Delay in the diagnosis of Brucella abortus bacteremia in a nonendemic country: a case report.

BACKGROUND: It is challenging to diagnose brucellosis in nonendemic regions because it is a nonspecific febrile disease. The accurate identification of Brucella spp. in clinical microbiology laboratories (CMLs) continues to pose difficulties. Most reports of misidentification are for B. melitensis, and we report a rare case of misidentified B. abortus. CASE PRESENTATION: A 67-year-old man visited an outpatient clinic complaining of fatigue, fever, and weight loss. The patient had a history of slaughtering cows with brucellosis one year prior, and his Brucella antibody tests were negative twice. After blood culture, the administration of doxycycline and rifampin was initiated. The patient was hospitalized due to a positive blood culture. Gram-negative coccobacilli were detected in aerobic blood culture bottles, but the CML's lack of experience with Brucella prevented appropriate further testing. Inaccurate identification results were obtained for a GN ID card of VITEK 2 (bioMérieux, USA) and matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) using a MALDI Biotyper (Bruker, Germany). The strain showed 100.0% identity with Brucella spp. according to 16S rRNA sequencing. MALDI-TOF MS peaks were reanalyzed using the CDC MicrobeNet database to determine Brucella spp. (score value: 2.023). The patient was discharged after nine days of hospitalization and improved after maintaining only doxycycline for six weeks. The isolate was also identified as Brucella abortus by genomic evidence. CONCLUSION: Automated identification instruments and MALDI-TOF MS are widely used to identify bacteria in CMLs, but there are limitations in accurately identifying Brucella spp. It is important for CMLs to be aware of the possibility of brucellosis through communication with clinicians. Performing an analysis with an additional well-curated MALDI-TOF MS database such as Bruker security-relevant (SR) database or CDC MicrobeNet database is helpful for quickly identifying the genus Brucella.

Detection of Brucella S19 Vaccine Strain DNA in Domestic and Wild Ungulates from Brazilian Pantanal.

The Pantanal region, the largest floodplain in the world, has a huge biodiversity and is an important livestock center. Bovine brucellosis has been reported in the region over the last three decades, posing implications for cattle industry as well as for the maintenance of biodiversity. We aimed to investigate the presence of B. abortus S19 vaccine strain DNA in unvaccinated domestic and wild ungulates from the Brazilian Pantanal. Fifty-two heifers, 63 ovine, 24 domestic pigs, 28 feral pigs, and three Pampas deer were sampled. Brucella spp. was detected through bcsp31 PCR of blood samples in 45.3% (77/170) of the sampled animals, of which 36.4% (28/77) showed positivity in ery PCR corresponding to B. abortus S19 strain. Feral pigs presented the highest occurrence of positive samples in bcsp31 PCR (75%), followed by ovine (47.6%), domestic pigs (41.7%), and unvaccinated heifers (30.8%). We did not observe positivity in Pampas deer. Our results strongly suggest that vaccination against bovine brucellosis may promote spill-over of B. abortus S19 strain in the Pantanal region. Moreover, our data indicate that wild strains of Brucella circulates in the Pantanal Biome.

Genomic analysis of Brucella isolates from animals and humans, Türkiye, 2010 to 2020.

BackgroundBrucellosis is a bacterial zoonosis causing severe illness in humans and animals and leading to economic losses in the livestock production in Türkiye and other endemic countries.AimWe aimed at investigating genomic differences of Brucella isolates from animals and humans in Türkiye.MethodsWe used whole genome sequencing (WGS) to assess the genetic diversity of Brucella isolates from 41 provinces in Türkiye and compared with isolates from other countries. We applied allele-based typing and core genome single nucleotide polymorphism (cgSNP) determination.ResultsOf the 106 Turkish Brucella isolates included, 57 were B. abortus and 49 were B. melitensis. One B. melitensis and two B. abortus isolates were identified as vaccine strains. Most (n = 55) B. abortus isolates clustered in three major branches, with no spatial discernible pattern. Of the B. melitensis isolates, 48 were assigned to the Eastern Mediterranean lineage with no discernible patterns between host species, location and sampling date. The Turkish isolates clustered with isolates from neighbouring countries such as Greece and Syria, but some also with isolates from human patients in European countries, like Germany, Norway and Sweden, suggesting that the source may be travel-related.ConclusionSeveral B. melitensis and B. abortus lineages are circulating in Türkiye. To decrease the prevalence and prevent brucellosis in animals and humans, stricter control measures are needed, particularly in areas where humans and animals have close contact. Furthermore, illegal transportation of animals across borders should be more closely controlled and regulated.

