Biology subjects

Fruth, A.

Publications and source records attributed to Fruth, A..

5 recordsLinked to original sources

bioRxiv2023

Rapid enzymatic detection of Shigatoxin-producing E. coli using fluorescence-labeled oligonucleotide substrates

Shigatoxin-producing E. coli (STEC) are important human pathogens causing disease ranging from diarrhea to severe hemolytic uremic syndrome. As STEC are transmitted via animals, food, and water, and may produce large outbreaks, their timely and qualified detection including isolate recovery is of high importance, but challenging and labor-intense. Thus, the availability of an easy-to-perform rapid test would be a tremendous advance. Since the common feature and major virulence factor of otherwise multifaceted STEC is the Shiga toxin (Stx), we developed a detection method for Stx, specifically for its catalytic RNA-N-glycosidase activity targeting the Sarcin Ricin Loop (SRL) of 28S ribosomal RNA. To this end, synthetic ssDNA substrates mimicking the SRL were designed and linked to a fluorophore and quencher pair, which conferred a fluorescence signal after cleavage by Stx. Optimal results using bacterial culture supernatants or single colonies were achieved for substrate StxSense 4 following 30 to 60 minutes incubation. Importantly, different Stx1 and Stx2 subtypes, diverse STEC serotypes, and Shigella were detected. In conclusion, the assay offers rapid and facile detection of STEC based on a real-time readout for Stx activity. Therefore, it may improve STEC risk evaluation, therapy decisions, outbreak and source detection, and simplify research for antimicrobials.

microbiology↗

bioRxiv2022

Recent O-antigen diversification masks highly pathogenic STEC O104:H4

Shiga toxin-producing E. coli (STEC) can give rise to a range of clinical outcomes from diarrhea to the life-threatening systemic condition, hemolytic uremic syndrome (HUS). Although STEC O157:H7 is the serotype most frequently associated with HUS, a major outbreak of HUS occurred in 2011 in Germany, and was caused by a rare serotype, STEC O104:H4. Prior to 2011 and since the outbreak, STEC O104:H4 strains have only rarely been associated with human infections. From 2012 to 2020 intensified STEC surveillance was performed in Germany where subtyping of [~]8,000 clinical isolates by molecular methods including whole genome sequencing was carried out. A rare STEC serotype O181:H4 associated with HUS was identified and, like the STEC O104:H4 outbreak strain, this strain belongs to sequence type (ST) 678. Genomic and virulence comparisons revealed that the two strains are phylogenetically related and differ principally in the gene cluster encoding their respective lipopolysaccharide O-antigens but exhibit similar virulence phenotypes. In addition, five other serotypes belonging to ST678 from human clinical infection, such as OX13:H4, O127:H4, OgN-RKI9:H4, O131:H4, and O69:H4, were identified from diverse locations worldwide. ImportanceOur data suggest the high virulence ensemble of the STEC O104:H4 outbreak strain remains a global threat because genomically similar strains cause disease worldwide, but that horizontal acquisition of O-antigen gene clusters has diversified the O-antigens of strains belonging to ST678. Thus, identification of these highly pathogenic strains is masked by diverse and rare O-antigens, thereby confounding the interpretation of their potential risk.

microbiology↗

bioRxiv2022

Genome-wide association reveals host-specific genomic traits in Escherichia coli

Escherichia coli is an opportunistic pathogen that can colonize or infect various host species. There is a significant gap in our understanding to what extent genetic lineages of E. coli are adapted or restricted to specific hosts. In addition, genomic determinants underlying such host specificity are unknown.By analyzing a randomly sampled collection of 1198 whole-genome sequenced E. coli isolates from four countries (Germany, UK, Spain, and Vietnam), obtained from five host species (human, pig, cattle, chicken, and wild boar) over 16 years, from both healthy and diseased hosts, we demonstrate that certain lineages of E. coli are frequently detected in specific hosts. We report a novel nan gene cluster, designated nan-9, putatively encoding acetylesterases and determinants of uptake and metabolism of sialic acid, to be associated with the human host as identified through genome wide association studies. In silico characterization predicts nan-9 to be involved in sialic acid (Sia) metabolism. In vitro growth experiments with a representative {Delta}nan E. coli mutant strain, using sialic acids 5-N-acetyl neuraminic acid (Neu5Ac) and N-glycolyl neuraminic acid (Neu5Gc) as the sole carbon source, indicate an impaired growth behaviour compared to the wild-type. In addition, we identified several additional E. coli genes that are potentially associated with adaptation to human, cattle and chicken hosts, but not for the pig host. Collectively, this study provides an extensive overview of genetic determinants which may mediate host specificity in E. coli. Our findings should inform risk analysis and epidemiological monitoring of (antimicrobial resistant) E. coli.

genomics↗

bioRxiv2021

Genome-wide insights into population structure and host specificity of Campylobacter jejuni

The zoonotic pathogen Campylobacter jejuni is among the leading causes of foodborne diseases worldwide. While C. jejuni colonises many wild animals and livestock, persistence mechanisms enabling the bacterium to adapt to host species guts are not fully understood. In order to identify putative determinants influencing host preferences of distinct lineages, bootstrapping based on stratified random sampling combined with a k-mer-based genome-wide association was conducted on 490 genomes from diverse origins in Germany and Canada. We show a strong association of both the core and the accessory genome characteristics with distinct host animal species, indicating multiple adaptive trajectories defining the evolution of C. jejuni lifestyle preferences in different ecosystems. Here, we demonstrate that adaptation towards a specific host niche ecology is most likely a long evolutionary and multifactorial process, expressed by gene absence or presence and allele variations of core genes. Several host-specific allelic variants from different phylogenetic backgrounds, including dnaE, rpoB, ftsX or pycB play important roles for genome maintenance and metabolic pathways. Thus, variants of genes important for C. jejuni to cope with specific ecological niches or hosts may be useful markers for both surveillance and future pathogen intervention strategies.

genomics↗

bioRxiv2020

Population structure-guided profiling of antibiotic resistance patterns in clinical Listeria monocytogenes isolates from Germany identifies pbpB3 alleles associated with low levels of cephalosporin resistance

AO_SCPLOWBSTRACTC_SCPLOWCase numbers of listeriosis have been increasing in Germany and the European Union during the last decade. In addition reports on the occurrence of antibiotic resistance in Listeria monocytogenes in clinical and environmental isolates are accumulating. The susceptibility towards 14 antibiotics was tested in a selection of clinical L. monocytogenes isolates to get a more precise picture of the development and manifestation of antibiotic resistance in the L. monocytogenes population. Based on the population structure determined by core genome multi locus sequence typing (cgMLST) 544 out of 1,220 sequenced strains collected in Germany between 2009 and 2019 were selected to cover the phylogenetic diversity observed in the clinical L. monocytogenes population. All isolates tested were susceptible towards ampicillin, penicillin and co-trimoxazole - the most relevant antibiotics in the treatment of listeriosis. Resistance to daptomycin and ciprofloxacin was observed in 493 (91%) and in 71 (13%) of 544 isolates, respectively. While all tested strains showed resistance towards ceftriaxone, the minimal inhibitory concentrations (MIC) observed varied widely between 4 mg/L up to >128 mg/L. An allelic variation of the penicillin binding protein gene pbpB3 could be identified as the cause of this difference in ceftriaxone resistance levels. This study is the first population structure-guided analysis of antimicrobial resistance in recent clinical isolates and confirms the importance of penicillin binding protein B3 (PBP B3) for the high level of intrinsic cephalosporin resistance of L. monocytogenes on a population-wide scale.

microbiology↗