2022, Wicaksono, Wisnu Adi, Erschen, Sabine, Krause, Robert, Müller, Henry, Cernava, Tomislav, Berg, Gabriele

Multi-species biofilms are more resistant against stress compared to single-species biofilms. However, the mechanisms underlying this common observation remain elusive. Therefore, we studied biofilm formation of well-known opportunistic pathogens (Acinetobacter baumanii, Enterococcus faecium, Escherichia coli, Staphylococcus haemolyticus and Stenotrophomonas maltophilia) in various approaches. Synergistic effects in their multi-species biofilms were observed. Using metatranscriptomics, changes in the gene expression of the involved members became evident, and provided explanations for the improved survivability under nutrient limitation and exposure to disinfectants. Genes encoding proteins for vitamin B6 synthesis and iron uptake were linked to synergism in the multi-species biofilm under nutrient-limited conditions. Our study indicates that sub-lethal concentrations of an alcohol-based disinfectant enhance biofilm yields in multi-species assemblages. A reduction of the dominant taxa in the multi-species biofilm under disinfectant pressure allowed minor taxa to bloom. The findings underline the importance of minor but antimicrobial-resistant species that serve as "protectors" for the whole assemblage due to upregulation of genes involved in defence mechanisms and biofilm formation. This ultimately results in an increase in the total yield of the multi-species biofilm. We conclude that inter-species interactions may be crucial for the survival of opportunistic pathogens; especially under conditions that are typically found under hospital settings.

2020, Monecke, Stefan, König, Elisabeth, Earls, Megan R., Leitner, Eva, Müller, Elke, Wagner, Gabriel E., Poitz, David M., Jatzwauk, Lutz, Vremerǎ, Teodora, Dorneanu, Olivia S., Simbeck, Alexandra, Ambrosch, Andreas, Zollner-Schwetz, Ines, Krause, Robert, Ruppitsch, Werner, Schneider-Brachert, Wulf, Coleman, David C., Steinmetz, Ivo, Ehricht, Ralf

We investigated why a clinical meticillin-resistant Staphylococcus aureus (MRSA) isolate yielded false-negative results with some commercial PCR tests for MRSA detection. We found that an epidemic European CC1-MRSA-IV clone generally exhibits this behaviour. The failure of the assays was attributable to a large insertion in the orfX/SCCmec integration site. To ensure the reliability of molecular MRSA tests, it is vital to monitor emergence of new SCCmec types and junction sites.