The Widespread Multidrug-Resistant Serotype O12 <i>Pseudomonas aeruginosa</i> Clone Emerged through Concomitant Horizontal Transfer of Serotype Antigen and Antibiotic Resistance Gene Clusters

The O-specific antigen (OSA) in Pseudomonas aeruginosa lipopolysaccharide is highly varied by sugar identity, side chains, and bond between O-repeats. These differences classified P. aeruginosa into 20 distinct serotypes. In the past few decades, O12 has emerged as the predominant serotype in clinical settings and outbreaks. These serotype O12 isolates exhibit high levels of resistance to various classes of antibiotics. Here, we explore how the P. aeruginosa OSA biosynthesis gene clusters evolve in the population by investigating the association between the phylogenetic relationships among 83 P. aeruginosa strains and their serotypes. While most serotypes were closely linked to the core genome phylogeny, we observed horizontal exchange of OSA biosynthesis genes among phylogenetically distinct P. aeruginosa strains. Specifically, we identified a “serotype island” ranging from 62 kb to 185 kb containing the P. aeruginosa O12 OSA gene cluster, an antibiotic resistance determinant (gyrA(C248T)), and other genes that have been transferred between P. aeruginosa strains with distinct core genome architectures. We showed that these genes were likely acquired from an O12 serotype strain that is closely related to P. aeruginosa PA7. Acquisition and recombination of the “serotype island” resulted in displacement of the native OSA gene cluster and expression of the O12 serotype in the recipients. Serotype switching by recombination has apparently occurred multiple times involving bacteria of various genomic backgrounds. In conclusion, serotype switching in combination with acquisition of an antibiotic resistance determinant most likely contributed to the dissemination of the O12 serotype in clinical settings

Pseudomonas aeruginosa displays an epidemic population structure.

peer reviewedBacteria can have population structures ranging from the fully sexual to the highly clonal. Despite numerous studies, the population structure of Pseudomonas aeruginosa is still somewhat contentious. We used a polyphasic approach in order to shed new light on this issue. A data set consisting of three outer membrane (lipo)protein gene sequences (oprI, oprL and oprD), a DNA-based fingerprint (amplified fragment length polymorphism), serotype and pyoverdine type of 73 P. aeruginosa clinical and environmental isolates, collected across the world, was analysed using biological data analysis software. We observed a clear mosaicism in the results, non-congruence between results of different typing methods and a microscale mosaic structure in the oprD gene. Hence, in this network, we also observed some clonal complexes characterized by an almost identical data set. The most recent clones exhibited serotypes O1, 6, 11 and 12. No obvious correlation was observed between these dominant clones and habitat or, with the exception of some recent clones, geographical origin. Our results are consistent with, and even clarify, some seemingly contradictory results in earlier epidemiological studies. Therefore, we suggest an epidemic population structure for P. aeruginosa, comparable with that of Neisseria meningitidis, a superficially clonal structure with frequent recombinations, in which occasionally highly successful epidemic clones arise

Pseudomonas aeruginosa Population Structure Revisited

At present there are strong indications that Pseudomonas aeruginosa exhibits an epidemic population structure; clinical isolates are indistinguishable from environmental isolates, and they do not exhibit a specific (disease) habitat selection. However, some important issues, such as the worldwide emergence of highly transmissible P. aeruginosa clones among cystic fibrosis (CF) patients and the spread and persistence of multidrug resistant (MDR) strains in hospital wards with high antibiotic pressure, remain contentious. To further investigate the population structure of P. aeruginosa, eight parameters were analyzed and combined for 328 unrelated isolates, collected over the last 125 years from 69 localities in 30 countries on five continents, from diverse clinical (human and animal) and environmental habitats. The analysed parameters were: i) O serotype, ii) Fluorescent Amplified-Fragment Length Polymorphism (FALFP) pattern, nucleotide sequences of outer membrane protein genes, iii) oprI, iv) oprL, v) oprD, vi) pyoverdine receptor gene profile (fpvA type and fpvB prevalence), and prevalence of vii) exoenzyme genes exoS and exoU and viii) group I pilin glycosyltransferase gene tfpO. These traits were combined and analysed using biological data analysis software and visualized in the form of a minimum spanning tree (MST). We revealed a network of relationships between all analyzed parameters and non-congruence between experiments. At the same time we observed several conserved clones, characterized by an almost identical data set. These observations confirm the nonclonal epidemic population structure of P. aeruginosa, a superficially clonal structure with frequent recombinations, in which occasionally highly successful epidemic clones arise. One of these clones is the renown and widespread MDR serotype O12 clone. On the other hand, we found no evidence for a widespread CF transmissible clone. All but one of the 43 analysed CF strains belonged to a ubiquitous P. aeruginosa “core lineage” and typically exhibited the exoS+/exoU− genotype and group B oprL and oprD alleles. This is to our knowledge the first report of an MST analysis conducted on a polyphasic data set

Quality-Controlled Small-Scale Production of a Well-Defined Bacteriophage Cocktail for Use in Human Clinical Trials

