Rapid detection of Listeria monocytogenes in food using culture enrichment combined with real-time PCR.

A rapid method for the detection of Listeria monocytogenes in foods combining culture enrichment and real-time PCR was compared to the ISO 11290-1 standard method. The culture enrichment component of the rapid method is based on the ISO standard and includes 24h incubation in half-Fraser broth, 4h incubation in Fraser broth followed by DNA extraction and real-time PCR detection of the ssrA gene of L. monocytogenes. An internal amplification control, which is co-amplified with the same primers as the L. monocytogenes DNA, was also included in the assay. The method has a limit of detection of 1-5CFU/25g food sample and can be performed in 2 working days compared to up to 7days for the ISO standard. A variety of food samples from retail outlets and food processing plants (n=175) and controls (n=31) were tested using rapid and conventional methods. The rapid method was 99.44% specific, 96.15% sensitive and 99.03% accurate when compared to the standard method. This method has the potential to be used as an alternative to the standard method for food quality assurance providing rapid detection of L. monocytogenes in food

APCR, factor V gene known and novel SNPs and adverse pregnancy outcomes in an Irish cohort of pregnant women

<p>Abstract</p> <p>Background</p> <p>Activated Protein C Resistance (APCR), a poor anticoagulant response of APC in haemostasis, is the commonest heritable thrombophilia. Adverse outcomes during pregnancy have been linked to APCR. This study determined the frequency of APCR, factor V gene known and novel SNPs and adverse outcomes in a group of pregnant women.</p> <p>Methods</p> <p>Blood samples collected from 907 pregnant women were tested using the Coatest^®Classic and Modified functional haematological tests to establish the frequency of APCR. PCR-Restriction Enzyme Analysis (PCR-REA), PCR-DNA probe hybridisation analysis and DNA sequencing were used for molecular screening of known mutations in the factor V gene in subjects determined to have APCR based on the Coatest^®Classic and/or Modified functional haematological tests. Glycosylase Mediated Polymorphism Detection (GMPD), a SNP screening technique and DNA sequencing, were used to identify SNPs in the factor V gene of 5 APCR subjects.</p> <p>Results</p> <p>Sixteen percent of the study group had an APCR phenotype. Factor V Leiden (FVL), FV Cambridge, and haplotype (H) R2 alleles were identified in this group. Thirty-three SNPs; 9 silent SNPs and 24 missense SNPs, of which 20 SNPs were novel, were identified in the 5 APCR subjects. Adverse pregnancy outcomes were found at a frequency of 35% in the group with APCR based on Classic Coatest^®test only and at 45% in the group with APCR based on the Modified Coatest^®test. Forty-eight percent of subjects with FVL had adverse outcomes while in the group of subjects with no FVL, adverse outcomes occurred at a frequency of 37%.</p> <p>Conclusions</p> <p>Known mutations and novel SNPs in the factor V gene were identified in the study cohort determined to have APCR in pregnancy. Further studies are required to investigate the contribution of these novel SNPs to the APCR phenotype. Adverse outcomes including early pregnancy loss (EPL), preeclampsia (PET) and intrauterine growth restriction (IGUR) were not significantly more frequent in subjects with APCR compared to normal pregnant women however Pregnancy induced hypertension (PIH) was found to be associated with FVL in our study group.</p

Rapid real-time PCR detection of Listeria monocytogenes in enriched food samples based on the ssrA gene, a novel diagnostic target

