Erythritol triggers expression of virulence traits in Brucella melitensis

Sweeteners affect biofilm formation and virulence gene expression in Pseudomonas aeruginosa PAO1

Pseudomonas aeruginosa is an opportunistic pathogen able to form biofilms, contributing to its virulence. With the increasing use of sweeteners in various foods, understanding their influence on bacterial behavior is critical. This study investigated the virulence of P. aeruginosa PAO1 exposed to sweeteners (erythritol, stevia, fructose, coconut sugar, cane sugar, demerara). Sweeteners didn't affect growth rates. Erythritol stimulated biofilm (100 µg/mL, 159.98% formation), while 10 µg/mL of coconut sugar, cane sugar, and demerara promoted lower levels (∼70% formation). Erythritol stimulated exopolysaccharides production but reduced biofilm eDNA. Stevia, fructose, and coconut sugar increased the expression of lasI, lasR, rhlI, rhlR, pqsA, mvfR, and pvdF. HPLC analysis confirmed sucrose as the major sugar in demerara, coconut and cane sugar. Erythritol stimulated biofilm and some virulence genes expression, while other sweeteners' effects varied. Cane sugar was a biofilm inhibitor with a limited gene expression effect. The sweeteners' impact on microorganisms is diverse and should be further investigated.

Taxonomic and functional profile of the anorectal microbiota in HIV-positive and HIV-negative men who have sex with men, using a metagenomic approach

INTRODUCTION

The study of bacterial diversity in human samples is crucial for developing biomarkers of health and disease. This research characterized the taxonomic and functional diversity of the anorectal bacterial microbiota in men who hae sex with men (MSM) with HIV compared to men from this group without HIV.

MATERIALS AND METHODS

In July and August 2023, self-collected anorectal swabs were obtained. DNA was extracted from each sample, and metagenomic sequencing was performed. With the obtained data, alpha and beta diversity, bacterial abundance, differential operational taxonomic units, and functional diversity were determined.

RESULTS

Initially, 90 samples were collected, with 20 discarded due to having less than 200 ng of DNA and 15 due to incomplete sequencing, leaving 55 samples analysed (15 HIV-positive and 40 HIV-negative). No significant differences were found between groups in terms of alpha diversity (Shannon index p = 0.45) and beta diversity (PERMANOVA R = -0.03). Prevotella was identified as the most abundant genus in both groups. Twelve genes were found to be more abundant in the anorectal microbiota of the HIV group, which promote bacterial growth, colonization and survival.

CONCLUSION

Alterations in the anorectal microbiota could influence the pathogenesis of HIV and its complications in this population, underscoring the need to investigate these mechanisms and explore interventions to improve health. Longitudinal studies are needed to analyse changes in the anorectal microbiota during HIV infection and its response to treatment, integrating metagenomic, clinical, and immunological data to better understand the interactions between HIV, the microbiota and host health.

Two Decades of Melioidosis in India: A Comprehensive Epidemiological Review

Melioidosis, caused by Burkholderia pseudomallei, is a potentially fatal infection, particularly affecting individuals with chronic conditions such as diabetes or kidney or liver diseases. This review examines melioidosis in India over the past two decades, focusing on its prevalence, risk factors and clinical manifestations. A PubMed search (2000-2024) identified a rise in melioidosis publications, with most from Southern India, followed by Eastern India, and an increase post-2019. Eight studies from 2010-2022 identified fever (86%), cough (26%) and joint pain (23%) as the most common symptoms, while diabetes (75%), alcohol abuse (19%) and cancer (6%) were primary predisposing factors. Severe clinical manifestations were also observed, including bacteremia (50%), pneumonia (37%) and splenic abscess (18%). Although environmental exposure risks were not significantly high, individuals with diabetes or chronic kidney disease, particularly those working in high-risk environments, were more likely to contract melioidosis. Cryptic environmental factors that might bridge known epidemiological risk factors are also addressed. The review emphasizes the increasing awareness and research in clinical epidemiology and also highlights a gap in studies on antimicrobial treatments, vaccines and environmental surveillance. Targeted interventions in diabetes and poverty hotspots could help control the disease more effectively.

Investigation into the sero-molecular prevalence of Brucella melitensis in small ruminants in districts Mohmand and Charsadda Khyber Pakhtunkhwa Pakistan

Globally, ruminants contribute largely to the livelihood and supply of quality food for human consumption. However, small ruminants face numerous problems, including infectious diseases, in lower- and middle-income countries (LMIC). Brucellosis is one of the important zoonotic diseases affecting the range of animals caused by Brucella species, including Brucella abortus and Brucella mellitensis. Although brucellosis caused by B. mellitensis in small ruminants has never been reported in the study areas, its zoonotic importance can never be underestimated. Therefore, this study was designed to investigate the sero-molecular prevalence of B. mellitensis in small ruminants in districts Mohmand and Charsadda of Khyber Pakhtunkhwa, Pakistan. A total of 400 blood samples were collected from sheep and goats (n = 200 from each species) and analyzed by Rose Bengal precipitation test (RBPT), the indirect enzyme-linked immunosorbent assay (i-ELISA) and polymerase chain reaction (PCR). The findings of the study indicated 13.5% and 7% of sheep while 12.5% and 12.5% of goat's samples by RBPT and (i-ELISA) respectively. The species-specific PCR confirmed B. abortus in 70% of sheep samples and 37.5% of goat's samples and B. mellitensis in 25% of sheep and 62.5% of goat's samples by targeting IS711. The findings of the study concluded that B. abortus and B. melitensis were circulating in sheep and goats with a higher prevalence in the study areas. This study detected the presence of B. mellitensis for the first time in small ruminants in the study areas.

Brucella induced upregulation of NO promote macrophages glycolysis through the NF-κB/G6PD pathway

Increased glycolytic metabolism recently emerged as an essential process driving host defense against Brucella, but little is known about how this process is regulated during infection. We have identified a critical role for nuclear factor kappa B (NF-κB) transcription factor regulation in glycolytic switching during Brucella infection for the first time. Chromatin immunoprecipitation with next-generation sequencing for NF-κB and DNA Pull-Down revealed two novel NF-κB-binding sites in the enhancer region of the Nitric oxide (NO)production-response regulator gene glucose-6-phosphate dehydrogenase (G6PD), which is important for the switch to glycolysis during a Brucella infection. These findings demonstrate that Brucella drives metabolic reprogramming by inhibiting host oxidative phosphorylation (OXPHOS) and enhancing its glycolysis via the NF-κB-G6PD-NO-pathway. These studies provide a theoretical basis for investigating drugs or vaccines to control Brucella colonization and induction of undulant by manipulating host metabolic patterns.

Brucellosis in pregnancy: a case report

Background

Brucella spp., a gram-negative bacterium, is one of the most prevalent zoonotic illnesses worldwide and is more commonly seen in animals; however, the disease may be present in humans. Clinical manifestations of brucellosis are variable and can range from asymptomatic to severe disease. In women who are pregnant, potential obstetrics complications are possible. The purpose of this report is to present a case of brucellosis in a pregnant patient and discuss the potential complications and treatment recommendations.

