Listeria monocytogenes can cause disease and death in humans and a large variety of animal species.Canine listeriosis seems, however, to be rare.In the present report, L. monocytogenes was isolated as a pure culture from the gallbladder of a dog with liver insufficiency.The animal suffered from auto-immune-mediated polyarthritis and had therefore been treated with prednisolone for several months.The L. monocytogenes isolate tested positive in PCR for the virulence genes inlA, inlB, hly, actA, sigB and prfA and expressed functional, full-length internalin.This is the first reported case of a dog with a L. monocytogenes infection of the gallbladder.Bacterial persistence in the gallbladder of pet animals may constitute a health hazard for their owner. SAMENVATTINGListeria monocytogenes kan ziekte en sterfte veroorzaken bij de mens en verschillende diersoorten.Listeriose komt echter zelden voor bij honden.In deze casuïstiek werd een reincultuur van L. monocytogenes geïsoleerd uit de galblaas van een hond met leverinsufficiëntie.Het dier leed aan auto-immuungemedieerde polyartritis waarvoor het gedurende meerdere maanden behandeld werd met prednisolone.In het L.
Shiga toxin-producing E. coli (STEC), of various serogroups harboring the intimin gene, form a serious threat to human health. They are asymptomatically carried by cattle. In this study, a quantitative real-time PCR (qPCR) method was developed as a molecular method to detect and quantify Shiga toxin genes stx1 and stx2 and the intimin gene eae. Subsequently, 59 fecal samples from six farms were tested using qPCR and a culture method as a reference. Three farms had contaminated animals as demonstrated by the culture method. Culture-positive farms showed moderate significantly higher stx prevalences than culture-negative farms (p = 0.05). This is the first study which showed preliminary results that qPCR can predict STEC farm contamination, with a specificity of 77% and a sensitivity of 83%, as compared with the culture method. Furthermore, the presence or quantity of stx genes in feces was not correlated to the isolation of STEC from the individual animal. Quantitative data thus did not add value to the results. Finally, the detection of both stx and eae genes within the same fecal sample or farm using qPCR was not correlated with the isolation of an eae-harboring STEC strain from the respective sample or farm using the culture method.
ABSTRACT In this study, a number of Listeria monocytogenes strains of different origins were evaluated for in vitro invasion capacity for various human cell types (monocytic THP-1, enterocytic Caco-2, and hepatocytic HepG2 cells) and for expression levels of specific virulence genes. For THP-1 cells, no differences between clinical and nonclinical L. monocytogenes strains in invasion capacity or in production of the proinflammatory cytokine interleukin-8 (IL-8) were observed, whereas for the Caco-2 and HepG2 cells, significant differences in invasion capacity were noticed. On average, the clinical strains showed a significantly lower invasion capacity than the nonclinical L. monocytogenes strains. Furthermore, it was shown that the clinical strains induce lower IL-8 levels in HepG2 cells than do the nonclinical strains. This observation led us to study the mRNA expression levels of inlA , inlB , and ami , important virulence genes mediating adhesion and invasion of eukaryotic cells, by real-time reverse transcription-PCR for 27 clinical and 37 nonclinical L. monocytogenes strains. Significant differences in inlA and inlB expression were observed, with clinical strains showing a lower expression level than nonclinical strains. These observations were in accordance with in vitro invasion of Caco-2 and HepG2 cells, respectively. The results of this study indicate that differential expression levels of inlA and inlB possibly play a role in the virulence capacities of L. monocytogenes strains. The lower capacity of clinical strains to invade HepG2 cells and to induce IL-8 is possibly a mechanism of immune evasion used by specific L. monocytogenes strains.
Salmonella Enteritidis strains of egg- and non-egg-related origin were characterized molecularly to find markers correlated with the egg-contaminating property of Salmonella Enteritidis. Isolates were examined by random amplified polymorphic DNA (RAPD), plasmid profiling and phage typing. Furthermore, the presence of 30 virulence genes was tested by PCR. In genetic fingerprinting and gene content, only small differences between the strains were found and no correlation was observed with the origin (egg-related versus non-egg-related). A major RADP group was present in both egg- and non-egg-related strains, but other smaller RAPD groups were present as well in both categories of strains. Phage types PT4 and PT21 were predominant. Differential mRNA expression levels of fimA and agfA under conditions of growth simulating the conditions during egg formation were determined by real-time RT-PCR. Although differences in fimA and agfA expression levels were observed between the strains, these could not be correlated with the origin of the strains (egg-related versus non-egg-related). The highest expression levels of agfA and fimA were only found in two non-egg-related strains, which seemed to be correlated with the presence of a 93 kb plasmid instead of the 60 kb virulence plasmid. Our results seem to indicate only a limited role for at least type I fimbriae (encoded by fim operon) in egg contamination by Salmonella Enteritidis.
