Bordetella Bronchiseptica Research Articles

The Transcriptional Regulator BpsR Controls the Growth of Bordetella bronchiseptica by Repressing Genes Involved in Nicotinic Acid Degradation.

Many of the pathogenic species of the genus Bordetella have an absolute requirement for nicotinic acid (NA) for laboratory growth. These Gram-negative bacteria also harbor a gene cluster homologous to the nic cluster of Pseudomonas putida which is involved in the aerobic degradation of NA and its transcriptional control. We report here that BpsR, a negative regulator of biofilm formation and Bps polysaccharide production, controls the growth of Bordetella bronchiseptica by repressing the expression of nic genes. The severe growth defect of the ΔbpsR strain in Stainer-Scholte medium was restored by supplementation with NA, which also functioned as an inducer of nic genes at low micromolar concentrations that are usually present in animals and humans. Purified BpsR protein bound to the nic promoter region, and its DNA binding activity was inhibited by 6-hydroxynicotinic acid (6-HNA), the first metabolite of the NA degradative pathway. Reporter assays with the isogenic mutant derivative of the wild-type (WT) strain harboring deletion in nicA, which encodes a putative nicotinic acid hydroxylase responsible for conversion of NA to 6-HNA, showed that 6-HNA is the actual inducer of the nic genes in the bacterial cell. Gene expression profiling further showed that BpsR dually activated and repressed the expression of genes associated with pathogenesis, transcriptional regulation, metabolism, and other cellular processes. We discuss the implications of these findings with respect to the selection of pyridines such as NA and quinolinic acid for optimum bacterial growth depending on the ecological niche.IMPORTANCE BpsR, the previously described regulator of biofilm formation and Bps polysaccharide production, controls Bordetella bronchiseptica growth by regulating the expression of genes involved in the degradation of nicotinic acid (NA). 6-Hydroxynicotinic acid (6-HNA), the first metabolite of the NA degradation pathway prevented BpsR from binding to DNA and was the actual in vivo inducer. We hypothesize that BpsR enables Bordetella bacteria to efficiently and selectively utilize NA for their survival depending on the environment in which they reside. The results reported herein lay the foundation for future investigations of how BpsR and the alteration of its activity by NA orchestrate the control of Bordetella growth, metabolism, biofilm formation, and pathogenesis.

The Adjuvant Bordetella Colonization Factor A Attenuates Alum-Induced Th2 Responses and Enhances Bordetella pertussis Clearance from Mouse Lungs.

The reemergence of pertussis or whooping cough in several countries highlights the need for better vaccines. Acellular pertussis vaccines (aPV) contain alum as the adjuvant and elicit Th2-biased immune responses that are less effective in protecting against infection than the reactogenic whole-cell pertussis vaccines (wPV), which elicit primarily a Th1/Th17 response. An important goal for the field is to devise aPV that will induce immune responses similar to those of wPV. We show that Bordetella colonization factor A (BcfA), an outer membrane protein from Bordetella bronchiseptica, has strong adjuvant function and elicits cellular and humoral immune responses to heterologous and Bordetella pertussis antigens. Addition of BcfA to a commercial aPV resulted in greater reduction of B. pertussis numbers from the lungs than that elicited by aPV alone. The more-efficient pathogen clearance was accompanied by increased interleukin-17 (IL-17) and reduced IL-5 and an increased ratio of IgG2/IgG1 antibodies. Thus, our results suggest that BcfA improves aPV-induced responses by modifying the alum-induced Th2-biased aPV response toward Th1/Th17. A redesigned aPV containing BcfA may allow better control of pertussis reemergence by reshaping immune responses to resemble those elicited by wPV immunization.

Robust Sub-nanomolar Library Preparation for High Throughput Next Generation Sequencing

