[Proposal for participation in intensive care and emergency medicine studies for patients unable to give informed consent (Cologne Model)]

When conducting clinical trials in intensive care and emergency medicine, physicians, ethics committees, and legal experts have differing views regarding the inclusion of patients who are incapable of giving consent. These different views on the participation of patients who are not capable of giving consent also complicate how clinical trials are prepared and conducted. Based on the results of a literature search, a consensus model (Cologne Model) was developed by physicians performing clinical research, ethics committees, and lawyers in order to provide patients, those scientifically responsible for the study, ethics committees, and probate (guardianship) judges with a maximum of patient safety and legal certainty, while simultaneously enabling scientific research.

Spanish Outbreak Isolates Bridge Phylogenies of European and American Bacillus anthracis

The geographical origin of a major present-day phylogenetic group (A branch WNA; A.Br.WNA) of American Bacillus anthracis is controversial. One hypothesis postulated that the anthrax pathogen reached North America via a then-existing land bridge from northeastern Asia thousands of years ago. A competing hypothesis suggested that B. anthracis was introduced to America a couple of hundred years ago, related to European colonization. The latter view is strongly supported by genomic analysis of a group of French B. anthracis isolates that are phylogenetically closely related to the North American strains of the A branch A.Br.WNA clade. In addition, three West African strains also belong to this relationship group. Recently, we have added a Spanish strain to these close relatives of the WNA lineage of American B. anthracis. Nevertheless, the diversity of Spanish B. anthracis remains largely unexplored, and phylogenetic links to European or American relatives are not well resolved. Here, we genome sequenced and characterized 29 new B. anthracis isolates (yielding 18 unique genotypes) from outbreaks in west central and central Spain in 2021. Applying comparative chromosomal analysis, we placed the chromosomes of these isolates within the established phylogeny of the A.Br.008/009 (A.Br.TEA) canonical SNP group. From this analysis, a new sub-clade, named A.Br.11/ESPc, emerged that constitutes a sister group of American A.Br.WNA.

Ultrasensitive Detection of Bacillus anthracis by Real-Time PCR Targeting a Polymorphism in Multi-Copy 16S rRNA Genes and Their Transcripts

The anthrax pathogen Bacillus anthracis poses a significant threat to human health. Identification of B. anthracis is challenging because of the bacterium's close genetic relationship to other Bacillus cereus group species. Thus, molecular detection is founded on species-specific PCR targeting single-copy genes. Here, we validated a previously recognized multi-copy target, a species-specific single nucleotide polymorphism (SNP) present in 2-5 copies in every B. anthracis genome analyzed. For this, a hydrolysis probe-based real-time PCR assay was developed and rigorously tested. The assay was specific as only B. anthracis DNA yielded positive results, was linear over 9 log10 units, and was sensitive with a limit of detection (LoD) of 2.9 copies/reaction. Though not exhibiting a lower LoD than established single-copy PCR targets (dhp61 or PL3), the higher copy number of the B. anthracis-specific 16S rRNA gene alleles afforded ≤2 unit lower threshold (Ct) values. To push the detection limit even further, the assay was adapted for reverse transcription PCR on 16S rRNA transcripts. This RT-PCR assay was also linear over 9 log10 units and was sensitive with an LoD of 6.3 copies/reaction. In a dilution series of experiments, the 16S RT-PCR assay achieved a thousand-fold higher sensitivity than the DNA-targeting assays. For molecular diagnostics, we recommend a real-time RT-PCR assay variant in which both DNA and RNA serve as templates (thus, no requirement for DNase treatment). This can at least provide results equaling the DNA-based implementation if no RNA is present but is superior even at the lowest residual rRNA concentrations.

Enzyme-Linked Phage Receptor Binding Protein Assays (ELPRA) Enable Identification of Bacillus anthracis Colonies

Bacteriophage receptor binding proteins (RBPs) are employed by viruses to recognize specific surface structures on bacterial host cells. Recombinant RBPs have been utilized for detection of several pathogens, typically as fusions with reporter enzymes or fluorescent proteins. Identification of Bacillus anthracis, the etiological agent of anthrax, can be difficult because of the bacterium's close relationship with other species of the Bacillus cereussensu lato group. Here, we facilitated the identification of B. anthracis using two implementations of enzyme-linked phage receptor binding protein assays (ELPRA). We developed a single-tube centrifugation assay simplifying the rapid analysis of suspect colonies. A second assay enables identification of suspect colonies from mixed overgrown solid (agar) media derived from the complex matrix soil. Thus, these tests identified vegetative cells of B. anthracis with little processing time and may support or confirm pathogen detection by molecular methods such as polymerase chain reaction.

Detection and Isolation of Emetic Bacillus cereus Toxin Cereulide by Reversed Phase Chromatography

The emetic toxin cereulide is a 1.2 kDa dodecadepsipeptide produced by the food pathogen Bacillus cereus. As cereulide poses a serious health risk to humans, sensitive and specific detection, as well as toxin purification and quantification, methods are of utmost importance. Recently, a stable isotope dilution assay tandem mass spectrometry (SIDA–MS/MS)-based method has been described, and an method for the quantitation of cereulide in foods was established by the International Organization for Standardization (ISO). However, although this SIDA–MS/MS method is highly accurate, the sophisticated high-end MS equipment required for such measurements limits the method’s suitability for microbiological and molecular research. Thus, we aimed to develop a method for cereulide toxin detection and isolation using equipment commonly available in microbiological and biochemical research laboratories. Reproducible detection and relative quantification of cereulide was achieved, employing reversed phase chromatography (RPC). Chromatographic signals were cross validated by ultraperformance liquid chromatography–mass spectrometry (UPLC–MS/MS). The specificity of the RPC method was tested using a test panel of strains that included non-emetic representatives of the B. cereus group, emetic B. cereus strains, and cereulide-deficient isogenic mutants. In summary, the new method represents a robust, economical, and easily accessible research tool that complements existing diagnostics for the detection and quantification of cereulide.

