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

Brucellosis an Unusual presentation as isolated septic mono-arthritis of the knee joint: A case report

Brucellosis is a zoonotic infection that is widely spread across the world. It is becoming more common in Middle Eastern countries such as Qatar, Saudi Arabia, and the Mediterranean region. Despite this, we need to remain vigilant as it is still prevalent in many parts of the world. The most common presentation is musculoskeletal, but it can also present as septic arthritis in the sacroiliac, hip, or knee joints. Brucella melitensis was only found in one extended culture of synovial fluid. Treatment involved a combination of antimicrobial therapy using gentamycin, doxycycline, and rifampin. A high level of suspicion for brucellosis is necessary for any patient coming from an endemic region with non-specific and chronic arthritis to ensure early diagnosis and treatment. In this case, we present a 28-year-old male who was diagnosed with Brucellosis after developing acute septic arthritis.

Seroprevalence of brucellosis in communal and smallholder cattle farming in North West Province, South Africa

Brucellosis is an important bacterial zoonosis responsible for considerable economic losses in livestock and health-related burden worldwide. The objective of this study was to determine the seroprevalence of brucellosis in communal and smallholder cattle farming in four districts of the North West province of South Africa (Dr Ruth Segomotsi Mompati, Ngaka Modiri Molema, Bojanala platinum and Dr Kenneth Kaunda districts). Seven hundred and seventy blood samples from farmed animals (n = 378) and abattoir-slaughtered animals (n = 392) were collected. In addition, milk samples (n = 22) were collected from lactating farmed cows. Rose Bengal test (RBT), complement fixation test (CFT) and milk ring test (MRT) were used to detect antibodies against Brucella species. The RBT showed a seroprevalence of 2% at 95% confidence interval (CI: 1.35-3.35), CFT confirmed an overall seroprevalence of 1.95% (95% CI: 1.14-3.12) for all four districts sampled. Although the seroprevalence of brucellosis was found to be low, the possibility of undetected cases of the disease could not be ruled out. Overall, the findings of this study confirmed that brucellosis is endemic in the surveyed areas of the North West province of South Africa.Contribution: The outcome of this study will contribute to the National Brucellosis Project organised by the Department of Agriculture, Land Reform and Rural Development (2016-2026) to assist in the effective implementation of the disease control measures with a view to prevent further outbreaks in the country's cattle population.

A Challenging Diagnosis of Febrile Pancytopenia in a Patient With a History of Autoimmune Disease

Pancytopenia is a hematologic condition characterized by a decrease in all three peripheral blood cell lines. There are many causes of pancytopenia, and the proper approach is required for accurate diagnosis. Brucellosis and systemic lupus erythematosus (SLE) are both diseases that can initially present as pancytopenia, both of which require a targeted workup to diagnose. Due to the immune system's complexity, many distinct diseases may have similar symptomatology. Furthermore, infections and rheumatological diseases can stimulate the same molecular pathways and trigger T and B cells. This creates a cross-reactivity between microbial peptides and self-peptides, allowing the spread of microbial-specific T cells that can also respond to self-peptides. Brucellosis has broad clinical manifestations, often mimicking many other diseases, such as rheumatoid arthritis, sarcoidosis, and SLE. In addition, brucellosis-induced autoantibody production has been described as a triggering factor for immunologic reactions, elevating rheumatological markers by a poorly understood mechanism. Finally, SLE is a well-known medical condition that can mimic several medical conditions, including brucellosis.  We present a case of a young patient who was admitted with febrile pancytopenia. The patient also had IgM antibodies positive for brucellosis and high immune markers for SLE. She was treated for both diseases, and afterward, in retrospect, it was confirmed that the patient did not have acute brucellosis.

Brucellosis unusually presented as septic knee arthritis: A case report

Brucellosis is one of the world's most prevalent zoonotic illnesses. The most often afflicted joints are the sacroiliac joints, although spondylitis and peripheral arthritis are becoming increasingly prevalent. We described a case of a 40‐year‐old male patient with Brucellosis presented as septic knee arthritis.