BackgroundCurrent library preparation protocols for Illumina HiSeq and MiSeq DNA sequencers require ≥2 nM initial library for subsequent loading of denatured cDNA onto flow cells. Such amounts are not always attainable from samples having a relatively low DNA or RNA input; or those for which a limited number of PCR amplification cycles is preferred (less PCR bias and/or more even coverage). A well-tested sub-nanomolar library preparation protocol for Illumina sequencers has however not been reported. The aim of this study is to provide a much needed working protocol for sub-nanomolar libraries to achieve outcomes as informative as those obtained with the higher library input (≥ 2 nM) recommended by Illumina’s protocols.ResultsExtensive studies were conducted to validate a robust sub-nanomolar (initial library of 100 pM) protocol using PhiX DNA (as a control), genomic DNA (Bordetella bronchiseptica and microbial mock community B for 16S rRNA gene sequencing), messenger RNA, microRNA, and other small noncoding RNA samples. The utility of our protocol was further explored for PhiX library concentrations as low as 25 pM, which generated only slightly fewer than 50% of the reads achieved under the standard Illumina protocol starting with > 2 nM.ConclusionsA sub-nanomolar library preparation protocol (100 pM) could generate next generation sequencing (NGS) results as robust as the standard Illumina protocol. Following the sub-nanomolar protocol, libraries with initial concentrations as low as 25 pM could also be sequenced to yield satisfactory and reproducible sequencing results.

Development and application of two multiplex real-time PCR assays for detection and speciation of bacterial pathogens in the koala.

Infectious diseases have contributed to the decline in the health of koala ( Phascolarctos cinereus) populations in the wild in some regions of Australia. Herein we report the development and validation of 2 multiplex real-time PCR (rtPCR) panels for the simultaneous detection of Mycoplasma spp., Ureaplasma spp., Bordetella bronchiseptica, and Chlamydia, including speciation and quantification of Chlamydia, in ocular, reproductive, and nasal swab samples in addition to semen and male urogenital and reproductive tissues, from koalas. Each rtPCR panel was developed for use as a single-tube reaction using pathogen-specific primers and fluorescently labeled probe sets. DNA extracted from reference strains and isolates was used for validation of sequence gene targets for the multiplex rtPCR panels. Each panel was shown to be sensitive and specific in detecting and differentiating the bacterial pathogens. The multiplex rtPCR panels were used to screen clinical samples from free-ranging and hospitalized koalas for multiple pathogens simultaneously. The multiplex rtPCR will improve turnaround time compared to individual-pathogen rtPCR methods used, to date, for confirmation of diagnosis and will provide the wildlife clinician with the ability to make treatment decisions more rapidly.

Antimicrobial susceptibility and genetic relatedness of respiratory tract pathogens in weaner pigs over a 12-month period

The collaboration project VASIB aims at reducing the antibiotic consumption in pig production by integrating information from consulting expertise in clinical inspection, hygiene, epidemiology, microbiology and pharmacology. In this VASIB subproject, we investigated the antimicrobial susceptibility and relatedness of porcine respiratory tract pathogens. Bordetella bronchiseptica (n = 47), Pasteurella multocida (n = 18) and Streptococcus suis (n = 58) were obtained from weaner pigs at two farms. Antimicrobial susceptibility testing was performed by broth microdilution according to CLSI standards. Resistance genes were detected via specific PCR assays. Macrorestriction analysis was conducted to determine the relatedness of the isolates and to identify clones. The B. bronchiseptica isolates showed indistinguishable (farm 1) or two closely related XbaI-patterns (farm 2). Different SmaI-PFGE patterns of P. multocida isolates were obtained at three different time points. In contrast, PFGE analysis of S. suis indicated more than one fragment pattern per pig and time point. Isolates exhibiting indistinguishable PFGE patterns were considered to represent the same clone. This study showed that only two closely related B. bronchiseptica clones were present in both farms, which had low MICs to all antimicrobials, except to β-lactams. Different P. multocida clones were present at the three time points. They showed overall low MIC values, with two clones being resistant and one intermediate to tetracycline. S. suis clones were resistant to tetracycline (n = 19) and/or erythromycin/clindamycin (n = 16). They harboured the tetracycline resistance genes tet(O), tet(M) or tet(L) and/or the macrolide/lincosamide/streptogramin B resistance gene erm(B). Five penicillin-resistant S. suis clones were also detected.

The Bordetella bronchiseptica nic locus encodes a nicotinic acid degradation pathway and the 6-hydroxynicotinate-responsive regulator BpsR.

