Specific PCR Detection Research Articles

Identification and virulence test of a new pathogen that causes verticillium striping on rapeseed in northwestern China

Five stems of rapeseed with abundant black microsclerotia were collected from Huangyuan County of Qinghai Province, China, and fungal isolates were obtained from the stems. They were identified based on morphology, molecular features and specific PCR detection. The results showed that the 10 fungal isolates belonged to Verticillium longisporum lineage A1/D3. One of the 10 isolates (HW7-1) was tested for virulence on three species of rapeseed, including B. napus Zhongshuang 9, B. rapa Qingyou 9 and B. juncea Tayou 2 by conidia inoculation of HW7-1 on roots of young seedlings. Control seedlings were inoculated with V. dahliae conidia or water alone. The seedlings of these treatments were transplanted in culture mix and incubated in a growth chamber (20 ​°C). Results suggested that the control seedlings of three cultivars appeared quite healthy, while the seedlings inoculated with HW7-1 turned yellowing leaves, seedling stunting or even death after 22 days post-inoculation. V. longisporum was re-isolated from he yellow leaves, thus fulfilling Koch's postulates. Moreover, compared to the control treatments, inoculation with HW7-1 caused flowering delay and seed yield reduction on Tayou 2 with production of microsclerotia on the stems. To our knowledge, this is the first report of V. longisporum lineage A1/D3 on rapeseed in northwestern China.

Application of PCR-based diagnostic tools that target Enterocytozoon hepatopenaei for the molecular detection of a Vittaforma-like microsporidium that infects Penaeus vannamei from Costa Rica

Several PCR methodologies are available for the detection of Enterocytozoon hepatopenaei (EHP) that target the SSU rRNA gene. However, these methodologies are reported as unsuitable for the detection of EHP due to specificity issues. Here, we report the applicability of two commonly used SSU rRNA methodologies for the detection of additional microsporidia from the genus Vittaforma that is present in cultured Penaeus vannamei from Costa Rica. The molecular detection of DNA of the novel microsporidia can only be achieved using SSU rRNA targeting methodologies and does not cross-react with the highly specific spore wall protein gene PCR detection method.

Molecular Characterization and Efficacy Evaluation of Transgenic Maize Harboring cry2Ab-vip3A-cp4epsps for Insect Resistance and Herbicide Tolerance.

Insect infestation and weed interference have a seriously negative impact on the growth, yield, and grain quality of maize. In this study, transgenic maize plants harboring three exogenous genes, cry2Ab, vip3A, and cp4epsps, that were constructed into a single T-DNA were developed for protection against insects and weeds. The transgene integration sites on the chromosomes in two transgenic maize events, CVC-1 and CVC-2, were determined using whole genome sequencing and specific PCR detection. As revealed by laboratory insect bioassays, these two transgenic events exhibited strong insecticidal toxicity against three major species of Lepidoptera insects, including Mythimna separata, Helicoverpa armigera, and Spodoptera frugiperda, with mortality rates exceeding 96%, 100%, and 100%, respectively, after six days of infestation. In addition, CVC-1 exhibited a high tolerance to glyphosate under field conditions. The successful expressions of cry2Ab, vip3A, and cp4epsps in various tissues at different developmental stages of CVC-1 were validated at the transcriptional and translational levels using quantitative real-time reverse transcription PCR (qRT-PCR) and enzyme-linked immunosorbent assay (ELISA), respectively. These findings demonstrated that the transgenic maize CVC-1 developed using this triple gene construct has excellent insect resistance and herbicide tolerance, which may provide a valuable germplasm resource and data support for future maize breeding of insect and weed control.