Evaluation of real-time PCR as an alternative for potency testing of Brucella abortus vaccines.

The aim of the research was to evaluate real-time PCR (qPCR) as an alternate method for quantitative detection of Brucella abortus strain 544 (S544) in the spleen of mice for potency testing of live B. abortus strain 19 (S19) vaccine. IS711 and eryC gene-based qPCR were optimized for calculating copy number. The copy number was further correlated with live Brucella count in the spleen by standard plate count (SPC) method. The mice were immunized with S19 and challenged with S544 on 30th Day post-immunization. The spleen of mice was collected at 15th, 21st, and 30th days post challenge (DPC) for estimation of S19 and S544 load via SPC as well as qPCR. The noteworthy difference was observed between immunized and unimmunized group by both methods at all time points. The maximum correlation between SPC and qPCR method was observed at 15th DPC in both immunized and unimmunized group. Repeated experiments at 15th DPC gave the parallel significant difference between immunized and unimmunized group by both methods. Thus novel, risk-free qPCR method can be used for the indirect culture-free potency evaluation of S19 vaccine in order to preclude the cultivation of zoonotic Brucella organisms from spleen samples.

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.

Multilocus variable number tandem repeat analysis (MLVA)-typing of Brucella abortus isolates of India reveals limited genetic diversity.

Multilocus variable number tandem repeat analysis (MLVA) technique has wide applications in studying phylogenies and short-term epidemiology of pathogens. The technique has been extensively used worldwide in molecular epidemiology of Brucella genus. Only one study on this aspect is reported from India despite its economic and public health significance in country. The present study isolated B. abortus from domesticated bovines of Jammu region of Jammu and Kashmir state, India, and applied MLVA for 16 loci (MLVA-16). MLVA results were compared with the results of a previous study and with MLVA data of Indian isolates present in http://microbesgenotyping.i2bc.paris-saclay.fr/database. In the study, 136 samples from bovines (cattle and buffaloes) of 47 farms of Jammu region were processed for isolation. Eleven isolates of B. abortus biovar 1 from 6 farms were obtained. In MLVA-16 analysis, although the isolates were classified in a single cluster, 5 genotypes were obtained with a specific genotype being prevalent on each farm. The study identifies that MLVA-16 is capable to differentiate B. abortus strains in an area having high genetic similarity among isolates. On comparing the results with previous study and database, the isolates were found to have high genetic similarity indicating that the genetic diversity of B. abortus in India is very limited. It probably indicates that India is contaminated recently with B. abortus. To test this hypothesis, analysis of whole genome sequencing data of diverse collection of Indian B. abortus strains is required.

Risk factors for new bovine brucellosis infections in Colombian herds.

BACKGROUND: Bovine brucellosis is a zoonotic disease that causes substantial economic losses and has a strong impact on public health. The main objective of this paper is to determine the risk factors for new infections of Brucella abortus on Colombian cattle farms previously certified as being free of brucellosis. A case-control study was conducted by comparing 98 cases (farms certified as brucellosis-free for three or more years but became infected) with 93 controls (farms that remained brucellosis-free during at least the previous three years). The farms were matched by herd size and geographical location (municipality). Information was obtained via a questionnaire completed by veterinary officers through a personal interview with the herd owners. RESULTS: Two-thirds of the herds (67%) were dairy herds, 16% were beef herds, and 17% were dual-purpose (beef and milk) herds. After exploratory univariate analysis, all explanatory variables with a p-value of ≤0.20 were included in a logistic regression model using the forward stepwise method to select the model with the best goodness of fit. The significant risk factors were the replacement of animals from farms not certified as brucellosis-free compared to replacement from certified brucellosis-free farms (OR = 4.84, p-value < 0.001) and beef cattle farms compared to dairy cattle farms (OR = 3.61, p-value = 0.017). When herds with and without artificial insemination were compared, it was observed that farms that used natural breeding with bulls from non-certified herds had a higher risk than farms using artificial insemination (OR = 2.45, p-value = 0.037), but when the bulls came from brucellosis-free farms, farms with natural breeding were less affected (OR = 0.30, p-value = 0.004) than farms using artificial insemination, whether with frozen semen from certified brucellosis-free herds or fresh semen from uncontrolled herds. The latter is commonly sold to neighbouring farms. CONCLUSIONS: The government should make efforts to inform farmers about the risks involved in the introduction of semen and replacement heifers from farms that are not certified as brucellosis-free and to establish measures to control these practices.