Mutant Strains of Escherichia coli and Methicillin-Resistant Staphylococcus aureus Obtained by Laboratory Selection To Survive on Metallic Copper Surfaces

Artificial laboratory evolution was used to produce mutant strains of Escherichia coli and methicillin-resistant Staphylococcus aureus (MRSA) able to survive on antimicrobial metallic copper surfaces. These mutants were 12- and 60-fold less susceptible to the copper-mediated contact killing process than their respective parent strains. Growth levels of the mutant and its parent in complex growth medium were similar. Tolerance to copper ions of the mutants was unchanged. The mutant phenotype remained stable over about 250 generations under nonstress conditions. The mutants and their respective parental strains accumulated copper released from the metallic surfaces to similar extents. Nevertheless, only the parental strains succumbed to copper stress when challenged on metallic copper surfaces, suffering complete destruction of the cell structure. Whole-genome sequencing and global transcriptome analysis were used to decipher the genetic alterations in the mutant strains; however, these results did not explain the copper-tolerance phenotypes on the systemic level. Instead, the mutants shared features with those of stressed bacterial subpopulations entering the early or "shallow" persister state. In contrast to the canonical persister state, however, the ability to survive on solid copper surfaces was adopted by the majority of the mutant strain population. This indicated that application of solid copper surfaces in hospitals and elsewhere has to be accompanied by strict cleaning regimens to keep the copper surfaces active and prevent evolution of tolerant mutant strains.IMPORTANCE Microbes are rapidly killed on solid copper surfaces by contact killing. Copper surfaces thus have an important role to play in preventing the spread of nosocomial infections. Bacteria adapt to challenging natural and clinical environments through evolutionary processes, for instance, by acquisition of beneficial spontaneous mutations. We wish to address the question of whether mutants can be selected that have evolved to survive contact killing on solid copper surfaces. We isolated such mutants from Escherichia coli and methicillin-resistant Staphylococcus aureus (MRSA) by artificial laboratory evolution. The ability to survive on solid copper surfaces was a stable phenotype of the mutant population and not restricted to a small subpopulation. As a consequence, standard operation procedures with strict hygienic measures are extremely important to prevent the emergence and spread of copper-surface-tolerant persister-like bacterial strains if copper surfaces are to be sustainably used to limit the spread of pathogenic bacteria, e.g., to curb nosocomial infections.

A copper site is required for iron transport by the periplasmic proteins P19 and FetP

Campylobacter jejuni is a leading cause of food-borne gastrointestinal disease in humans and uropathogenic Escherichia coli is a leading cause of urinary tract infections. Both human pathogens harbour a homologous iron uptake system (termed cjFetM-P19 in C. jejuni and ecFetM-FetP in E. coli). Although these systems are important for growth under iron limitation, the mechanisms by which these systems function during iron transport remain undefined. The copper ions bound to P19 and FetP, the homologous periplasmic proteins, are coordinated in an uncommon penta-dentate manner involving a Met-Glu-His3 motif and exhibit positional plasticity. Here we demonstrate the function of the Met and Glu residues in modulating copper binding and controlling copper positioning through site-directed variants, binding assays, and crystal structures. Growth of C. jejuni strains with these p19 variants is impaired under iron limited conditions as compared to the wild-type strain. Additionally, an acidic residue-rich secondary site is required for binding iron and function in vivo. Finally, western blot analyses demonstrate direct and specific interactions between periplasmic P19 and FetP with the large periplasmic domain of their respective inner membrane transporters cjFetM and ecFetM.

A Rare Glimpse into the Past of the Anthrax Pathogen Bacillus anthracis

The bacterium Bacillus anthracis is the causative agent of the zoonotic disease anthrax. While genomics of extant B. anthracis isolates established in-depth phylogenomic relationships, there is scarce information on the historic genomics of the pathogen. Here, we characterized the oldest documented B. anthracis specimen. The inactive 142-year-old material originated from a bovine diseased in Chemnitz (Germany) in 1878 and is contemporary with the seminal studies of Robert Koch on B. anthracis. A specifically developed isolation method yielded high-quality DNA from this specimen for genomic sequencing. The bacterial chromosome featuring 242 unique base-characters placed it into a major phylogenetic clade of B. anthracis (B.Branch CNEVA), which is typical for central Europe today. Our results support the notion that the CNEVA-clade represents part of the indigenous genetic lineage of B. anthracis in this part of Europe. This work emphasizes the value of historic specimens as precious resources for reconstructing the past phylogeny of the anthrax pathogen.

Genotyping and phylogenetic placement of Bacillus anthracis isolates from Finland, a country with rare anthrax cases

Background

Anthrax, the zoonotic disease caused by the gram-positive bacterium Bacillus anthracis, is nowadays rare in northern parts of Europe including Finland and Scandinavia. Only two minor outbreaks of anthrax in 1988 and in 2004 and one sporadic infection in 2008 have been detected in animals in Finland since the 1970’s. Here, we report on two Finnish B. anthracis strains that were isolated from spleen and liver of a diseased calf related to the outbreak in 1988 (strain HKI4363/88) and from a local scrotum and testicle infection of a bull in 2008 (strain BA2968). These infections occurred in two rural Finnish regions, i.e., Ostrobothnia in western Finland and Päijänne Tavastia in southern Finland, respectively.

Results

The isolates were genetically characterized by PCR-based methods such as multilocus variable number of tandem repeat analysis (MLVA) and whole genome-sequence analysis (WGS). Phylogenetic comparison of the two strains HKI4363/88 and BA2968 by chromosomal single nucleotide polymorphism (SNP) analysis grouped these organisms within their relatives of the minor canonical A-branch canSNP-group A.Br.003/004 (A.Br.V770) or canonical B-branch B.Br.001/002, respectively. Strain HKI4363/88 clustered relatively closely with other members of the A.Br.003/004 lineage from Europe, South Africa, and South America. In contrast, strain BA2968 clearly constituted a new sublineage within B.Br.001/002 with its closest relative being HYO01 from South Korea.

Conclusions

Our results suggest that Finland harbors both unique (autochthonous) and more widely distributed, common clades of B. anthracis. We suspect that members of the common clades such as strains HKI4363/88 have been introduced only recently by anthropogenic activities involving importation of contaminated animal products. On the other hand, autochthonous strains such as isolate BA2968 probably have an older history of their introduction into Finland as evidenced by a high number of single nucleotide variant sites in their genomes.

