Development of a droplet digital PCR method for detection of Streptococcus agalactiae.

BACKGROUND: Streptococcus agalactiae (GBS) is the causative pathogen of puerperal sepsis in pregnant women and pneumonia, sepsis and meningitis in infants. Infection of GBS is responsible for the increased morbidity in pregnant women and the elderly, and bring challenges to clinical diagnosis and treatment. However, culture-based approaches to detect S.agalactiae is time-consuming with limited sensitivity. Besides, real-time quantitative PCR demands expensive instruments with tedious steps. Thus, we aim to establish a new detection method for more accurate and rapid detection of S.agalactiae. RESULTS: The ddPCR primer targeted the CpsE gene showed better amplified efficiency in the reaction. The limit of detection for GBS DNA with ddPCR was able to reach 5 pg/µL. Moreover, no positive amplified signals could be detected in the reactions which served 11 non-GBS strains DNA as templates. Furthermore, the coefficient of variation of this method was 4.5%, indicating excellent repeatability of ddPCR assay. CONCLUSIONS: In our study, ddPCR was performed as a rapid detection of S.agalactiae with high sensitivity and specificity. This technique can promote the accuracy of the diagnosis of GBS infection and provide a scientific basis for clinical treatment.

Diagnostic accuracy of LAMP assay for HBV infection.

BACKGROUND: Detection of hepatitis B virus (HBV) is vital for the diagnosis of hepatitis B infection. A novel test loop-mediated isothermal amplification (LAMP) has been successfully applied to detect various pathogens. However, the accuracy of LAMP in diagnosing HBV remains unclear. Therefore, in the present study, the accuracy of LAMP for HBV detection was evaluated systematically. METHODS: Embase, Cochrane Library, and PubMed databases were searched for studies using LAMP to detect HBV. Then, two researchers extracted data and assessed the quality of literature using the QUADAS-2 tool independently. I2 statistic and chi-square test were analyzed to investigate the heterogeneity, and Deek's funnel plot assessed the publication bias. The pooled sensitivity (SEN), specificity (SPE), positive LR (PLR), negative LR (NLR), diagnostic odds ratio (DOR), and 95% confidence intervals were displayed in forest plots. We calculated the area under the curve (AUC) to assess the overall efficiency of LAMP for HBV detection. RESULTS: A total of nine studies with 1298 samples were finally included in this evaluation. The pooled sensitivity and specificity of HBV detection were 0.91 (95% CI: 0.89 ~ 0.92) and 0.97 (95% CI: 0.94 ~ 0.99), respectively. The PLR, NLR, and DOR were 16.93 (95% CI: 6.15 ~ 46.55), 0.08 (95% CI: 0.05 ~ 0.14), and 397.57 (95% CI: 145.41 ~ 1087.07). Besides, the AUC was 0.9872, and Deek's plot suggested that there existed publication bias in the studies. CONCLUSION: Compared with PCR, LAMP is a simple, rapid, and effective assay to diagnose HBV. However, additional evidence is essential to confirm that LAMP can replace other methods in diagnosing HBV infection.

Autophagy protects type II alveolar epithelial cells from Mycobacterium tuberculosis infection.

This study was designed to investigate the protective effect of the autophagy signaling pathway against Mycobacterium tuberculosis infection in type II alveolar epithelial cells. An in vitro M. tuberculosis system was established using human A549 cells. Infection-induced changes in the expression of the autophagic marker LC3 were assessed by reverse transcription-PCR and Western blotting. Morphological changes in autophagosomes were detected by transmission electron microscopy (TEM). The function of the autophagy signaling pathway during infection was assessed by measuring the level of cell death and the amount of lactate dehydrogenase (LDH) released in the presence or absence of the inhibitor 3-methyladenine (3-MA). In addition, effects on LDH release were assessed after the siRNA-mediated knockdown of the essential autophagosomal structural membrane protein Atg5. LC3 mRNA expression was significantly reduced in M.tuberculosis-infected A549 cells (16888.76 ± 1576.34 vs. uninfected: 12744.29 ± 1089.37; P < 0.05). TEM revealed M.tuberculosis bacilli-containing compartments that were surrounded by double membranes characteristic of the autophagic process. M.tuberculosis-infected A549 cells released more LDH (1.45 ± 0.12 vs. uninfected: 0.45 ± 0.04; P < 0.05). The inhibition of autophagy signaling significantly enhanced M.tuberculosis-induced necrosis (3-MA: 75 ± 5% vs. untreated: 15 ± 1%; P < 0.05) and LDH release (3-MA: 2.50 ± 0.24 vs. untreated: 0.45 ± 0.04; Atg5 knockdown: 3.19 ± 0.29 vs. untreated: 1.28 ± 0.11; P < 0.05). Our results indicate that autophagy signaling pathway prevents apoptosis in type II alveolar epithelial cells infected with M.tuberculosis and may represent a molecular target for promoting cell survival during infection by respiratory pathogens.

