Biology subjects

Drissner, D.

Publications and source records attributed to Drissner, D..

3 recordsLinked to original sources

bioRxiv2025

Correlation of in vitro biofilm formation capacity with persistence of antibiotic-resistant Escherichia coli on gnotobiotic lamb's lettuce

Bacterial contamination of fresh produce is a growing concern for food safety, as apart from human pathogens, antibiotic-resistant bacteria can persist on fresh leafy produce. A prominent persistence trait in bacteria is biofilm formation, as it provides increased tolerance to stressful conditions. We screened a comprehensive collection of 174 antibiotic-susceptible and -resistant Escherichia coli originating from fresh leafy produce and its production environment. We tested the ability of these strains to produce biofilms, ranging from none or weak to extreme biofilm-forming bacteria. Next, we tested the ability of selected antibiotic-resistant isolates to colonize gnotobiotic lambs lettuce (Valerianella locusta) plants. We hypothesized that a higher in vitro biofilm formation capacity correlates with increased colonization of gnotobiotic plant leaves. Despite a marked difference in the ability to form in vitro biofilms for a number of E. coli strains, in vitro biofilm formation was not associated with increased survival on gnotobiotic V. locusta leaf surfaces. However, all tested strains persisted for at least 21 days, highlighting potential food safety risks through unwanted ingestion of resistant bacteria. Population densities of biofilm-forming E. coli exhibited a complex pattern, with subpopulations more successful in colonizing gnotobiotic V. locusta leaves. These findings emphasise the complex behaviour of antibiotic-resistant bacteria on leaf surfaces and their implications to human safety. ImportanceEach raw food contains a collection of microorganisms, including bacteria. This is of special importance for fresh produce such as leafy salads or herbs, as these foods are usually consumed raw or after minimal processing, whereby higher loads of living bacteria are ingested than with a food that is heated before consumption. A common bacterial lifestyle involves living in large groups embedded in secreted protective substances. Such bacterial assemblies, so-called biofilms, confer high persistence and resistance of bacteria to external harsh conditions. In our research we investigated whether stronger in vitro biofilm formation of antibiotic-resistant Escherichia coli correlates with a better survival on lambs lettuce leaves. Although no clear correlation was observed between biofilm formation capacity and population density on the salad, all tested isolates could survive for at least three weeks with no significant decline over time, highlighting a potential food safety risk independently of in vitro biofilm formation.

microbiology↗

bioRxiv2024

Genomic analysis of antimicrobial resistant Escherichia coli isolated from manure and manured agricultural grasslands

Antimicrobial resistance (AMR) is a multifactorial issue involving an intertwining relationship between animals, humans and the environment. The environment can harbour bacteria that are pathogenic to human health, including Escherichia coli, an indicator of environmental faecal contamination. Through culture dependent approaches this study identified 46 E. coli isolates in porcine and bovine manure, non-manured and manured soil, and the phyllosphere of manured grass. The grass isolation highlights grass as an environmental reservoir for E. coli. Whole genome sequencing identified 11 different multi-locus sequence types. We also identified a diverse plasmidome with 23 different plasmid replicon types. The E. coli isolates were phenotypically antibiotic resistance, predominantly multidrug resistant. Additionally, whole genome sequencing identified 31 antibiotic resistance genes, and mutations in the gyrA, parC, and parE genes, conferring fluoroquinolone resistance. The main virulence genes were associated actin mediated locomotion (icsP/sopA), siderophore production and alginate production (algA), which suggest adaptation to survive in the non-gut environment or the UV environment of grass surfaces. These results suggest that E. coli in soils and grasses may adapt to their new environments evolving novel strategies. This study demonstrates grass as an understudied environmental niche of AMR E. coli, which directly links the environment to the grass grazing animal and vice-versa via the circular economy of manure application. Impact statementEscherichia coli is capable of surviving across biomes within One Health. This study sheds light on the genomic elements present in AMR E. coli in the understudied niche of agricultural grassland. Data summaryThe genome sequences have been deposited in Genbank. Bioproject number PRJNA1080214 and SRP491607 in the sequence read archive https://www.ncbi.nlm.nih.gov/sra/?term=SRP491607.

microbiology↗

bioRxiv2018

Conjugation dynamics of self-transmissible and mobilisable plasmids into E. coli O157:H7 on Arabidopsis thaliana rosettes

Many antibiotic resistance genes present in human pathogenic bacteria are believed to originate from environmental bacteria and conjugation of antibiotic resistance conferring plasmids is considered to be one of the major reasons for the increasing prevalence of antibiotic resistances. A hotspot for plasmid-based horizontal gene transfer is the phyllosphere, i.e. the surfaces of aboveground plant parts. Bacteria in the phyllosphere might serve as intermediate hosts with transfer capability to human pathogenic bacteria. In this study, the exchange of mobilisable and self-transmissible plasmids via conjugation was evaluated. The conjugation from the laboratory strain E. coli S17-1, the model phyllosphere colonizer Pantoea eucalypti 299R, and the model pathogen E. coli O157:H7{triangleup} stx to the recipient strain E. coli O157:H7::MRE1O3{triangleup} stx in the phyllosphere of Arabidopsis thaliana was determined. The results suggest that short-term occurrence of a competent donor is sufficient to fix plasmids in a recipient population of E. coli O157:H7::MRE1O3{triangleup} stx. The spread of self-transmissible plasmids was limited after initial steep increases of transconjugants that contributed up to 10% of the total recipient population. The here-presented data of plasmid transfer will be important for future modelling approaches to estimate environmental spread of antibiotic resistance in agricultural production environments.\n\nImportanceThis study investigated the transfer of antibiotic resistance conferring plasmids to enteropathogenic E. coli on plant leaf surfaces. The results indicate that plasmid transfer may be high within the first 24 hours after inoculation. Transconjugant populations are maintained and stable for a considerable time frame on plant leaves, but invasion of the plasmid to the recipient population is limited.

microbiology↗