Electronic supplementary material

The online version of this article (10.1186/s12866-018-1250-4) contains supplementary material, which is available to authorized users.

The identification of novel single nucleotide polymorphisms to assist in mapping the spread of Bacillus anthracis across the Southern Caucasus

Anthrax is common as a zoonotic disease in the southern Caucasus area including parts of Turkey and Georgia. In this region, population genetics of the etiological agent Bacillus anthracis comprises, where known, the major canonical single nucleotide polymorphism (canSNP) groups A.Br.Aust94 and A.Br.008/009 of the pathogen's global phylogeny, respectively. Previously, isolates of B. anthracis from Turkey have been genotyped predominantly by multi locus variable number of tandem repeat analysis (MLVA) or canSNP typing. While whole genome sequencing is the future gold standard, it is currently still costly. For that reason we were interested in identifying novel SNPs which could assist in further distinguishing closely related isolates using low cost assay platforms. In this study we sequenced the genomes of seven B. anthracis strains collected from the Kars province of Eastern Anatolia in Turkey and discovered new SNPs which allowed us to assign these and other geographically related strains to three novel branches of the major A-branch canSNP-group (A.Br.) Aust94. These new branches were named Kafkas-Geo 1-3 and comprised isolates from the Kars region and the neighboring republic of Georgia suggesting a common ancestry. The novel SNPs identified in this study connect the population genetics of B. anthracis in the South Caucasus and Turkey and will likely assist efforts to map the spread of the pathogen across this region.

Is the Urokinase-type Plasminogen Activator System a Reliable Prognostic Factor in Gastric Cancer?

Aim

The aim of this prospective study was to evaluate the clinical and prognostic impact of immunohisto-chemically assessed uPA and PAI-1 in patients with gastric cancer.

Methods

This prospective study analyzed specimens obtained from 105 gastric cancer patients who underwent gastrectomy with extended lymphadenectomy. The immunohistochemical expression of uPA and PAI-1 was studied semiquantitatively in the tumor epithelium and was correlated with the clinicopathological features of each patient.

Results

Univariate analysis revealed no statistically significant association of uPA levels with pT and pN category (p=0.655 and 0.053, respectively), grading (p=0.374), depth of tumor invasion (p=0.665), UICC classification (p=0.21) and the Laurén classification (p=0.578). PAI-1 expression showed no statistically significant correlation with pT, pN and M category (p=0.589, 0.414, and 0.167, respectively), grading (p=0.273), and the Laurén classification (p=0.368). Only the UICC classification was significantly correlated with PAI-1 (p=0.016). Kaplan-Meier analysis revealed no significant association of uPA and PAI-1 with overall survival (p=0.0929 and 0.0870, respectively).

Conclusions

Our results could not verify any prognostic value of uPA and PAI-1 levels in patients with gastric carcinoma. Therefore, the uPA-system as a biologically defined prognostic marker to identify high-risk gastric cancers should be applied with caution. However, considering the number of patients involved and the borderline level of significance observed in this study, a larger number of events may have resulted in significant differences.

Understanding pine wilt disease: roles of the pine endophytic bacteria and of the bacteria carried by the disease-causing pinewood nematode

Pine wilt disease (PWD) is one of the most destructive diseases in trees of the genus Pinus and is responsible for environmental and economic losses around the world. The only known causal agent of the disease is the pinewood nematode (PWN) Bursaphelenchus xylophilus. Despite that, bacteria belonging to several different genera have been found associated with PWN and their roles in the development of PWD have been suggested. Molecular methodologies and the new era of genomics have revealed different perspectives to the problem, recognizing the manifold interactions between different organisms involved in the disease. Here, we reviewed the possible roles of nematode-carried bacteria in PWD, what could be the definition of this group of microorganisms and questioned their origin as possible endophytes, discussing their relation within the endophytic community of pine trees. The diversity of the nematode-carried bacteria and the diversity of pine tree endophytes, reported until now, is revised in detail in this review. What could signify a synergetic effect with PWN harming the plant, or what could equip bacteria with functions to control the presence of nematodes inside the tree, is outlined as two possible roles of the microbial community in the etiology of this disease. An emphasis is put on the potential revealed by the genomic data of isolated organisms in their potential activities as effective tools in PWD management.

Unexpected genomic relationships between Bacillus anthracis strains from Bangladesh and Central Europe

The zoonosis anthrax caused by the bacterium Bacillus anthracis has a broad geographical distribution. Active enzootic areas are typically located away from central and northern Europe where cases of the disease occur only sporadically and in limited numbers. In contrast, a few out of the 64 districts of Bangladesh are hyper-endemic for anthrax and there the disease causes major losses in live-stock. In this study we genotyped eight strains of B. anthracis collected from the districts of Sirajganj and Tangail in 2013. All these strains belonged to canSNP group A.Br.001/002 Sterne differing only in a few of 31 tandem-repeat (MLVA)-markers. Whole genome sequences were obtained from five of these strains and compared with genomic information of B. anthracis strains originating from various geographical locations. Characteristic signatures were detected defining two "Bangladesh" clusters potentially useful for rapid molecular epidemiology. From this data high-resolution PCR assays were developed and subsequently tested on additional isolates from Bangladesh and Central Europe. Remarkably, this comparative genomic analysis focusing on SNP-discovery revealed a close genetic relationship between these strains from Bangladesh and historic strains collected between 1991 and 2008 in The Netherlands and Germany, respectively. Possible explanations for these phylogenetic relationships are discussed.

Whole Genome Analysis of Injectional Anthrax Identifies Two Disease Clusters Spanning More Than 13 Years

Background

Anthrax is a rare disease in humans but elicits great public fear because of its past use as an agent of bioterrorism. Injectional anthrax has been occurring sporadically for more than ten years in heroin consumers across multiple European countries and this outbreak has been difficult to trace back to a source.

Methods

We took a molecular epidemiological approach in understanding this disease outbreak, including whole genome sequencing of Bacillus anthracis isolates from the anthrax victims. We also screened two large strain repositories for closely related strains to provide context to the outbreak.