Case Description

We present a case of a 17-year-old gravida 2, parity 1 (G2P1) at 35 weeks and 2 days (35w2d) with brucellosis after she assisted in the delivery of puppies. All puppies were stillborn and the dog was confirmed positive for B. canis on serological testing. Our patient was also found to have B. canis, which is a particularly rare cause of human brucellosis. She was treated with ceftriaxone, rifampin, and gentamicin before delivery and switched to doxycycline and ceftriaxone postpartum until negative. The patient was instructed not to breastfeed. After treatment, the patient felt well and the baby was healthy.

Conclusions

When evaluating patients, it is necessary to obtain a social history including animal exposures to rule in or rule out zoonotic infections such as brucellosis. It is important to establish a suspected brucellosis infection in pregnancy and begin antibiotic treatment as soon as possible to prevent maternal and fetal complications. The treatment regimen we administered was an effective strategy, particularly for pregnancy, when typical treatments are contraindicated.

An 8000 years old genome reveals the Neolithic origin of the zoonosis Brucella melitensis

Brucella melitensis is a major livestock bacterial pathogen and zoonosis, causing disease and infection-related abortions in small ruminants and humans. A considerable burden to animal-based economies today, the presence of Brucella in Neolithic pastoral communities has been hypothesised but we lack direct genomic evidence thus far. We report a 3.45X B. melitensis genome preserved in an ~8000 year old sheep specimen from Menteşe Höyük, Northwest Türkiye, demonstrating that the pathogen had evolved and was circulating in Neolithic livestock. The genome is basal with respect to all known B. melitensis and allows the calibration of the B. melitensis speciation time from the primarily cattle-infecting B. abortus to approximately 9800 years Before Present (BP), coinciding with a period of consolidation and dispersal of livestock economies. We use the basal genome to timestamp evolutionary events in B. melitensis, including pseudogenization events linked to erythritol response, the supposed determinant of the pathogen's placental tropism in goats and sheep. Our data suggest that the development of herd management and multi-species livestock economies in the 11th-9th millennium BP drove speciation and host adaptation of this zoonotic pathogen.

Brucellosis: Unveiling the complexities of a pervasive zoonotic disease and its global impacts

One zoonotic infectious animal disease is brucellosis. The bacteria that cause brucellosis belong to the genus Brucella. Numerous animal and human species are affected by brucellosis, with an estimated 500,000 human cases recorded annually worldwide. The occurrence of new areas of infection and the resurgence of infection in already infected areas indicate how dynamically brucellosis is distributed throughout different geographic regions. Bacteria originate from the blood and are found in the reticuloendothelial system, the liver, the spleen, and numerous other locations, including the joints, kidneys, heart, and genital tract. Diagnosis of this disease can be done by bacterial isolation, molecular tests, modified acid-fast stain, rose bengal test (RBT), milk ring test, complement fixation test, enzyme-linked immunosorbent assay, and serum agglutination test. The primary sign of a Brucella abortus infection is infertility, which can result in abortion and the birth of a frail fetus that may go on to infect other animals. In humans, the main symptoms are acute febrile illness, with or without localization signs, and chronic infection. Female cattle have a greater risk of contracting Brucella disease. Human populations at high risk of contracting brucellosis include those who care for cattle, veterinarians, slaughterhouse employees, and butchers. Antibiotic treatment of brucellosis is often unsuccessful due to the intracellular survival of Brucella and its adaptability in macrophages. A "one health" strategy is necessary to control illnesses like brucellosis.

Seroepidemiology and associated risk factors of brucellosis in small ruminants of district Khanewal, Pakistan

Objectives

Keeping in view the economic and veterinary public health importance of brucellosis, this research was conducted to determine its seroprevalence and associated risk determinants in small ruminants in district Khanewal, Southern Punjab, Pakistan.

Materials and Methods

Two-stage cluster sampling technique was used for sampling, and the sample size was calculated using C-survey 2.0. Accordingly, sera samples (n = 392) were collected from small ruminants in the study area from October 2022 to July 2023. All the samples were tested for the presence of anti-Brucella antibodies by Rose Bengal Plate Test (RBPT), followed by confirmation of all the samples using an enzyme linked immunosorbent assay (ELISA) kit (ID.vet®, France; sensitivity and specificity=100%, each).

Results

The seropositivity rate of brucellosis was 7.14% [n = 28/392; 95% confidence interval (CI) = 4.87%-10.12%] by RBPT, whereas the results of ELISA showed an overall seroprevalence rate of 7.40% (n = 29/392; 95% CI = 5.11%-10.37%) in the study population. Univariate analysis of risk factors revealed that abortion history (AH), retained fetal membranes (RFMs), repeat breeding, flock size (FS), educational status of farmers (ESFs), awareness about brucellosis (AB), and farm hygiene had a significant association with the seroprevalence of brucellosis (p < 0.05). The multivariate analysis using a binary logistic regression model revealed that variables including tehsil, FS, AH, RFM, ESF, AB, and farming system were significant factors (p < 0.05) associated with brucellosis in the target population.

Conclusion

Brucellosis is prevalent in small ruminants in Khanewal, Pakistan. The disease burden can be reduced by improving the reproductive health of animals, farm hygiene, and farmers' awareness about the diseases. Further studies are needed on a larger scale to devise stringent disease control strategies to avoid losses associated with brucellosis at regional, national, and global levels.

Erythronate utilization activates VdtR regulating its metabolism to promote Brucella proliferation, inducing abortion in mice

Brucella is a facultative intracellular pathogen that preferentially colonizes reproductive organs and utilizes erythritol as a preferred carbon source for its survival and proliferation. In this study, we identified a virulence-related DeoR-family transcriptional regulator (VdtR) and an erythronate metabolic pathway responsible for four-carbon acid sugar metabolism of D-erythronate and L-threonate in Brucella. We found that VdtR plays an important role in Brucella intracellular survival and trafficking to the endoplasmic reticulum in RAW 264.7 macrophages and in virulence in a mouse model. More importantly, we found that VdtR negatively regulates the erythronate metabolic pathway to promote extracellular proliferation of Brucella, depending on utilization of D-erythronate, an oxidative product of erythritol in the host. In a pregnant mouse model, the erythronate metabolic pathway was shown to cooperate with erythritol metabolism and play a crucial role in Brucella proliferation in the placenta, inducing placentitis and finally resulting in abortion or stillbirth. Our results demonstrate that, in addition to erythritol, erythronate is a preferred carbon source for Brucella utilization to promote its extracellular proliferation. This discovery updates the information on the preferential colonization of reproductive organs by Brucella and provides a novel insight into the Brucella-associated induction of abortion in pregnant animals. IMPORTANCE Brucella is an intracellular parasitic bacterium causing zoonosis, which is distributed worldwide and mainly characterized by reproductive disorders. Erythritol is found in allantoic fluid, chorion, and placenta of aborted animals, preferentially utilized by Brucella to cause infertility and abortion. However, the erythritol metabolism-defected mutant was unable to function as a vaccine strain due to its residual virulence. Here, we found that erythronate, an oxidative product of erythritol in the host, was also preferentially utilized by Brucella relying on the function of a deoxyribonucleoside regulator-family transcriptional regulator VdtR. Erythronate utilization activates VdtR regulation of the erythronate metabolic pathway to promote Brucella extracellular proliferation, inducing placentitis/abortion in mice. Double mutations on Brucella erythritol and D-erythronate metabolisms significantly reduced bacterial virulence. This study revealed a novel mechanism of Brucella infection-induced abortion, thus providing a new clue for the study of safer Brucella attenuated vaccines.