Development and Single Laboratory Evaluation of a Refined and specific Real-time PCR Detection Method, Using Mitochondrial Primers (Mit1C), for the Detection of Cyclospora cayetanensis in Produce

Regulatory methods for detection of the foodborne protozoan parasite Cyclospora cayetanensis must be specific and sensitive. To that end, we designed and evaluated (in a single laboratory validation) a novel and improved primer/probe combination (Mit1C) for real-time PCR detection of C. cayetanensis in produce. The newly developed primer/probe combination targets a conserved region of the mitochondrial genome of C. cayetanensis that varies in other closely related organisms. The primer/probe combination was evaluated both in silico and using several real-time PCR kits and polymerases against an inclusivity/exclusivity panel comprised of a variety of C. cayetanensis oocysts, as well as DNA from other related Cyclospora spp. and closely related parasites. The new primer/probe combination amplified only C. cayetanensis, thus demonstrating specificity. Sensitivity was evaluated by artificially contaminating cilantro, raspberries, and romaine lettuce with variable numbers (200 and 5) of C. cayetanensis oocysts. As few as 5 oocysts were detected in 75%, 67.7%, and 50% of the spiked produce samples (cilantro, raspberries, and romaine lettuce), respectively, all uninoculated samples and no-template real-time PCR controls were negative. The improved primer/probe combination should prove an effective analytical tool for the specific detection of C. cayetanensis in produce.

Detection, genotyping and virulence characterization of Fusarium wilt race 4 (VCG0114) causing cotton wilt in three Texas fields

AbstractFusarium wilt of cotton, caused by the soilborne fungus Fusarium oxysporum f.sp. vasinfectum race 4 (Fov4, VCG0114), is a serious disease that has adversely affected cotton production in California since 2001 and in the Upper Rio Grande Region near El Paso in the border areas between Texas and New Mexico since 2017. Fov4 was isolated from cotton stem samples collected from wilted or asymptomatic plants adjacent to the wilting plants from the El Paso area. The MT genotype was the only Fov4 genotype found in two fields in the Lower Valley of El Paso and the T genotype was the only Fov4 genotype found in one field in the Upper Valley Region of El Paso. No N, MiT or mixed genotypes of Fov4 were detected in any of these fields. Furthermore, the F. oxysporum f.sp. vasinfectum isolates were exclusively Fov4. The results support the observation that the MT genotype of Fov4 is mainly distributed in the Lower Valley of El Paso and the T genotype of Fov4 is mainly distributed in the Upper Valley Region of El Paso. Virulence of the MT genotype of Fov4 was higher than that of the T genotype. PCR methods previously developed for Fov4 specific PCR detection and multiplex Fov4 genotyping were validated by VCG analyses of the newly obtained isolates. These PCR methods were adapted for the in planta detection of Fov4, but Fov4 genotyping was limited to the detection of T, MT and MiT genotypes. It is important to continue to monitor dynamic population structure of Fov4 genotypes to prevent the spread of Fov4 and optimize disease control.

Highly Specific Droplet-Digital PCR Detection of Universally Methylated Circulating Tumor DNA in Endometrial Carcinoma.

No circulating biomarker is available for endometrial carcinoma (EC). We aimed to identify DNA positions universally hypermethylated in EC, and to develop a digital droplet PCR (ddPCR) assay for detection of hypermethylated circulating tumor DNA (meth-ctDNA) in plasma from patients with EC. DNA positions hypermethylated in EC, and without unspecific hypermethylation in tissue/cell types releasing circulating cell-free DNA in plasma, were identified in silico from TCGA/Gene Expression Omnibus (GEO) data. A methylation-specific ddPCR (meth-ddPCR) assay following bisulfite conversion of DNA extracted from plasma was optimized for detection of meth-ctDNA according to dMIQE guidelines. Performances were validated on a retrospective cohort (n = 78 tumors, n = 30 tumor-adjacent tissues), a prospective pilot cohort (n = 33 stage I-IV patients), and 55 patients/donors without cancer. Hypermethylation of zinc finger and SCAN domain containing 12 (ZSCAN12) and/or oxytocin (OXT) classified EC samples from multiple noncancer samples with high diagnostic specificity/sensitivity [>97%; area under the curve (AUC) = 0.99; TCGA/GEO tissues/blood samples]. These results were confirmed in the independent retrospective cohort (AUC = 0.99). Meth-ddPCR showed a high analytical specificity (limit of blank = 2) and sensitivity (absolute lower threshold of detection = 50 pgmethDNA/mLplasma). In the pilot cohort, meth-ctDNA was detected in pretreatment plasma samples from 9/11 and 5/20 patients with advanced and non-advanced EC, respectively. 2 of 9 patients had ctDNA detected after macroscopic complete surgery and experienced progression within 6 months. No healthy donors had any copy of hypermethylated DNA detected in plasma. Meth-ddPCR of ZSCAN12/OXT allows a highly specific and sensitive detection of ctDNA in plasma from patients with EC and appears promising for personalized approaches for these patients.

