IDENTIFICATION OF E. COLI O157 IN A BOVINE MILK FARM BY MULTIPLEX REAL-TIME PCR

Law provisions about direct sell of raw bovine milk require VTEC O157 monitoring in bovine milk farms (milk and faeces). It has been showed that culture-based methods used for this scope, besides being cumbersome and time-consuming, may be also less sensitive, compared to molecular approaches. In this study, a multiplex Real-Time PCR, able to identify VTEC O157, Salmonella spp and Listeria monocytogenes, has been used to analyse milk, filter, sewage and stool samples from a milk farm, in comparison with standard OIE methods. The performances of the molecular protocol have been preliminary assessed with lyophilized samples from proficiency testing VLA, showing 100% accordance. Results from field samples indicated the absence of the pathogen in milk, and the higher sensitivity of Real-Time PCR with other matrices, suggesting its potential use for fast VTEC O157 identification

Rapid Qualitative Urinary Tract Infection Pathogen Identification by SeptiFast® Real-Time PCR

Background Urinary tract infections (UTI) are frequent in outpatients. Fast pathogen identification is mandatory for shortening the time of discomfort and preventing serious complications. Urine culture needs up to 48 hours until pathogen identification. Consequently, the initial antibiotic regimen is empirical. Aim To evaluate the feasibility of qualitative urine pathogen identification by a commercially available real-time PCR blood pathogen test (SeptiFast®) and to compare the results with dipslide and microbiological culture. Design of study Pilot study with prospectively collected urine samples. Setting University hospital. Methods 82 prospectively collected urine samples from 81 patients with suspected UTI were included. Dipslide urine culture was followed by microbiological pathogen identification in dipslide positive samples. In parallel, qualitative DNA based pathogen identification (SeptiFast®) was performed in all samples. Results 61 samples were SeptiFast® positive, whereas 67 samples were dipslide culture positive. The inter-methodological concordance of positive and negative findings in the gram+, gram- and fungi sector was 371/410 (90%), 477/492 (97%) and 238/246 (97%), respectively. Sensitivity and specificity of the SeptiFast® test for the detection of an infection was 0.82 and 0.60, respectively. SeptiFast® pathogen identifications were available at least 43 hours prior to culture results. Conclusion The SeptiFast® platform identified bacterial DNA in urine specimens considerably faster compared to conventional culture. For UTI diagnosis sensitivity and specificity is limited by its present qualitative setup which does not allow pathogen quantification. Future quantitative assays may hold promise for PCR based UTI pathogen identification as a supplementation of conventional culture methods

A new platform for Real-Time PCR detection of Salmonella spp., Listeria monocytogenes and Escherichia coli O157 in milk

Intoxications and infections caused by food-borne pathogens represent an increasing public health problem, and diagnostic tests in multiplex format are needed for the rapid identification of food contaminations caused by more than one microbial species. We have developed a multiple PCR-based platform for the simultaneous detection of the widespread milk-associated pathogens Salmonella spp., Listeria monocytogenes and Escherichia coli O157. The assay combines an enrichment step in a medium properly formulated for the simultaneous growth of target pathogens, a DNA isolation method, and a multiplex Real-Time PCR detection system based either on dual-labelled probes (mRT-PCR), or on melting curve analysis (mHRM). The second, producing a distinct peak for each amplification product, allows the qualitative assessment of pathogen presence. Moreover, the internal amplification control (IAC) included in the reaction, ensuring the reliability of results, complies with quality management programmes. Inclusivity and exclusivity were 100% each, with a detection limit of 1 CFU for each pathogen in a total of five 25 ml-aliquots of raw milk, and a duration of two working days. The assay represents an alternative approach for the qualitative detection of the cited bacterial species, suitable for a relatively inexpensive screening of several milk samples, reducing the turnaround time and the workload

Detection of Listeria monocytogenes using a commercial PCR kit and different DNA extraction methods

The aim of our work was to evaluate a new commercial test kit for the detection of Listeria monocytogenes by PCR, using different DNA extraction methods. Food samples (pork sausage and ‘‘mozzarella’’ cheese) were spiked with known concentrations of L. monocytogenes and culture-enriched for 24 h. DNA extracted using three commercial kits and two standard methods, was amplified in speciesspecificPCR employing a L. monocytogenes PCR Detection Kit (Diatheva). The PCR-based method proved to be a reliable means of detecting the pathogen in food samples independently from the extraction procedure used, even for a contamination cell number of 1 cfu/g before culture enrichment. The molecular assay, showing perfect agreement with standard microbiological tests and a considerably shortened analysis time, provides a sensitive and rapid alternative for applications in the testing of foods for microbiological contamination, and highlights the potential of PCR technology in routine food control

Noticias de algunos señores de la familia de Howard, barones de Effingham (ingleses). [Manuscrito]

Pertenece a la Colección Salazar y Castro de la RA

Simultaneous direct detection of Salmonella spp., Listeria Monocytogenes and Escherichia Coli o157 in milk samples by magnetic extraction and multiplex PCR

The aim of our work was to develop a new molecular method for the simultaneous detection of Salmonella spp., Listeria monocytogenes and Escherichia coli O157 directly in milk samples. Three specific target sequences were chosen for a multiplex polymerase chain reaction (PCR) assay: a 155-bp region of the Salmonella spp. tetrathionate reductase (ttr) locus; a 173-bp region of the L. monocytogenes listeriolysin O gene (hlyA); a 217-bp region of the E. coli O157 lipopolysaccharide gene (rfbE). An internal amplification control was also included to detect PCR inhibition. In addition, a magnetic-based extraction method was also developed to isolate PCR-ready DNA from milk. The assay was able to detect, whether alone or mixed, also with a difference of 2 log units, as few as 102 cells of each pathogen per 10 mL of spiked milk