The classical Bordetella species use amino acids as carbon sources and can catabolize organic acids and tricarboxylic acid cycle intermediates. They are also auxotrophic for nicotinamide adenine dinucleotide (NAD) pathway precursors such as nicotinic acid. Bordetellae have a putative nicotinate catabolism gene locus highly similar to that characterized in Pseudomonas putida KT2440. This study determined the distribution of the nic genes among Bordetella species and analyzed the regulation of this nicotinic acid degradation system. Transcription of the Bordetella bronchiseptica nicC gene was repressed by the NicR ortholog, BpsR, previously shown to regulate extracellular polysaccharide synthesis genes. nicC expression was derepressed by nicotinic acid or by the first product of the degradation pathway, 6-hydroxynicotinic acid, which was shown to be the inducer. Results using mutants with either a hyperactivated pathway or an inactivated pathway showed a marked effect on growth on nicotinic acid that indicated this degradation pathway influences NAD biosynthesis. Pathway dysregulation also affected Bordetella BvgAS-mediated virulence gene regulation, demonstrating that fluctuation of intracellular nicotinic acid pools impacts Bvg phase transition responses.

Bacterial and Pneumocystis Infections in the Lungs of Gene-Knockout Rabbits with Severe Combined Immunodeficiency.

Using the CRISPR/Cas9 gene-editing technology, we recently produced a number of rabbits with mutations in immune function genes, including FOXN1, PRKDC, RAG1, RAG2, and IL2RG. Seven founder knockout rabbits (F0) and three male IL2RG null (−/y) F1 animals demonstrated severe combined immunodeficiency (SCID), characterized by absence or pronounced hypoplasia of the thymus and splenic white pulp, and absence of immature and mature T and B-lymphocytes in peripheral blood. Complete blood count analysis showed severe leukopenia and lymphocytopenia accompanied by severe neutrophilia. Without prophylactic antibiotics, the SCID rabbits universally succumbed to lung infections following weaning. Pathology examination revealed severe heterophilic bronchopneumonia caused by Bordetella bronchiseptica in several animals, but a consistent feature of lung lesions in all animals was a severe interstitial pneumonia caused by Pneumocystis oryctolagi, as confirmed by histological examination and PCR analysis of Pneumocystis genes. The results of this study suggest that these SCID rabbits could serve as a useful model for human SCID to investigate the disease pathogenesis and the development of gene and drug therapies.

Prevalence of microorganisms associated with feline gingivostomatitis.

Feline gingivostomatitis (FGS) is a painful chronic inflammatory disease of the oral cavity. The purpose of this study was to examine the frequency of detection of certain common feline bacteria and viruses to determine any potential associations with FGS. A multicentre case-control study design was conducted. In total, 72 control cats and 32 cats with FGS were included in the study. Oral swabs were cultured for bacterial identification and a PCR assay was carried out to examine the infection of feline calicivirus (FCV), feline herpesvirus-1 (FHV-1), Chlamydia felis, Mycoplasma felis and Bordetella bronchiseptica. There was a significant difference in age distribution between the control and the FGS group. Based on a PCR assay, the positive rate of FCV was significantly higher in FGS cats than control animals. For other infectious pathogens, including FHV-1, C felis and M felis, there was no significant difference. Bacterial culture of oral swabs revealed that Pasteurella multocida was most frequently detected, but the detection rate was significantly lower in FGS cats. In FGS cats, the incidence of Enterococcus faecalis and anaerobic bacteria were more frequently isolated than in control cats. This study indicates that the positive rate of FCV was significantly higher in cats with FGS, and the microflora of the oral cavity of cats with FGS might be disrupted, although additional studies are required to compare the oral microbiome in cats of a variety of ages.

Membrane Vesicles Derived from Bordetella bronchiseptica: Active Constituent of a New Vaccine against Infections Caused by This Pathogen.