Whole genome analysis and specific PCR primer development for Vibrio coralliilyticus, combined with transcription and metabolome analysis of red spotting disease in the sea urchin, Strongylocentrotus intermedius

Vibrio coralliilyticus is a notorious pathogen that causes disease in coral. Recently, we identified a pathogenic strain of V. coralliilyticus, Rb102, from farmed sea urchins that had "red spotting disease". In this study, we performed whole genome sequencing for Rb102 and compared the sequence with ten common aquatic pathogens. A specific PCR detection method was then developed for V. coralliilyticus. In addition, disease–resistant sea urchins and those suffering from red spotting disease were sent for comparative analysis of the transcriptome and metabolome. The complete genome was found to be 5758,353 bp and contains two large chromosomes (Chr1 and Chr2) and one plasmid. The groEL gene was chosen for the design of specific PCR identification primers. Differential transcriptome analysis between diseased and disease resistant groups revealed that there are 1845 differentially expressed genes (DEGs), with the largest number enriched in the purine metabolic pathway. Significant differences were detected between the two groups in 91 cationic metabolites and 43 anionic metabolites. Deoxyinosine was the most significantly down–regulated metabolite and is found in the purine metabolic pathway. The results of this study provide an important reference and data foundation for further study of "red spotting disease" in sea urchin farms.

Identification and pathogenicity of Alternaria species associated with leaf blotch disease and premature defoliation in French apple orchards.

Leaf blotch caused by Alternaria spp. is a common disease in apple-producing regions. The disease is usually associated with one phylogenetic species and one species complex, Alternaria alternata and the Alternaria arborescens species complex (A. arborescens SC), respectively. Both taxa may include the Alternaria apple pathotype, a quarantine or regulated pathogen in several countries. The apple pathotype is characterized by the production of a host-selective toxin (HST) which is involved in pathogenicity towards the apple. A cluster of genes located on conditionally dispensable chromosomes (CDCs) is involved in the production of this HST (namely AMT in the case of the apple pathotype). Since 2016, leaf blotch and premature tree defoliation attributed to Alternaria spp. have been observed in apple-producing regions of central and south-eastern France. Our study aimed to identify the Alternaria species involved in apple tree defoliation and assess the presence of the apple pathotype in French orchards. From 2016 to 2018, 166 isolates were collected and identified by multi-locus sequence typing (MLST). This analysis revealed that all these French isolates belonged to either the A. arborescens SC or A. alternata. Specific PCR detection targeting three genes located on the CDC did not indicate the presence of the apple pathotype in France. Pathogenicity was assessed under laboratory conditions on detached leaves of Golden Delicious and Gala apple cultivars for a representative subset of 28 Alternaria isolates. All the tested isolates were pathogenic on detached leaves of cultivars Golden Delicious and Gala, but no differences were observed between the pathogenicity levels of A. arborescens SC and A. alternata. However, the results of our pathogenicity test suggest that cultivar Golden Delicious is more susceptible than Gala to Alternaria leaf blotch. Implications in the detection of the Alternaria apple pathotype and the taxonomic assignment of Alternaria isolates involved in Alternaria leaf blotch are discussed.