Occurrence and Risk Factors of Brucellosis in Commercial Cattle Farms from Selected Districts of the Eastern Coast Zone, Tanzania

Brucellosis is a disease of major socio-economic importance worldwide, particularly in low-income countries. This retrospective study aimed to estimate seroprevalence and risk factors associated with brucellosis in commercial cattle farms in the eastern coast zone of Tanzania (ECZT). A total of 1,052 serum samples collected from 20 commercial farms were subjected to rose bengal plate test (RBPT) and indirect enzyme-linked immunosorbent assay (i-ELISA). Descriptive analysis was employed to determine frequencies and proportions. To establish risk factors, a multivariate logistic regression analysis was carried out using a backward elimination procedure, following a univariate analysis, with 0.1 set as a cut-off point for the selection of putative risk factors. Agreement between RBPT and i-ELISA was determined using a Kappa coefficient (κ). The overall animal-level seroprevalence was 25.9% based on i-ELISA. Logistic regression analysis revealed that odds of infection were significantly higher in females (OR = 1.8, 95% CI: 1.2-2.5, p = 0.002) and in young animals than in adults (OR = 3.6, CI: 2.1-6.2, p < 0.001). In addition, odds of infection were higher during the wet season (OR = 3.4, CI: 3.2-5.2, p < 0.001), in cattle reared in rural farms (OR = 4.8, CI: 2.0-11.5, p < 0.001), in cattle reared in areas, not in contact with wildlife (OR = 2.9, CI: 1.4-2.3, p = 0.004), and in medium-sized farms (OR = 12.5, CI: 6.9-22.9, p < 0.001). These findings confirm that bovine brucellosis was prevalent among commercial cattle farms in the ECZT, posing a serious public health concern to the community living in these settings. The one health approach should be adopted for effective control of brucellosis.

The Effect of Erythritol Injection in Decreasing of Abortion Rate in Local Breed Ewes

This study designed to evaluate the effect of Erythritol injection in decreasing of abortion rate in local breed ewes. Fifty pregnant ewes from local breed aged 2-4 years with a history of abortion except G1, were fed ad libitum hay and grains with water. The study was carried out in Salah Aldein province at special farm at a period of July-November 2022. These animals were tests for brucella by using rose Bengal and ELISA at zero day for confirmation; these animals were divided into 5 groups: G1 was brucella -ve and pregnant at 60 days, G2 was brucella +ve and pregnant at 60 days, G3 brucella+ve pregnant animals and treated by antibiotics gentamicin 10%, 3 ml/animal for 3 days, G4 brucella +ve and pregnant and giving erythritol, 10 ml S/C of 10% solution (solve in water and glycerol), and G5 was brucella +ve, and all pregnant and giving Erythritol+ gentamycin 10%, 3 ml/animal for 3 days. The experiment takes 12 weeks. Blood was withdrawn at different times of experiment (0, 2 weeks and end of experiment). The seroprevalence of brucellosis was shown that all animals at G4 and G5 where seropositive after 14 days of experiment, at end of pregnancy the seropositivity were highly significantly in G4 and G5 as compared with another groups. The current results showed that percentages of abortion were higher in G2, followed by G3, while it has been reduced significantly in G4 and G1. In conclusion, Erythritol alone can decrease the rate of abortion by making the bacteria extracellular far from placenta and evading of infection by immunity and/or gentamicin injection. Also, erythritol can be used as elicit diagnosis of brucellosis in latent infected animals.

The Flagellar Transcriptional Regulator FtcR Controls Brucella melitensis 16M Biofilm Formation via a betI-Mediated Pathway in Response to Hyperosmotic Stress

The expression of flagellar proteins in Brucella species likely evolved through genetic transference from other microorganisms, and contributed to virulence, adaptability, and biofilm formation. Despite significant progress in defining the molecular mechanisms behind flagellar gene expression, the genetic program controlling biofilm formation remains unclear. The flagellar transcriptional factor (FtcR) is a master regulator of the flagellar system’s expression, and is critical for B. melitensis 16M’s flagellar biogenesis and virulence. Here, we demonstrate that FtcR mediates biofilm formation under hyperosmotic stress. Chromatin immunoprecipitation with next-generation sequencing for FtcR and RNA sequencing of ftcR-mutant and wild-type strains revealed a core set of FtcR target genes. We identified a novel FtcR-binding site in the promoter region of the osmotic-stress-response regulator gene betI, which is important for the survival of B. melitensis 16M under hyperosmotic stress. Strikingly, this site autoregulates its expression to benefit biofilm bacteria’s survival under hyperosmotic stress. Moreover, biofilm reduction in ftcR mutants is independent of the flagellar target gene fliF. Collectively, our study provides new insights into the extent and functionality of flagellar-related transcriptional networks in biofilm formation, and presents phenotypic and evolutionary adaptations that alter the regulation of B. melitensis 16M to confer increased tolerance to hyperosmotic stress.

Survival characteristics and transcriptome profiling reveal the adaptive response of the Brucella melitensis 16M biofilm to osmotic stress

Brucella can inhabit hostile environments, including osmotic stress. How Brucella responds collectively to osmotic stress is largely unexplored, particularly in spatially structured communities such as a biofilm. To gain insight into this growth mode, we set out to characterize the Brucella melitensis 16M biofilm, describe its phenotype, and carry out a comparative transcriptomic analysis between biofilms under osmotic stress and control conditions. We determined that the bacteria challenged with 1.5 M NaCl had a reduced ability to aggregate and form clumps and develop a biofilm; however, the salt stress promoted the release of the outer membrane vesicles from the biofilm. Together with the genotypical response to osmotic stress, we identified 279 differentially expressed genes in B. melitensis 16M grown under osmotic conditions compared with control conditions; 69 genes were upregulated and 210 downregulated. Under osmotic stress, the main changed genes of biofilm were predicted to be involved in flagellar assembly, cell envelope, translation, small RNA regulation, transport and binding proteins, and energy metabolism. In addition, the ABC transporter was enriched in the Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. We highlight 12 essential ABC transporter genes associated with a bacterial response to osmotic stress at the biofilm stage, including one specific locus, BME_RS12880, mediating betaine accumulation in biofilms to eliminate osmotic stress. The current study results can help researchers gain insights into B. melitensis 16M biofilm adaptation to osmotic stress and provide information for developing intervention strategies to control Brucella.