Factors Associated With Diagnostic Delays in Human Brucellosis in Tongliao City, Inner Mongolia Autonomous Region, China

The diagnostic delays pose a huge challenge to human brucellosis (HB), which increases the risk of chronicity and complications with a heavy disease burden. This study aimed to quantify and identify the associated factors in the diagnostic delays to its prevention, reduction, and elimination. This study analyzed risk factors associated with the diagnostic delays in a cross-sectional study with data collected from Tongliao City, Inner Mongolia Autonomous Region of China. Diagnostic delays were defined with a cutoff of 30, 60, and 90 days. In different delay groups, risk factors of diagnostic delays were analyzed by univariate analysis and modeled by multivariate logistic regression analysis. A total of 14,506 cases were collected between January 1, 2005, and December 31, 2017, of which the median diagnostic delays was 29 days [interquartile range (IQR): 14–54 days]. Logistic regression analysis indicated that the older age category was associated with longer diagnostic delays across all groups. Longer diagnostic delays increase with age among three delay groups (p for trend <0.001). Occupation as herdsman was associated with shorter diagnostic delays in group 1 with 30 days [adjusted odds ratio (aOR), 0.890 (95% CI 0.804–0.986)]. Diagnostic delays was shorter in patients with brucellosis who were reported in CDC in all delay groups [aOR 0.738 (95% CI 0.690–0.790), 0.539 (95% CI 0.497–0.586), and 0.559 (95% CI 0.504–0.621)]. Pastoral/agricultural area was associated with shorter diagnostic delays in group 1 with 30 days [aOR, 0.889 (95%CI 0.831–0.951)] and group 3 with 90 days [aOR, 0.806 (95%CI 0.727–0.893)]. Stratified analysis showed that the older age category was associated with an increased risk of a long delay in both genders (p < 0.05). The older age group-to-youth group OR increased along with increased delay time (p for trend <0.001). Furthermore, the pastoral/agricultural area was associated with a shorter delay in males (p < 0.05). Delays exist in the diagnosis of HB. We should pay great attention to the risk factors of diagnostic delays, such as older population, non-herdsman, non-pastoral/agricultural area, non-disease prevention, and control agencies. Effective measures should shorten the diagnostic delays, achieve early detection, diagnosis, and treatment, and reduce the risk of HB's chronicity, complications, and economic burden.

Using a One Health Case-Based Investigation for Improved Control of Brucellosis in Isiolo, Kenya

Brucella is a highly pathogenic bacteria endemic in Kenya, and in spite of its severity in humans, the highly inadequate Febrile Antigen Brucella Agglutination Test (FBAT) remains a primary tool for its diagnosis. Blood samples were collected from febrile patients in Kinna health center and screened by the local routine. Milk samples were purchased from local milk hawkers and analyzed for Brucella antibodies using the milk ring test (MRT). The MRT-positive milk was traced to farms, and lactating cattle were sampled for milk and blood. Milk was MRT-tested and the serum was analyzed using the Rose Bengal test (RBT) and iELISA. Available patient and farm samples were stored on FTA cards for qPCR analyses. Despite a limited sample size, our study, in line with previous reports, shows a low diagnostic sensitivity (67%) and specificity (40%) of FBAT when compared to qPCR. As many as 48% of the raw bulk cattle milk samples were MRT-positive for Brucella antibodies and 60% of cattle on three visited farms were IS711 qPCR-positive. This case-based One Health investigation confirms the suspected Brucella presence, suggesting a targeted vaccination at high-prevalence farms, urgent interventions on milk safety, and a re-evaluation of the diagnostic and treatment regimen.

Validation of real-time polymerase chain reaction versus conventional polymerase chain reaction for diagnosis of brucellosis in cattle sera

Background and Aim:

Different polymerase chain reaction (PCR) techniques have and are still being used for the direct detection of Brucella DNA in serum samples of different animal species and humans without being validated or properly validated, resulting in discrepancies. Thus, this study aimed to evaluate the diagnostic performance of the TaqMan Real-Time-PCR (RT-PCR) targeting the bcsp31 gene versus conventional PCR for the accurate diagnosis of brucellosis at the genus level in cattle sera.

Materials and Methods:

One hundred and eighty-four serum samples were collected from bacteriologically positive and negative cows with ages ranging from 1 to 5 years old at some infected private farms in the Nile Delta under quarantine measures as well as brucellosis free farms. These samples were classified into four groups after serological diagnosis and investigated by TaqMan RT-PCR and conventional PCR targeting the IS711 gene for Brucella DNA detection. The diagnostic performance characteristics of both PCR techniques were estimated considering the bacteriological results as a gold standard.