Antagonism and biocontrol of walnut blight by sweet osmanthus endophytic bacterium OFE17

Walnut blight caused by Xanthomonas arboricola pv. juglandis (Xaj) is an important bacterial disease for walnut production worldwide. The objective of the present study was to characterize one endophytic bacterium, namely OFE17 from Osmanthus fragrans leaves, evaluate its potential biocontrol efficiency against the disease, and identify the underlying probable mechanisms of its function. Based on morphology, biochemical and physiological characteristics, 16S-rDNA and gyrB sequences, and antibiotic production genes, the endophyte OFE17 was tentatively identified as Bacillus sp. A disease control efficiency of up to 68.69% was observed through a biocontrol test on detached immature walnut fruits under controlled conditions. OFE17 can produce protease, cellulase, amylase, siderophores, and demonstrates phosphate dissolving ability. However, the OFE17 is unable to produce extracellular lipase, IAA (indoleacetic acid), and has no nitrogen fixation capability. The active compounds of OFE17 were primarily non-protein compounds, and the optimum organic extraction solvent was chloroform. Through specific PCR detection, it contains the genes ituA and ituD which play a key role in active compound synthesis of iturin A synthetase. This study added a promising biocontrol agent candidate for the disease control and laid a foundation for further exploration.

A TaqMan-based quantitative real-time PCR assay for identification of the goose circovirus

Goose circovirus (GoCV) is a potential immunosuppressive virus that poses a great hazard to the goose industry and has been shown to be widely distributed throughout China. We have established a fast, sensitive and highly specific TaqMan real-time quantitative PCR detection method for this virus. Specific primers and probes were designed against the conserved regions of the genomic GoCV Rep gene. The results showed that the assay was highly specific and sensitive for GoCV and did not cross-react with other non-targeted waterfowl viruses. The established method will be helpful for epidemiological detection and may be effective in the prevention and control of the disease.

Specific and sensitive PCR detection of Cadophora luteo-olivacea associated with grapevine trunk diseases

Grapevine trunk diseases, caused by different fungal pathogens, are the most relevant group of diseases that affect vineyards, causing important economic losses. Quality control for sanitary purposes should be applied for different diseases in every stages of the plant development, from the nursery during propagation to the vineyard during grape production. Petri disease has been identified as one of the most dangerous for vine plants causing economic losses in cellars worldwide. Petri disease is caused by the infection of different fungal pathogens, mainly, Phaeomoniella chlamydospora, Phaeocremonium minimum and Cadophora luteo-olivacea. The molecular detection of plant pathogens is topical due to its facility, reproducibility and accuracy. Here we have described a PCR protocol based in a pair of new designed specific primers for the rapid detection of C. luteo-olivacea. The described procedure is intended for the direct inspection of plants suspected of being infected. Bovine serum albumin and MgCl2 were used as PCR adjuvants in order to cope with the presence of polymerase inhibitors from wood samples. Several assays have been settled out in order to assign the sensitivity and specificity of the developed technique. Under the conditions tested, the procedure has a low detection limit (10 pg) and it is specific for C. luteo-olivacea detection among other Cadophora species and fungal endophytes of Vitis vinifera.

Comparison of Five Endogenous Reference Genes for Specific PCR Detection and Quantification of Rice

Endogenous reference genes (ERGs) provide vital information regarding genetically modified organisms (GMOs). The successful detection of ERGs can identity GMOs and the source of genes, verify stability and reliability of the detection system, and calculate the level of genetically modified (GM) ingredients in mixtures. The reported ERGs in rice include sucrose-phosphate synthase (SPS), phospholipase D (PLD), RBE4 and rice root-specific GOS9 genes. Based on the characteristics of ERGs, a new ERG gene, phosphoenolpyruvate carboxylase (PEPC), was selected, and further compared with the four existing genes. A total of 18 rice varieties and 29 non-rice crops were used to verify the interspecies specificity, intraspecies consistency, sensitivity, stability and reliability of these five ERGs using qualitative and quantitative PCR. Qualitative detection indicated that SPS and PEPC displayed sufficient specificity, and the detection sensitivity was 0.05% and 0.005%, respectively. Although the specificity of both RBE4 and GOS9 were adequate, the amplicons were small and easily confused with primer dimers. Non-specific amplification of the PLD gene was present in maize and potato. Real-time quantitative PCR detection indicated that PLD, SPS and PEPC displayed good specificity, with R2 of the standard curve greater than 0.98, while the amplification efficiency ranged between 90% and 110%. Both the detection sensitivities of PLD and PEPC were five copies and that of SPS was ten copies. RBE4 showed typical amplification in maize, beet and Arabidopsis, while GOS9 was found in maize, tobacco and oats. PEPC exhibited excellent detection sensitivity and species specificity, which made it a potentially useful application in GM-rice supervision and administration. Additionally, SPS and PLD are also suitable for GM-rice detection. This study effectively established a foundation for GMO detection, which not only provides vital technical support for GMO identification, but also is of great significance for enhancing the comparability of detection results, and the standardization of ERG testing in GM-rice.

