Project description:Among the multidrug-resistant (MDR) clones of Mycobacterium tuberculosis (Mtb) that were epidemiologically particularly successful, the 100-32 MDR Beijing clone, also called B0/W148 clone, has emerged since the early sixties. These B0/W148 strains belonging to the lineage 2 within the global Mtb phylogeny, are the main contributors to the MDR epidemic in Russia and Eastern Europe, and since the USSR’s fall, have also propagated to Western Europe. Among the various mutations that were identified as being specific for the MDR B0/W148 clone, we focused on two found in the transcriptional regulators KdpDE and WhiB6 and characterized in a H37Rv strain background the transcriptional profile associated with these mutations and their potential impact on the in vitro and in vivo growth characteristics.
Project description:Among the multidrug-resistant (MDR) clones of Mycobacterium tuberculosis (Mtb) that were epidemiologically particularly successful, the 100-32 MDR Beijing clone, also called B0/W148 clone, has emerged since the early sixties. These B0/W148 strains belonging to the lineage 2 within the global Mtb phylogeny, are the main contributors to the MDR epidemic in Russia and Eastern Europe, and since the USSR’s fall, have also propagated to Western Europe. Among the various mutations that were identified as being specific for the MDR B0/W148 clone, we focused on two found in the transcriptional regulators KdpDE and WhiB6 and characterized in a H37Rv strain background the transcriptional profile associated with these mutations and their potential impact on the in vitro and in vivo growth characteristics.
Project description:The spread of multidrug-resistant (MDR) bacteria, such as the skin commensal Staphylococcus aureus, is a worldwide heath challenge; therefore, new methods to counteract the over-colonization and virulence of opportunistic pathogenic biotypes are highly urgent. We characterized and compared the activity of Lacticaseibacillus rhamnosus LR06 (DSM 21981) and Lactobacillus johnsonii LJO02 (DSM 33828) cell-free supernatants (CFSs), produced in a conventional animal-based MRS medium and in an innovative vegetal TIL, versus the MDR Staphylococcus aureus (ATCC 43300). CFSs were analysed via high-resolution mass spectrometry and gas-chromatography for short chain fatty acids (SCFAs), lactic acid and protein composition, while their activity was assessed towards i) the viability and metabolic activity of the MRSA strain through optical density and alamarBlue assay, and ii) the capability to inhibit/disaggregate the pathogenic biofilm, via crystal violet staining. All the CFSs reduce viable and metabolically active S. aureus, with the TIL medium more efficient, respect to MRS, in stimulating lactic acid bacteria metabolism and reducing the virulent biofilm. CFSs from LJO02 produced in TIL are the best, thanks to specific SCFAs and proteic metabolites. In conclusion, antagonistic non-pathogenic CFSs represent a promising and strategic approach, with potential applications as bacteriotherapy, and bioremediation of hospital equipments surfaces.
Project description:The epidemic community-acquired methicillin-resistant S. aureus (CA-MRSA) clone USA300 has recently become a leading cause of hospital-associated bloodstream infections (BSI). Leveraging this recent introduction into hospitals and the limited genetic variation across the USA300 strains, we combined microbial comparative genomics with phenotypic analyses to discover adaptive mutations. USA300 isolates from BSI were found to have independently evolved single nucleotide variants in the transcriptional regulator sarZ. sarZ inactivation lead to altered expression of virulence factors, resulting in increased lethality in a murine model of BSI. Thus, USA300 strains can optimize their fitness in hospitals through evolution of higher virulence.
Project description:The aim of this experiment was to compare the transciptome of the peach-potato aphid (Myzus persicae) clone 4106a (a laboratory insecticide-susceptible standard collected from potato in Scotland in 2000) with clone 5191A (an insecticide resistant aphid clone collected from tobacco in Greece in 2007) to identify which genes are over or underexpressed in the resistant phenotype. Two-condition experiment, 4106a vs. 5191a Myzus persicae clones. Biological replicates: 4 pools of RNA extracted from ten 15 day old aphids of each clone. Technical Replicates: Two technical reps incorporating a dye swap. Total replication: eight replicates for each clone.
Project description:Phages have emerged as prime suspects in the adaptation of pathogens to new hosts and the emergence of new pathogens or epidemic clones. Here we describe the genomic features of “swarms” of three related prophages (Ab105-1ϕ, Ab105-2ϕ and Ab105-3ϕ) present in the ST-2 epidemic clone of Acinetobacter baumannii clinical strain Ab105 GEIH-2010 and not present in genetically related Ab155 GEIH-2000 strain isolated 10 years before. The “Quasicore genome” of Ab105-1ϕ, Ab105-2ϕ and Ab105-3ϕ prophages revealed genes that promote bacterial-host fitness. The results of microarray analysis under stress conditions, SOS response and Quorum Sensing (QS) activation revealed 42% and 21% of genes expressed by Ab105-2ϕ and Ab105-3ϕ prophages (which produce bacterial lysis) in the first case and underexpression of these genes from prophages in the second case. Hence, the QS system plays a major role in the evolution of phages in their natural hosts and environments. Interestingly, in host-virus interactions, RT-PCR showed several mechanisms of overexpression of the SOS response in relation to phage defence mechanisms: i) SAM or AdoMet-MTase (methyltransferases) and MazG protein (pyrophosphohydrolase) associated with phage defence in response to bacterial attack; ii) eukaryotic-like protein kinase (glutamate 5-kinase) associated with prevention of secondary infection by the same or a closely related virus. Overexpression of secretory virulence factors such as oxidoreductase (DsbA-like), anfo-nitrogenase and chromosome segregation proteins were also observed. Moreover, under iron-deficient growth, there was an overexpression by RT-PCR of the a new interesting cluster of genes located following a “Moron” organization in the Ab105-3ϕ prophage being associated with iron uptake systems (Xanthine dehydrogenase gene cluster, Anthranilate operon, ABC transporter and TonB dependent receptor). In conclusion, study of the co-evolution of phages (virus) and bacteria may be essential in the search for means of combatting multi-resistant epidemic clones. Two parental clinical strains of A. baumannii (90% identity, indicated by PFGE, and ST2, indicated by Multilocus Sequence Typing, MLST) isolated in the same Intensive Care Unit (ICU) of a Spanish hospital, in 2000 and 2010, during the “I Multicenter Study GEIH-REIPI-Ab-2000” (Ab155 GEIH-2000) and “II Multicenter Study GEIH-REIPI-Ab-2010” (Ab105 GEIH-2010), respectively. Three replicates from RNA of the AB105 GEIH-2010 strain x 2 conditions (SOS response by Mitomycin C) and (Quorum Sensing activation by AHLs mixture).