Bordetella bronchiseptica, a Gram-negative bacterium, causes chronic respiratory tract infections in a wide variety of mammalian hosts, including humans (albeit rarely). We recently designed Bordetella pertussis and Bordetella parapertussis experimental vaccines based on outer membrane vesicles (OMVs) derived from each pathogen, and we obtained protection against the respective infections in mice. Here, we demonstrated that OMVs derived from virulent-phase B. bronchiseptica (OMVBbvir+) protected mice against sublethal infections with different B. bronchiseptica strains, two isolated from farm animals and one isolated from a human patient. In all infections, we observed that the B. bronchiseptica loads were significantly reduced in the lungs of vaccinated animals; the lung-recovered CFU were decreased by ≥4 log units, compared with those detected in the lungs of nonimmunized animals (P < 0.001). In the OMVBbvir+-immunized mice, we detected IgG antibody titers against B. bronchiseptica whole-cell lysates, along with an immune serum having bacterial killing activity that both recognized B. bronchiseptica lipopolysaccharides and polypeptides such as GroEL and outer membrane protein C (OMPc) and demonstrated an essential protective capacity against B. bronchiseptica infection, as detected by passive in vivo transfer experiments. Stimulation of cultured splenocytes from immunized mice with OMVBbvir+ resulted in interleukin 5 (IL-5), gamma interferon (IFN-γ), and IL-17 production, indicating that the vesicles induced mixed Th2, Th1, and Th17 T-cell immune responses. We detected, by adoptive transfer assays, that spleen cells from OMVBbvir+-immunized mice also contributed to the observed protection against B. bronchiseptica infection. OMVs from avirulent-phase B. bronchiseptica and the resulting induced immune sera were also able to protect mice against B. bronchiseptica infection.IMPORTANCEBordetella bronchiseptica, a Gram-negative bacterium, causes chronic respiratory tract infections in a wide variety of mammalian hosts, including humans (albeit rarely). Several vaccines aimed at preventing B. bronchiseptica infection have been developed and used, but a safe effective vaccine is still needed. The significance and relevance of our research lie in the characterization of the OMVs derived from B. bronchiseptica as the source of a new experimental vaccine. We demonstrated here that our formulation based on OMVs derived from virulent-phase B. bronchiseptica (OMVBbvir+) was effective against infections caused by B. bronchiseptica isolates obtained from different hosts (farm animals and a human patient). In vitro and in vivo characterization of humoral and cellular immune responses induced by the OMVBbvir+ vaccine enabled a better understanding of the mechanism of protection necessary to control B. bronchiseptica infection. Here we also demonstrated that OMVs derived from B. bronchiseptica in the avirulent phase and the corresponding induced humoral immune response were able to protect mice from B. bronchiseptica infection. This realization provides the basis for the development of novel vaccines not only against the acute stages of the disease but also against stages of the disease or the infectious cycle in which avirulence factors could play a role.

Characterization of isolates of &lt;i&gt;Bordetella bronchiseptica&lt;/i&gt; from horses

ABSTRACTBordetella bronchiseptica is a well-known Gram-negative bacterial pathogen causing a plethora of diseases in different animals. Although its infection has been reported from pigs and dogs in India, no report of B. bronchiseptica from horses is described. We report for the first time, isolation, identification and characterization of strains of B. bronchiseptica from respiratory infection in horses from different states in India. The antimicrobial susceptibility testing showed resistance to penicillins, ceftazidime, and chloramphanicol. The virulence capability of the strains was confirmed by sequencing genes such as adenylate cyclase toxin (cyaA), bordetella virulence gene (bvgA) and by PCR detection of flagellin gene (fla). We demonstrate the involvement of B. bronchiseptica strains in respiratory tract infection in horses in India.

Antioxidants, antimicrobial and cytotoxic potential of Swertia chirata

The current study was designed to evaluate the properties of various fractions of methanolic extract prepared from aerial parts of Swertia chirata. Five fractions, RA-78, RA-91, RA-112, RA-14 and RA-15 showed significantly high DPPH scavenging capacity. In finding out antimicrobial activities, different fractions have shown mild activities against Bordetella bronchiseptica and Micrococcus luteus, while all fractions showed significant results against Aspergillus fumigatus followed by Mucor species and five fractions were active against Aspergillus niger. In measurement of brine shrimp cytotoxic potential of different fractions, three fractions RA-12, RA-34 and RA-78 had shown the best cytotoxic results with zero LD50. In determining antileishmanial properties of different fractions, the best results were exhibited by fraction RA-78 and RA-112 with zero percent survival of Leishmania parasite. Various fractions of methanolic extract prepared from aerial parts of Swertia chirata promisingly possess antioxidant, antimicrobial, brine shrimp cytotoxic, and antileishmanial activities.

A Good Case of Recurrent Pneumonia.