Results:

TaqMan RT-PCR revealed superiority over conventional PCR; it was able to detect Brucella DNA in 95% (67/70) and 89% (25/28) of the cattle sera samples belonging to Group 1 (serologically and bacteriologically positive) and Group 2 (serologically negative but bacteriologically positive), respectively. On evaluating the diagnostic performance, TaqMan RT-PCR showed superior diagnostic sensitivity (93.9%), diagnostic specificity (88.4%), performance index (182.3), almost perfect kappa agreement (0.825±0.042), strong positive correlation (r=0.826), high accuracy based on the receiver operating characteristic (ROC) curve, and area under the ROC curve (0.911) at p<0.05 and CI of 95%.

Conclusion:

A cattle serum sample is not the metric of choice for targeting Brucella genomic DNA by conventional PCR. The time-saving and rapid TaqMan RT-PCR method revealed a better diagnostic performance in the detection of Brucella DNA in cattle sera. Such performance offered by TaqMan RT-PCR may be considered a step toward the possibility of using such technology in the direct differentiation between Brucella-infected and -vaccinated cattle immunized by smooth vaccines from cattle sera using primers specific for such vaccines.

The State of the Art in Biodefense Related Bacterial Pathogen Detection Using Bacteriophages: How It Started and How It's Going

Accurate pathogen detection and diagnosis is paramount in clinical success of treating patients. There are two general paradigms in pathogen detection: molecular and immuno-based, and phage-based detection is a third emerging paradigm due to its sensitivity and selectivity. Molecular detection methods look for genetic material specific for a given pathogen in a sample usually by polymerase chain reaction (PCR). Immuno-methods look at the pathogen components (antigens) by antibodies raised against that pathogen specific antigens. There are different variations and products based on these two paradigms with advantages and disadvantages. The third paradigm at least for bacterial pathogen detection entails bacteriophages specific for a given bacterium. Sensitivity and specificity are the two key parameters in any pathogen detection system. By their very nature, bacteriophages afford the best sensitivity for bacterial detection. Bacteria and bacteriophages form the predator-prey pair in the evolutionary arms race and has coevolved over time to acquire the exquisite specificity of the pair, in some instances at the strain level. This specificity has been exploited for diagnostic purposes of various pathogens of concern in clinical and other settings. Many recent reviews focus on phage-based detection and sensor technologies. In this review, we focus on a very special group of pathogens that are of concern in biodefense because of their potential misuse in bioterrorism and their extremely virulent nature and as such fall under the Centers for Disease and Prevention (CDC) Category A pathogen list. We describe the currently available phage methods that are based on the usual modalities of detection from culture, to molecular and immuno- and fluorescent methods. We further highlight the gaps and the needs for more modern technologies and sensors drawing from technologies existing for detection and surveillance of other pathogens of clinical relevance.

A Proof of Principle for the Detection of Viable Brucella spp. in Raw Milk by qPCR Targeting Bacteriophages

Brucellosis is still a global health issue, and surveillance and control of this zoonotic disease in livestock remains a challenge. Human outbreaks are mainly linked to the consumption of unpasteurized dairy products. The detection of human pathogenic Brucella species in food of animal origin is time-consuming and laborious. Bacteriophages are broadly applied to the typing of Brucella isolates from pure culture. Since phages intracellularly replicate to very high numbers, they can also be used as specific indicator organisms of their host bacteria. We developed a novel real-time PCR (qPCR) assay targeting the highly conserved helicase sequence harbored in all currently known Brucella-specific lytic phages. Quality and performance tests determined a limit of detection of <1 genomic copy/µL. In raw milk artificially contaminated with Brucella microti, Iz_v phages were reliably detected after 39 h of incubation, indicating the presence of viable bacteria. The qPCR assay showed high stability in the milk matrix and significantly shortened the time to diagnosis when compared to traditional culture-based techniques. Hence, our molecular assay is a reliable and sensitive method to analyze phage titers, may help to reduce the hands-on time needed for the screening of potentially contaminated food, and reveals infection risks without bacterial isolation.