Circulating tumor DNA (ctDNA) in metastatic melanoma (MM) patients (pts) with brain metastases (mets).

9581 Background: Brain mets are common in pts with MM, occurring in up 50% of pts. Serial ctDNA levels at baseline and early on therapy predict objective response (OR) and overall survival (OS) in MM pts without brain mets receiving immune checkpoint inhibitors (ICI). The predictive utility in pts with brain mets is unknown. Methods: BRAF/NRAS ctDNA at baseline and early on ICI therapy (week 3-8) was analysed using mutation specific digital droplet PCR (detection threshold 2.5 copies/ml plasma) in MM pts with brain mets. Intracranial (IC) and extracranial (EC) disease volume (sum of product of diameters of ALL mets [SPD]) and OR, progression-free survival (PFS) and OS were analyzed. Results: 48 pts with brain mets were studied, 40 with concurrent EC disease (SPD EC med 892mm2 [25-22417mm2], IC med 200mm2 [9-1487mm2]) and 8 with isolated IC mets (SPD med 150mm2 [66-1035mm2]). At baseline, ctDNA was detectable in 28 (58%) pts, 28/40 (70%) with IC + EC mets and 0/8 with isolated IC mets. Baseline ctDNA reflected EC disease volume (Pearson’s r = 0.4, p = 0.01) but not IC volume (r = 0.1, p = 0.5). Baseline ctDNA did not associate with IC or EC OR or PFS, however, undetectable ctDNA was associated with superior OS (HR 0.4, p = 0.01). Early on therapy, ctDNA predicted EC response but not IC response; EC OR was 65% if ctDNA undetectable and 6% if detectable (p < 0.01), IC OR was 35% if undetectable and 12% if detectable (p = 0.1). Nevertheless, undetectable ctDNA early on therapy was associated with a superior PFS (HR 0.3, p < 0.01) and OS (HR 0.2, p < 0.01), indicating survival is largely determined by extracranial disease activity. In the 8 pts with IC disease only, 7/8 had disease progressive disease as best response. 1/8 subsequently developed detectable ctDNA at week 12, with multiple new EC mets seen at first restaging scan at this time. Conclusions: ctDNA does not appear to be a useful biomarker for detecting brain mets nor monitoring brain response in melanoma pts receiving ICI. This has important implications when using ctDNA in the setting of surveillance in the metastatic and adjuvant setting.

Antibiotics for amniotic-fluid colonization by Ureaplasma and/or Mycoplasma spp. to prevent preterm birth: A randomized trial.

ObjectiveTo assess whether antibiotics used for treatment in asymptomatic second-trimester women positive for Mycoplasma or Ureaplasma spp. detected by amniotic-fluid PCR prevents preterm delivery.DesignA randomized, double-blind, placebo-controlled trial.Setting10 maternal fetal medicine centers in France.PopulationWomen with a singleton pregnancy who underwent amniocentesis between 16 and 20 weeks’ gestation (weeks) for Down syndrome screening. A sample of 238 women with PCR-positive findings per treatment group was needed to show a 50% reduction in the preterm delivery rate.MethodsAmniotic fluid was tested. Women with positive findings on real-time PCR of amniotic fluid for Mycoplasma hominis, Mycoplasma genitalium, Ureaplasma urealyticum and Ureaplasma parvum were randomized to receive josamycin or placebo. Amniotic fluid was also tested for 16S PCR.Main outcome measuresThe primary outcome was delivery before 37 weeks.ResultsIn total, 1043 women underwent amniotic-fluid screening with specific PCR detection between July 2008 and July 2011: PCR detection failed in 27 (2.6%), and 20 (1.9%) underwent termination of pregnancy. Among the 1016 women with PCR results, 980 had available data for the primary outcome (delivery before 37 weeks) and 29 (3.0%) were positive for Ureaplasma and/or Mycoplasma spp. Because of the low rate of women with PCR-positive findings, the trial was stopped prematurely. In total, 19 women were randomized to receive placebo (n = 8) or josamycin (n = 11) and their characteristics were comparable, as was the rate of preterm delivery and secondary outcomes. In comparing all PCR-positive and -negative women regardless of treatment, PCR positivity for Ureaplasma and/or Mycoplasma spp. was not associated with any adverse pregnancy or neonatal outcome. Amniotic-fluid screening by 16S PCR showed no other bacterial colonization associated with preterm birth.ConclusionsBecause of a low amniotic fluid colonization rate, the trial was interrupted. Maternal amniotic-fluid colonization by Mycoplasma and/or Ureaplasma spp. at 16–20 weeks in asymptomatic women is rare and not associated with adverse pregnancy outcomes.Trial registrationClinicalTrials.gov NCT00718705