Diagnostic Accuracy of Xpert Xpress Flu/RSV for the Detection of Influenza and Respiratory Syncytial Viruses.

Xpert Xpress Flu/RSV is a fast and automated real-time nucleic acid amplification tool for detecting influenza virus and respiratory syncytial virus (RSV). The aim of this study was to verify the accuracy of Xpert Xpress Flu/RSV for detecting influenza virus and RSV. PubMed, EMBASE, Cochrane Library, and Web of Science databases were searched up to October 2020. The quality of the original research was assessed using the Quality Assessment of Diagnostic Accuracy Studies-2 guidelines. Meta-DiSc 1.4 software was used to analyze the sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, diagnostic odds ratio, and summary receiver operating characteristic curve. Deek's funnel plot asymmetry test was used to evaluate the publication bias using the Stata 12.0 software. Ten studies with 25 fourfold tables were included in the analysis. The sensitivity of Xpert Xpress Flu/RSV for detecting influenza A, influenza B, and RSV were 0.97, 0.98, and 0.96, respectively, and the specificities were 0.97, 1.00, and 1.00, respectively. Compared with other common clinical real-time reverse transcription-polymerase chain reaction (RT-PCR), Xpert Xpress Flu/RSV is a valuable tool for diagnosing influenza virus and RSV with high sensitivity and specificity.

Evaluation of GeneXpert vanA/vanB in the early diagnosis of vancomycin-resistant enterococci infection.

PURPOSE: Vancomycin-resistant enterococci infection is a worrying worldwide clinical problem. To evaluate the accuracy of GeneXpert vanA/vanB in the diagnosis of VRE, we conducted a systematic review in the study. METHODS: Experimental data were extracted from publications until May 03 2021 related to the diagnostic accuracy of GeneXpert vanA/vanB for VRE in PubMed, Embase, Web of Science and the Cochrane Library. The accuracy of GeneXpert vanA/vanB for VRE was evaluated using summary receiver to operate characteristic curve, pooled sensitivity, pooled specificity, positive likelihood ratio, negative likelihood ratio, and diagnostic odds ratio. RESULTS: 8 publications were divided into 3 groups according to two golden standard references, vanA and vanB group, vanA group, vanB group, including 6 researches, 5 researches and 5 researches, respectively. The pooled sensitivity and specificity of group vanA and vanB were 0.96 (95% CI, 0.93-0.98) and 0.90 (95% CI, 0.88-0.91) respectively. The DOR was 440.77 (95% CI, 37.92-5123.55). The pooled sensitivity and specificity of group vanA were 0.86 (95% CI, 0.81-0.90) and 0.99 (95% CI, 0.99-0.99) respectively, and those of group vanB were 0.85 (95% CI, 0.63-0.97) and 0.82 (95% CI, 0.80-0.83) respectively. CONCLUSION: GeneXpert vanA/vanB can diagnose VRE with high-accuracy and shows greater accuracy in diagnosing vanA.

Evaluation of the Diagnostic Efficacy of Xpert CT/NG for Chlamydia trachomatis and Neisseria gonorrhoeae.

BACKGROUND: Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) are widely spread across the world. Asymptomatic or inconspicuous CT/NG infections are difficult to diagnose and treat. Traditional methods have the disadvantages of low detection rate, inaccurate results, and long detection time. However, Xpert CT/NG makes up for the aforementioned shortcomings and has research value and popularization significance. METHODS: PubMed, Embase, Cochrane Library, and Web of Science were systematically searched, and studies were screened using Xpert CT/NG for diagnosing CT/NG. QUADAS-2 was used to evaluate the quality of the eligible studies. Then, two groups of researchers independently extracted data from these studies. Meta-analyses of sensitivity (SEN), specificity (SPE), positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR), and the area under the curve (AUC) of the summary receiver operating characteristic (SROC) curve were conducted using Meta-DiSc 1.4. Finally, Deek's funnel plots were made using Stata 12.0 to evaluate publication bias. RESULTS: 14 studies were identified, and 46 fourfold tables were extracted in this meta-analysis. The pooled SEN, SPE, PLR, NLR, DOR, and AUC in diagnosing CT were 0.94 (95% confidence interval (CI): 0.93-0.95), 0.99 (95% CI: 0.99-1.00), 97.17 (95% CI: 56.76-166.32), 0.07 (95% CI: 0.04-0.12), 1857.25 (95% CI: 943.78-3654.86), and 0.9960, respectively. The pooled SEN, SPE, PLR, NLR, DOR, and AUC in diagnosing NG were 0.95 (95% CI: 0.93-0.96), 1.00 (95% CI: 1.00-1.00), 278.15 (95% CI: 152.41-507.63), 0.08 (95% CI: 0.06-0.12), 4290.70 (95% CI: 2161.78-8516.16), and 0.9980, respectively. CONCLUSIONS: Xpert CT/NG had high diagnostic sensitivity and specificity for CT and NG. However, more evidence is required to confirm that Xpert CT/NG might serve as the primary method for detecting CT and NG and even the gold standard for diagnosis in the future.