Findings

Analyzing 60 Bacillus anthracis isolates associated with injectional anthrax cases and closely related reference strains, we identified 1071 Single Nucleotide Polymorphisms (SNPs). The synapomorphic SNPs (350) were used to reconstruct phylogenetic relationships, infer likely epidemiological sources and explore the dynamics of evolving pathogen populations. Injectional anthrax genomes separated into two tight clusters: one group was exclusively associated with the 2009–10 outbreak and located primarily in Scotland, whereas the second comprised more recent (2012–13) cases but also a single Norwegian case from 2000.

Interpretation

Genome-based differentiation of injectional anthrax isolates argues for at least two separate disease events spanning > 12 years. The genomic similarity of the two clusters makes it likely that they are caused by separate contamination events originating from the same geographic region and perhaps the same site of drug manufacturing or processing. Pathogen diversity within single patients challenges assumptions concerning population dynamics of infecting B. anthracis and host defensive barriers for injectional anthrax.

Funding

This work was supported by the United States Department of Homeland Security grant no. HSHQDC-10-C-00,139 and via a binational cooperative agreement between the United States Government and the Government of Germany. This work was supported by funds from the German Ministry of Defense (Sonderforschungsprojekt 25Z1-S-431,214). Support for sequencing was also obtained from Illumina, Inc. These sources had no role in the data generation or interpretation, and had not role in the manuscript preparation.

Panel 1: Research in Context Systematic Review

We searched PubMed for any article published before Jun. 17, 2015, with the terms “Bacillus anthracis” and “heroin”, or “injectional anthrax”. Other than our previously published work (Price et al., 2012), we found no other relevant studies on elucidating the global phylogenetic relationships of B. anthracis strains associated with injectional anthrax caused by recreational heroin consumption of spore-contaminated drug. There were, however, publically available genome sequences of two strains involved (Price et al., 2012, Grunow et al., 2013) and the draft genome sequence of Bacillus anthracis UR-1, isolated from a German heroin user (Ruckert et al., 2012) with only limited information on the genotyping of closely related strains (Price et al., 2012, Grunow et al., 2013).

Lay Person Interpretation

Injectional anthrax has been plaguing heroin drug users across Europe for more than 10 years. In order to better understand this outbreak, we assessed genomic relationships of all available injectional anthrax strains from four countries spanning a > 12 year period. Very few differences were identified using genome-based analysis, but these differentiated the isolates into two distinct clusters. This strongly supports a hypothesis of at least two separate anthrax spore contamination events perhaps during the drug production processes. Identification of two events would not have been possible from standard epidemiological analysis. These comprehensive data will be invaluable for classifying future injectional anthrax isolates and for future geographic attribution.

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Whole genome sequences of injectional anthrax B. anthracis isolates fall in two tight but distinct genomic clusters.

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The distinct genomic clusters are consistent with two or more disease events that overlap in time and space.

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Defining pathogen clusters will lead to better public health responses to difficult to track disease outbreaks.

Microevolution of Anthrax from a Young Ancestor (M.A.Y.A.) Suggests a Soil-Borne Life Cycle of Bacillus anthracis

During an anthrax outbreak at the Pollino National Park (Basilicata, Italy) in 2004, diseased cattle were buried and from these anthrax-foci Bacillus anthracis endospores still diffuse to the surface resulting in local accumulations. Recent data suggest that B. anthracis multiplies in soil outside the animal-host body. This notion is supported by the frequent isolation of B. anthracis from soil lacking one or both virulence plasmids. Such strains represent an evolutionary dead end, as they are likely no longer able to successfully infect new hosts. This loss of virulence plasmids is explained most simply by postulating a soil-borne life cycle of the pathogen. To test this hypothesis we investigated possible microevolution at two natural anthrax foci from the 2004 outbreak. If valid, then genotypes of strains isolated from near the surface at these foci should be on a different evolutionary trajectory from those below residing in deeper-laying horizons close to the carcass. Thus, the genetic diversity of B. anthracis isolates was compared conducting Progressive Hierarchical Resolving Assays using Nucleic Acids (PHRANA) and next generation Whole Genome Sequencing (WGS). PHRANA was not discriminatory enough to resolve the fine genetic relationships between the isolates. Conversely, WGS of nine isolates from near-surface and nine from near-carcass revealed five isolate specific SNPs, four of which were found only in different near-surface isolates. In support of our hypothesis, one surface-isolate lacked plasmid pXO1 and also harbored one of the unique SNPs. Taken together, our results suggest a limited soil-borne life cycle of B. anthracis.

Colonization resistance against genetically modified Escherichia coli K12 (W3110) strains is abrogated following broad-spectrum antibiotic treatment and acute ileitis

Escherichia coli K12 (EcK12) is commonly used for gene technology purposes and regarded as a security strain due to its inability to adhere to epithelial cells. The conventional intestinal microbiota composition is critical for physiological colonization resistance against most bacterial species including pathogens. We were therefore interested whether intestinal colonization by a genetically modified EcK12 (W3110) strain carrying a chloramphenicol resistance cassette was facilitated following broad-spectrum antibiotic treatment eradicating the intestinal microbiota or induction of small intestinal inflammation accompanied by distinct microbiota shifts. Whereas conventional C57BL/6 and BALB/c mice had virtually expelled the EcK12 (W3110) strain within the first 3 days upon peroral infection, EcK12 (W3110) could establish within the small and large intestines of gnotobiotic mice generated by quintuple antibiotic treatment. Gnotobiotic mice perorally infected with EcK12 (W3110) plus fecal transplant from conventional donors harbored lower intestinal EcK12 (W3110) loads compared to animals challenged with EcK12 (W3110) alone. Furthermore, EcK12 (W3110) infection of conventional mice after but not before induction of ileitis resulted in stable colonization of ileum and colon by EcK12 (W3110). Taken together, broad-spectrum antibiotic treatment and intestinal inflammation compromise colonization resistance and thus facilitate colonization of the intestinal tract with genetically modified EcK12 security strains.