Comparative Review of Brucellosis in Small Domestic Ruminants

Brucella melitensis and Brucella ovis are the primary etiological agents of brucellosis in small domestic ruminants. B. melitensis was first isolated in 1887 by David Bruce in Malta Island from spleens of four soldiers, while B. ovis was originally isolated in Australia and New Zealand in early 1950's from ovine abortion and rams epididymitis. Today, both agents are distributed worldwide: B. melitensis remains endemic and associated with an extensive negative impact on the productivity of flocks in -some regions, and B. ovis is still present in most sheep-raising regions in the world. Despite being species of the same bacterial genus, B. melitensis and B. ovis have extensive differences in their cultural and biochemical characteristics (smooth vs. rough colonial phases, serum and CO2 dependence for in vitro growth, carbohydrate metabolism), host preference (female goat and sheep vs. rams), the outcome of infection (abortion vs. epididymitis), and their zoonotic potential. Some of these differences can be explained at the bacterial genomic level, but the role of the host genome in promoting or preventing interaction with pathogens is largely unknown. Diagnostic techniques and measures to prevent and control brucellosis in small ruminants vary, with B. melitensis having more available tools for detection and prevention than B. ovis. This review summarizes and analyzes current available information on: (1) the similarities and differences between these two etiological agents of brucellosis in small ruminants, (2) the outcomes after their interaction with different preferred hosts and current diagnostic methodologies, (3) the prevention and control measures, and (4) alerting animal producers about the disease and raise awareness in the research community for future innovative activities.

Mining the Flavoproteome of Brucella ovis, the Brucellosis Causing Agent in Ovis aries

Flavoproteins are a diverse class of proteins that are mostly enzymes and contain as cofactors flavin mononucleotide (FMN) and/or flavin adenine dinucleotide (FAD), which enable them to participate in a wide range of physiological reactions. We have compiled 78 potential proteins building the flavoproteome of Brucella ovis (B. ovis), the causative agent of ovine brucellosis. The curated list of flavoproteins here reported is based on (i) the analysis of sequence, structure and function of homologous proteins, and their classification according to their structural domains, clans, and expected enzymatic functions; (ii) the constructed phylogenetic trees of enzyme functional classes using 19 Brucella strains and 26 pathogenic and/or biotechnological relevant alphaproteobacteria together with B. ovis; and (iii) the evaluation of the genetic context for each entry. Candidates account for ∼2.7% of the B. ovis proteome, and 75% of them use FAD as cofactor. Only 55% of these flavoproteins belong to the core proteome of Brucella and contribute to B. ovis processes involved in maintenance activities, survival and response to stress, virulence, and/or infectivity. Several of the predicted flavoproteins are highly divergent in Brucella genus from revised proteins and for them it is difficult to envisage a clear function. This might indicate modified catalytic activities or even divergent processes and mechanisms still not identified. We have also detected the lack of some functional flavoenzymes in B. ovis, which might contribute to it being nonzoonotic. Finally, potentiality of B. ovis flavoproteome as the source of antimicrobial targets or biocatalyst is discussed. IMPORTANCE Some microorganisms depend heavily on flavin-dependent activities, but others maintain them at a minimum. Knowledge about flavoprotein content and functions in different microorganisms will help to identify their metabolic requirements, as well as to benefit either industry or health. Currently, most flavoproteins from the sheep pathogen Brucella ovis are only automatically annotated in databases, and only two have been experimentally studied. Indeed, certain homologues with unknown function are not characterized, and they might relate to still not identified mechanisms or processes. Our research has identified 78 members that comprise its flavoproteome, 76 of them flavoenzymes, which mainly relate to bacteria survival, virulence, and/or infectivity. The list of flavoproteins here presented allows us to better understand the peculiarities of Brucella ovis and can be applied as a tool to search for candidates as new biocatalyst or antimicrobial targets.

Seroprevalence of camel brucellosis in Qatar

Brucellosis is a significant zoonotic disease and one of the most common neglected diseases worldwide. It can infect a wide range of domestic and wild animal species. Infected animals are usually culled, causing substantial economic losses to animal owners and the country's economy in general. The disease is endemic among cattle, sheep, and goats in many countries around the Middle East and prevalent in most Gulf Cooperation Council countries, comprising a significant public health risk in the region. This study investigated the seroprevalence of brucellosis among camels in Qatar. Two hundred and forty-eight samples were collected from dromedary camels from 28 farms across the entire country. Each sample was tested for Brucella antibodies with both Rose Bengal and competitive enzyme-linked immunosorbent assay. Only samples that tested positive by both tests were considered seropositive for brucellosis. The overall prevalence was (20.6%, 95% CI, 15.7-26.1). The association between sex and seropositivity was slightly significant (Χ² = 4.32, P = 0.04), with higher seroprevalence in females. Camels below breeding age (i.e., < 4 years old) showed decreased seropositivity (3.4%, 95% CI, 0.1-17.8), compared to (22.8%, 95% CI, 17.4-29.0) seropositivity in camels ≥ 4 years of age, with a significant association between age groups and seropositivity (P = 0.02). Our results indicate that the seroprevalence of brucellosis in Qatar's camels is alarming, mandating more efforts to control the disease. The findings of this study will aid in selecting better effective measures to control camel brucellosis in Qatar. Further studies need to be conducted on Brucella infection among camels to determine the predisposing risk factors and the steps that should be followed to control brucellosis.

A 'Multiomic' Approach of Saliva Metabolomics, Microbiota, and Serum Biomarkers to Assess the Need of Hospitalization in Coronavirus Disease 2019

BACKGROUND AND AIMS

The SARS-CoV-2 pandemic has overwhelmed the treatment capacity of the health care systems during the highest viral diffusion rate. Patients reaching the emergency department had to be either hospitalized (inpatients) or discharged (outpatients). Still, the decision was taken based on the individual assessment of the actual clinical condition, without specific biomarkers to predict future improvement or deterioration, and discharged patients often returned to the hospital for aggravation of their condition. Here, we have developed a new combined approach of omics to identify factors that could distinguish coronavirus disease 19 (COVID-19) inpatients from outpatients.

METHODS

Saliva and blood samples were collected over the course of two observational cohort studies. By using machine learning approaches, we compared salivary metabolome of 50 COVID-19 patients with that of 270 healthy individuals having previously been exposed or not to SARS-CoV-2. We then correlated the salivary metabolites that allowed separating COVID-19 inpatients from outpatients with serum biomarkers and salivary microbiota taxa differentially represented in the two groups of patients.

