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Extended spectrum beta lactamases producing Enterobacteriaceae are a major player in the antibiotic resistance challenge. In general, the situation regarding antibiotic resistance in Austria is very good compared to many other countries. Perhaps this is why there is a lack of data on the distribution of ESBL genes in the clinical setting. The aim of this study was to collect data on ESBL genes from a larger sample of human non-invasive clinical isolates from one region in Austria. In total, 468 isolates from different sample materials isolated at the Medical University of Graz from 2017 were examined. The most frequent organisms were Escherichia coli and Klebsiella pneumoniae. Among the enzymes produced, CTX-M-15 was clearly dominant, exotic ESBLs were only represented by three Proteus mirabilis isolates harboring genes for VEB-6 and one P. mirabilis for CTX-M-2, respectively. Compared to other countries, the results are in line with the expectations. The data help to better classify the many studies from the non-clinical field in Austria and to shift the focus slightly away from the exotic results and sample sites.

The authors wish to make the following corrections to this paper [1]: In all instances mentioning “2 kG·m−1”, these gradients should be replaced by “770 G·m−1 (WCM 62081992) and 740 G·m−1 (WCM 62083545)”: Abstract, page 1, line 4; Chapter 1 [...]

In 2012 Coey proposed a theory on the mechanism of magnetic water treatment based on the gradient of the applied field rather than its absolute strength. We tested this theory by measuring the effect of very weak field magnets (≤ 10 G) containing strong magnetic inhomogeneities (ΔB = 770 G·m−1 (WCM 62081992) and 740 G·m−1 (WCM 62083545)) on tap water samples by the use of electric impedance spectroscopy (EIS) and laser scattering. Our results show an increased formation of nm-sized prenucleation clusters (dynamically ordered liquid like oxyanion polymers or “DOLLOPs”) due to the exposure to the magnetic field and thus are consistent with Coey’s theory which is therefore also applicable to very weak magnetic fields as long as they contain strong gradients.

Biofilms may interfere with membrane performance in at least three ways: (i) increase of the transmembrane pressure drop, (ii) increase of feed channel (feed-concentrate) pressure drop, and (iii) increase of transmembrane passage. Given the relevance of biofouling, it is surprising how few data exist about the hydraulic resistance of biofilms that may affect the transmembrane pressure drop and membrane passage. In this study, biofilms were generated in a lab scale cross flow microfiltration system at two fluxes (20 and 100 L m−2 h−1) and constant cross flow (0.1 m s−1). As a nutrient source, acetate was added (1.0 mg L−1 acetate C) besides a control without nutrient supply. A microfiltration (MF) membrane was chosen because the MF membrane resistance is very low compared to the expected biofilm resistance and, thus, biofilm resistance can be determined accurately. Transmembrane pressure drop was monitored. As biofilm parameters, thickness, total cell number, TOC, and extracellular polymeric substances (EPS) were determined, it was demonstrated that no internal membrane fouling occurred and that the fouling layer actually consisted of a grown biofilm and was not a filter cake of accumulated bacterial cells. At 20 L m−2 h−1 flux with a nutrient dosage of 1 mg L−1 acetate C, the resistance after 4 days reached a value of 6×1012 m−1. At 100 L m−2 h−1 flux under the same conditions, the resistance was 5×1013 m−1. No correlation of biofilm resistance to biofilm thickness was found; Biofilms with similar thickness could have different resistance depending on the applied flux. The cell number in biofilms was between 4×107 and 5×108 cells cm−2. At this number, bacterial cells make up less than a half percent of the overall biofilm volume and therefore did not hamper the water flow through the biofilm significantly. A flux of 100 L m−2 h−1 with nutrient supply caused higher cell numbers, more biomass, and higher biofilm resistance than a flux of 20 L m−2 h−1. However, the biofilm thickness after 4 days at a flux of 100 L m−2 h−1 (97 μm) was in the same order of magnitude as the thickness of a biofilm at a flux of 20 L m−2 h−1 (114 μm). An increase of flux caused an increased biofilm resistance while a decrease of flux caused a decreased resistance. The effect was reversible. It is suggested that the biofilm resistance is mainly attributed to EPS, probably due to the tortuosity (“hair-in-sink-effect”) of the biopolymers to water molecules travelling across the biofilm. The data show clearly that biofilm resistance (6×1012 m−1) was high compared to the intrinsic resistance of the employed MF membrane (5×1011 m−1). However, in nanofiltration (intrinsic membrane resistance ca. 2×1013 m−1) and reverse osmosis membranes (intrinsic resistance ca. 9×1013 m−1), the biofilm will not contribute significantly to the overall resistance.