The evolution of molecular diagnosis using digital polymerase chain reaction to detect cancer via cell-free DNA and circulating tumor cells

Cancer is one of the most important causes of death worldwide. The onset of cancer may be initiated due to a variety of factors such as environment, genetics or even due to personal lifestyle choices. To counteract this tremendous increase, the demand for a new technology has risen. By this means, the use of digital polymerase chain reaction (dPCR) has been shown to be a promising methodology in the early detection of many types of cancers. Furthermore, several researchers confirmed that the use of tumor cell-free DNA (cfDNA) and circulating tumor cells (CTC) in peripheral blood is essential in revealing an early prognosis of such diseases. Besides this, it was established that dPCR might be used in a much more efficient, accurate, and reliable manner to amplify a variety of genetic material up to the identification of mutations in hematological diseases. Therefore, this article demonstrates the differences between conventional PCR and dPCR as a molecular technique to detect the early onset of cancer. Furthermore, CTC and cfDNA were officially approved by the Food and Drug Administration as new biological biomarkers in cancer development and monitoring.

Optimization and validation of a real-time polymerase chain reaction protocol for the diagnosis of human brucellosis

Due to limitations in commercial diagnostic methods, this study aimed to develop a reliable real-time polymerase chain reaction (Rt-PCR) assay for early diagnosis of brucellosis. Optimization of the Rt-PCR method was performed on serum samples spiked by Brucella melitensis with different densities ranging from 10¹ to 10⁸ colony-forming units (cfu)/mL; each density was prepared in ten samples. The limit of detection was investigated by using Thermo DNA extraction kit with Maxima SYBR Green Rt-PCR and two TaqMan probe-based Rt-PCR protocols performed by QuantiTect and TEMPase multiplex PCR master mixes in two thermal cyclers, which were Rotor-Gene and Bio-Rad. The validation of the optimized protocol was carried on 20 brucellosis-negative samples and 20 samples spiked with B. melitensis by using a combination of Thermo DNA extraction kit with TEMPase PCR master mix. SYBR Green Rt-PCR yielded positive results on all samples having ≥ 10⁴ cfu/mL of B. melitensis in both thermal cyclers. Its limit of detection was 112 DNA copies per reaction. The positivity of both probe-based Rt-PCR protocols was 100% and 80% on the samples having 10³ cfu/mL and 10² cfu/mL of B. melitensis, respectively. The limit of detection of probe-based protocols was defined as 4 DNA copies per reaction. The optimized Rt-PCR protocol showed high-level accuracy, precision, specificity, and sensitivity, each having a rate of 100%. The current study indicated that the TaqMan probe-based Rt-PCR protocol optimized and validated with serum samples can be reliably used for early diagnosis of brucellosis.

Prevalence and Detection of Trichomonas vaginalis in HIV-Infected Pregnant Women

BACKGROUND

Trichomonas vaginalis is a sexually transmitted infection associated with increased transmission of HIV and significant adverse birth outcomes; culture and polymerase chain reaction (PCR) are commonly used in diagnosis.

METHODS

Consenting HIV-infected pregnant women were recruited from clinics in South Africa and screened for T. vaginalis using PCR. Polymerase chain reaction-positive women provided an additional sample for culture. We compared T. vaginalis detection between PCR and culture, and investigated how PCR cycle threshold (Ct) values differ among culture results.

RESULTS

A total of 359 women were enrolled and 76 (20%) tested T. vaginalis PCR positive. Cultures were obtained from 61 of the PCR-positive women, and 38 (62%) were culture positive. The median baseline Ct of the PCR-positive/culture-positive group was 22.6 versus 38.0 among those who were PCR positive/culture negative (P < 0.001). Culture-positive cases had lower Ct values (higher DNA load); a Ct value less than 30 predicted positivity with a sensitivity of 97% and a specificity of 96%.

CONCLUSIONS

Culture was positive in roughly half of PCR-positive cases. The culture-negative cases had significantly higher Ct values, indicating a lower concentration of T. vaginalis DNA. A Ct value of 30 provides a reliable threshold for predicting culture positivity. The clinical significance of culture-negative infections detected by PCR is still unclear.

