Plasmid-mediated dissemination of antibiotic resistance among fecal Enterobacteriaceae in natural ecosystems may contribute to the persistence of antibiotic resistance genes in anthropogenically impacted environments. Plasmid transfer frequencies measured under laboratory conditions might lead to overestimation of plasmid transfer potential in natural ecosystems. This study assessed differences in the conjugative transfer of an IncP-1 (pKJK5) plasmid to three natural Escherichia coli strains carrying extended-spectrum beta-lactamases, by filter mating. Matings were performed under optimal laboratory conditions (rich LB medium and 37°C) and environmentally relevant temperatures (25, 15 and 9°C) or nutrient regimes mimicking environmental conditions and limitations (synthetic wastewater and soil extract). Under optimal nutrient conditions and temperature, two recipients yielded high transfer frequencies (5 × 10–1) while the conjugation frequency of the third strain was 1000-fold lower. Decreasing mating temperatures to psychrophilic ranges led to lower transfer frequencies, albeit all three strains conjugated under all the tested temperatures. Low nutritive media caused significant decreases in transconjugants (−3 logs for synthetic wastewater; −6 logs for soil extract), where only one of the strains was able to produce detectable transconjugants. Collectively, this study highlights that despite less-than-optimal conditions, fecal organisms may transfer plasmids in the environment, but the transfer of pKJK5 between microorganisms is limited mainly by low nutrient conditions.
MULTIFILE
This report presents the highlights of the 7th European Meeting on Molecular Diagnostics held in Scheveningen, The Hague, The Netherlands, 12-14 October 2011. The areas covered included molecular diagnostics applications in medical microbiology, virology, pathology, hemato-oncology,clinical genetics and forensics. Novel real-time amplification approaches, novel diagnostic applications and new technologies, such as next-generation sequencing, PCR lectrospray-ionization TOF mass spectrometry and techniques based on the detection of proteins or other molecules, were discussed. Furthermore, diagnostic companies presented their future visions for molecular diagnostics in human healthcare.
The quantification and identification of new plasmid-acquiring bacteria in representative mating conditions is critical to characterize the risk of horizontal gene transfer in the environment. This study aimed to quantify conjugation events resulting from manure application to soils and identify the transconjugants resulting from these events. Conjugation was quantified at multiple time points by plating and flow cytometry, and the transconjugants were recovered by fluorescence-activated cell sorting and identified by 16S rRNA sequencing. Overall, transconjugants were only observed within the first 4 days after manure application and at values close to the detection limits of this experimental system (1.00–2.49 log CFU/g of manured soil, ranging between 10–5 and 10–4 transconjugants-to-donor ratios). In the pool of recovered transconjugants, we found amplicon sequence variants (ASVs) of genera whose origin was traced to soils (Bacillus and Nocardioides) and manure (Comamonas and Rahnella). This work showed that gene transfer from fecal to soil bacteria occurred despite the less-than-optimal conditions faced by manure bacteria when transferred to soils, but these events were rare, mainly happened shortly after manure application, and the plasmid did not colonize the soil community. This study provides important information to determine the risks of AMR spread via manure application.
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Routine neuropathology diagnostic methods are limited to histological staining techniques or directed PCR for pathogen detection and microbial cultures of brain abscesses are negative in one-third of the cases. Fortunately, due to improvements in technology, metagenomic sequencing of a conserved bacterial gene could provide an alternative diagnostic method. For histopathological work up, formalin-fixed paraffin-embedded (FFPE) tissue with highly degraded nucleic acids is the only material being available. Innovative amplicon-specific next-generation sequencing (NGS) technology has the capability to identify pathogens based on the degraded DNA within a few hours. This approach significantly accelerates diagnostics and is particularly valuable to identify challenging pathogens. This ensures optimal treatment for the patient, minimizing unnecessary health damage. Within this project, highly conserved primers in a universal PCR will be used, followed by determining the nucleotide sequence. Based on the obtained data, it is then precisely determined which microorganism(s) is/are responsible for the infection, even in cases of co-infection with multiple pathogens. This project will focus to answer the following research question; how can a new form of rapid molecular diagnostics contribute to the identification of microbial pathogens in CNS infections? The SME partner Molecular Biology Systems B.V. (MBS) develops and sells equipment for extremely rapid execution of the commonly used PCR. In this project, the lectorate Analysis Techniques in the Life Sciences (Avans) will, in collaboration with MBS, Westerdijk Institute (WI-KNAW) and the Institute of Neuropathology (Münster, DE) establish a new molecular approach for fast diagnosis within CNS infections using this MBS technology. This enables the monitoring of infectious diseases in a fast and user-friendly manner, resulting in an improved treatment plan.
