A duplex PCR for rapid and simultaneous detection of Brucella spp. in human blood samples

Advances in endotoxin analysis

The outer membrane of gram-negative bacteria is primarily composed of lipopolysaccharide (LPS). In addition to protection, LPS defines the distinct serogroups used to identify bacteria specifically. Furthermore, LPS also act as highly potent stimulators of innate immune cells, a phenomenon essential to understanding pathogen invasion in the body. The complex multi-step process of LPS binding to cells involves several binding partners, including LPS binding protein (LBP), CD14 in both membrane-bound and soluble forms, membrane protein MD-2, and toll-like receptor 4 (TLR4). Once these pathways are activated, pro-inflammatory cytokines are eventually expressed. These binding events are also affected by the presence of monomeric or aggregated LPS. Traditional techniques to detect LPS include the rabbit pyrogen test, the monocyte activation test and Limulus-based tests. Modern approaches are based on protein, antibodies or aptamer binding. Recently, novel techniques including electrochemical methods, HPLC, quartz crystal microbalance (QCM), and molecular imprinting have been developed. These approaches often use nanomaterials such as gold nanoparticles, quantum dots, nanotubes, and magnetic nanoparticles. This chapter reviews current developments in endotoxin detection with a focus on modern novel techniques that use various sensing components, ranging from natural biomolecules to synthetic materials. Highly integrated and miniaturized commercial endotoxin detection devices offer a variety of options as the scientific and technologic revolution proceeds.

A time-resolved fluorescence lateral flow immunoassay for rapid and quantitative serodiagnosis of Brucella infection in humans

Brucellosis is a worldwide infectious zoonotic disease, posing severe threats to human health and social-economic development. By comparing with time-consuming, low sensitive and non-quantitative conventional serological methods, herein, protein G (prG) coupled with europium nanospheres (EuNPs) (detection probe) and highly purified Brucella lipopolysaccharide (LPS) (capture antigen) were used to develop a novel time-resolved fluorescence lateral flow immunoassay (TF-LFIA) for detecting anti-Brucella IgG antibody in human plasmas. The entire testing took 15 min. With a satisfactory purity, the purified LPS weakly cross-reacted with Y. enterocolitica O9 diagnostic antibody; however, none reacted with sera from patients with other Gram-negative bacterial infections. Following coefficient of determination (R² = 0.9961), 0.3 IU/mL was reported as the limit of detection (LOD), much lower than those of Serological Agglutination Test (SAT), Rose-Bengal Plate Agglutination Test (RBPT) and colloidal gold LFIA (CG-LFIA). Intra-day and inter-day precisions (CV, coefficient variation) of TF-LFIA varied less than 8% or 12 %, while intra-day and inter-day accuracies were 94-106 % or 93-107 %, respectively. The correlation coefficient (R²) of TF-LFIA measurement to the different concentrations of spiked Brucella antibody was 0.9967, suggesting TF-LFIA had high reliability and reproducibility. TF-LFIA was demonstrated for 100 % specificity, 98.57 % sensitivity and 99.63 % accuracy in detection of Brucella antibody from clinical samples, respectively, significantly higher compared to SAT and RBPT. In conclusion, the established TF-LFIA is a simple, rapid and quantitative immunoassay for early diagnosis or epidemiological surveillance of Brucella infection in humans.

Differentiation of Brucella abortus and B. melitensis biovars using PCR-RFLP and REP-PCR

Brucellosis is one of the most common zoonotic diseases of animal and human beings. This study aimed to differentiate the Brucella spp. and determines the patterns of biovars by using repetitive element palindromic (REP)-PCR and PCR restriction fragment length polymorphism (RFLP) methods. A total of 100 blood specimens suspected of harbouring brucellosis were collected. Conventional culture methods and multiplex PCR were used for the detection of Brucella genus and species; and REP-PCR was used for Brucella spp. differentiation and polymorphisms sequence analysis. In addition, to identify the biovar patterns of REP-PCR, PCR-RFLP was used. Eighty-three samples were identified as harbouring Brucella spp. by the implementation of multiplex PCR, 72 of which were detected as Brucella melitensis and 11 as B. abortus. Also, through analysing the results of PCR-RFLP, it was found that of 72 B. melitensis samples, 69 were B. melitensis biovar 1 and three species were from other biovars. In addition, the obtained patterns for all of the B. abortus samples were from biovars 3, 5, 6 and 9. This study also optimized a test for the detection of Brucella biovar with the REP-PCR method such that Brucella spp. and biovars could be separated in the shortest possible time.