RESULTS

We identified nine salivary metabolites that allowed assessing the need of hospitalization. When combined with serum biomarkers, just two salivary metabolites (myo-inositol and 2-pyrrolidineacetic acid) and one serum protein, chitinase 3-like-1 (CHI3L1), were sufficient to separate inpatients from outpatients completely and correlated with modulated microbiota taxa. In particular, we found Corynebacterium 1 to be overrepresented in inpatients, whereas Actinomycetaceae F0332, Candidatus Saccharimonas, and Haemophilus were all underrepresented in the hospitalized population.

CONCLUSION

This is a proof of concept that a combined omic analysis can be used to stratify patients independently from COVID-19.

Brucella and Its Hidden Flagellar System

Brucella, a Gram-negative bacterium with a high infective capacity and a wide spectrum of hosts in the animal world, is found in terrestrial and marine mammals, as well as amphibians. This broad spectrum of hosts is closely related to the non-classical virulence factors that allow this pathogen to establish its replicative niche, colonizing epithelial and immune system cells, evading the host's defenses and defensive response. While motility is the primary role of the flagellum in most bacteria, in Brucella, the flagellum is involved in virulence, infectivity, cell growth, and biofilm formation, all of which are very important facts in a bacterium that to date has been described as a non-motile organism. Evidence of the expression of these flagellar proteins that are present in Brucella makes it possible to hypothesize certain evolutionary aspects as to where a free-living bacterium eventually acquired genetic material from environmental microorganisms, including flagellar genes, conferring on it the ability to reach other hosts (mammals), and, under selective pressure from the environment, can express these genes, helping it to evade the immune response. This review summarizes relevant aspects of the presence of flagellar proteins and puts into context their relevance in certain functions associated with the infective process. The study of these flagellar genes gives the genus Brucella a very high infectious versatility, placing it among the main organisms in urgent need of study, as it is linked to human health by direct contact with farm animals and by eventual transmission to the general population, where flagellar genes and proteins are of great relevance.

Effect of erythritol and xylitol on Streptococcus pyogenes causing peritonsillar abscesses

Polyols are effective against caries-causing streptococci but the effect on oropharynx-derived pyogenic streptococci is not well characterised. We aimed to study the effect of erythritol (ERY) and xylitol (XYL) against Streptococcus pyogenes isolated from peritonsillar abscesses (PTA). We used 31 clinical isolates and 5 throat culture collection strains. Inhibition of bacterial growth by polyols at 2.5%, 5% and 10% concentrations was studied and the results were scored. Amylase levels in PTA pus were compared to polyol effectivity scores (PES). Growth curves of four S. pyogenes isolates were analysed. Our study showed that XYL was more effective than ERY inhibiting 71–97% and 48–84% of isolates, respectively, depending of concentrations. 48% of clinical and all throat strains were inhibited by polyols in all concentrations (PES 3). PES was negative or zero in 26% of the isolates in the presence of ERY and in 19% of XYL. ERY enhanced the growth of S. pyogenes isolated from pus with high amylase levels. Polyols in all concentrations inhibited the growth in exponential phase. In conclusion, ERY and XYL are potent growth inhibitors of S. pyogenes isolated from PTA. Therefore, ERY and XYL may have potential in preventing PTA in the patients with frequent tonsillitis episodes.

Pathological changes, distribution and detection of Brucella melitensis in foetuses of experimentally-infected does

Background

Brucellosis of goats is caused by Brucella melitensis. It is a re-emerging zoonotic disease in many countries due to transmission from domestic animals and wildlife such as ibex, deer and wild buffaloes.

Objective

To describe the pathological changes, identification and distribution of B. melitensis in foetuses of experimentally infected does.

Methods

Twelve female goats of approximately 90 days pregnant were divided into 4 groups. Group 1 was exposed intra-conjunctival to 100 µL of sterile PBS while goats of Groups 2, 3 and 4 were similarly exposed to 100 µL of an inoculum containing 10⁹ CFU/mL of live B. melitensis. Goats of these groups were killed at 15, 30 and 60 days post-inoculation, respectively. Foetal fluid and tissues were collected for bacterial identification (using direct bacterial culture, PCR and immuno-peroxidase staining) and histopathological examination.

Results

Bilateral intra-conjunctival exposure of pregnant does resulted in in-utero infection of the foetuses. All full-term foetuses of group 4 were either aborted or stillborn, showing petechiations of the skin or absence of hair coat with subcutaneous oedema. The internal organs showed most severe lesions. Immune-peroxidase staining revealed antigen distribution in all organs that became most extensive in group 4. Brucella melitensis was successfully isolated from the stomach content, foetal fluid and various other organs.

Conclusion

Vertical transmission of caprine brucellosis was evident causing mild to moderate lesions in different organs. The samples of choice for isolation and identification of B. melitensis are stomach content as well as liver and spleen tissue.

Phenotypic changes in group B streptococci grown in the presence of the polyols, erythritol, sorbitol and mannitol

BACKGROUND

Group B streptococci (GBS) are important neonatal bacterial pathogens that can cause severe invasive disease in the newborn. It is thought that in many cases of invasive neonatal GBS disease, the bacteria ascend the vagina into the uterus and infect the amniotic fluid surrounding the fetus. Important constituents of this environment include the polyols or sugar alcohols of which erythritol, sorbitol and mannitol are examples. The aim of our study was to investigate the effect of polyols on GBS grown in media containing these sugar alcohols.

RESULTS

GBS incubated in varying concentrations of polyols (erythritol, sorbitol or mannitol) did not display any significant enhancement or inhibition of bacterial growth. However, growth of GBS in the presence of erythritol significantly increased the surface expression of GBS-PGK (a plasminogen binding protein) 1.25 to 1.5-fold depending on the erythritol concentration and significantly enhanced the survival in human blood 3X to 18X depending on the concentration of polyol used. Interestingly, GBS grown in 1% erythritol significantly increased invasion by the bacteria of HeLa cells (epithelial cell line) (150% vs 100%) however, at higher concentrations (2% or 4% of polyol) the number of CFUs was significantly reduced (55-75% vs 100%) suggesting higher concentrations of polyols may inhibit invasion. Erythritol also increased GBS hemolytic activity as well as enhancing biofilm formation 1.4X to 3.3X depending on the concentration of polyol used.

CONCLUSIONS

GBS grown in the presence of polyols alters the bacteria's phenotype resulting in changes associated with GBS virulence. This effect was greatest for the polyol erythritol.

Seroconversion to Brucella spp. and Toxoplasma gondii in Sheep and Goats in Dohuk Province, Iraq and Its Association with Pregnancy Loss

Simple Summary

Brucellosis and toxoplasmosis cause economic losses in small ruminants, notably through abortions. Both Brucella melitensis and Toxoplasma gondii are important zoonotic agents with infection of the former arising from contact with infected small ruminants or their products and the latter through ingestion of tissue cysts in undercooked/raw meat products of livestock or from oocysts from cats. In Iraq, factors which influence reproductive failure in small ruminants are mostly unknown; however, of the many endemic diseases present, brucellosis and toxoplasmosis are considered important in reducing reproductive output and productivity. This study is part of an integrated research project aiming at understanding the epidemiology of reproductive diseases in small ruminants in northern Iraq. We present in this work a prospective cohort study aiming to determine the incidence risk of seroconversion to Brucella and Toxoplasma and the association of seroconversion with the reproductive outcome in pregnant sheep and goats in Dohuk, northern Iraq.