Impact of metal ion homeostasis of genetically modified Escherichia coli Nissle 1917 and K12 (W3110) strains on colonization properties in the murine intestinal tract

Metal ions are integral parts of pro- as well as eukaryotic cell homeostasis. Escherichia coli proved a valuable in vitro model organism to elucidate essential mechanisms involved in uptake, storage, and export of metal ions. Given that E. coli Nissle 1917 is able to overcome murine colonization resistance, we generated several E. coli Nissle 1917 mutants with defects in zinc, iron, copper, nickel, manganese homeostasis and performed a comprehensive survey of the impact of metal ion transport and homeostasis for E. coli colonization capacities within the murine intestinal tract. Seven days following peroral infection of conventional mice with E. coli Nissle 1917 strains exhibiting defined defects in zinc or iron uptake, the respective mutant and parental strains could be cultured at comparable, but low levels from the colonic lumen. We next reassociated gnotobiotic mice in which the microbiota responsible for colonization resistance was abrogated by broad-spectrum antibiotics with six different E. coli K12 (W3110) mutants. Seven days following peroral challenge, each mutant and parental strain stably colonized duodenum, ileum, and colon at comparable levels. Taken together, defects in zinc, iron, copper, nickel, and manganese homeostasis do not compromise colonization capacities of E. coli in the murine intestinal tract.

A whole-cell biosensor for the detection of gold

Geochemical exploration for gold (Au) is becoming increasingly important to the mining industry. Current processes for Au analyses require sampling materials to be taken from often remote localities. Samples are then transported to a laboratory equipped with suitable analytical facilities, such as Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) or Instrumental Neutron Activation Analysis (INAA). Determining the concentration of Au in samples may take several weeks, leading to long delays in exploration campaigns. Hence, a method for the on-site analysis of Au, such as a biosensor, will greatly benefit the exploration industry. The golTSB genes from Salmonella enterica serovar typhimurium are selectively induced by Au(I/III)-complexes. In the present study, the golTSB operon with a reporter gene, lacZ, was introduced into Escherichia coli. The induction of golTSB::lacZ with Au(I/III)-complexes was tested using a colorimetric β-galactosidase and an electrochemical assay. Measurements of the β-galactosidase activity for concentrations of both Au(I)- and Au(III)-complexes ranging from 0.1 to 5 µM (equivalent to 20 to 1000 ng g(-1) or parts-per-billion (ppb)) were accurately quantified. When testing the ability of the biosensor to detect Au(I/III)-complexes(aq) in the presence of other metal ions (Ag(I), Cu(II), Fe(III), Ni(II), Co(II), Zn, As(III), Pb(II), Sb(III) or Bi(III)), cross-reactivity was observed, i.e. the amount of Au measured was either under- or over-estimated. To assess if the biosensor would work with natural samples, soils with different physiochemical properties were spiked with Au-complexes. Subsequently, a selective extraction using 1 M thiosulfate was applied to extract the Au. The results showed that Au could be measured in these extracts with the same accuracy as ICP-MS (P<0.05). This demonstrates that by combining selective extraction with the biosensor system the concentration of Au can be accurately measured, down to a quantification limit of 20 ppb (0.1 µM) and a detection limit of 2 ppb (0.01 µM).

Injection anthrax--a new outbreak in heroin users

BACKGROUND

Injection anthrax is a rare disease that affects heroin users and is caused by Bacillus anthracis. In 2012, there were four cases in Germany, one of which was fatal, as well as a small number of cases in other European countries, including Denmark, France, and the United Kingdom. Three cases among drug users occurred in Germany in 2009/2010, in the setting of a larger outbreak centered on Scotland, where there were 119 cases. CASE PRESENTATION AND CLINICAL COURSE: We present three cases of injection anthrax, two of which were treated in Regensburg and one in Berlin. One patient died of multi-organ-system failure on the day of admission to the hospital. The others were treated with antibiotics, one of them also with surgical wound debridement. The laboratory diagnosis of injection anthrax is based on the demonstration of the pathogen, generally by culture and/or by polymerase chain reaction, in material removed directly from the patient's wound. The diagnosis is additionally supported by the detection of specific antibodies.

CONCLUSION

Injection anthrax may be viewed either as an independent disease entity or as a special type of cutaneous anthrax with massive edema, necrotizing fasciitis in many cases, and about 30% mortality. It has appeared in recent years among heroin users in various European countries. In patients with suggestive clinical presentation and a history of heroin use, anthrax infection must be suspected early, so that the appropriate diagnostic tests can be performed without delay. Timely treatment can be life-saving. It is therefore important that physicians--and the individuals at risk--should be well-informed about this disease.

Antimicrobial metallic copper surfaces kill Staphylococcus haemolyticus via membrane damage

Recently, copper (Cu) in its metallic form has regained interest for its antimicrobial properties. Use of metallic Cu surfaces in worldwide hospital trials resulted in remarkable reductions in surface contaminations. Yet, our understanding of why microbes are killed upon contact to the metal is still limited and different modes of action have been proposed. This knowledge, however, is crucial for sustained use of such surfaces in hospitals and other hygiene-sensitive areas. Here, we report on the molecular mechanisms by which the Gram-positive Staphylococcus haemolyticus is inactivated by metallic Cu. Staphylococcus haemolyticus was killed within minutes on Cu but not on stainless steel demonstrating the antimicrobial efficacy of metallic Cu. Inductively coupled plasma mass spectroscopy (ICP-MS) analysis and in vivo staining with Coppersensor-1 indicated that cells accumulated large amounts of Cu ions from metallic Cu surfaces contributing to lethal damage. Mutation rates of Cu- or steel-exposed cells were similarly low. Instead, live/dead staining indicated cell membrane damage in Cu- but not steel-exposed cells. These findings support a model of the cellular targets of metallic Cu toxicity in bacteria, which suggests that metallic Cu is not genotoxic and does not kill via DNA damage. In contrast, membranes constitute the likely Achilles’ heel of Cu surface-exposed cells.