A real-time PCR assay was designed to detect a 162-bp fragment of the ssrA gene in Listeria monocytogenes. The specificity of the assay for L. monocytogenes was confirmed against a panel of 6 Listeria species and 26 other bacterial species. A detection limit of 1-10 genome equivalents was determined for the assay. Application of the assay in natural and artificially contaminated culture enriched foods, including soft cheese, meat, milk, vegetables and fish, enabled detection of 1-5 CFU L. monocytogenes per 25g/ml of food sample in 30h. The performance of the assay was compared with the Roche Diagnostics 'LightCycler foodproof Listeria monocytogenes Detection Kit'. Both methods detected L. monocytogenes in all artificially contaminated retail samples (n=27) and L. monocytogenes was not detected by either system in 27 natural retail food samples. The method developed in this study has the potential to enable the specific detection of L. monocytogenes in a variety of food types in a time-frame considerably faster than current standard methods. The potential of the ssrA gene as a nucleic acid diagnostic (NAD) target has been demonstrated in L. monocytogenes. We are currently developing NAD tests based on the ssrA gene for a range of common foodborne and clinically relevant bacterial pathogens

Acquired Activated Protein C Resistance, Thrombophilia and Adverse Pregnancy Outcomes: A Study Performed in an Irish Cohort of Pregnant Women

The combination of thrombophilia and pregnancy increases the risk of thrombosis and the potential for adverse outcomes during pregnancy. The most significant common inherited risk factor for thrombophilia is activated protein C resistance (APCR), a poor anticoagulant response of APC in haemostasis, which is mainly caused by an inherited single-nucleotide polymorphism (SNP), factor V G1691A (FV Leiden) (FVL), referred as inherited APCR. Changes in the levels of coagulation factors: FV, FVIII, and FIX, and anticoagulant factors: protein S (PS) and protein C (PC) can alter APC function causing acquired APCR. Prothrombin G20210A and methylenetetrahydrofolate reductase (MTHFR) C677T are prothrombotic SNPs which in association with APCR can also increase the risk of thrombosis amongst Caucasians. In this study, a correlation between an acquired APCR phenotype and increased levels of factors V, VIII, and IX was demonstrated. Thrombophilic mutations amongst our acquired APCR pregnant women cohort are relatively common but do not appear to exert a severe undue adverse effect on pregnancy

Apcr, factor v gene known and novel snps and adverse pregnancy outcomes in an irish cohort of pregnant women

Background: Activated Protein C Resistance (APCR), a poor anticoagulant response of APC in haemostasis, is the commonest heritable thrombophilia. Adverse outcomes during pregnancy have been linked to APCR. This study determined the frequency of APCR, factor V gene known and novel SNPs and adverse outcomes in a group of pregnant women. Methods: Blood samples collected from 907 pregnant women were tested using the Coatest (R) Classic and Modified functional haematological tests to establish the frequency of APCR. PCR-Restriction Enzyme Analysis (PCR-REA), PCR-DNA probe hybridisation analysis and DNA sequencing were used for molecular screening of known mutations in the factor V gene in subjects determined to have APCR based on the Coatest (R) Classic and/or Modified functional haematological tests. Glycosylase Mediated Polymorphism Detection (GMPD), a SNP screening technique and DNA sequencing, were used to identify SNPs in the factor V gene of 5 APCR subjects. Results: Sixteen percent of the study group had an APCR phenotype. Factor V Leiden (FVL), FV Cambridge, and haplotype (H) R2 alleles were identified in this group. Thirty-three SNPs; 9 silent SNPs and 24 missense SNPs, of which 20 SNPs were novel, were identified in the 5 APCR subjects. Adverse pregnancy outcomes were found at a frequency of 35% in the group with APCR based on Classic Coatest (R) test only and at 45% in the group with APCR based on the Modified Coatest (R) test. Forty-eight percent of subjects with FVL had adverse outcomes while in the group of subjects with no FVL, adverse outcomes occurred at a frequency of 37%. Conclusions: Known mutations and novel SNPs in the factor V gene were identified in the study cohort determined to have APCR in pregnancy. Further studies are required to investigate the contribution of these novel SNPs to the APCR phenotype. Adverse outcomes including early pregnancy loss (EPL), preeclampsia (PET) and intrauterine growth restriction (IGUR) were not significantly more frequent in subjects with APCR compared to normal pregnant women however Pregnancy induced hypertension (PIH) was found to be associated with FVL in our study group