Evaluating the efficiency of TaqMan real-time PCR and serological methods in the detection of Brucella spp. in clinical specimens collected from suspected patients in Ardabil, Iran

Evaluating the efficacy of serological testing of clinical specimens collected from patients with suspected brucellosis

BACKGROUND

This study aims to evaluate the efficacy of the standard agglutination test (SAT), the Brucellacapt test and enzyme-linked immunosorbent assay (ELISA) in clinical specimens collected from patients with suspected brucellosis.

METHODS

A prospective study was conducted from December 2020 to December 2021. Brucellosis was diagnosed on the basis of clinical evidence, and confirmed by isolation of Brucella or a four-fold rise in SAT titer. All samples were tested by the SAT, ELISA and the Brucellacapt test. Titers ≥1:100 were considered as SAT positive; ELISA was considered positive when an index greater than 11 was detected, while titers ≥1/160 indicated positivity on the Brucellacapt test. The specificity, sensitivity, and positive (PPVs) and negative predictive values (NPVs) of the three different methods were calculated.

RESULTS

A total of 149 samples were collected from patients with suspected brucellosis. The sensitivities for the SAT, IgG, and IgM detection were 74.42%, 88.37% and 74.42%, respectively. The specificities were 95.24%, 93.65%, and 88.89%, respectively. The simultaneous measurement of IgG and IgM improved the sensitivity (98.84%) but reduced the specificity (84.13%) compared to each antibody test separately. The Brucellacapt test had excellent specificity (100%) and a high PPV (100%); however, the sensitivity and NPV were 88.37% and 86.30%, respectively. The combination of IgG detection by ELISA and the Brucellacapt test had excellent diagnostic performance, with 98.84% sensitivity and 93.65% specificity.

CONCLUSION

This study showed that the simultaneous performance of IgG detection by ELISA and the Brucellacapt test has the potential to overcome the current limitations of detection.

Prevalence, diagnosis, and manifestations of brucellosis: A systematic review and meta-analysis

Objectives

Brucellosis is one of the most prevalent zoonotic diseases common between humans and animals. Despite eradication efforts, the burden of the disease is well-known in endemic countries and in countries where brucellosis has not been an important health issue until recently. The aim of this study was to evaluate the prevalence, diagnosis, and manifestations of brucellosis.

Methods

In this study, PubMed, Web of Science, Scopus, Embase, and Google scholar databases were systematically searched to find studies published from 2011 to 2021. The search was conducted using text words and Medical Subject Headings (MeSH) Terms on the prevalence of brucellosis. Stata software 14.0 was used for all analyses.

Results

Based on the results, the pooled prevalence of brucellosis was 15.27% (95% CI: 9.68-21.86; heterogeneity I 2 index: 97.43; p < 0.001) for man and 15.33% (95% CI: 7.19-25.75; heterogeneity I 2 index: 98.19; p < 0.001) for woman. Age (coefficient: 0.240; p = 0.480), gender (coefficient: -0.017; p = 0.800), and publication year (coefficient: 0.114; p = 0.861) showed no significant effect on heterogeneity among studies. Egger's test indicated a significant publication bias for the prevalence of brucellosis (coefficient 3.894; p < 0.001). Moreover, the trim-and-fill method exhibited that the adjusted prevalence of brucellosis (18.30%, 95% CI: 14.10-22.52) was not significantly different from the original prevalence of brucellosis.

Conclusion

The pooled estimate for brucellosis prevalence was estimated as 15.53%. To better understand the epidemiology of brucellosis globally, more extensive studies are needed to be conducted throughout the world, especially in developing and low-income countries.

Recombinant protein G/Au nanoparticles/graphene oxide modified electrodes used as an electrochemical biosensor for Brucella Testing in milk

In this study, a simple label-free biosensor for Brucella was constructed, which based on the screen-printed carbon electrode (SPCE) modified by Recombinant protein G/gold nanoparticles/graphene oxide (RpG/Au/GO). The impedance responses of the proposed biosensor were measured by electrochemical AC impedance method in Brucella antigen gradient concentration solutions. The results showed that the linear range of this biosensor was from 1.6 × 102 CFU/mL to 1.6 × 108 CFU/mL with the minimum detection limit of 3.2 × 102 CFU/mL (S/N = 3). Moreover, the biosensor for Brucella detection possessed acceptable reproducibility with a relative standard deviation of 5.15% and acceptable stability with a relative standard deviation of 4.68%. The spiked recovery rate in actual pasteurized milk samples was more than 92%. Therefore, the developed biosensor exhibits excellent prospects in the selective quantification detection of Brucella abortus.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13197-022-05544-8.

Development and evaluation of a rapid RPA/CRISPR-based detection of Francisella tularensis

Francisella tularensis is a dangerous pathogen that causes an extremely contagious zoonosis in humans named tularemia. Given its low-dose morbidity, the potential to be fatal, and aerosol spread, it is regarded as a severe threat to public health. The US Centers for Disease Control and Prevention (CDC) has classified it as a category A potential agent for bioterrorism and a Tier 1 Select Agent. Herein, we combined recombinase polymerase amplification (RPA) with CRISPR/Cas12a system to select the F. tularensis target gene (TUL4), creating a two-pronged rapid and ultrasensitive diagnostic method for detecting F. tularensis. The real-time RPA (RT-RPA) assay detected F. tularensis within 10 min at a sensitivity of 5 copies/reaction, F. tularensis genomic DNA of 5 fg, and F. tularensis of 2 × 102 CFU/ml; the RPA-CRISPR/Cas12a assay detects F. tularensis within 40 min at a sensitivity of 0.5 copies/reaction, F. tularensis genomic DNA of 1 fg, and F. tularensis of 2 CFU/ml. Furthermore, the evaluation of specificity showed that both assays were highly specific to F. tularensis. More importantly, in a test of prepared simulated blood and sewage samples, the RT-RPA assay results were consistent with RT-PCR assay results, and the RPA-CRISPR/Cas12a assay could detect a minute amount of F. tularensis genomic DNA (2.5 fg). There was no nonspecific detection with blood samples and sewage samples, giving the tests a high practical application value. For example, in on-site and epidemic areas, the RT-RPA was used for rapid screening and the RPA-CRISPR/Cas12a assay was used for more accurate diagnosis.