Mycobacterium tuberculosis (Mtb) strains are classified into different phylogenetic lineages (L), three of which (L2/L3/L4) emerged from a common progenitor after the loss of the MmpS6/MmpL6-encoding Mtb-specific deletion 1 region (TbD1). These TbD1-deleted “modern” lineages are responsible for globally-spread tuberculosis epidemics, whereas TbD1-intact “ancestral” lineages tend to be restricted to specific geographical areas, such as South India and South East Asia (L1) or East Africa (L7). By constructing and characterizing a panel of recombinant TbD1-knock-in and knock-out strains and comparison with clinical isolates, here we show that deletion of TbD1 confers to Mtb a significant increase in resistance to oxidative stress and hypoxia, which correlates with enhanced virulence in selected cellular, guinea pig and C3HeB/FeJ mouse infection models, the latter two mirroring in part the development of hypoxic granulomas in human disease progression. Our results suggest that loss of TbD1 at the origin of the L2/L3/L4 Mtb lineages was a key driver for their global epidemic spread and outstanding evolutionary success.

Sepsis is defined as a systemic inflammatory dysfunction strictly associated with infectious diseases, which represents an important health issue whose incidence is continuously increasing worldwide. Nowadays, sepsis is considered as one of the main causes of death that mainly affects critically ill patients in clinical settings, with a higher prevalence in low-income countries. Currently, sepsis management still represents an important challenge, since the use of traditional techniques for the diagnosis does not provide a rapid response, which is crucial for an effective infection management. Biosensing systems represent a valid alternative due to their characteristics such as low cost, portability, low response time, ease of use and suitability for point of care/need applications. This review provides an overview of the infectious agents associated with the development of sepsis and the host biomarkers suitable for diagnosis and prognosis. Special focus is given to the new emerging biosensing technologies using electrochemical and optical transduction techniques for sepsis diagnosis and management.

Staphylococcus aureus implant-associated infections are difficult to treat because of the ability of bacteria to form biofilm on medical devices. Here, the efficacy of Sb-1 to control or prevent S. aureus colonization on medical foreign bodies was investigated in a Galleria mellonella larval infection model. For colonization control assays, sterile K-wires were implanted into larva prolegs. After 2 days, larvae were infected with methicillin-resistant S. aureus ATCC 43300 and incubated at 37 °C for a further 2 days, when treatments with either daptomycin (4 mg/kg), Sb-1 (10⁷ PFUs) or a combination of them (3 x/day) were started. For biofilm prevention assays, larvae were pre-treated with either vancomycin (10 mg/kg) or Sb-1 (10⁷ PFUs) before the S. aureus infection. In both experimental settings, K-wires were explanted for colony counting two days after treatment. In comparison to the untreated control, more than a 4 log¹⁰ CFU and 1 log¹⁰ CFU reduction was observed on K-wires recovered from larvae treated with the Sb-1/daptomycin combination and with their singular administration, respectively. Moreover, pre-infection treatment with Sb-1 was found to prevent K-wire colonization, similarly to vancomycin. Taken together, the obtained results demonstrated the strong potential of the Sb-1 antibiotic combinatory administration or the Sb-1 pretreatment to control or prevent S. aureus-associated implant infections.

Agglutinin like sequence (Als) cell-wall proteins play a key role in adhesion and virulence of Candida species. Compared to the well-characterized Candida albicans ALS genes, little is known about ALS genes in the Candida parapsilosis species complex. Three incomplete ALS genes were identified in the genome sequence for Candida orthopsilosis strain 90–125 (GenBank assembly ASM31587v1): CORT0C04210 (named CoALS4210), CORT0C04220 (CoALS4220) and CORT0B00800 (CoALS800). To complete the gene sequences, new data were derived from strain 90–125 using Illumina (short-read) and Oxford Nanopore (long-read) methods. Long-read sequencing analysis confirmed the presence of 3 ALS genes in C. orthopsilosis 90–125 and resolved the gaps located in repetitive regions of CoALS800 and CoALS4220. In the new genome assembly (GenBank PQBP00000000), the CoALS4210 sequence was slightly longer than in the original assembly. C. orthopsilosis Als proteins encoded features well-known in C. albicans Als proteins such as a secretory signal peptide, N-terminal domain with a peptide-binding cavity, amyloid-forming region, repeated sequences, and a C-terminal site for glycosylphosphatidylinositol anchor addition that, in yeast, suggest localization of the proteins in the cell wall. CoAls4210 and CoAls800 lacked the classic C. albicans Als tandem repeats, instead featuring short, imperfect repeats with consensus motifs such as SSSEPP and GSGN. Quantitative RT-PCR showed differential regulation of CoALS genes by growth stage in six genetically diverse C. orthopsilosis clinical isolates, which also exhibited length variation in the ALS alleles, and strain-specific gene expression patterns. Overall, long-read DNA sequencing methodology was instrumental in generating an accurate assembly of CoALS genes, thus revealing their unconventional features and first insights into their allelic variability within C. orthopsilosis clinical isolates.