Bordetella bronchiseptica infection is a common cause of pneumonia in animals but rarely causes disease in humans. Additionally, coinfection with Pneumocystis jirovecii is very uncommon and is occasionally seen in patients with acquired immunodeficiency syndrome (AIDS). We report a case of a 61-year-old HIV-negative man, who presented with hypoxic respiratory failure 2 days after completion of systemic intravenous antibiotic treatment for B bronchiseptica. His past medical history was significant for a benign thymoma. The patient was found to be coinfected with B bronchiseptica and P jirovecii. Laboratory results showed panhypogammaglobulinemia and low absolute B- and CD4 T-cells. Therefore, the patient was diagnosed with Good’s syndrome. However, despite treatment with intravenous antibiotics and intravenous immunoglobulin, the patient continued to deteriorate and expired. This patient demonstrates the importance of recognizing this rare immunodeficiency early in order to improve morbidity and mortality. Furthermore, this case highlights the importance of early immunoglobulin screening in the presence of asymptomatic thymoma.

Detection of specific bacterial agents by quantitative PCR assays in the bronchoalveolar lavage fluid of dogs with eosinophilic bronchopneumopathy vs. dogs with chronic bronchitis and healthy dogs

In humans, Mycoplasma pneumoniae and Bordetella pertussis infections are suggested to trigger or exacerbate asthma. Whether Mycoplasma or Bordetella are associated with chronic inflammatory bronchial diseases in dogs has not been investigated. The aim of this study was to assess detection rates of Mycoplasma canis (M. canis), M. cynos and Bordetella bronchiseptica (Bb), in dogs with eosinophilic bronchopneumopathy (EBP) and chronic bronchitis (CB), compared with healthy dogs. Specific quantitative PCR (qPCR) analysis for M. canis, M. cynos and Bb were retrospectively performed on bronchoalveolar lavage fluid (BALF) collected from 24 dogs with EBP, 21 dogs with CB and 15 healthy dogs. Possible associations between qPCR results and age, BALF cytology or clinical severity scores (CSS) in dogs with EBP were investigated.There was no difference in M. canis, M. cynos and Bb detection rates in dogs with EBP (n=6, n=2 and n=6, respectively) and dogs with CB (n=2, n=2 and n=2, respectively) compared with control dogs (n=4, n=2 and n=2, respectively). In dogs with EBP, the proportion that were qPCR-positive for Bb was higher in dogs with higher CSS (P=0.014) and BALF from Bb-positive dogs had higher percentage of neutrophils (P<0.001). Among dogs that were qPCR-positive for Bb, moderate to high loads were only detected in dogs with EBP. M. canis and M. cynos detection was not associated with EBP or CB; higher Bb loads were only present in dogs with EBP and high CSS. A possible cause and effect relationship between Bb infection or load and EBP remains unclear and requires further investigation.

Recovery of Bordetella bronchiseptica sequence type 82 and B. pseudohinzii from urban rats in Terengganu, Malaysia.

Rodents have historically been associated with zoonotic pandemics that claimed the lives of large human populations. Appropriate pathogen surveillance initiatives could contribute to early detection of zoonotic infections to prevent future outbreaks. Bordetella species are bacteria known to cause mild to severe respiratory disease in mammals and, some have been described to infect, colonize and spread in rodents. There is a lack of information on the population diversity of bordetellae among Malaysian wild rodents. Here, bordetellae recovered from lung tissues of wild rats were genotypically characterized using 16S rDNA sequencing, MLST and nrdA typing. A novel B. bronchiseptica ST82, closely related to other human-derived isolates, was discovered in three wild rats (n=3) from Terengganu (5.3333° N, 103.1500° E). B. pseudohinzii, a recently identified laboratory mice inhabitant, was also recovered from one rat (n=1). Both bordetellae displayed identical antimicrobial resistance profiles, indicating the close phylogenetic association between them. Genotyping using the 765-bp nrdA locus was shown to be compatible with the MLST-based phylogeny, with the added advantage of being able to genotype non-classical bordetellae. The recovery of B. pseudohinzii from wild rat implied that this bordetellae has a wider host range than previously thought. The findings from this study suggest that bordetellae surveillance among wild rats in Malaysia has to be continued and expanded to other states to ensure early identification of species capable of causing public health disorder.

