2021, Richter, Robert, Kamal, Mohamed A.M., Koch, Marcus, Niebuur, Bart-Jan, Huber, Anna-Lena, Goes, Adriely, Volz, Carsten, Vergalli, Julia, Kraus, Tobias, Müller, Rolf, Schneider-Daum, Nicole, Fuhrmann, Gregor, Pagès, Jean-Marie, Lehr, Claus-Michael

When searching for new antibiotics against Gram-negative bacterial infections, a better understanding of the permeability across the cell envelope and tools to discriminate high from low bacterial bioavailability compounds are urgently needed. Inspired by the phospholipid vesicle-based permeation assay (PVPA), which is designed to predict non-facilitated permeation across phospholipid membranes, outer membrane vesicles (OMVs) of Escherichia coli either enriched or deficient of porins are employed to coat filter supports for predicting drug uptake across the complex cell envelope. OMVs and the obtained in vitro model are structurally and functionally characterized using cryo-TEM, SEM, CLSM, SAXS, and light scattering techniques. In vitro permeability, obtained from the membrane model for a set of nine antibiotics, correlates with reported in bacterio accumulation data and allows to discriminate high from low accumulating antibiotics. In contrast, the correlation of the same data set generated by liposome-based comparator membranes is poor. This better correlation of the OMV-derived membranes points to the importance of hydrophilic membrane components, such as lipopolysaccharides and porins, since those features are lacking in liposomal comparator membranes. This approach can offer in the future a high throughput screening tool with high predictive capacity or can help to identify compound- and bacteria-specific passive uptake pathways.

2019, Kittler, Sophie, Seinige, Diana, Meemken, Diana, Müller, Anja, Wendlandt, Sarah, Ehricht, Ralf, Monecke, Stefan, Kehrenberg, Corinna

Methicillin-resistant Staphylococcus aureus (MRSA) are a major concern for public health, and broiler farms are a potential source of MRSA isolates. In this study, a total of 56 MRSA isolates from 15 broiler farms from 4 different counties in Germany were characterised phenotypically and genotypically. Spa types, dru types, SCCmec types, and virulence genes as well as resistance genes were determined by using a DNA microarray or specific PCR assays. In addition, PFGE profiles of isolates were used for analysis of their epidemiological relatedness. While half of the isolates belonged to spa type t011, the other half was of spa types t1430 and t034. On 3 farms, more than 1 spa type was found. The most common dru type was dt10a (n = 19), followed by dt11a (n = 17). Susceptibility testing of all isolates by broth microdilution revealed 21 different resistance phenotypes and a wide range of resistance genes was present among the isolates. Up to 10 different resistance phenotypes were found on individual farms. Resistance to tetracyclines (n = 53), MLSB antibiotics (n = 49), trimethoprim (n = 38), and elevated MICs of tiamulin (n = 29) were most commonly observed. Microarray analysis detected genes for leucocidin (lukF/S), haemolysin gamma (hlgA), and other haemolysines in all isolates. In all t1430 isolates, the egc cluster comprising of genes encoding enterotoxin G, I, M, N, O, U, and/or Y was found. The splitstree analysis based on microarray and PCR gene profiles revealed that all CC9/SCCmec IV/t1430/dt10a isolates clustered apart from the other isolates. These findings confirm that genotypic patterns were specific for clonal lineages rather than for the origin of isolates from individual farms.

2020, Senok, Abiola, Nassar, Rania, Celiloglu, Handan, Nabi, Anju, Alfaresi, Mubarak, Weber, Stefan, Rizvi, Irfan, Müller, Elke, Reissig, Annett, Gawlik, Darius, Monecke, Stefan, Ehricht, Ralf

Reports from Arabian Gulf countries have demonstrated emergence of novel methicillin resistant Staphylococcus aureus (MRSA) strains. To address the lack of data from the United Arab Emirates (UAE), genetic characterisation of MRSA identified between December 2017 and August 2019 was conducted using DNA microarray-based assays. The 625 MRSA isolates studied were grouped into 23 clonal complexes (CCs) and assigned to 103 strains. CC5, CC6, CC22 and CC30 represented 54.2% (n/N = 339/625) of isolates with other common CCs being CC1, CC8, CC772, CC361, CC80, CC88. Emergence of CC398 MRSA, CC5-MRSA-IV Sri Lanka Clone and ST5/ST225-MRSA-II, Rhine-Hesse EMRSA/New York-Japan Clone in our setting was detected. Variants of pandemic CC8-MRSA-[IVa + ACME I] (PVL+) USA300 were detected and majority of CC772 strains were CC772-MRSA-V (PVL+), “Bengal- Bay Clone”. Novel MRSA strains identified include CC5-MRSA-V (edinA+), CC5-MRSA-[VT + fusC], CC5-MRSA-IVa (tst1+), CC5-MRSA-[V/VT + cas + fusC + ccrA/B-1], CC8-MRSA-V/VT, CC22-MRSA-[IV + fusC + ccrAA/(C)], CC45-MRSA-[IV + fusC + tir], CC80-MRSA-IVa, CC121-MRSA-V/VT, CC152-MRSA-[V + fusC] (PVL+). Although several strains harboured SCC-borne fusidic acid resistance (fusC) (n = 181), erythromycin/clindamycin resistance (ermC) (n = 132) and gentamicin resistance (aacA-aphD) (n = 179) genes, none harboured vancomycin resistance genes while mupirocin resistance gene mupR (n = 2) and cfr gene (n = 1) were rare. An extensive MRSA repertoire including CCs previously unreported in the region and novel strains which probably arose locally suggest an evolving MRSA landscape. © 2020, The Author(s).