Fatal anthrax infection in a heroin user from southern Germany, June 2012

Blood cultures from a heroin user who died in June 2012, a few hours after hospital admission, due to acute septic disease, revealed the presence of Bacillus anthracis. This report describes the extended diagnosis by MALDI-TOF and real-time PCR and rapid confirmation of the anthrax infection through reference laboratories. Physicians and diagnostic laboratories were informed and alerted efficiently through the reporting channels of German public health institutions, which is essential for the prevention of further cases.

Fatal anthrax infection in a heroin user from southern Germany, June 2012

Blood cultures from a heroin user who died in June 2012, a few hours after hospital admission, due to acute septic disease, revealed the presence of Bacillus anthracis. This report describes the extended diagnosis by MALDI-TOF and real-time PCR and rapid confirmation of the anthrax infection through reference laboratories. Physicians and diagnostic laboratories were informed and alerted efficiently through the reporting channels of German public health institutions, which is essential for the prevention of further cases.

Primary Exploration of Radial Nerve is Not Required for Radial Nerve Palsy while Treating Humerus Shaft Fractures with Unreamed Humerus Nails (UHN)

BACKGROUND

Today, humerus nails have become the surgical method of choice in the treatment of humerus shaft fractures. Whether or not the radial nerve should be intraoperatively examined by default in case of primary paresis is currently under discussion.

PATIENTS AND METHODS

Clinical findings from 38 patients with humeral shaft fractures surgically treated with unreamed humerus nail (UHN) at the Department of Accident Surgery, University Clinics Bonn, Germany, between 2000 and 2003 were retrospectively assessed. Constant Score was applied for evaluation of functional results.

RESULTS

In 40% of patients, primary radial nerve paresis was present. This was especially common after high energy trauma (e.g. traffic accident) and significantly increased in fractures of the middle third. In 93% of cases, spontaneous remission of motor and sensory loss was observed. No iatrogenic radial nerve impairment occurred.

CONCLUSION

Due to the high rates of spontaneous remissions of radial nerve palsy after treatment with UHN in humerus shaft fractures, primar exploration of the radial nerve does not appear to be necessary.

Characterization of a dipartite iron uptake system from uropathogenic Escherichia coli strain F11

In the uropathogenic Escherichia coli strain F11, in silico genome analysis revealed the dicistronic iron uptake operon fetMP, which is under iron-regulated control mediated by the Fur regulator. The expression of fetMP in a mutant strain lacking known iron uptake systems improved growth under iron depletion and increased cellular iron accumulation. FetM is a member of the iron/lead transporter superfamily and is essential for iron uptake by the Fet system. FetP is a periplasmic protein that enhanced iron uptake by FetM. Recombinant FetP bound Cu(II) and the iron analog Mn(II) at distinct sites. The crystal structure of the FetP dimer reveals a copper site in each FetP subunit that adopts two conformations: CuA with a tetrahedral geometry composed of His(44), Met(90), His(97), and His(127), and CuB, a second degenerate octahedral geometry with the addition of Glu(46). The copper ions of each site occupy distinct positions and are separated by ∼1.3 Å. Nearby, a putative additional Cu(I) binding site is proposed as an electron source that may function with CuA/CuB displacement to reduce Fe(III) for transport by FetM. Together, these data indicate that FetMP is an additional iron uptake system composed of a putative iron permease and an iron-scavenging and potentially iron-reducing periplasmic protein.

Roseomonas pecuniae sp. nov., isolated from the surface of a copper-alloy coin

Strain N75T was isolated from the surface of a copper-alloy 50 Euro cent coin collected from general circulation. Phylogenetic analysis of the 16S rRNA gene sequence revealed that strain N75T formed a distinct branch within the genus Roseomonas and placed it in the Alphaproteobacteria. Strain N75T showed 16S rRNA gene sequence similarities of 92.4–97.1 % to type strains of species of the genus Roseomonas. Strain N75T was a Gram-negative, non-spore-forming, non-motile coccoid, with an optimum growth temperature of about 30 °C; the strain did not grow at 5 or 37 °C. Strain N75T did not grow in medium containing NaCl. The major respiratory quinone was ubiquinone 10 (Q-10). The major fatty acids were unsaturated C16 : 1 ω7c/C16 : 1 ω6c and C18 : 1 ω7c (around 70 % of the total fatty acids); the third most abundant fatty acid was the hydroxylated C18 : 1 2-OH. The major polar lipids were phosphatidylcholine, phosphatidylethanolamine and an unknown aminolipid. The DNA G+C content was 72.8 mol%. On the basis of the phylogenetic analysis and physiological and biochemical characteristics, we conclude that strain N75T represents a novel species of the genus Roseomonas, for which we propose the name Roseomonas pecuniae sp. nov. (type strain N75T =LMG 25481T =CIP 110074T).

Correspondence

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Survival of bacteria on metallic copper surfaces in a hospital trial

Basic chemistry of copper is responsible for its Janus-faced feature: on one hand, copper is an essential trace element required to interact efficiently with molecular oxygen. On the other hand, interaction with reactive oxygen species in undesired Fenton-like reactions leads to the production of hydroxyl radicals, which rapidly damage cellular macromolecules. Moreover, copper cations strongly bind to thiol compounds disturbing redox-homeostasis and may also remove cations of other transition metals from their native binding sites in enzymes. Nature has learned during evolution to deal with the dangerous yet important copper cations. Bacterial cells use different efflux systems to detoxify the metal from the cytoplasm or periplasm. Despite this ability, bacteria are rapidly killed on dry metallic copper surfaces. The mode of killing likely involves copper cations being released from the metallic copper and reactive oxygen species. With all this knowledge about the interaction of copper and its cations with cellular macromolecules in mind, experiments were moved to the next level, and the antimicrobial properties of copper-containing alloys in an "everyday" hospital setting were investigated. The alloys tested decreased the number of colony-forming units on metallic copper-containing surfaces by one third compared to control aluminum or plastic surfaces. Moreover, after disinfection, repopulation of the surfaces was delayed on copper alloys. This study bridges a gap between basic research concerning cellular copper homeostasis and application of this knowledge. It demonstrates that the use of copper-containing alloys may limit the spread of multiple drug-resistant bacteria in hospitals.