Osteoarticular manifestations of human brucellosis: A review

Brucellosis is a common global zoonotic disease, which is responsible for a range of clinical manifestations. Fever, sweating and musculoskeletal pains are observed in most patients. The most frequent complication of brucellosis is osteoarticular involvement, with 10% to 85% of patients affected. The sacroiliac (up to 80%) and spinal joints (up to 54%) are the most common affected sites. Spondylitis and spondylodiscitis are the most frequent complications of brucellar spinal involvement. Peripheral arthritis, osteomyelitis, discitis, bursitis and tenosynovitis are other osteoarticular manifestations, but with a lower prevalence. Spinal brucellosis has two forms: focal and diffuse. Epidural abscess is a rare complication of spinal brucellosis but can lead to permanent neurological deficits or even death if not treated promptly. Spondylodiscitis is the most severe form of osteoarticular involvement by brucellosis, and can have single- or multi-focal involvement. Early and appropriate diagnosis and treatment of the disease is important in order to have a successful management of the patients with osteoarticular brucellosis. Brucellosis should be considered as a differential diagnosis for sciatic and back pain, especially in endemic regions. Patients with septic arthritis living in endemic areas also need to be evaluated in terms of brucellosis. Physical examination, laboratory tests and imaging techniques are needed to diagnose the disease. Radiography, computed tomography, magnetic resonance imaging (MRI) and bone scintigraphy are imaging techniques for the diagnosis of osteoarticular brucellosis. MRI is helpful to differentiate between pyogenic spondylitis and brucellar spondylitis. Drug medications (antibiotics) and surgery are the only two options for the treatment and cure of osteoarticular brucellosis.

In silico design and in vitro development of a highly accurate test to detect Brucella species

Background/aim

Conventional methods of detecting Brucella spp. suffer from technical and biological complications. Besides, newly characterized species of the genus Brucella could be neglected by previously designed polymerase chain reaction (PCR) tests. Therefore, a more accurate PCR-based test seems to be imminently needed.

Materials and methods

Blood samples were collected from 39 patients diagnosed with brucellosis and 25 healthy controls. Multiple sequence alignments (MSA) were performed on 500 Omp2-related protein and gene sequences. Thereafter, specific primers were designed and synthesized for the regions with highest conservancy. The collected samples were assessed by PCR test. To overcome the cross-reactivity issue, PCR thermal program was optimized regarding annealing time and temperature.

Results

The MSA results indicated that the N terminus region of the Omp2 protein (DNA 5’ end) is associated with highest conservancy. Primers with highest specificity were designed and synthesized. A two-step PCR reaction was successfully designed and optimized. The desirable bands were observed in clinical samples with high accuracy.

Conclusion

It should be pointed out that using a precisely designed primer pair would bring about early infection detection, more success to detect all natural variants and higher cost-to-efficacy ratio in comparison to other detection methods.

Fluorescence polarization assay: Diagnostic evaluation for porcine brucellosis

Brucellosis in pigs, caused by the bacterium Brucella suis, is an important zoonotic infection. In the present study, fluorescence polarization assay (FPA) was standardized and compared with indirect enzyme linked immunosorbent assay (iELISA) and competitive ELISA (cELISA) for diagnosis of porcine brucellosis. Test performances were evaluated using representative panel (n = 100), samples from swine brucellosis outbreak (n = 300), samples from brucellosis suspected animals (n = 291) and sera samples from apparently healthy animals (n = 1121). With panel samples, the FPA cut-off ≥11ΔmP was arrived with sensitivity (Se) and specificity (Sp) of 95.00 and 98.75%, respectively. Testing of samples from swine brucellosis outbreak, the diagnostic Se and Sp of 100 and 95.14% by iELISA, 73.91 and 100% by cELISA and 86.96 and 100% by FPA, respectively were recorded. Similarly, in case of swine brucellosis suspected samples, relative performance of FPA with cELISA had revealed higher kappa value of 0.864 with an accuracy of 93.47. Indirect ELISA was found to be highly sensitive but showed cross reactivity mainly for Yersinia enterocolitica O9 antibodies than cELISA and FPA. The high specificity of FPA test recorded in various types of samples in the study indicated that, FPA could serve as confirmatory test for individual animal diagnosis, outbreak confirmation, surveillance and quarantine of swine brucellosis cases.

Outbreak of human brucellosis in Southern Brazil and historical review of data from 2009 to 2018

Background

Human brucellosis (HB) is a bacterial zoonosis that is more frequent in low income and middle-income countries; it is sometimes associated with outbreaks. The aim of this study was to describe the largest outbreak of HB in Brazil.