We describe the small-scale, laboratory-based, production and quality control of a cocktail, consisting of exclusively lytic bacteriophages, designed for the treatment of Pseudomonas aeruginosa and Staphylococcus aureus infections in burn wound patients. Based on succesive selection rounds three bacteriophages were retained from an initial pool of 82 P. aeruginosa and 8 S. aureus bacteriophages, specific for prevalent P. aeruginosa and S. aureus strains in the Burn Centre of the Queen Astrid Military Hospital in Brussels, Belgium. This cocktail, consisting of P. aeruginosa phages 14/1 (Myoviridae) and PNM (Podoviridae) and S. aureus phage ISP (Myoviridae) was produced and purified of endotoxin. Quality control included Stability (shelf life), determination of pyrogenicity, sterility and cytotoxicity, confirmation of the absence of temperate bacteriophages and transmission electron microscopy-based confirmation of the presence of the expected virion morphologic particles as well as of their specific interaction with the target bacteria. Bacteriophage genome and proteome analysis confirmed the lytic nature of the bacteriophages, the absence of toxin-coding genes and showed that the selected phages 14/1, PNM and ISP are close relatives of respectively F8, φKMV and phage G1. The bacteriophage cocktail is currently being evaluated in a pilot clinical study cleared by a leading Medical Ethical Committee

Wages in high-tech start-ups - do academic spin-offs pay a wage premium?

Due to their origin from universities, academic spin‐offs operate at the forefront of the technological development. Therefore, spin‐offs exhibit a skill‐biased labour demand, i.e. spin‐offs have a high demand for employees with cutting edge knowledge and technical skills. In order to accommodate this demand, spin‐offs may have to pay a relative wage premium compared to other high‐tech start‐ups. However, neither a comprehensive theoretical assessment nor the empirical literature on wages in start‐ups unambiguously predicts the existence and the direction of wage differentials between spin‐offs and non‐spin‐offs. This paper addresses this research gap and examines empirically whether or not spin‐offs pay their employees a wage premium. Using a unique linked employer‐employee data set of German high‐tech start‐ups, we estimate Mincer‐type wage regressions applying the Hausman‐Taylor panel estimator. Our results show that spin‐offs do not pay a wage premium in general. However, a notable exception from this general result is that spin‐offs that commercialise new scientific results or methods provide higher wages to employees with linkages to the university sector – either as university graduates or as student workers

Glycerol treatment as recovery procedure for cryopreserved human skin allografts positive for bacteria and fungi

Human donor skin allografts are suitable and much used temporary biological (burn) wound dressings. They prepare the excised wound bed for final autografting and form an excellent substrate for revascularisation and for the formation of granulation tissue. Two preservation methods, glycerol preservation and cryopreservation, are commonly used by tissue banks for the long-term storage of skin grafts. The burn surgeons of the Queen Astrid Military Hospital preferentially use partly viable cryopreserved skin allografts. After mandatory 14-day bacterial and mycological culture, however, approximately 15% of the cryopreserved skin allografts cannot be released from quarantine because of positive culture. To maximize the use of our scarce and precious donor skin, we developed a glycerolisation-based recovery method for these culture positive cryopreserved allografts. The inactivation and preservation method, described in this paper, allowed for an efficient inactivation of the colonising bacteria and fungi, with the exception of spore-formers, and did not influence the structural and functional aspects of the skin allografts

Technology transfer offices as boundary spanners in the pre-spin-off process: the case of a hybrid model

Over the past decades, universities have increasingly become ambidextrous organizations reconciling scientific and commercial missions. In order to manage this ambidexterity, technology transfer offices (TTOs) were established in most universities. This paper studies a specific, often implemented, but rather understudied type of TTO, namely a hybrid TTO model uniting centralized and decentralized levels. Employing a qualitative research design, we examine how and why the two TTO levels engage in diverse boundary spanning activities to help nascent spin-off companies move through the pre-spin-off process. Our research identifies differences in the types of boundary spanning activities that centralized and decentralized TTOs perform and in the parties they engage with. We find geographical, technological and organizational proximity to be important antecedents of the TTOs’ engagement in external and internal boundary spanning activities. These results have important implications for both academics and practitioners interested in university technology transfer through spin-off creation

From green technology development to green innovation: inducing regulatory adoption of pathogen detection technology for sustainable forestry

Technological entrepreneurship has been widely acknowledged as a key driver of modern industrial economies, and more recently, a panacea for environmental and social problems. However, our current understanding of how green-technology ventures emerge and diffuse more sustainable innovations remains limited. We advance theory on green entrepreneurship by drawing on institutional work to refine and extend our understanding of how entrepreneurs may influence government policies and practices in their attempts to diffuse green technology. We develop a theoretical framework that combines institutional work with a search tool, the technological, commercial, organizational, and societal (TCOS) framework of innovative uncertainties, which identifies key opportunities, hurdles, and potential unintended consequences at early stages of technology development. We present a detailed case study of a potential university-based green-tech venture developing pathogen detection technology for forestry protection. Foreign pathogens spread by international trade can have major detrimental impacts on forests and the industries that rely on them. Our analysis found that green technology demonstrating technological feasibility is necessary but not sufficient; green-tech ventures must also engage in institutional work, in this case, articulating the technology’s benefits to regulators to establish legitimacy and avoid misuse that can hinder its adoption. We thus add to previous studies by emphasizing that institutional work could be a main activity for a green-tech venture, a core entrepreneurial strategy rather than an afterthought