Phenotypic and genotypic characteristics of Brucella isolates from the Republic of Kazakhstan.

The purposes of this study were to determine phenotypic and genotypic characteristics of Brucella isolates from the Republic of Kazakhstan and to determine their biotype. The focus was laid on culture-morphological, biochemical, and biological properties of 59 Brucella isolates from primary cultures. Material was isolated from blood and tissue of serum-positive killed, dead diseased, or aborted domestic cattle from different regions of Kazakhstan where brucellosis is a common problem. Multiple-locus variable number tandem repeat analysis (MLVA) of all strains, isolated in different regions, has shown that Brucella isolates from the epizootic form two clusters. Based on the comparison with strains available in the MLVA database, B. abortus 0015/B is alike the B. abortus strains isolated from Italy and Portugal. B. melitensis 0016/B isolated from the Almaty region fits the third cluster and is alike the B. melitensis strains isolated from humans in Turkey, China, and Portugal. More than 90% of the overall B. abortus samples were isolated from the northern regions of the East and West Kazakhstan, while B. melitensis strains were registered in the southeast Kazakhstan. The most frequently recorded B. abortus biovar is biovar 3. The most frequently recorded B. melitensis biovars are biovars 1 and 3. SIGNIFICANCE AND IMPACT OF STUDY: These results contribute to a better understanding of the geographic pattern of Brucella infection in Kazakh cattle also important for developing the specific control measures. The results of current research can be used for creating a gene bank of Brucella strains circulating in Kazakhstan for producing diagnostic and therapeutic agents. The research material will be used to solve the problems of genetic characterization of Brucella species and to establish the phylogenetic relationships of strains.

Identification of Brucella abortus biovar 4 of bovine origin in Colombia.

The objective of this study was to identify twelve Brucella abortus isolates of bovine origin from the department of Nariño in Colombia up to the biovar level. These isolates are included in the collection of the Germplasm Bank of Microorganisms of Animal Health Interest - Bacteria and Virus (BGSA-BV). The identification was carried out through conventional methods such as macro and microscopic morphological descriptions, enzymatic activity, biochemical profile, substrate use and sensitivity to dyes. Complementary genotypic characterization was carried out using multiplex PCR for B. abortus, Brucella melitensis, Brucella ovis, and Brucella suis-Erytritol (AMOS-ERY-PCR), RFLP-IS711, by southern blot hybridization, as well as by the multiple locus variable number of tandem repeat analysis (MLVA) using the ery gene and the insertion sequence IS711 and variable number of tandem repeats (VNTR) as molecular markers. The results of the phenotypic and molecular characterization allowed to identify twelve isolates as B. abortus biovar 4 as well as to differentiate field from vaccine strains. This is the first study on the phenotypic and molecular identification of B. abortus isolates in Colombia. It was concluded that the phenotypic and molecular identification of twelve isolates as B. abortus biovar 4 could be achieved using conventional and molecular techniques with enough resolution power. The identification of these isolates to the biovar level in taxonomic and epidemiological terms will allow the use of this genetic resource as reference strains in future research. This finding constitutes the basis for identifying biotypes not previously reported in the country that might be useful to support brucellosis survey programs in Colombia.

Optimization of Brucella abortus Protocols for Downstream Molecular Applications.