Detection of ASXL1 Mutation and CALR Mutation Coexistance in Patients with Ph Negative Myeloproliferative Neoplasm and Its Clinical Gignificance

To explore the coexistence of ASXL1 and CALR gene mutations in patients with essential thrombocytheima (ET) and with primary myelofibrosis(PMF), and to compare the differences of clinical characteristics between ET and PMF patients carrying ASXL1 and CALR mutations, and ET and PMF patients carrying solitary gene mutation, and ET and PMF patients without any mutations. The mutations of ASXL1 gene at exon 12, CALR gene at exon 9 and MPL gene at exon 10 in 263 essential ET patients and 29 PMF patients were detected by PCR amplification followed by direct sequencing of genomic DNA. The JAK2V617F mutations were used by allele specific PCR detection. 72.6%(212/292)of patients harbored at least one mutation. The incidences of ASXL1 and CALR mutations were 5.8% and 30.5%, respectively. The frequencies of JAK2V617F and MPL mutations were 39.0% and 2.4%, respectively. 5.1%(15/292) of patients had double mutations, including ASXL1 and CALR(n=11), ASXL1 and JAK2V617F(n=2), MPL and CALR(n=1) and ASXL1 and MPL(n=1). The frequency of concurrent ASXL1 and CALR mutations was found to be high. Significant difference was found on hemoglobin levels and platelet counts between CALR and ASXL1 mutations and single mutation (P<0.05),however, the difference on leukocyte counts and median age was not found. Compared with negative patients, the presence of ASXL1 and CALR mutations was found to be significantly correlative with lower hemoglobin level (P=0.045), lower leukocyte count (P=0.002) and with higher platelet counts(P=0.001), but the difference of median age was not found. The frequency of concurrent ASXL1 and CALR mutations is higher in ET patients. The coexistence of ASXL1 and CALR gene mutations significantly associated with lower hemoglobin level and higher platelet count.

Aptamer-Based Trapping: Enrichment of Bacillus cereus Spores for Real-Time PCR Detection.

Aptamer-based trapping techniques are in general suitable to replace common antibody-based enrichment approaches. A time-consuming isolation or clean-up is often necessary during sample preparation, e.g. for the detection of spores. For the development of bioanalytical routine approaches, aptamers with a high affinity to B. cereus spores were applied for the establishment and validation of an aptamer-based trapping technique in milk with fat contents between 0.3 and 3.5%. Thereby, enrichment factors of up to sixfold were achieved. The combination of an aptamer-based enrichment by magnetic separation and the subsequent specific real-time PCR detection represents a reliable and rapid detection system.

Specific PCR Detection of Fusarium oxysporum f. sp. vasinfectum California Race 4 Based on a Unique Tfo1 Insertion Event in the PHO Gene.

