Hettich, Timm
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Hettich, Timm
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- PublikationValidation of a commercial enzyme-linked immunosorbent assay for allopregnanolone in the saliva of healthy pregnant women(MDPI, 27.09.2022) Grötsch, Maria Katharina; Wietor, Denise Margret; Hettich, Timm; Ehlert, Ulrike [in: Biomolecules]Enzyme-linked immunosorbent assays (ELISAs) for saliva are simple, non-invasive methods for hormone detection. Allopregnanolone (ALLO) is a neuroactive steroid hormone that plays a crucial role in the aetiology of reproductive mood disorders. To better understand the relationship between ALLO and mood, a validated method to measure peripheral hormone levels is required. Currently, there is no commercially available ELISA with which to measure ALLO in saliva. We validated two ELISAs, developed for use with blood, with the saliva samples of 25 pregnant women, examining the range and sensitivity, intra- and inter-assay precision, parallelism, linearity of dilution, and recovery. The samples were simultaneously analysed using the liquid-chromatography–mass-spectrometry (LC-MS) method. The kits differed in range (31.2–2000 pg/mL vs. 1.6–100 ng/mL) and sensitivity (<9.5 pg/mL vs. 0.9 ng/mL), with the latter showing significant matrix effects and the former fulfilling the acceptance criteria of all the parameters. The concentrations measured with LC–MS were below the lower limit of quantification (<1.0 ng/mL) and no signal was detected. One of the tested ELISAs is a valid method for detecting ALLO in the saliva of pregnant women. It has a suitable measurement range and higher sensitivity than the conventional LC–MS method.01A - Beitrag in wissenschaftlicher Zeitschrift
- PublikationTradeoff between micropollutant abatement and bromate formation during ozonation of concentrates from nanofiltration and reverse osmosis processes(Elsevier, 2022) Wünsch, Robin; Hettich, Timm; Prahtel, Marlies; Thomann, Michael; Wintgens, Thomas; Von Gunten, Urs [in: Water Research]Water treatment with nanofiltration (NF) or reverse osmosis (RO) membranes results in a purified permeate and a retentate, where solutes are concentrated and have to be properly managed and discharged. To date, little is known on how the selection of a semi-permeable dense membrane impacts the dissolved organic matter in the concentrate and what the consequences are for micropollutant (MP) abatement and bromate formation during concentrate treatment with ozone. Laboratory ozonation experiments were performed with standardized concentrates produced by three membranes (two NFs and one low-pressure reverse osmosis (LPRO) membrane) from three water sources (two river waters and one lake water). The concentrates were standardized by adjustment of pH and concentrations of dissolved organic carbon, total inorganic carbon, selected micropollutants (MP) with a low to high ozone reactivity and bromide to exclude factors which are known to impact ozonation. NF membranes had a lower retention of bromide and MPs than the LPRO membrane, and if the permeate quality of the NF membrane meets the requirements, the selection of this membrane type is beneficial due to the lower bromate formation risks upon concentrate ozonation. The bromate formation was typically higher in standardized concentrates of LPRO than of NF membranes, but the tradeoff between MP abatement and bromate formation upon ozonation of the standardized concentrates was not affected by the membrane type. Furthermore, there was no difference for the different source waters. Overall, ozonation of concentrates is only feasible for abatement of MPs with a high to moderate ozone reactivity with limited bromate formation. Differences in the DOM composition between NF and LPRO membrane concentrates are less relevant than retention of MPs and bromide by the membrane and the required ozone dose to meet a treatment target.01A - Beitrag in wissenschaftlicher Zeitschrift
- PublikationWhole-genome sequence-informed MALDI-TOF MS diagnostics reveal importance of Klebsiella oxytoca group in invasive infections: a retrospective clinical study(Springer, 2021) Cuenod, Aline; Wüthrich, Daniel; Seth-Smith, Helena; Ott, Chantal; Gehringer, Christian; Foucaul, Frederic; Mouchet, Roxanne; Kassim, Ali; Revathi, Gunturu; Vogt, Deborah; von Felten, Stefanie; Bassetti, Stefano; Tschudin-Sutter, Sarah; Hettich, Timm; Schlotterbeck, Götz; Homberger, Christina; Casanova, Carlo; Moran-Gilad, Jakob; Sagi, Orli; Rodriguez-Sanchez, Belen; Müller, Franco; Aerni, Martina; Gaia, Valeria; van Dessel, Helke; Kampinga, Greetje; Müller, Claudia; Daubenberger, Claudia; Pflüger, Valentin; Egli, Adrian [in: Genome Medicine]Background Klebsiella spp. are opportunistic pathogens which can cause severe infections, are often multi-drug resistant and are a common cause of hospital-acquired infections. Multiple new Klebsiella species have recently been described, yet their clinical impact and antibiotic resistance profiles are largely unknown. We aimed to explore Klebsiella group- and species-specific clinical impact, antimicrobial resistance (AMR) and virulence. Methods We analysed whole-genome sequence data of a diverse selection of Klebsiella spp. isolates and identified resistance and virulence factors. Using the genomes of 3594 Klebsiella isolates, we predicted the masses of 56 ribosomal subunit proteins and identified species-specific marker masses. We then re-analysed over 22,000 Matrix-Assisted Laser Desorption Ionization - Time Of Flight (MALDI-TOF) mass spectra routinely acquired at eight healthcare institutions in four countries looking for these species-specific markers. Analyses of clinical and microbiological endpoints from a subset of 957 patients with infections from Klebsiella species were performed using generalized linear mixed-effects models. Results Our comparative genomic analysis shows group- and species-specific trends in accessory genome composition. With the identified species-specific marker masses, eight Klebsiella species can be distinguished using MALDI-TOF MS. We identified K. pneumoniae (71.2%; n = 12,523), K. quasipneumoniae (3.3%; n = 575), K. variicola (9.8%; n = 1717), “K. quasivariicola” (0.3%; n = 52), K. oxytoca (8.2%; n = 1445), K. michiganensis (4.8%; n = 836), K. grimontii (2.4%; n = 425) and K. huaxensis (0.1%; n = 12). Isolates belonging to the K. oxytoca group, which includes the species K. oxytoca, K. michiganensis and K. grimontii, were less often resistant to 4th-generation cephalosporins than isolates of the K. pneumoniae group, which includes the species K. pneumoniae, K. quasipneumoniae, K. variicola and “K. quasivariicola” (odds ratio = 0.17, p < 0.001, 95% confidence interval [0.09,0.28]). Within the K. pneumoniae group, isolates identified as K. pneumoniae were more often resistant to 4th-generation cephalosporins than K. variicola isolates (odds ratio = 2.61, p = 0.003, 95% confidence interval [1.38,5.06]). K. oxytoca group isolates were found to be more likely associated with invasive infection to primary sterile sites than K. pneumoniae group isolates (odds ratio = 2.39, p = 0.0044, 95% confidence interval [1.05,5.53]). Conclusions Currently misdiagnosed Klebsiella spp. can be distinguished using a ribosomal marker-based approach for MALDI-TOF MS. Klebsiella groups and species differed in AMR profiles, and in their association with invasive infection, highlighting the importance for species identification to enable effective treatment options.01A - Beitrag in wissenschaftlicher Zeitschrift