We compared the performances of various DNA extraction kits for their ability to recover Brucella abortus strain 19 inoculated into Brucella-free bovine tissues. Tissues were homogenized in a FastPrep bead homogenizer and extracted in triplicate by using one of five kits (Qiagen DNeasy, GE Illustra, Omega Bio-tek E.Z.N.A., Quanta Extracta, and IBI Science DNA Tissue kit). Whole blood was also taken from animals prior to chemical euthanasia, aliquoted, and then fractioned into buffy coat, red blood cells, and plasma. DNA was extracted from whole blood, buffy coat, and plasma by using four kits (Qiagen DNeasy, Omega Bio-tek E.Z.N.A., IBI Science DNA Blood kit, and 5PRIME PerfectPure). Previously reported primers targeting strain 19 were used to amplify extracted DNA and identify the optimal extraction kit. Real-time PCR was performed, and kits were compared for statistical differences by using quantification cycles as an outcome measure. Omega Bio-tek E.Z.N.A. was superior (P < 0.0068) in its lower quantification cycle values across all tissue kits. The IBI Science DNA Blood kit was superior to Qiagen DNeasy, 5PRIME PerfectPure, and Quanta Extracta (P < 0.0001, P = 0.0004, and P = 0.0013, respectively) but was not different from Omega Bio-tek E.Z.N.A. (P = 1.0). In summary, the optimal extraction kit for B. abortus strain 19 for tissues is Omega Bio-tek E.Z.N.A., and that for blood and its fractions is the IBI Science Mini Genomic DNA kit. Eluted DNA was also concentrated by using the Zymo Research DNA Clean & Concentrator-25 kit. Concentrated eluted DNA with the target was superior (P = <0.0001) to unconcentrated eluted DNA.

Brucella abortus: determination of survival times and evaluation of methods for detection in several matrices.

BACKGROUND: Brucella abortus is a highly pathogenic zoonotic agent, tempting for the development of a rapid diagnostic method to enable adequate treatment and prevent further spread. Enrichment of the bacteria is often used as a first step in diagnostics to increase the bacterial number above the detection limit of the real-time PCR. The enrichment of Brucella spp. takes at least 3 days, which might be avoidable if sensitive PCR methods can be used. Since many matrices contain PCR inhibitors, the limit of detection (LOD) must be determined for each separate matrix. Another aim of this study was the determination of survival of Brucella abortus in the analyzed matrices. METHODS: The LOD for the detection of B. abortus in 14 matrices, relevant for human medicine, veterinary medicine and food and feed safety, was determined to evaluate the need of a pre-enrichment step prior to real-time PCR. The survival of B. abortus in the spiked matrices was tested by plate count in a 7-day interval for 132 days. RESULTS: The limit of detection for B. abortus in most matrices was in the range of 103-104 CFU/g for cultivation and 104-105 CFU/g for direct real-time PCR. The survival time of B. abortus was less than 21 days in apple purée and stomach content and 28 days in water while B. abortus remained viable at day 132 in milk, blood, spinach and minced meat. CONCLUSIONS: A direct PCR analysis without enrichment of bacteria saves at least 3 days. However, the limit of detection between direct PCR and plate count differs in a 10 fold range. We conclude that this lower sensitivity is acceptable in most cases especially if quick analysis are required.

A rapid minor groove binder PCR method for distinguishing the vaccine strain Brucella abortus 104M.

BACKGROUND: Brucellosis is a widespread zoonotic disease caused by Gram-negative Brucella bacteria. Immunisation with attenuated vaccine is an effective method of prevention, but it can interfere with diagnosis. Live, attenuated Brucella abortus strain 104M has been used for the prevention of human brucellosis in China since 1965. However, at present, no fast and reliable method exists that can distinguish this strain from field strains. Single nucleotide polymorphism (SNP)-based assays offer a new approach for such discrimination. SNP-based minor groove binder (MGB) and Cycleave assays have been used for rapid identification of four Brucella vaccine strains (B. abortus strains S19, A19 and RB51, and B. melitensis Rev1). The main objective of this study was to develop a PCR assay for rapid and specific detection of strain 104M. RESULTS: We developed a SNP-based MGB PCR assay that could successfully distinguish strain 104M from 18 representative strains of Brucella (B. abortus biovars 1, 2, 3, 4, 5, 6, 7 and 9, B. melitensis biovars 1, 2 and 3, B. suis biovars 1, 2, 3 and 4, B. canis, B. neotomae, and B. ovis), four Brucella vaccine strains (A19, S19, S2, M5), and 55 Brucella clinical field strains. The assay gave a negative reaction with four non-Brucella species (Escherichia coli, Pasteurella multocida, Streptococcus suis and Pseudomonas aeruginosa). The minimum sensitivity of the assay, evaluated using 10-fold dilutions of chromosomal DNA, was 220 fg for the 104M strain and 76 fg for the single non-104M Brucella strain tested (B. abortus A19). The assay was also reproducible (intra- and inter-assay coefficients of variation = 0.006-0.022 and 0.012-0.044, respectively). CONCLUSIONS: A SNP-based MGB PCR assay was developed that could straightforwardly and unambiguously distinguish B. abortus vaccine strain 104M from non-104M Brucella strains. Compared to the classical isolation and identification approaches of bacteriology, this real-time PCR assay has substantial advantages in terms of simplicity and speed, and also reduces potential exposure to live Brucella. The assay developed is therefore a simple, rapid, sensitive, and specific tool for brucellosis diagnosis and control.