Porcine Reproducive and Respiratory Syndrome (PRRS) and secondary co-infections: New aspects, economic impact and update situation in Greece

The clinical manifestations of PRRS virus infection vary from subclinical to severe reproductive failure and/or respiratory disease. Severity of PRRS virus associated disease may result from interactions among factors involving differences in virulence among PRRS virus isolates, probable recombination between the different isolates that are responsible for the clinical manifestation of PRRS in the same farm, differences in concurrent infections (other viruses and bacteria) and hygiene monitoring programme. It is known that viruses and bacteria interacted and the most common model of this interaction is that pathogens bacteria complicate the lesions that are due to viruses. PRRS virus induces predisposition to Streptococcus suis in nursery age pigs and increases susceptibility to Salmonella choleraesuis, Bordetella bronchiseptica and Mycoplasma hyopneumoniae. Furthermore, PRRS virus is involved in aetiology and predispose to appearance of Porcine Respiratory Disease Complex (PRDC) Postweaning Multisystemic Wasting Syndrome (PMWS) and Porcine Dermatitis and Nephropathy Syndrome (PDNS). The respiratory form of PRRS co-infection with Aujeszky' disease causes severe losses in swine herds due to respiratory problems. In cases of PRRS co-infections with other agents, the cost of pork meat production is raised from the treatments and other special management strategies. Up to date, in Greece, PRRS is appeared with the enzootic form (independendy of the season) with elevations and declines. In Greek swine industry, PRRS virus is involved as primary pathogen agent in cautions of mortality of growing/finishing pigs. During the last years, the presence of the new syndromes of PRDC, PMWS and PDNS causes additional economical losses and increases the cost of Greek pork meat production. The unpublished data of editors indicate that during last year, PRRS caused severe losses in Greek swine industry. Cases of PRRS were noticed in farms which purchased gilts or piglets without keeping out preventive facilities of biosecurity as quarantine, serology examinations etc. The syndrome was appeared with the respiratory form in growing/finishing pigs associated with severe losses, due to the entrance of «new» different isolates of PRRS virus from the purchase of gilts or piglets. It is probably that these «new» different isolates were more virulent than the preexisted isolates or/and predominated with them. In cases, where severe respiratory signs in growing/finishing pigs and no or moderate reproductive form of PRRS were noticed, it is probable that the vaccinations of sows against PRRS did not protect the growing/finishing pigs or the «new» different isolates of PRRS virus had more respiratory than reproductive tropism or coexistenced in all earlier circumstances. Today, PRRS is a dangerous risk factor for the Greek swine industry and for this reason it is important to apply all preventive facilities as: vaccinations, reduction of the introduction gilts and maintenance of a grandparent nucleus in the farm for producing gilts, quarantine and serological monitoring for all introduced animals (gilts and piglets), as well as the purchase of animals from PRRS-negative farms. The purchase of piglets has to be avoided because it induces negative effects on the clinical manifestation and control of PRRS.

Activation of Bvg-Repressed Genes in Bordetella pertussis by RisA Requires Cross Talk from Noncooperonic Histidine Kinase RisK.

The two-component response regulator RisA, encoded by open reading frame BP3554 in the Bordetella pertussis Tohama I genomic sequence, is a known activator of vrg genes, a set of genes whose expression is increased under the same environmental conditions (known as modulation) that result in repression of the bvgAS virulence regulon. Here we demonstrate that RisA is phosphorylated in vivo and that RisA phosphorylation is required for activation of vrg genes. An adjacent histidine kinase gene, risS, is truncated by frameshift mutation in B. pertussis but not in Bordetella bronchiseptica or Bordetella parapertussis Neither deletion of risS' or bvgAS nor phenotypic modulation with MgSO4 affected levels of phosphorylated RisA (RisA∼P) in B. pertussis However, RisA phosphorylation did require the histidine kinase encoded by BP3223, here named RisK (cognate histidine kinase of RisA). RisK was also required for expression of the vrg genes. This requirement could be obviated by the introduction of the phosphorylation-mimicking RisAD60E mutant, indicating that an active conformation of RisA, but not phosphorylation per se, is crucial for vrg activation. Interestingly, expression of vrg genes is still modulated by MgSO4 in cells harboring the RisAD60E mutation, suggesting that the activated RisA senses additional signals to control vrg expression in response to environmental stimuli.IMPORTANCE In B. pertussis, the BvgAS two-component system activates the expression of virulence genes by binding of BvgA∼P to their promoters. Expression of the reciprocally regulated vrg genes requires RisA and is also repressed by the Bvg-activated BvgR. RisA is an OmpR-like response regulator, but RisA phosphorylation was not expected because the gene for its presumed, cooperonic, histidine kinase is inactivated by mutation. In this study, we demonstrate phosphorylation of RisA in vivo by a noncooperonic histidine kinase. We also show that RisA phosphorylation is necessary but not sufficient for vrg activation but, importantly, is not affected by BvgAS status. Instead, we propose that vrg expression is controlled by BvgAS through its regulation of BvgR, a cyclic di-GMP (c-di-GMP) phosphodiesterase.