Abstract

In this study, sera from 240 small ruminants (192 sheep and 48 goats) belonging to 12 farms in Dohuk Province, northern Iraq, were collected on two occasions to investigate the incidence risk of seroconversion to Brucella spp. and Toxoplasma gondii. All selected animals were confirmed pregnant (approximately 2 months pregnant) by ultrasound examination at the time of the first blood collection. A second ultrasound examination and blood sampling were undertaken two months after the initial scanning/sampling. Antibodies to Brucella were tested using the Rose Bengal Test (RBT) and an indirect enzyme-linked immunosorbent assay (iELISA), and the results were interpreted in series. The Latex Agglutination Test (LAT) and an indirect enzyme-linked immunosorbent assay (iELISA) were also used in series to confirm the presence of antibodies to T. gondii. The seroprevalence for Brucella and Toxoplasma increased significantly between the two sampling times (p = 0.0003 and 0.03 in first and second sampling, respectively). The incidence risk of seroconversion to Brucella over the two months was 10.6% (95% CI: 6.9–15.3) and 7.3% (95% CI: 4.3–11.6) for Toxoplasma. Animals that seroconverted to Brucella were 2.9 times more likely to lose their pregnancy (95% CI: 1.6–5.5) than animals that remained seronegative; however, seroconversion to Toxoplasma had no significant impact on loss of pregnancy. This study is the first reported investigation on the association of seroconversion to Brucella and Toxoplasma with the reproductive outcome of pregnant sheep and goats in northern Iraq. Brucellosis and toxoplasmosis continue to negatively impact small ruminants’ reproductive performance and compromising food security in Iraq. It is hoped that this study will assist the development of a better-informed economic model to estimate Brucella and Toxoplasma burden in small animals in northern Iraq, and such a model could be used to validate the impact of various potential intervention programs in.

Uncovering the Hidden Credentials of Brucella Virulence

Bacteria in the genus Brucella are important human and veterinary pathogens. The abortion and infertility they cause in food animals produce economic hardships in areas where the disease has not been controlled, and human brucellosis is one of the world's most common zoonoses. Brucella strains have also been isolated from wildlife, but we know much less about the pathobiology and epidemiology of these infections than we do about brucellosis in domestic animals. The brucellae maintain predominantly an intracellular lifestyle in their mammalian hosts, and their ability to subvert the host immune response and survive and replicate in macrophages and placental trophoblasts underlies their success as pathogens. We are just beginning to understand how these bacteria evolved from a progenitor alphaproteobacterium with an environmental niche and diverged to become highly host-adapted and host-specific pathogens. Two important virulence determinants played critical roles in this evolution: (i) a type IV secretion system that secretes effector molecules into the host cell cytoplasm that direct the intracellular trafficking of the brucellae and modulate host immune responses and (ii) a lipopolysaccharide moiety which poorly stimulates host inflammatory responses. This review highlights what we presently know about how these and other virulence determinants contribute to Brucella pathogenesis. Gaining a better understanding of how the brucellae produce disease will provide us with information that can be used to design better strategies for preventing brucellosis in animals and for preventing and treating this disease in humans.

Seroprevalence of Bovine Brucellosis in Selected Districts of Zambia

Brucellosis is an infectious zoonosis that has huge economic and public health implications globally. The disease is prevalent in humans, livestock and wildlife in Sub-Saharan Africa. A cross-sectional study was conducted between 6 May 2017 and 31 July 2020 during which 1712 sera from 175 cattle herds in five districts from Southern, Western and Eastern Provinces of Zambia were collected and screened against brucellosis. The Rose Bengal Test (RBT) and competitive Enzyme-linked Immuno Assay (c-ELISA) were used in serial testing for the detection of antibodies against Brucella species. A total of 127 animals from 37 herds tested positive, giving overall individual animal and herd-level seroprevalences of 7.53% (95% CI: 6.28–8.78%) and 21.14% (95% CI: 15.0–27.2%), respectively. Namwala district had the highest herd seroprevalence (33.9%, 95% CI: 21.6–46.1%), while Lundazi did not record any seropositivity. Comparably, Southern Province had the highest individual animal (8.97%, 95% CI: 7–11%) and herd-level (28.5%, 95% CI: 20.3–36.7%) seroprevalences, although this was not statistically significant. Within Southern Province, higher seropositivity was observed in Namwala district (OR: 8.55; CI: 2.66–27.44), among female animals (OR: 2.48; CI: 1.38–4.46) and in those aged 11 years and above (OR: 2.67; CI: 1.34–5.34) as well as in gravid cows (OR: 4.34; CI: 2.08–8.92). Seropositivity was also observed among some animals with hygromas (OR: 6.5; CI: 0.45–94.08) and those with a history of abortion (OR: 1.13; CI: 0.18–7.28) although the findings were not statistically significant. Brucella seroprevalence among traditional cattle in Zambia remains high. Control programs against bovine brucellosis must be introduced to reduce its impact on human health and animal production.

Seroprevalence and risk factors of brucellosis and the brucellosis model at the individual level of dairy cattle in the West Bandung District, Indonesia

Background and Aim

Brucellosis is a zoonotic bacterial infectious disease. West Bandung is a center for dairy farming in West Java Province District and endemic for brucellosis. The aim of the study was to determine the prevalence, the associated risk factors, and the brucellosis model at the individual level of dairy cattle in the West Bandung District.

Materials and Methods

The research was conducted through a cross-sectional study. The samples were collected from the serum blood of dairy cattle. Data obtained from the questionnaire were used to investigate risk factors. Multistage random sampling was applied as the sampling technique; therefore, a sample size of 540 cows was selected. The number of farms and cattle on each farm was calculated using a variant effect design of the farm as well as 108 farms was selected with five cattle samples per farm. The results in regard of the research sample acquisition in the West Bandung District included 588 dairy cows from 116 farms, exceeds the number of samples calculated (540 dairy cows and 108 farms). The rose Bengal test (RBT) and the complement fixation test (CFT) were performed for brucellosis testing. Data associated with brucellosis cases at the individual level of the dairy cattle were analyzed using descriptive statistics univariate, bivariate with Chi-square, and odds ratio (OR). Moreover, multivariate logistic regression was used for the analysis during modeling.