Point mutations change specificity and kinetics of metal uptake by ZupT from Escherichia coli

The ZIP (ZRT-, IRT-like Protein) protein ZupT from Escherichia coli is a transporter with a broad substrate range. Phenotypic and transport analysis showed that ZupT, in addition to Zn(II), Fe(II) and Co(II) uptake, is also involved in transport of Mn(II) and Cd(II). Competition experiments with other substrate cations suggested that ZupT has a slight preference for Zn(II) and kinetic parameters for Zn(II) in comparison to Co(II) and Mn(II) transport support this observation. Metal uptake into cells by ZupT was optimum at near neutral pH and inhibited by ionophores. Bicarbonate or other ions did not influence metal-uptake via ZupT. Amino acid residues of ZupT contributing to substrate specificity were identified by site directed mutagenesis. ZupT with a H89A exchange lost Co(II) and Fe(II) transport activity, while the S117V mutant no longer transported Mn(II). ZupT with E152D was impaired in overall metal uptake but completely lost its ability to transport the substrates Zn(II) and Mn(II). These experimental findings expand our knowledge on the substrate specificity of ZupT and provide further insight into the function of ZupT as a bacterial member of the vastly distributed and important ZIP family.

Clinicopathological significance of MMP-2 and its specific inhibitor TIMP-2 in gastric cancer

Matrix metalloproteinases (MMPs) can degrade type IV collagen of extracellular matrices and basal membranes and thus play a key role in the migration of malignant cells. In vivo, MMPs are inhibited by tissue inhibitors of metalloproteinases (TIMPs). Since in a previous study we showed that the expression of MMP-2 correlates with clinicopathological parameters in gastric cancer, we have now investigated a possible correlation of MMP-2 and TIMP-2 expression with survival in gastric cancer, as well as the possible association of TIMP-2 with clinicopathological parameters. Tissue samples were obtained from 116 gastric cancer patients who underwent gastrectomy with extended lymphadenectomy. MMP-2 and TIMP-2 expression was analysed using immunohistochemical staining and was graded semiquantitatively (score 0 - 3). High epithelial MMP-2 immunoreactivity was significantly associated with tumor stage and poor survival using the Kaplan-Meier log-rank statistical method (log-rank statistics). However, using Cox regression analysis, high epithelial MMP-2 immunoreactivity was not an independent prognostic factor. TIMP-2 showed no association with survival in gastric cancer, but the intensity of TIMP-2 staining in tumor cells correlated significantly with tumor differentiation based on the WHO and Lauren and Ming classifications, as well as with presence of distant metastasis. Our results show that high epithelial MMP-2 expression in gastric cancer is associated with poor survival, although it is not an independent prognostic factor, and that aggressive forms of gastric cancer are associated with low TIMP-2 expression.

A robust metallo-oxidase from the hyperthermophilic bacterium Aquifex aeolicus

The gene, Aquifex aeolicus AAC07157.1, encoding a multicopper oxidase (McoA) and localized in the genome as part of a putative copper-resistance determinant, has been cloned, over-expressed in Escherichia coli and the recombinant enzyme purified to homogeneity. The purified enzyme shows spectroscopic and biochemical characteristics typical of the well-characterized multicopper oxidase family of enzymes. McoA presents higher specificity (k(cat)/K(m)) for cuprous and ferrous ions than for aromatic substrates and is therefore designated as a metallo-oxidase. Addition of copper is required for maximal catalytic efficiency. A comparative model structure of McoA has been constructed and a striking structural feature is the presence of a methionine-rich region (residues 321-363), reminiscent of those found in copper homeostasis proteins. The kinetic properties of a mutant enzyme, McoADeltaP321-V363, deleted in the methionine-rich region, provide evidence for the key role of this region in the modulation of the catalytic mechanism. McoA has an optimal temperature of 75 degrees C and presents remarkable heat stability at 80 and 90 degrees C, with activity lasting for up to 9 and 5 h, respectively. McoA probably contributes to copper and iron homeostasis in A. aeolicus.

A new ferrous iron-uptake transporter, EfeU (YcdN), from Escherichia coli

Escherichia coli possesses multiple routes for iron uptake. Here we present EfeU (YcdN), a novel iron acquisition system of E. coli strain Nissle 1917. Laboratory strains of E. coli such as K12 lack a functional (efeU) ycdN gene caused by a frameshift mutation. EfeU, a member of the oxidase-dependent iron transporters (OFeT), is a homologue of the iron permease Ftr1p from yeast. The ycdN gene is part of the ycdNOB tricistronic operon which is expressed in response to iron deprivation in a Fur-dependent manner. Expression of efeU resulted in improved growth of an E. coli mutant lacking all known iron-uptake systems and mediated increased iron uptake into cells. Furthermore, the presence of other divalent metal cations did not impair growth of strains expressing efeU. The EfeU protein functioned as ferrous iron permease in proteoliposomes in vitro. Topology analysis indicated that EfeU is an integral cytoplasmic membrane protein exhibiting seven transmembrane helices. Two REXXE motifs within transmembrane helices of OFeT family members are implicated in iron translocation. Site-directed mutagenesis of each REGLE motif of EfeU diminished iron uptake in vivo and growth yield. In vitro the EfeU variant protein with an altered first REGLE motif was impaired in iron permeation, whereas activity of the EfeU variant with a mutation in the second motif was similar to the wild-type protein.

The RcnRA (YohLM) system of Escherichia coli: A connection between nickel, cobalt and iron homeostasis

The transporter RcnA has previously been implicated in Ni(II) and Co(II) detoxification in E. coli probably through efflux. Here we demonstrate that the divergently described rcnA and rcnR gene products constitute a link between nickel, cobalt and iron homeostasis. Deletion of the rcnA gene resulted in increased cellular nickel, cobalt and iron concentrations. Expression of rcnA was induced by Ni(II) or Co(II). Overproduction of rcnR inhibited induction of rcnA by metal cations but RcnR did not bind to the rcnA promoter in vitro. When rcnR or fur, the gene of the global repressor of iron homeostasis, was deleted, expression of rcnA was also induced by iron. The promoter region of rcnA was positive in a Fur titration (FURTA) in vivo assay indicative of Fur binding. Thus, rcnA is part of the Fur regulon of E. coli. The implications of a connection between the homoeostasis of closely related transition metals are discussed.

