Evaluation of serological diagnostic tests for bovine brucellosis in dairy cattle herds in an endemic area: a multicenter study.

Brucellosis is known as one of the most common zoonotic diseases worldwide affecting both livestock and humans. It causes abortions, reduces milk production, and infertility in infected animals. The disease is routinely diagnosed through three serological techniques, such as rose bengal plate test (RBPT), standard agglutination test (SAT), and indirect enzyme-linked immunosorbent assay (I-ELISA). The aim of this study was to identify and compare the brucellosis seroprevalence among dairy cattle farms through these different serological tests. From 2112 sampled dairy cattle in different parts of Iran, RBPT, SAT, and I-ELISA led to 296 (14.02%), 215 (10.18%), and 297 (14.06%) positive results, respectively. Brucella abortus biovar 3 (62 cases) was identified as the most common cause of brucellosis in tested animals. Our results showed that the specificity and sensitivity of I-ELISA were higher than those obtained by RBPT and SAT. In this study, the overall agreement of RBPT and SAT with I-ELISA reached 95.21% and 94.12% in dairy cattle farms, respectively. Furthermore, Cohen's kappa statistical analysis revealed that the best degree of agreement was seen between RBPT and I-ELISA (0.80), followed by RBPT and SAT (0.78) and finally SAT and I-ELISA (0.72), thereby indicating a strong agreement between RBPT and I-ELISA methods and good agreement between SAT and I-ELISA methods. The McNemar analysis also showed that a significant difference exists between positive and negative results determined by SAT and I-ELISA methods (p < 0.0001). However, the positive and negative results determined by I-ELISA and RBPT did not show a significant difference (p = 0.9207). Therefore, I-ELISA was a more specific and sensitive serological test when compared to RBPT and SAT and could remarkably decrease non-specific reaction by improving the serological screening specificity for an accurate brucellosis diagnosis in endemic areas.

Isolation of Brucella abortus biovar 1 from human lumbar disc bulging: a case report of brucellar discitis.

BACKGROUND: Brucellosis is an endemic zoonotic disease with rising health and economic concerns in many areas worldwide. Musculoskeletal pains are among the main complications of human brucellosis, which are often difficult to diagnose due to the variability of clinical symptoms. Brucellar discitis is a very disabling problem in some chronic forms of the disease which may lead to serious vertebral and neurological consequences. CASE PRESENTATION: In this case report, we reported the isolation of Brucella abortus from lumbar disc bulging in a woman who had rheumatoid arthritis and diabetes mellitus as underlying conditions. The patient had several negative brucellosis serological tests and dorsolumbar pains with urinary incontinence over a 2-month period. The diagnosis was confirmed by magnetic resonance imaging (MRI) examination of lumbar spine as well as disc culture. MRI examination was performed without intravenous contrast and revealed the presence of disc bulging, left foraminal narrowing at L5-S1, left foraminal narrowing, anterolisthesis grade II at L4-L5. The diagnosis was also confirmed by isolation of B. abortus biovar 1 from bulging disc culture. The isolate was characterized by AMOS PCR, Bruce-ladder PCR and biotyping, resulting in the identification of B. abortus from L4-L5 and L5-S1 disc bulging regions. The patient was treated with two drugs i.e. doxycycline and rifampin for 3 months. In the follow-up, in addition to improving the patient's general condition, low-back pain was also significantly reduced. CONCLUSIONS: MRI, serology, cultural and molecular test along with patient history are important to make a rapid diagnosis of brucellosis' discitis, thereby decreasing the delay for the brucellosis treatment. The present report suggests that the infection by Brucella spp. should be fundamentally considered among the causative agents of back pain especially in the endemic areas of Brucella infections.

Brucella species circulating in rural and periurban dairy cattle farms: a comparative study in an endemic area.

Brucellosis is among the most important zoonotic infectious diseases worldwide affecting both humans and domestic animals. The present study aimed to determine and compare the seroprevalence of brucellosis among rural and periurban dairy cattle farms of four Iranian provinces from 2017 to 2019. We applied different serological tests, including RBT, SAT, and iELISA to evaluate the brucellosis prevalence among 2808 dairy cattle. Species-specific multiplex PCR and biotyping tests were also used to further identify the implicated Brucella species. Serological screening using RBT, SAT, and iELISA led to 157 (5.6%), 112 (3.9%), and 139 (4.9%) positive results among tested cattle, respectively. Brucella abortus biovars 1 (2 cases) and biovars 3 (42 cases) were identified by biotyping experiments and multiplex PCR in all 44 tested lymph node samples. Further, Cohen's kappa statistical analysis revealed that the best degree of agreement was seen between RBT and iELISA (99.4%), followed by SAT/iELISA (98.5%) and finally RBT/SAT (98.4%). Our results also showed a significantly lower seroprevalence of brucellosis in periurban dairy cattle when compared to rural dairy cattle population (p value= 0.01). These results reflect the need for better vaccine coverage using RB51 combined with an appropriate test-and-slaughter program in the rural dairy cattle population.

Characterization of Brucella spp. circulating in industrial dairy cattle farms in Iran: a field study 2016 - 2023.