A highly virulent race 4 (Cal race 4) of Fusarium oxysporum f. sp. vasinfectum was identified in California cotton fields in 2001, and has since been found in increasing numbers of fields. Cal race 4 isolates contain a unique Tfo1 transposon insertion in the PHO gene that was not found in other F. oxysporum f. sp. vasinfectum genotypes. Based on this insertion, a multiplex polymerase chain reaction method was developed to detect the Cal race 4 pathogen. A panel of F. oxysporum f. sp. vasinfectum isolates representing different vegetative compatibility groups (VCG) and DNA sequence types was assembled to test the specificity of the detection method. In all, 16 of 17 Cal race 4 isolates produced a 583-bp amplicon; the other isolate produced a 396-bp amplicon reflecting the absence of the Tfo1 insertion. This isolate was a moderately virulent pathogen among Cal race 4 isolates. In total, 80 other F. oxysporum isolates associated with cotton and 11 other formae speciales of F. oxysporum produced only the 396-bp amplicon. The method also distinguished Cal race 4 isolates from India race 4 isolates and China race 7 isolates, which did not possess the unique Tfo1 insertion but otherwise had identical DNA sequences, and all belong to VCG0114. The method is capable of detecting the pathogen directly from infected stem tissues even before external symptom appears and, thus, provides an effective tool for timely identification of infested fields and seed lots, and should help reduce dissemination of Cal race 4 in the U.S. Cotton Belt.

Emergence of Multidrug-Resistant New Delhi Metallo-β-Lactamase-1-Producing Klebsiella pneumoniae in Egypt.

Despite expansion of the New Delhi metallo-β-lactamase-1 (NDM-1) worldwide, the incident of outbreaks regarding Egypt is still uncommon. In this survey, we denounce the emanation of multidrug-resistant NDM-1-producing Klebsiella pneumoniae in Egypt. We have reclaimed 46 unrepeatable carbapenem-resistant K. pneumoniae isolates at El-demerdash hospital, Ain Shams University, Cairo, Egypt. All the isolates showed a decreased sensitivity to imipenem and meropenem via the disc diffusion method. Among the isolates, 10 were proven as NDM-1 producers by utilizing the phenotypic methods (modified Hodge test and EDTA synergistic test) and specific PCR detection of NDM-1 encoding gene, blaNDM-1. The isolates hosting the blaNDM-1 showed an elevated resistance to several classes of β-lactam and non β-lactam antibiotics. All blaNDM-1-harboring isolates have showed positivity for one or more other plasmid-mediated bla genes; in addition, the isolates carried class 1 integron. Enterobacterial repetitive intergenic consensus (ERIC)-PCR results revealed that majority of the isolates, including the NDM-1 producers, are unrelated to each other. This highlights the danger of horizontal transfer of plasmids encoding for such carbapenemases, including NDM-1, between the isolates of K. pneumoniae. In summary, this study has confirmed the incidence of blaNDM-1 together with other bla genes among the K. pneumoniae isolates in Egypt. Control and prevention of infection can be achieved through early detection of resistance genes among bacterial isolates; through limiting the dispersal of these organisms.

Rapid Identification of Blumea balsamifera by Specific PCR and Fluorescence Detection

Rapid Identification of Blumea balsamifera by Specific PCR and Fluorescence Detection

Effective use of the TSPY gene-specific copy number in determining fetal DNA in the maternal blood of cynomolgus monkeys.

Since the available concentration of single-copy fetal genes in maternal blood DNA is sometimes lower than detection limits by PCR methods, the development of specific and quantitative PCR detection methods for fetal DNA in maternal blood is anticipated, which may broaden the methods that can be used to monitor pregnancy. We used the TaqMan qPCR amplification for DYS14 multi-copy sequence and the SRY gene in maternal blood plasma (cell-free DNA) and fractional precipitated blood cells (cellular DNA) from individual cynomolgus monkeys at 22 weeks of pregnancy. The availability of cell-free fetal DNA was higher in maternal blood plasma than that of cellular DNA from fractional precipitated blood cells. There was a significantly higher (P < 0.001) mean copy number of fetal male DYS14 from maternal plasma (4.4 × 10(4) copies/mL) than that of detected fetal cellular DNA from fractional blood cell pellets. The sensitivity of the DYS14 PCR assay was found to be higher than that of the SRY assay for the detection of fetal DNA when its presence was at a minimum. The DYS14 assay is an improved method for quantifying male fetal DNA in circulating maternal blood in the primate model.