Results

The results showed that the prevalence of brucellosis at the individual level in the West Bandung District was 5.10%. Risk factors associated with brucellosis in cattle included the history of abortion (p=0.000; OR=9.9), the history of placental retention (p=0.000; OR=6.6), the history of endometritis (p=0.000; OR=5.5), the history of stillbirth (p=0.043; OR=3.0), the history of pregnancy abortion age at 7-8 months (p=0.000; OR=15.2), and the history of pregnancy abortion at the age of 4-6 months (p=0.007; OR=3.8). The model of brucellosis in dairy cows was the following: = -3.2843+3.41033 the history of pregnancy abortion at the age of 7-8 months +2.54503 the history of pregnancy abortion at the age of 4-6 months +1.86185 age of cattle >2 years - 1.0469 Calving interval 12 months. The model showed the factors that were associated with brucellosis at the individual level of dairy cattle included the history of pregnancy abortion at the age of 7-8 months (β=+3.41033; OR=30.3), the history of pregnancy abortion at the age of 4-6 months (β=+2.54503; OR=12.7); age of cattle >2 years (β=+1.86185; OR=1.2), and Calving interval ≤12 months (β=-1.04691; OR=0.34).

Conclusion

The results of this research showed that the prevalence of brucellosis at the individual level of dairy cattle in the West Bandung district was 5.10%. The risk factors could contribute to the increase of the brucellosis cases, that is, the history of pregnancy abortion at the age of 7-8, the history of pregnancy abortion at the age of 4-6 months, and the age of cattle >2 years. The risk factors can be decreased in the brucellosis cases, that is, calving intervals ≤12 months.

Urinary profiles associated with bacterial metabolites from asymptomatic pregnant women with at term or preterm premature rupture of membranes: a pilot study

Objective: Premature rupture of membranes (PROM) and preterm premature rupture of membranes (pPROM) are frequent conditions with a not fully understood multifactorial etiology. It has been suggested that infection may be the leading cause of pPROM. Metabolomics is nowadays recognized as a successful and versatile approach for the investigation of several pathological conditions, including pregnancy-related ones. However, collecting samples such as fetal fluids or placenta poses a limit on the clinical application of this strategy. Therefore, the aim of this study was to detect urinary metabolites that could be associated with bacterial infection in PROM and pPROM and to understand its role in these different conditions, using readily available samples such as urines.Methods: Urine samples were collected from pregnant women who experienced rupture of membranes: (1) at term (≥37 weeks) not in labor (NLPROM); (2) at term in labor (LPROM); (3) preterm (<37 weeks) not in labor (pPROM). Samples were analyzed using a GC-MS platform. Student's t-test, Pearson correlation coefficient, principal component analysis (PCA), and partial least squares discriminant analysis (PLS-DA) were applied to observe differences between groups.Results: Results showed that lactic acid, erythritol, and ethanolamine levels were significantly higher in pPROM than in PROM (NLPROM + LPROM considered as one single group). These three metabolites might be associated with bacterial infections since they derive from bacterial metabolic processes and environments.Conclusions: This study might be useful to understand the mechanisms underlying the etiology of pPROM and PROM, and urine samples might represent a useful and readily available sample to discriminate preterm high-risk women.

Association of brucellosis to abortions in humans and domestic ruminants in Kagera ecosystem, Tanzania

Brucellosis is a worldwide zoonotic disease of socio-economic importance. Understanding the association of this disease with pregnancy outcome has the potential of contributing to the reduction of its reproductive burden in humans and animals among pastoral communities in Tanzania. A prospective cohort study was conducted in Kagera Region on pregnant women (n = 76) and gravid ruminants (121 cattle, 125 goats and 111 sheep). Exposed and non-exposed groups to brucellosis were followed for 6 months (from 15 November 2017 to 15 April 2018). Sera were collected and analysed using Rose Bengal Test (RBT) and Fluorescence polarization assay (FPA) test. Measures of effect, univariable and multivariable logistic regression analyses were computed. Positivity to both RBT and FPA tests was 21% (95% CI: 12.5-32) in pregnant women and 5% (95% CI: 3.1-8) in gravid ruminants. Among aborted cases, four women (out of nine), two cows (out of seven), two goats (out of 26) and zero sheep (out of 11) were positive to brucellosis. The abortion rate in humans and ruminants was 11.8% and 12.3%, respectively. Seropositivity to brucellosis was similar in aborted and non-aborted cases in humans (p = .08) and in ruminants (p = .2). At the population level, brucellosis was associated with abortions (population attributable risk: PAR) at 3.5% in pregnant women and at 0.5% in gravid ruminants in the study area. Infections to brucellosis were increased in exposed pregnant women (OR = 19; 95% CI: 1.8-203, p = .01) and in cattle (OR = 11; 95% CI: 1.3-88, p = .02). There is an indication that brucellosis could be contributing to abortions in pregnant women and domestic ruminants Kagera Region. Molecular tools could support more the results from serological tests to avoid cross-reaction with other pathogen agents. Control of brucellosis in animals is likely to reduce the threat of abortions in humans.

Characterizing the transport and utilization of the neurotransmitter GABA in the bacterial pathogen Brucella abortus

The neurotransmitter gamma-aminobutyric acid (GABA) is the most abundant inhibitory neurotransmitter in the human brain; however, it is becoming more evident that this non-proteinogenic amino acid plays multiple physiological roles in biology. In the present study, the transport and function of GABA is studied in the highly infectious intracellular bacterium Brucella abortus. The data show that 3H-GABA is imported by B. abortus under nutrient limiting conditions and that the small RNAs AbcR1 and AbcR2 negatively regulate this transport. A specific transport system, gts, is responsible for the transport of GABA as determined by measuring 3H-GABA transport in isogenic deletion strains of known AbcR1/2 regulatory targets; however, this locus is unnecessary for Brucella infection in BALB/c mice. Similar assays revealed that 3H-GABA transport is uninhibited by the 20 standard proteinogenic amino acids, representing preference for the transport of 3H-GABA. Metabolic studies did not show any potential metabolic utilization of GABA by B. abortus as a carbon or nitrogen source, and RNA sequencing analysis revealed limited transcriptional differences between B. abortus 2308 with or without exposure to GABA. While this study provides evidence for GABA transport by B. abortus, questions remain as to why and when this transport is utilized during Brucella pathogenesis.

Substantial Virulence Genes among Brucella melitensis Field Strains Isolated from Cattle in Egypt

BACKGROUND AND OBJECTIVE

The economic losses due to brucellosis as well as its potential public health in human worldwide encourage more researches to find novel pathways for effective control methods of the disease. The objective of this study was to investigate the most prevalent Brucella strains obtained from cattle and their virulence genes.

MATERIALS AND METHODS

Three hundred small-holders cows in Menoufia governorate, Egypt, were screened for brucellosis using rose bengal test (RBT) and confirmed by complement fixation test (CFT). Milk samples and supra-mammary lymph nodes of serologically positive cows were collected for bacteriological isolation and identification. The obtained isolates were genotyped using PCR and their virulence genes (omp25, omp31, manA, manB, virB and znuA) were screened.