High level of B19 strain detection in Brazilian cattle semen.

Semen contaminated with microorganisms can disseminate serious diseases including brucellosis. The objectives of this study were to detect Brucella-specific antibodies and Brucella abortus DNA in samples of blood and fresh semen from 100 animals older than 20 months. The samples were collected on farms and in semen collection and processing centers (CCPS). The serum samples were evaluated by Rose Bengal test (RBT). B. abortus DNA was detected by a polymerase chain reaction (PCR) using BAB and IS771 primers. The difference between the vaccine field strain was identified using ery-1, ery-2, and ery-3 primers, using the hemi-nested PCR method. No anti-B. abortus antibodies were detected in the serum samples. Out of the total semen samples, 68% (68/100) presented amplifications of the B. abortus genes. All (68/68) were identified as B19 strain of Brucella abortus vaccine. It was concluded that even bulls that are seronegative for brucellosis can eliminate the bacteria in the semen. The presence in the DNA of the B19 vaccine strain should be investigated for a better understanding of the epidemiological importance of this strain in these animals.

Documenting the absence of brucellosis in cattle, goats and dogs in a "One Health" interface in the Mnisi community, Limpopo, South Africa.

This study shows the absence of the world's most common bacterial zoonoses caused by Brucella abortus and Brucella melitensis in cattle, goats and dogs in an agro-pastoral community in South Africa, where heifer vaccination against brucellosis with the live Strain 19 vaccine is compulsory. The study site is bordering wildlife reserves with multiple wildlife species infected with brucellosis. The results showed a low seroprevalence (1.4%) in cattle. Seroprevalence in cattle decreased with age after 4 years in females, males were less positive than females and a tissue culture from a brucellin skin test-positive male was negative. The results indicate that Brucella seropositivity in cattle is due to S19 vaccination and not natural infections. This conclusion is reinforced by the absence of Brucella seropositivity in goats (1/593 positive result) and dogs (0/315), which can be seen as potential spillover hosts. Therefore, the close proximity of brucellosis-infected wildlife is not a threat to domestic animals in this controlled setting with vaccination, fencing and movement control.

ANTIBODIES AGAINST BRUCELLA ABORTUS AND LEPTOSPIRA SPP. IN CAPTIVE MAMMALS IN THE STATES OF PARá AND RIO GRANDE DO NORTE, BRAZIL.

Brazil has a large variety of wild animal species, but limited data are available on the occurrence of Brucella abortus and Leptospira spp. antibodies in these animals. Sera from 141 captive mammals belonging to 11 different species from the Northern and Northeastern regions of Brazil were screened. Antibodies against B. abortus and Leptospira spp. (24 live serovars) were investigated using the Rose Bengal plate and microscopic agglutination tests, respectively. Associations between the age, gender, and place of captivity were analyzed using the Pearson chi-square or the Fisher exact test. None of the animals were antibody positive for B. abortus. Among the animals tested, 11 (7.8%) were seropositive for Leptospira spp. These included one red brocket deer ( Mazama americana), two tufted capuchin ( Sapajus apella), seven agoutis ( Dasyprocta aguti), and one lowland paca ( Cuniculus paca). No association was observed between sex, age, and the occurrence of Leptospira spp. antibodies ( P > 0.05). However, an association was observed according to the place of captivity ( P = 0.046). From these 11 positive animals, six (54.5%) reacted to the serovars from the Icterohaemorraghiae serogroup, which is mainly responsible for the clinical cases of human leptospirosis in Brazil. To our knowledge, this is the first report of Leptospira spp. antibodies in M. americana and C. paca.

Prevalence of Brucella in raw milk: An example from Turkey.

