Search

Objective: To develop a new multiplex allele-specific polymerase chain reaction (MAS-PCR) assay to detect the main mutations in the rifampin resistance dependent region, which has been reported to account for the majority of clinic Mycobacterium tuberculosis resistant to rifampin., Methods: Based on the sequence of rpoB gene, three specific primers were designed for the MAS-PCR to detect the most common mutations in codons 531, 526, 516 of rpoB gene., Results: The purified DNA preparations of 91 clinical strains of Mycobacterium tuberculosis were used to optimize the PCR. The mutations in codon 531, 526, 516 were detected by the MAS-PCR. Compared with the results of direct sequencing of rpoB gene, no mutation was detected in the sensitive strains. For rifampin-resistant strains, the total sensitivity was 81.5% (66/81)., Conclusions: MAS-PCR is a new molecular method with a high sensitivity and specificity, which can be used to detect the 3 main mutations of rpoB gene rapidly and economically. It can be used in clinical laboratories to detect the rifampin-resistant strains of Mycobacterium tuberculosis.

Objective: To develop a new method that can determine the apolipoprotein E(apoE) genotypes rapidly in high throughput., Methods: Genome DNA samples were extracted from the anticoagulated peripheral blood samples of 79 patients with Alzheimer's disease(AD) and 63 healthy individuals, and the 492 bp apoE gene fragments including 112 and 158 codons were amplified by polymerase chain reaction (PCR). With one PCR product, three recombined alleles (epsilon 2, epsilon 3 and epsilon 4) of apoE gene as controls were obtained by cloning and site-directed mutagenesis. The excess primers and dNTPs in all PCR products were removed by treatment with clean up reagents, then template-directed dye-terminator incorporation reaction (TDI) was performed and R110 or TAMRA labeled Acyclo-terminators were added into the mutation sites specifically. Fluorescence polarization value (FP) was measured using victor 2 multilabel counter and the polymorphisms in 112 and 158 condons of apoE gene were investigated., Results: The apoE genotypes in recombined plasmid controls and all serum samples were analyzed using the authors' TDI-FP method, and the reliability and specificity were confirmed by DNA sequencing. The frequency of epsilon 4 allele in patients was significantly higher than that in controls, suggesting that apoE epsilon 4 allele gene is a risk factor for late-onset AD., Conclusion: TDI-FP is an easy, reliable and high throughput technology in analyzing polymorphism of apoE gene; it can be used in the prediction of susceptibility to AD in elderly individuals. Furthermore, it is an ideal method for large-scale screening and for studying the relationship between the allelic and genotypic frequencies of apoE and other diseases.

Pulmonary infections are among the most common and important infectious diseases due to their high morbidity and mortality, especially in older and immunocompromised individuals. However, due to the limitations in sensitivity and the long turn-around time (TAT) of conventional diagnostic methods, pathogen detection and identification methods for pulmonary infection with greater diagnostic efficiency are urgently needed. In recent years, unbiased metagenomic next generation sequencing (mNGS) has been widely used to detect different types of infectious pathogens, and is especially useful for the detection of rare and newly emergent pathogens, showing better diagnostic performance than traditional methods. There has been limited research exploring the application of mNGS for the diagnosis of pulmonary infections. In this study we evaluated the diagnostic efficiency and clinical impact of mNGS on pulmonary infections. A total of 100 respiratory samples were collected from patients diagnosed with pulmonary infection in Shanghai, China. Conventional methods, including culture and standard polymerase chain reaction (PCR) panel analysis for respiratory tract viruses, and mNGS were used for the pathogen detection in respiratory samples. The difference in the diagnostic yield between conventional methods and mNGS demonstrated that mNGS had higher sensitivity than traditional culture for the detection of pathogenic bacteria and fungi (95% vs 54%; p<0.001). Although mNGS had lower sensitivity than PCR for diagnosing viral infections, it identified 14 viral species that were not detected using conventional methods, including multiple subtypes of human herpesvirus. mNGS detected viruses with a genome coverage >95% and a sequencing depth >100× and provided reliable phylogenetic and epidemiological information. mNGS offered extra benefits, including a shorter TAT. As a complementary approach to conventional methods, mNGS could help improving the identification of respiratory infection agents. We recommend the timely use of mNGS when infection of mixed or rare pathogens is suspected, especially in immunocompromised individuals and or individuals with severe conditions that require urgent treatment. [ABSTRACT FROM AUTHOR]

The article presents a case study of a 32-year-old traveller with central nervous system (CNS) infection caused by Pseudallescheria (P.) boydii. It mentions that the patient experienced a motorcycle accident and aspirated polluted water from a roadside ditch. It notes that polymerase chain reaction (PCR)-based techniques would enable the identification of fungus.

Background: Talaromyces marneffei, is an opportunistic pathogenic fungus that is most commonly reported in Southeast Asia and disseminated T.marneffei infection predominantly occurs in patients with immunodeficiency. With a potential to invade multiple organs, it can be fatal for patients if diagnosis and treatment are delayed. In current clinical practice, the diagnosis of T.marneffei infection relies heavily on tissue culture and histologic analysis, which may suffer from limited positive rate and is sometimes time consuming. The rapid and accurate diagnosis of disseminated T.marneffei infection remains challenging.Case Presentation: A 22-year-old man gradually developed fever, cough, lower extremities weakness, jaundice and rash, for which a 3-month extensive investigation failed to reach a diagnosis. After admitted into our hospital, laboratory and radiological tests revealed multiple lesions in the patient's brain, spinal cord, and lungs. We performed next generation sequencing on the patient's skin tissue, bone marrow, blood and cerebrospinal fluid, which all identified numerous Talaromyces marneffei nucleotide sequences and leaded to the rapid diagnosis and treatment of disseminated T.marneffei infection.Conclusions: This case underline the clinical significance of T.marneffei as a possible pathogen in immune-competent patients. This successful application of the next generation sequencing assisting the rapid diagnosis of disseminated T.marneffei infection provides a new perspective in the clinical approach to the systematic fungi infections and highlights the potential of this technique in rapid etiological diagnosis. [ABSTRACT FROM AUTHOR]