toit, 1977; Meredith and Schneider, 1984; Wiedmann et al., 1994, 1999).…”

Section: Introductionmentioning

confidence: 99%

Outbreak of Clinical Listeriosis in Sheep: Evaluation from possible Contamination Routes from Feed to Raw Produce and Humans

Wagner¹,

Melzner²,

Bagó³

et al. 2005

Journal of Veterinary Medicine, Series B

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We report the results of clinical and microbiological investigations on Listeria monocytogenes infections in a flock of 55 sheep and describe the implications for the safety of the raw milk and raw-milk cheeses produced in the on-farm dairy. The outbreak was caused by feeding grass silage, which was contaminated with 5 log10 CFU L. monocytogenes/g. Clinically, although having been fed from the same batch of silage, abortive (nine ewes), encephalitic (one ewe) and septicaemic (four ewes) forms of listeriosis were observed during the outbreak phase. As the starting point of feeding the contaminated silage was known we could calculate an incubation period of 18+/-2 and 26 days for the abortive and the encephalitic form of listeriosis, respectively. Pathologically, the septicaemic cases suffered from Listeria accumulation at comparable numbers in visceral organs but not in the brain. Only a single ewe developed central nervous symptoms and a rhomb-encephalitis was immunohistologically confirmed. In this case the infection proceeded from the nasal mucosa into the brain, with no infections of the liver, spleen and other visceral organs. Sampling of the cheese production chain, the farm environment and the persons living at the farm revealed the exposure of a farm-worker to an isolate genetically indistinguishable from the outbreak clone, obviously through the consumption of faecally contaminated bovine raw milk. The cheese under processing was free of Listeria because, as a result of intensive consultations, the farmer ensured a proper acidification of the cheese. The epidemiological findings suggest that food safety matters should be assessed in any case where infection of food-producing animals with potential human pathogens is observed.

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“…However, only few PFGE studies of clinical Listeria strains from animals have been carried out (Ramage et al 1999;Vela et al 2001), and as far as we know this is the first study of L. monocytogenes in healthy animals involving PFGE. Ribotyping (RT) has been applied for epidemiological surveys of clinical L. monocytogenes strains from humans and animals (Baloga and Harlander 1991;Graves et al 1991;Jacquet et al 1992;Nørrung and Gerner-Smidt 1993;Wiedmann et al 1994Wiedmann et al , 1997. It is not as discriminatory as PFGE, but has been reported to be of value when used in combination with this typing method Swaminathan et al 1996).…”

Section: Introductionmentioning

confidence: 99%

The diversity of Listeria monocytogenes strains from 10 Icelandic sheep farms

et al. 2004

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Aims: The purpose of this study was to examine the diversity of Listeria monocytogenes strains from healthy sheep, winter feed and environment of sheep farms in Iceland. Methods and Results: A total of 104 L. monocytogenes isolates from animals, winter feed and environment on 10 Icelandic sheep farms were compared by serotyping, ribotyping, and pulsed-field gel electrophoresis with ApaI and AscI. The isolates were divided into 24 genotypes, all identified as serovars 1/2a, 1/2b, or 4b. Nine genotypes were detected on more than one farm. On three of the farms there seemed to be a dominant strain of L. monocytogenes. Isolates from incidents of listeriosis in animals occurring on two of the farms belonged to the genotype most commonly found on the particular farm. Nine of the 24 genotypes found on the sheep farms have been associated with disease in animals and/or humans elsewhere in Iceland. Conclusions: Certain strains of L. monocytogenes seem to be widely distributed on Icelandic sheep farms. On some farms there appears to be a dominant strain of L. monocytogenes. Incidents of listeriosis in animals may tend to be associated with strains commonly found on the farm. Significance and Impact of the Study: This study demonstrates the diversity of L. monocytogenes present in healthy sheep and their environment.

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Diagnosis and epidemiological association of Listeria monocytogenes strains in two outbreaks of listerial encephalitis in small ruminants

Cited by 50 publications

References 21 publications

Ribotype diversity of Listeria monocytogenes strains associated with outbreaks of listeriosis in ruminants

Ribotype diversity of Listeria monocytogenes strains associated with outbreaks of listeriosis in ruminants

Outbreak of Clinical Listeriosis in Sheep: Evaluation from possible Contamination Routes from Feed to Raw Produce and Humans

The diversity of Listeria monocytogenes strains from 10 Icelandic sheep farms

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