AIM: Brucellosis is a highly contagious zoonotic infection affecting livestock and human beings. This study aimed to investigate the prevalence of Brucella in raw milk collected from a provincial center and central villages in the Central Anatolian region. MATERIALS AND METHODS: This cross-sectional study was completed between March and September of 2016. The sample size for research was calculated as 263 milk samples with the Epi Info 2000 program. Samples were tested with the milk ring test, Rose Bengal test, and standard Brucella tube agglutination test. Suspicious samples according to these tests were seeded on medium for observation. RESULTS: In this study, 202 cow's milk samples collected from 14 central villages were researched for the presence of Brucella abortus, a Brucella species bacterium. According to the medium seeding results, 35 of 202 raw cow's milk samples (17.32%) were identified as suspicious. CONCLUSION: The research investigated the prevalence of Brucella in milk samples collected from bovine farms used for consumption and production of raw milk products. The most significant infection route in our region is considered to be consumption of milk and milk products such as raw milk and fresh cheese. Especially in rural areas, households consuming their own produced milk are common. In regions with family-style milk and milk product production and consumption, interventional studies with the aim of improving knowledge, attitudes, and behavior related to zoonotic diseases should not be neglected.

Brucella abortus Induces the Premature Death of Human Neutrophils through the Action of Its Lipopolysaccharide.

Most bacterial infections induce the activation of polymorphonuclear neutrophils (PMNs), enhance their microbicidal function, and promote the survival of these leukocytes for protracted periods of time. Brucella abortus is a stealthy pathogen that evades innate immunity, barely activates PMNs, and resists the killing mechanisms of these phagocytes. Intriguing clinical signs observed during brucellosis are the low numbers of Brucella infected PMNs in the target organs and neutropenia in a proportion of the patients; features that deserve further attention. Here we demonstrate that B. abortus prematurely kills human PMNs in a dose-dependent and cell-specific manner. Death of PMNs is concomitant with the intracellular Brucella lipopolysaccharide (Br-LPS) release within vacuoles. This molecule and its lipid A reproduce the premature cell death of PMNs, a phenomenon associated to the low production of proinflammatory cytokines. Blocking of CD14 but not TLR4 prevents the Br-LPS-induced cell death. The PMNs cell death departs from necrosis, NETosis and classical apoptosis. The mechanism of PMN cell death is linked to the activation of NADPH-oxidase and a modest but steadily increase of ROS mediators. These effectors generate DNA damage, recruitments of check point kinase 1, caspases 5 and to minor extent of caspase 4, RIP1 and Ca++ release. The production of IL-1ß by PMNs was barely stimulated by B. abortus infection or Br-LPS treatment. Likewise, inhibition of caspase 1 did not hamper the Br-LPS induced PMN cell death, suggesting that the inflammasome pathway was not involved. Although activation of caspases 8 and 9 was observed, they did not seem to participate in the initial triggering mechanisms, since inhibition of these caspases scarcely blocked PMN cell death. These findings suggest a mechanism for neutropenia in chronic brucellosis and reveal a novel Brucella-host cross-talk through which B. abortus is able to hinder the innate function of PMN.

Origins and global context of Brucella abortus in Italy.

BACKGROUND: Brucellosis is a common and chronic disease of cattle and other bovids that often causes reproductive disorders. Natural infection in cattle is caused by Brucella abortus and transmission typically occurs during abortions, calving, or nursing. Brucellosis is also a major zoonotic disease due to contamination of dairy products or contact with the tissues of infected animals. Brucellosis has been eradicated from most of the developed world in the last 40 years but persists in many regions-the disease remains prevalent in portions of Africa, the Middle East, Asia, and Central and South America, as well as in the Mediterranean basin. In Italy, B. abortus has persisted in southern regions in both cattle and water buffalo. Previous attempts at analyzing the phylogenetics of B. abortus in Italy have been challenging due to limited genetic variability and unresolved global population genetic structure of this pathogen. RESULTS: We conducted genome-wide phylogenetic analyses on 11 representative strains of B. abortus from Italy, and compared these sequences to a worldwide collection of publically available genomes. Italian isolates belong to three clades that are basal to the main and global B. abortus lineage. Using six SNP-based assays designed to identify substructure within the Italian clades, we surveyed a collection of 261 isolates and found that one clade predominates throughout endemic districts in the country, while the other two clades are more geographically restricted to portions of southern Italy. CONCLUSIONS: Although related strains exist worldwide, B. abortus isolates from Italy are substantially different than those found in much of the rest of Europe and North America, and are more closely related to strains from the Middle East and Asia. Our assays targeting genetic substructure within Italy allowed us to identify the major lineages quickly and inexpensively, without having to generate whole genome sequences for a large isolate collection. These findings highlight the importance of genetic studies to assess the status and the history of pathogens.

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.

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.