Detecting Biothreat Agents: From Current Diagnostics to Developing Sensor Technologies

Although a fundamental understanding of the pathogenicity of most biothreat agents has been elucidated and available treatments have increased substantially over the past decades, they still represent a significant public health threat in this age of (bio)terrorism, indiscriminate warfare, pollution, climate change, unchecked population growth, and globalization. The key step to almost all prevention, protection, prophylaxis, post-exposure treatment, and mitigation of any bioagent is early detection. Here, we review available methods for detecting bioagents including pathogenic bacteria and viruses along with their toxins. An introduction placing this subject in the historical context of previous naturally occurring outbreaks and efforts to weaponize selected agents is first provided along with definitions and relevant considerations. An overview of the detection technologies that find use in this endeavor along with how they provide data or transduce signal within a sensing configuration follows. Current "gold" standards for biothreat detection/diagnostics along with a listing of relevant FDA approved in vitro diagnostic devices is then discussed to provide an overview of the current state of the art. Given the 2014 outbreak of Ebola virus in Western Africa and the recent 2016 spread of Zika virus in the Americas, discussion of what constitutes a public health emergency and how new in vitro diagnostic devices are authorized for emergency use in the U.S. are also included. The majority of the Review is then subdivided around the sensing of bacterial, viral, and toxin biothreats with each including an overview of the major agents in that class, a detailed cross-section of different sensing methods in development based on assay format or analytical technique, and some discussion of related microfluidic lab-on-a-chip/point-of-care devices. Finally, an outlook is given on how this field will develop from the perspective of the biosensing technology itself and the new emerging threats they may face.

Diversity of virulence genes in Brucella melitensis and Brucella abortus detected from patients with rheumatoid arthritis

The presence of Brucella melitensis and Brucella abortus genomes were investigated in the synovial fluid (SF) samples from 90 patients with rheumatoid arthritis (RA). DNA extraction and PCR assay were performed for simultaneous identification and discrimination of B. melitensis and B. abortus from the SF using three specific primers. After gel electrophoresis, the PCR products were confirmed by DNA sequencing. The cbg, omp31, manA, virB, and znuA virulence genes typing were performed by multiplex-PCR. Of the 90 samples, 14 were positive for B. melitensis (n = 9; 10%) and B. abortus (n = 5; 5.5%). The virulotyping of positive samples revealed the presence of all five virulence genes in B. melitensis. The virB, cbg, and om31 were detected in all five samples of B. abortus. In addition, zhuA and manA were detected in three (60%) and four (80%) samples, respectively, of the B. abortus-positive samples. Moreover, a total of 94.2% and 89.2% of the 14 positive samples were also found positive for manA and znuA, respectively. Our findings revealed that the Brucella spp. genomes can be detected in the SF of RA patients by the PCR-based method. We thus suggest that physicians should consider the Brucella spp. as indicators of potential RA for the timely diagnosis and treatment of RA.

Epidemiology of brucellosis in Iran: A comprehensive systematic review and meta-analysis study

Brucellosis is still one of the most challenging issues for health and the economy in many developing countries such as Iran. Considering the high prevalence of brucellosis, the aim of the current study was to systematically review published data about the annual incidence rate of this infection from different parts of Iran and provide an overall relative frequency (RF) for Iran using meta-analysis. We searched several databases including PubMed, ISI Web of Science, Scopus, google scholar, IranMedex and Iranian Scientific Information Database (SID) by using the following keywords: "Brucella", "Brucellosis", "Malta fever", "Mediterranean fever", "undulant fever", "zoonosis" and "Iran" in Title/Abstract/Keywords fields. Articles/Abstracts, which used clinical specimens and reported the incidence of brucellosis, were included in this review. Quality of studies was assessed by STROB and PRISMA forms. All statistical analyses were performed using STATA 11.0 (STATA Corp, College Station, TX) and P-values under 0.05 were considered statistically significant. Out of the 8326 results, we found 34 articles suitable, according to inclusion and exlusion criteria, for inclusion in this systematic review and meta-analysis. The pooled incidence of brucellosis was estimated 0.001% (95% confidence interval (CI) = 0.0005-0.0015%) annually. Relative frequency of brucellosis in different studies varied from 7.0/100000 to 276.41/100000 in Qom and Kermanshah provinces, respectively. This systematic-review and meta-analysis study showed that the highest incidences of brucellosis are occurred in west and northwest regions of Iran. Totally, the incidence of the disease in Iran is in the high range.