RESULTS

The prevalence rate of bovine brucellosis was 15 (5%), 11 (3.6%) and 7 (2.33%) by RBT, CFT and bacteriological examination, respectively. The seven isolates were identified and genotyped as Brucella melitensis biotype3. Furthermore, the molecular detection of substantial virulence genes revealed that manA, manB, omp25 and omp31 genes were detected in all tested B. melitensis strains. Meanwhile, the virB genes were detected in 4 strains and the znuA genes were detected in 3 strains among the isolated B. melitensis strains.

CONCLUSION

It was concluded that B. melitensis biotype3 was the pre-dominant Brucella spp. as well as omp25, omp31, manA and manB were the most common related-virulence genes which assumed to play a worthy function in the pathogenesis of brucellosis.

Serosurveillance of Brucella antibody in food animals and role of slaughterhouse workers in spread of Brucella infection in Southeast Nigeria

Aim:

The study was carried out to determine the seroprevalence of Brucella antibody in slaughter cattle and goats; and the role of slaughterhouse workers (SHWs) in spread of Brucella infection during slaughterhouse operations in Enugu State, Southeast Nigeria.

Materials and Methods:

Rose Bengal plate test was used to screen for Brucella antibody in 484 cattle and 340 goats slaughtered for human consumption in the state. Structured and pretested questionnaire was used to elicit information from randomly selected SHWs, on socioeconomic characteristics, awareness of brucellosis and involvement in practices that aid dissemination of Brucella infection during slaughterhouse operations.

Results:

Suspected seroprevalence of 2.5% and 4.1% were recorded for Brucella antibody in cattle and goats respectively. There was poor awareness of brucellosis (32.1%) among the workers surveyed. Slaughterhouse practices that aid acquisition or spread of Brucella infection and percentage of SHWs engaged in the practices are: non-use of personal protective clothing during slaughterhouse operations (70.8%), discharge of eviscerated fetuses or pregnant uterine contents by open-air dump method of refuse disposal (64.9%) and illegal sell of eviscerated fetuses or gravid uterine contents for human consumption (59.9%) or preparation of dog food (71.5%).

Conclusion:

The 4.1% suspected seroprevalence of Brucella antibodies in goats represents 128% increase from 1.8% seroprevalence earlier reported in the same species and study area in 2009. Significant amounts of Brucella antibody was detected in the food animals screened. Slaughterhouse workers played significant roles in spread of Brucella infection by their involvement in risk practices and behaviours that facilitate pathogen transmission. Therefore, massive awareness campaign and coordinated brucellosis control program in Enugu State are imperative to forestall the zoonotic and economic consequences associated with brucellosis.

Comparisons of brucellosis between human and veterinary medicine

Brucellosis is the world's most widespread zoonosis, but also ranks as one of the seven most neglected diseases, according to the World Health Organization. Additionally, it is recognized as the world's most common laboratory-acquired infection. There are a reported 500,000 incident cases of human brucellosis per year. However, true incidence is estimated to be 5,000,000 to 12,500,000 cases annually. Once diagnosed, focus is directed at treating individual patients with antibiotic regimes, yet overall neglecting the animal reservoir of disease. Countries with the highest incidence of human brucellosis are Syria (1,603.4 cases per 1,000,000 individuals), Mongolia (391.0), and Tajikistan (211.9). Surveillance on animal populations is lacking in many developed and developing countries. According to the World Animal Health Information Database, Mexico had the largest number of reported outbreaks, 5,514 in 2014. Mexico is followed by China (2,138), Greece (1,268), and Brazil (1,142). The majority of these outbreaks is Brucella abortus, the etiologic agent of bovine brucellosis. Brucellosis is an ancient disease that still plagues the world. There are still knowledge gaps and a need for better diagnostics and vaccines to make inroads towards control and eradication.

EUF1 - a newly identified gene involved in erythritol utilization in Yarrowia lipolytica

The gene YALI0F01562g was identified as an important factor involved in erythritol catabolism of the unconventional yeast Yarrowia lipolytica. Its putative role was identified for the first time by comparative analysis of four Y. lipolytica strains: A-101.1.31, Wratislavia K1, MK1 and AMM. The presence of a mutation that seriously damaged the gene corresponded to inability of the strain Wratislavia K1 to utilize erythritol. RT-PCR analysis of the strain MK1 demonstrated a significant increase in YALI0F01562g expression during growth on erythritol. Further studies involving deletion and overexpression of the selected gene showed that it is indeed essential for efficient erythritol assimilation. The deletion strain Y. lipolytica AMM∆euf1 was almost unable to grow on erythritol as the sole carbon source. When the strain was applied in the process of erythritol production from glycerol, the amount of erythritol remained constant after reaching the maximal concentration. Analysis of the YALI0F01562g gene sequence revealed the presence of domains characteristic for transcription factors. Therefore we suggest naming the studied gene Erythritol Utilization Factor - EUF1.

Erythritol feeds the pentose phosphate pathway via three new isomerases leading to D-erythrose-4-phosphate in Brucella

Erythritol is an important nutrient for several α-2 Proteobacteria, including N2-fixing plant endosymbionts and Brucella, a worldwide pathogen that finds this four-carbon polyol in genital tissues. Erythritol metabolism involves phosphorylation to L-erythritol-4-phosphate by the kinase EryA and oxidation of the latter to L-3-tetrulose 4-phosphate by the dehydrogenase EryB. It is accepted that further steps involve oxidation by the putative dehydrogenase EryC and subsequent decarboxylation to yield triose-phosphates. Accordingly, growth on erythritol as the sole C source should require aldolase and fructose-1,6-bisphosphatase to produce essential hexose-6-monophosphate. However, we observed that a mutant devoid of fructose-1,6-bisphosphatases grew normally on erythritol and that EryC, which was assumed to be a dehydrogenase, actually belongs to the xylose isomerase superfamily. Moreover, we found that TpiA2 and RpiB, distant homologs of triose phosphate isomerase and ribose 5-phosphate isomerase B, were necessary, as previously shown for Rhizobium. By using purified recombinant enzymes, we demonstrated that L-3-tetrulose-4-phosphate was converted to D-erythrose 4-phosphate through three previously unknown isomerization reactions catalyzed by EryC (tetrulose-4-phosphate racemase), TpiA2 (D-3-tetrulose-4-phosphate isomerase; renamed EryH), and RpiB (D-erythrose-4-phosphate isomerase; renamed EryI), a pathway fully consistent with the isotopomer distribution of the erythrose-4-phosphate-derived amino acids phenylalanine and tyrosine obtained from bacteria grown on (13)C-labeled erythritol. D-erythrose-4-phosphate is then converted by enzymes of the pentose phosphate pathway to glyceraldehyde 3-phosphate and fructose 6-phosphate, thus bypassing fructose-1,6-bisphosphatase. This is the first description to our knowledge of a route feeding carbohydrate metabolism exclusively via D-erythrose 4-phosphate, a pathway that may provide clues to the preferential metabolism of erythritol by Brucella and its role in pathogenicity.