Accuracy of matrix-assisted LASER desorption ionization-time of flight mass spectrometry for identification of Candida.

BACKGROUND: Candida is a fungus that causes various types of candidemia, which is the fourth major infectious disease of the blood system. MALDI-TOF-MS is a simple and rapid detection instrument. The aim of the present study was to verify the accuracy of MALDI-TOF-MS in detecting Candida. METHOD: A pooled analysis of articles on MALDI-TOF-MS for diagnosis of candidemia was performed. The quality of original research was assessed using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) guidelines. Stata 12.0 software was used to merge the correct identification rates of Candida and Candida subspecies and obtain pooled sensitivity and specificity of the diagnostic methods. Heterogeneity was found in the subgroup analysis of the included articles. Hence, we explored the factors causing the heterogeneity and its impact on the overall situation. Sensitivity analysis was used to examine the effect of Candida level on total response. Egger's test was used to evaluate the publication bias of the included articles. RESULTS: A total of 16 articles in Pubmed, 79 articles in Embase, 1 article in Cochrane Library, 30 articles in Web of Science and 3 from other sources were identified, of which 10 articles were included based on the inclusion and exclusion criteria. The overall identification accuracy was 100%. CONCLUSION: The accuracy of MALDI-TOF-MS for the identification of Candida was 100%. Further research is necessary to determine whether MALDI-TOF-MS can be used as a clinical diagnostic standard for the identification of Candida.

MiR-34b/c rs4938723 Polymorphism Significantly Decreases the Risk of Digestive Tract Cancer: Meta-analysis.

BACKGROUND: Previous studies investigating the association between miR-34b/c rs4938723 polymorphism and cancer risk showed inconclusive. Here, we performed meta-analysis to investigate the association between miR- 34b/c rs4938723 polymorphism and digestive cancer risk. MATERIALS AND METHODS: Literature database including PubMed, OVID, Chinese National Knowledge Infrastructure (CNKI) were searched for publications concerning the association between the miR-34b/c rs4938723 polymorphism and digestive cancer risk. RESULTS: A total of 6 studies consisting of 3246 cases and 3568 controls were included in this meta-analysis. The combined analysis suggested the miR-34b/c rs4938723 polymorphism significantly reduced digestive cancer risk under allelic model, homogeneous co-dominant model and recessive model (C vs T: OR=0.88, 95%CI=0.82-0.95, p-value=0.001; CC vs TT: OR =0.67, 95%CI=0.57-0.80, p-value=0.000; CC vs TT/TC: OR=0.68, 95%CI=0.58-0.80, p-value=0.000). Q-test and I2 test revealed no significant heterogeneity in all genotype comparisons. The Begger's funnel plot and Egger's test did not show significant publication bias. CONCLUSIONS: The current evidence supports the conclusion that the miR-34b/c rs4938723 polymorphism decreases an individual's susceptibility to digestive cancers.

The G801A polymorphism in the CXCL12 gene and risk of breast carcinoma: evidence from a meta-analysis including 2,931 subjects.

More and more evidence indicates that the G801A polymorphism in the CXCL12 gene might be associated with susceptibility to breast carcinoma in humans being. However, individually published results have been inconsistent. The purpose of this meta-analysis was to investigate the association between the G801A polymorphism in the CXCL12 gene and breast carcinoma risk. A complete search strategy was done by the electronic databases including PubMed and Chinese Biomedical Literature Database. A meta-analysis including seven individual studies was carried out in order to explore the association between the G801A polymorphism in the CXCL12 gene polymorphisms and breast carcinoma. The pooled odds ratios (ORs) and their corresponding 95% confidence intervals (95%CIs) between the G801A polymorphism in the CXCL12 gene and breast carcinoma risk were assessed by the random-effects model. A significant relationship between the G801A polymorphism in the CXCL12 gene and breast carcinoma was discovered in an allelic genetic model (OR: 1.214, 95%CI: 1.085- 1.358, p=0.001), a homozygote model (OR: 1.663, 95%CI: 1.240-2.232, p=0.001), a heterozygote model (OR: 1.392, 95%CI: 1.190-1.629, p=0.000), a recessive genetic model (OR: 1.407, 95%CI: 1.060-1.868, p=0.018) and a dominant genetic model (OR: 1.427, 95%CI: 1.228-1.659, p=0.000). On sub-group analysis based on ethnicity, significance was observed between the European group and the mixed group. A significant relationship was found between the G801A polymorphism in the CXCL12 gene and breast carcinoma risk. Individuals with the A allele of the G801A polymorphism in the CXCL12 gene are under a higher risk for breast carcinoma.