Molecular investigation of virulence factors of Brucella melitensis and Brucella abortus strains isolated from clinical and non-clinical samples

Brucella is zoonotic pathogen that induces abortion and sterility in domestic mammals and chronic infections in humans called Malta fever. It is a facultative intracellular potential pathogen with high infectivity. The virulence of Brucella is dependent upon its potential virulence factors such as enzymes and cell envelope associated virulence genes. The aim of this study was to investigate the Brucella virulence factors among strains isolated from humans and animals in different parts of Iran. Seventy eight strains of Brucella species isolated from suspected human and animal cases from several provinces of Iran during 2015-2016 and identified by phenotypic and molecular methods. The multiplex-PCR (M-PCR) assay was performed in order to detect the ure, wbkA, omp19, mviN, manA and perA genes by using gene specific primers. Out of 78 isolates of Brucella spp., 57 (73%) and 21 (27%) isolates were detected as B. melitensis and B. abortus, respectively, by molecular method. The relative frequency of virulence genes ure, wbkA, omp19, mviN, manA and perA were 74.4%, 89.7%, 93.6%, 94.9%, 100% and 92.3%, respectively. Our results indicate that the most of Brucella strains isolated from this region possess high percent of virulence factor genes (ure, wbkA, omp19, mviN, manA and perA) in their genome. So, each step of infection can be mediated by a number of virulence factors and each strain may have a unique combination of these factors that affected the rate of bacterial pathogenesis.

Microarray-based long oligonucleotides probe designed for Brucella Spp. detection and identification of antibiotic susceptibility pattern

Brucella spp. is a common zoonotic infection referred to as Brucellosis, and it is a serious public health problem around the world. There are currently six classical species (pathogenic species in both animals and humans) within the genus Brucella. The ability and practicality facilitated by a microarray experiment help us to recognize Brucella spp. and its antibiotic resistant gene. Rapid phenotypic determination of antibiotic resistance is not possible by disk diffusion methods. Thus, evaluating antibiotics pattern and Brucella detection appear necessary technique by molecular methods in brucellosis. So, the aim of this study was to design a microarray long oligonucleotides probe and primer for the complete diagnosis of Brucella spp. and obtaining genetic profiles for antibiotic resistance in bacteria at the same time. In this study, we designed 16 antibiotic-resistant gene solid-phase primers with similar melting temperatures of 60 °C and 16 long oligonucleotide probes. These primers and probes can identify tetracycline-, chloramphenicol-, and aminoglycoside-resistant genes, respectively. The design of microarray probes is a versatile process that be done in a wide range of selections. Since the long oligo microarray probes are the best choices for specific diagnosis and definite treatment, this group of probes was designed in the present survey.

Polymerase chain reaction-based assays for the diagnosis of human brucellosis

Polymerase chain reaction (PCR) is an in vitro technique for the nucleic acid amplification, which is commonly used to diagnose infectious diseases. The use of PCR for pathogens detection, genotyping and quantification has some advantages, such as high sensitivity, high specificity, reproducibility and technical ease. Brucellosis is a common zoonosis caused by Brucella spp., which still remains as a major health problem in many developing countries around the world. The direct culture and immunohistochemistry can be used for detecting infection with Brucella spp. However, PCR has the potential to address limitations of these methods. PCR are now one of the most useful assays for the diagnosis in human brucellosis. The aim of this review was to summarize the main PCR techniques and their applications for diagnosis and follow-up of patients with brucellosis. Moreover, advantages or limitation of the different PCR methods as well as the evaluation of PCR results for treatment and follow-up of human brucellosis were also discussed.