Methods

A retrospective cohort study of patients suspected of having contracted HB in the state of Paraná, Southern Brazil from January 2009 to January 2017. Following an outbreak of 51 cases of HB in a slaughterhouse at Paiçandu in 2014, HB was defined as an obligatory reportable disease in the State. Diagnostic tests for HB included serum agglutination, ELISA (IgG or IgM) and polymerase chain reaction (PCR). Clinical, laboratorial and epidemiological data were analyzed. A P value of 0.05 was considered statistically significant.

Results

Out of a total of 3,941 patients, 754 presented with a positive test result for HB. After 2014, there was a significant increase in the number of cases, exceeding 100 cases per trimester. In the beginning of 2015, the workgroup of HB started several actions for prevention and treatment, and the number of cases progressively diminished to fewer than 20 cases per trimester. Of 191 reported cases, an occupational risk was found in 84.7%; most cases occurred in farmers (60.0%), veterinarians (17.6%) and slaughterhouse workers (14.7%). Manipulation of animals and unpasteurized milk consumption were associated with positive Brucella IgM ELISA with an odds ratio (OR) of 1.42 (1.09–1.84) and 1.48 (1.01–2.15), respectively.

Conclusions

HB outbreaks can occur in low to middle-income countries and are associated with slaughterhouse work, handling of unpasteurized milk and animal manipulation. Intensive programs for control of HB are important to reduce the number of cases.

Human brucellosis (HB) is a bacterial zoonosis more frequent in low income and middle-income countries. The number of cases has increased in Southern Brazil since 2014. Considering the risk of dissemination of the disease, the authors evaluated the whole spectrum of the disease in the State of Paraná, where cases were reported. More than 3,500 patients at risk for the disease were evaluated and 754 presented with positive blood test results for human brucellosis. The local Health Agency established a program of brucellosis treatment and prevention in the following year. After the intensive control program, there was a significant reduction in the number of HB cases.

An Overview of Brucellosis in Cattle and Humans, and its Serological and Molecular Diagnosis in Control Strategies

Brucellosis is one of the most common contagious and communicable zoonotic diseases with high rates of morbidity and lifetime sterility. There has been a momentous increase over the recent years in intra/interspecific infection rates, due to poor management and limited resources, especially in developing countries. Abortion in the last trimester is a predominant sign, followed by reduced milk yield and high temperature in cattle, while in humans it is characterized by undulant fever, general malaise, and arthritis. While the clinical picture of brucellosis in humans and cattle is not clear and often misleading with the classical serological diagnosis, efforts have been made to overcome the limitations of current serological assays through the development of PCR-based diagnosis. Due to its complex nature, brucellosis remains a serious threat to public health and livestock in developing countries. In this review, we summarized the recent literature, significant advancements, and challenges in the treatment and vaccination against brucellosis, with a special focus on developing countries.

Real-time PCR assays for diagnosing brucellar spondylitis using formalin-fixed paraffin-embedded tissues

It is difficult to diagnose brucellar spondylitis because of its nonspecific clinical, radiological, and histological characteristics. This study aimed to determine whether real-time polymerase chain reaction (PCR) using formalin-fixed paraffin-embedded (FFPE) tissues was superior to conventional serum-based methods for diagnosing brucellar spondylitis.This retrospective study included 31 patients with brucellosis and a control group of 20 people with no history of brucellosis or exposure to Brucella spp. Samples from all patients with brucellar spondylitis were evaluated using Giemsa staining, the standard tube agglutination (STA) test, blood culture, and real-time PCR.The brucellar spondylitis was acute in 7 patients (22.6%), subacute in 15 patients (48.4%), and chronic in 9 patients (29%). Serological assays provided positive results for 25 patients (80.1%), real-time PCR provided positive results for 29 patients (93.5%), and blood cultures provided positive results for 11 patients (35.5%). The real-time PCR provided sensitivity of 93.5%, specificity of 100%, a positive predictive value of 100%, and a negative predictive value of 100%. The corresponding values for the STA test were 80.1%, 100%, 100%, and 76.9%, respectively. Real-time PCR provided better sensitivity than Giemsa staining, the STA test, and blood culture, although the difference between PCR and STA was not statistically significant (P = .22). B melitensis was the only pathogen that was detected in patient with brucellar spondylitis using real-time PCR.These results suggest that real-time PCR provides a high sensitivity for diagnosing brucellar spondylitis. Furthermore, the real-time PCR results indicate that B melitensis was the causative pathogen in these cases.