How diversity-generating retroelements promote mutation and adaptation in myriad microbes

After infecting the bacterium Bordetella bronchiseptica (shown here) with a bacteriophage, researchers stumbled on findings that led them to diversity-generating retroelements, part of a potentially important microbial mechanism for generating a diverse range of proteins. Image courtesy of CDC/Janice Carr.

The impacts of a lower protein and energy density diet in aged male Sprague Dawley rat studies

The collaboration project VASIB aims at reducing the antibiotic consumption in pig production by integrating information from consulting expertise in clinical inspection, hygiene, epidemiology, microbiology and pharmacology. In this VASIB subproject, we investigated the antimicrobial susceptibility and relatedness of porcine respiratory tract pathogens. Bordetella bronchiseptica (n = 47), Pasteurella multocida (n = 18) and Streptococcus suis (n = 58) were obtained from weaner pigs at two farms. Antimicrobial susceptibility testing was performed by broth microdilution according to CLSI standards. Resistance genes were detected via specific PCR assays. Macrorestriction analysis was conducted to determine the relatedness of the isolates and to identify clones. The B. bronchiseptica isolates showed indistinguishable (farm 1) or two closely related XbaI-patterns (farm 2). Different SmaI-PFGE patterns of P. multocida isolates were obtained at three different time points. In contrast, PFGE analysis of S. suis indicated more than one fragment pattern per pig and time point. Isolates exhibiting indistinguishable PFGE patterns were considered to represent the same clone. This study showed that only two closely related B. bronchiseptica clones were present in both farms, which had low MICs to all antimicrobials, except to β-lactams. Different P. multocida clones were present at the three time points. They showed overall low MIC values, with two clones being resistant and one intermediate to tetracycline. S. suis clones were resistant to tetracycline (n = 19) and/or erythromycin/clindamycin (n = 16). They harboured the tetracycline resistance genes tet(O), tet(M) or tet(L) and/or the macrolide/lincosamide/streptogramin B resistance gene erm(B). Five penicillin-resistant S. suis clones were also detected.

Bordetella bronchiseptica pneumonia in a patient with lung cancer; a case report of a rare infection

BackgroundBordetella bronchiseptica (B.bronchiseptica) is a frequent cause of respiratory infections in animals but rarely causes serious infection in humans. We present a rare case of B. bronchiseptica pneumonia in a patient with lung cancer.Case presentationA 52-year-old white male with non small cell lung cancer developed fever during treatment with nivolumab. A persistent productive cough and a deterioration in his clinical condition led to his hospitalization for evaluation. Bronchoscopy was performed and a diagnosis of B. bronchiseptica pneumonia was made. The infection was successfully managed by antiobiotic therapy.ConclusionsB. bronchiseptica is a pathogen that can cause serious infection in humans, especially in immunocompromised or immunoincompetent individuals. In our patient it showed unusual resistance to cephalosporins and poor sensitivity to amikacin. To our knowledge this is the first case of such an infection in a lung cancer patient undergoing treatment with nivolumab. When B. bronchiseptica is identified, the possibility of a nosocomial transmission must be considered.

Crystal structures of a ZIP zinc transporter reveal a binuclear metal center in the transport pathway.

Zrt/Irt-like proteins (ZIPs) play fundamental roles in metal metabolism/homeostasis and are broadly involved in numerous physiological and pathological processes. The lack of high-resolution structure of the ZIPs hinders understanding of the metal transport mechanism. We report two crystal structures of a prokaryotic ZIP in lipidic cubic phase with bound metal substrates (Cd2+ at 2.7 Å and Zn2+ at 2.4 Å). The structures revealed a novel 3+2+3TM architecture and an inward-open conformation occluded at the extracellular side. Two metal ions were trapped halfway through the membrane, unexpectedly forming a binuclear metal center. The Zn2+-substituted structure suggested asymmetric functions of the two metal-binding sites and also revealed a route for zinc release. Mapping of disease-causing mutations, structure-guided mutagenesis, and cell-based zinc transport assay demonstrated the crucial role of the binuclear metal center for human ZIP4. A metal transport mechanism for the ZIP from Bordetella bronchiseptica was proposed, which is likely applicable to other ZIPs.