Sulphate assimilation under Cd2+ stress in Physcomitrella patens--combined transcript, enzyme and metabolite profiling

Cd(2+) causes disturbance of metabolic pathways through severe damage on several levels. Here we present a comprehensive study of Cd(2+)-mediated effects on transcript, enzyme and metabolite levels in a plant without phytochelatin (PC). The moss Physcomitrella patens (Hedw.) B.S.G. was stressed with up to 10 microm Cd(2+) to investigate the regulation of gene transcription and activities of enzymes involved in the assimilatory sulphate reduction pathway and in glutathione biosynthesis. Real-time PCR, specific enzyme assays as well as thiol peptide profiling techniques were applied. Upon supplementation of 10 microm Cd(2+), the moss showed a more than fourfold increase in expression of genes encoding ATP sulphurylase (ATPS), adenosylphosphosulphate reductase, phosphoradenosylphosphorsulphate reductase, sulphite reductase (SiR) and gamma-glutamyl cysteine synthetase (gamma-ECS). Likewise, elevated enzyme activities of gamma-ECS and glutathione synthetase were observed. Contrarily, activity of O-acetylserine (thiol) lyase (OAS-TL), responsible for biosynthesis of cysteine, was diminished. At the metabolite level, nearly doubling of intracellular cysteine and glutathione content was noted, while the moss did not produce any detectable amounts of PCs. These results suggest a Cd(2+)-induced activation of the assimilatory sulphate reduction pathway as well as of glutathione biosynthesis on different levels of regulation.

Control of expression of a periplasmic nickel efflux pump by periplasmic nickel concentrations

There is accumulating evidence that transenvelope efflux pumps of the resistance, nodulation, cell division protein family (RND) are excreting toxic substances from the periplasm across the outer membrane directly to the outside. This would mean that resistance of Gram-negative bacteria to organic toxins and heavy metals is in fact a two-step process: one set of resistance factors control the concentration of a toxic substance in the periplasm, another one that in the cytoplasm. Efficient periplasmic detoxification requires periplasmic toxin sensing and transduction of this signal into the cytoplasm to control expression of the periplasmic detoxification system. Such a signal transduction system was analyzed using the Cnr nickel resistance system from Cupriavidus (Wautersia, Ralstonia, Alcaligenes) metallidurans strain CH34. Resistance is based on nickel efflux mediated by the CnrCBA efflux pump encoded by the cnrYHXCBAT metal resistance determinant. The products of the three genes cnrYXH transcriptionally regulate expression of cnr. CnrY and CnrX are membrane-bound proteins probably functioning as anti sigma factors while CnrH is a cnr-specific extracytoplasmic functions (ECF) sigma factors. Experimental data provided here indicate a signal transduction chain leading from nickel in the periplasm to transcription initiation at the cnr promoters cnrYp and cnrCp, which control synthesis of the nickel efflux pump CnrCBA.

Iron Transport in Escherichia Coli: All has not been said and Done

During recent years new systems involved in iron transport were identified in the old workhorse Escherichia coli (and in other enterobacteria). This came as a bit of a surprise because one might think transport of this essential trace element was already thoroughly studied. Moreover, it appears that iron homeostasis consists not only of uptake but also of efflux of this potentially toxic redox-active metal. New findings in E. coli will be discussed and compared to the situation in other bacteria.

[After care of fractures of the extremities]

Today, early mobilization is recommended, irrespective of whether a patient with a fracture of the extremities has been treated conservatively or surgically. In this way, morbidity and mortality risks can be considerably reduced, in particular in the elderly patient. As a result of the continuing trend towards an ever shorter hospital stay, the general physician is faced with the task of providing aftercare to such patients at an early stage in the healing process of the fracture. This includes wound care, prevention of thromboembolism, the timely initiation of physiotherapeutic measures, and the requesting of x-ray follow-up.

[Primary care of fractures of the extremities]

The initial care of a fractured bone provided by the general physician includes reduction followed by immobilization and the treatment of pain. Open fractures must be covered by a sterile dressing, prior to the transportation of the patient to a hospital. Depending upon the severity of the injury, further treatment is provided by an orthopedic surgeon or in an appropriate hospital.

[Fractures of the extremities--surgical or conservative treatment?]

When a fracture of an extremity has been established, the question immediately arises: should it be treated conservatively or surgically? For each of these options the three "R's" of fracture treatment apply "reduction, retention, rehabilitation". In humans, the most common fracture is that of the distal radius, which is usually amenable to conservative treatment. A fracture of the ankle is treated conservatively only when it is stable with no syndesmotic injury, and the fragments are in good alignment. Should surgical treatment be necessary, stabilization is accomplished with a plate and screws. The advantages and disadvantages of each of the options must be weighed up on an individual basis.

TolC is involved in enterobactin efflux across the outer membrane of Escherichia coli

Escherichia coli excretes the catecholate siderophore enterobactin in response to iron deprivation. While the mechanisms underlying enterobactin biosynthesis and ferric enterobactin uptake and utilization are widely understood, nearly nothing is known about how enterobactin is exported from the cell. Mutant and high-performance liquid chromatography analyses demonstrated that the outer membrane channel tunnel protein TolC but none of the respective seven resistance nodulation cell division (RND) proteins CusA, AcrB, AcrD, AcrF, MdtF (YhiV), or the twin RND MdtBC (YegNO) was essential for enterobactin export across the outer membrane. Mutant E. coli strains with additional deletion of tolC or the major facilitator entS were growth deficient in iron-depleted medium. Strains with deletion of tolC or entS, but not with deletion of genes encoding RND transporters, excreted very little enterobactin into the growth medium. Enterobactin excretion in E. coli is thus probably a two-step process involving the major facilitator EntS and the outer membrane channel tunnel protein TolC. Quantitative reverse transcription-PCR analysis of gene-specific transcripts showed no significant changes in tolC expression upon iron depletion. However, iron starvation led to increased expression of the RND gene mdtF and a decrease in acrD.