Highly Sensitive Bacteriophage-Based Detection of Brucella abortus in Mixed Culture and Spiked Blood

For decades, bacteriophages (phages) have been used for Brucella species identification in the diagnosis and epidemiology of brucellosis. Traditional Brucella phage typing is a multi-day procedure including the isolation of a pure culture, a step that can take up to three weeks. In this study, we focused on the use of brucellaphages for sensitive detection of the pathogen in clinical and other complex samples, and developed an indirect method of Brucella detection using real-time quantitative PCR monitoring of brucellaphage DNA amplification via replication on live Brucella cells. This assay allowed the detection of single bacteria (down to 1 colony-forming unit per milliliter) within 72 h without DNA extraction and purification steps. The technique was equally efficient with Brucella abortus pure culture and with mixed cultures of B. abortus and α-proteobacterial near neighbors that can be misidentified as Brucella spp., Ochrobactrum anthropi and Afipia felis. The addition of a simple short sample preparation step enabled the indirect phage-based detection of B. abortus in spiked blood, with the same high sensitivity. This indirect phage-based detection assay enables the rapid and sensitive detection of live B. abortus in mixed cultures and in blood samples, and can potentially be applied for detection in other clinical samples and other complex sample types.

Molecular prevalence of putative virulence-associated genes in Brucella melitensis and Brucella abortus isolates from human and livestock specimens in Iran

Molecular prevalence of nine putative virulence factors in two more prevalent Brucella species in Iranian patients and livestock was investigated. During five years (2010-2015), 120 human and animal specimens were collected from three geographical areas of Iran. All samples were cultured in blood culture media and subcultured into Brucella agar medium. Nine primer pairs were designed for detection of VirB2, VirB5, VceC, BtpA, BtpB, PrpA, BetB, BPE275 and BSPB virulence factors using PCR and sequence analysis. Totally, 68 Brucella isolates including 60 B. melitensis and 8 B. abortus were isolated from the human and animal specimens examined. Approximately, all B. melitensis and B. abortus strains were positive (100%) regarding btpA, btpB, virB5, vceC, bpe275, bspB, and virB2 genes except for prpA and betB that were detected in 86% and 97% of the strains, respectively. Significant relationships were found between the presence of prpA and human B. melitensis isolates (P = 0.04), and also between the presence of betB and human isolates of B. abortus (P = 0.03). In conclusion, our results revealed that Iranian Brucella strains, regardless of human or animal sources, are extremely virulent due to high prevalence of virulence attributes in almost all strains studied.

Polymerase Chain Reaction-Based Assays for the Diagnosis of Active and Relapsed Cases of Human Brucellosis

This study aimed to compare polymerase chain reaction (PCR) with serum agglutination test (SAT) in the diagnosis of patients before and 6 months after treatment. Peripheral blood specimens from 50 patients with brucellosis (case group) and 30 subjects without brucellosis (control group) were selected and entered into the study. The diagnosis of brucellosis was established using SAT ≥ 1:160 and 2-mercaptoethanol (2-ME) ≥ 1:80 with clinical signs and symptoms compatible with brucellosis. For each case, both before treatment and 6 months after completion of therapy, SAT, 2-ME, and PCR were performed. Subjects in the control group were assessed by the same tests at the initial visit. In the case group, 50 patients (36 males, 14 females) with the mean age of 43.6 ± 14.5 years were evaluated. The mean age of the control group was 40.6 ± 14 years. Among the 50 patients whose nested PCR assays were initially positive, 43 (86%) were negative 6 months after completing treatment. Relapse occurred in five (10%) patients within 6 months after treatment and all were PCR positive. None of the patients in the control group was PCR positive. Results show that PCR seems to be highly sensitive and specific, and therefore is a useful method for both the initial diagnosis and detection of relapse or chronic brucellosis.

Brucella Septic Arthritis: Case Reports and Review of the Literature

Brucellosis is one of the commonest zoonotic infections worldwide. The disease is endemic in Saudi Arabia, the Middle East, and the Mediterranean area. Osteoarticular involvement is a frequent manifestation of brucellosis. It tends to involve the sacroiliac joints more commonly; however, spondylitis and peripheral arthritis are increasingly reported. Brucellosis can be overlooked especially in the presence of companion bacteria. Hence, it should be suspected in all patients with septic arthritis in endemic areas or in patients visiting such areas.