Characterization of Cronobacter recovered from dried milk and related products.

BACKGROUND: Cronobacter is a recently proposed genus consisting of six genomospecies that encompass the organisms previously identified as Enterobacter sakazakii. Cronobacter are opportunistic pathogens and are known to cause serious infections in infants, particularly neonates. High case fatality rates have been associated with infections and acute sequelae can occur in survivors with severe ramifications on neurological development. Infant formula has been identified as one route of transmission for infection in infants. However, the primary reservoirs for subsequent contamination of foods with Cronobacter remain undefined due to the ubiquitous nature of these organisms. More recently, infections in adults have been reported, especially amongst the elderly and patients who are immunocompromised. To help prevent the transmission of infection, it is important to identify the main food sources for Cronobacter. The aim of this study was to identify and characterize Cronobacter isolated from dried-milk and related products available in an Egyptian food market. RESULTS: In total sixteen Cronobacter strains were isolated from 152 dairy-based products. These were identified and characterized using pheno- and genotyping experiments. Real-time PCR confirmed the detection of Cronobacter. Following antibiotic susceptibility tests, 3 strains showed resistance to trimethoprim and/or neomycin. Phenotype profiles were generated based on key biochemical distinguishing tests. Pulsed-field gel electrophoresis (PFGE) identified 8 PFGE types amongst the collection of strains. Repetitive sequence based PCR (rep-PCR) analysis identified 3 rep-PCR types amongst the collection of strains. Sequencing of the recN gene was used to differentiate among the recently described species of Cronobacter. CONCLUSION: This study identified the presence of Cronobacter in dried milk and related products sourced from the Nile-Delta region of Egypt. Although the majority of the strains were susceptible to the antibiotics tested, resistance was observed in three isolates, highlighting the risks associated with Cronobacter contamination in foods. Phenotype and genotype analysis should be applied to further characterize Cronobacter spp. and prevent its transmission into food products.

Evaluation of a new one-step enrichment in conjunction with a chromogenic medium for the detection of Cronobacter spp. (Enterobacter sakazakii) in powdered infant formula.

The aim of the present study was to evaluate a new one-step enrichment protocol, consisting of a combined preenrichment and enrichment broth (Cronobacter Enrichment Broth [CEB]) used in conjunction with selective-differential agar ChromID Sakazakii, to facilitate a shortened 2-day cultural method for detection of Cronobacter spp. (Enterobacter sakazakii) in powdered infant formula (PIF). The CEB was evaluated using samples artificially inoculated with low concentrations of 10 lyophilized strains, representative of the genus Cronobacter. The detection of strains was compared in parallel with the enrichment medium from ISO/TS 22964 and a recently proposed differential screening broth for the detection of Cronobacter. All of the Cronobacter strains were recovered using the CEB, and a significantly higher final bacterial concentration was obtained with the CEB than with the other enrichment broths (P < 0.01). There was no significant difference between the cell concentrations for cultures grown in CEB at 37 degrees C and those grown at 41.5 degrees C. Cronobacter was recovered from both 1/10 (50 g:450 ml) and 1/5.5 (100 g:450 ml) sample-to-broth ratios, with no significant difference observed between the final bacterial concentrations obtained from the two ratios. Further studies on a wider range of PIFs, including naturally contaminated samples, are warranted to determine if the use of this protocol may facilitate the rapid release (within 40 to 48 h) of PIF.

A novel real-time ultrasonic method for prion protein detection using plasminogen as a capture molecule.

BACKGROUND: High resolution ultrasonography (HR-US) can monitor the molecular changes and biochemical interactions between proteins in real-time. The aim of this study was to use HR-US to characterize the real-time interactions between plasminogen coated beads and PrPSc and to determine if this approach could be applied to the identification of animals affected by prion diseases. Plasminogen, immobilized to beads, was used as a capturing tool for PrPSc in brain homogenates from scrapie affected sheep and the binding reaction was monitored in real-time in an ultrasonic cell. RESULTS: Changes in the ultrasonic parameters suggested that three processes occurred during the incubation: binding, protein-protein network formation and precipitation and that these processes occurred in a concentration dependent manner. Conversely, when homogenates from normal sheep were similarly examined, no evidence for the occurrence of these processes was found indicating the specificity of the interaction between the plasminogen coated beads and PrPSc. CONCLUSION: These results indicate firstly, that the plasminogen coated beads binded selectively to PrPSc and secondly, that a HR-US system can discriminate between scrapie affected and non-affected samples and thus has potential as a tool for the rapid diagnosis for prion diseases. This approach has the significant advantage of not requiring a proteinase K pre-digestion step, which is routinely used in current PrPSc detection assays.

Bovine paramphistomes in Ireland.

Paramphistome infections have been associated with significant morbidity, caused chiefly by the activity of juvenile flukes in the intestine of the ruminant final host. Most cases have been reported in tropical and sub-tropical areas. However, recent reports of an apparent increase in the incidence of rumen fluke and its geographical range in Europe have renewed interest in a parasite previously thought to be of little significance in temperate regions. Moreover, the identity of rumen flukes present in the British Isles is currently being revised. As a result, work is underway throughout Europe to review and re-assess the clinical and economic significance of rumen flukes. During the present study, historical diagnostic laboratory records were interrogated for recent changes in the incidence of rumen fluke in Ireland. Three cattle herds were monitored for the presence of paramphistome eggs using coprological analysis over a period of 2 months (in the case of a group of housed steers) and 14 months (in the case of two extensively operated farms), respectively. Adult rumen fluke collected following slaughter were weighed and typed in two loci. We found that Calicophoron daubneyi is the most common if not only paramphistome species present in Ireland and that infections in cattle are now much more prevalent than was the case five or six years ago. The pylogenetic relationship of our isolates to the only published sequence and to C. daubneyi isolates from Northern Ireland was analysed. Genetic heterogeneity was similar all over the island and comparable to that of Fasciola hepatica, a fact that may have implications for the parasite's ability to develop resistance to the very limited number of drugs currently available for treatment. The same haplotypes predominated throughout the island. Although the clinical significance of C. daubneyi is still uncertain, considering the apparent pervasiveness of the parasite, rumen fluke should be considered a differential diagnosis when treating scour or ill-thrift in young calves, and goats and sheep of any age.