Bovine brucellosis, an infectious disease transmitted by Brucella melitensis and Brucella abortus, presents a significant zoonotic risk for agricultural economics and animal health. The primary objective of this study was to present a comprehensive understanding of the prevalence and features of Brucella strains within the industrial dairy farming sector in Iran. Rose Bengal plate test, standard agglutination test, and indirect enzyme linked immunosorbent assay tests were used to confirm all seropositive animals. A total number of 1,311 bovine samples from seropositive animals including were collected from 224 farms in 21 provinces of different regions of Iran and examined. The discovered Brucella isolates were phenotyped and molecularly characterized. The isolates were all B. abortus or B. melitensis. Bacteria analysis revealed that 70.53% of seropositive farms were tested positive for Brucella strains, predominantly B. melitensis biovar 1 (43.42%) and B. abortus biovar 3 (27.11%). Geographical distribution revealed that B. melitensis biovar 1 was the most common in dairy cow farms (16 provinces), followed by B. abortus biovar 3 (six provinces). Also, the prevalence of B. melitensis biovar 2, B. melitensis biovar 3, B. abortus biovar 1, B. abortus biovar 2 and RB51 vaccine were restricted to certain provinces. AMOS (abortus melitensis ovis suis)-polymerase chain reaction and Bruce-ladder PCR confirmed species identification. These results highlighted the complexity of bovine brucellosis in Iran and illustrated that B. melitensis was spread from small ruminants to cattle. This study provided important epidemiological insights for targeting future brucellosis control programs in the Iranian dairy farms.

Antimicrobial susceptibility of Brucella spp. isolated from Iranian patients during 2016 to 2018.

BACKGROUND AND OBJECTIVES: Brucellosis is a widespread zoonotic disease with a high prevalence in both animals and humans. The present study was aimed to evaluate the susceptibility of Brucella strains isolated from human clinical specimens against commonly used antimicrobial agents. MATERIALS AND METHODS: A total of 360 blood specimens were collected during 2016-2018 and subjected to culture and Brucella spp. identification. The classical biotyping for Brucella isolates was performed according to Alton and coworker's guidelines. Antimicrobials susceptibility test carried out using disk diffusion and minimal inhibitory concentration (MIC) methods. RESULTS: In this study, sixty B. melitensis strains were isolated from blood samples (16%) and all them belonged to biovar 1. Majority of the tested antibacterial agents, excepting ampicillin-sulbactam had an effective activity against B. melitensis isolates in E-test (MIC) and disk diffusion method. Moreover, probable resistance to rifampin and ampicillin-sulbactam were observed in 60 (100%), 1 (1.7%), 11 (18.4%) and 2 (3.4%) isolates, respectively. CONCLUSION: Our data suggest that the efficacy of commonly used antibiotics for brucellosis treatment should be regularly monitored. In conclusion, appropriate precaution should be exercised in the context of antibiotic administration to prevent future antibiotic resistance.

Molecular identification of Brucella species and biovars associated with animal and human infection in Iran.

Brucellosis is a costly contagious disease of human, domestic and wild animals. It is a serious health problem in Iran causing significant economic losses therefore, control approaches to prevent its spread are of great importance. In Iran, the species and biovars of virulent Brucella species are still under-reported due to the inadequate diagnostic protocols and insufficient laboratory facilities. The objective of this study was to characterize Brucella isolates obtained from passive animal and human surveillance in Iran from 2011 to 2018 in order to understand the current epidemiological situation of the disease. A total of 419 samples (milk, blood, cerebrospinal fluid, abomasum content and aborted fetus tissues) were collected from 65 cases/case series (human and animals) and examined bacteriologically. The initially identified Brucella isolates were further characterized using phenotypic and molecular approaches. All recovered isolates were either B. abortus or B. melitensis. The infection in sheep appeared to be exclusively associated with B. melitensis, but both B. abortus and B. melitensis were common in bovine samples. Samples from one sheep and one goat were confirmed to be infected by the B. melitensis vaccine strain Rev1. In spite of B. abortus burden in animals (14 cases in cattle and camel), brucellosis in human was predominantly associated with B. melitensis (15 cases). The results confirmed that B. melitensis biovar 1 and B. abortus biovar 3 remain the most prevalent biovars in Iran. This report builds a picture of the significance of different Brucella species in different hosts in Iran and provides applicable information for the healthcare professionals about the public health risks of brucellosis and relevant preventive strategies.

A Novel PCR Assay for Detecting Brucella abortus and Brucella melitensis.

OBJECTIVES: Brucellosis is a major zoonotic disease that poses a significant public health threat worldwide. The classical bacteriological detection process used to identify Brucella spp. is difficult and time-consuming. This study aimed to develop a novel molecular assay for detecting brucellosis. METHODS: All complete sequences of chromosome 1 with 2.1-Mbp lengths were compared among all available Brucella sequences. A unique repeat sequence (URS) locus on chromosome 1 could differentiate Brucella abortus from Brucella melitensis. A primer set was designed to flank the unique locus. A total of 136 lymph nodes and blood samples were evaluated and classified by the URS-polymerase chain reaction (PCR) method in 2013-2014. RESULTS: Biochemical tests and bacteriophage typing as the golden standard indicated that all Brucella spp. isolates were B. melitensis biovar 1 and B. abortus biovar 3. The PCR results were the same as the bacteriological method for detecting Brucella spp. The sensitivity and specificity of the URS-PCR method make it suitable for detecting B. abortus and B. melitensis. CONCLUSION: Quick detection of B. abortus and B. melitensis can provide the most effective strategies for control of these bacteria. The advantage of this method over other presented methods is that both B. abortus and B. melitensis are detectable in a single test tube. Furthermore, this method covered 100% of all B. melitensis and B. abortus biotypes. The development of this URS-PCR method is the first step toward the development of a novel kit for the molecular identification of B. abortus and B. melitensis.