Simonetti, D. | bioRxiv Science

bioRxiv2020

Long-term (1990-2019) monitoring of tropical moist forests dynamics

Accurate characterization of the tropical moist forests changes is needed to support conservation policies and to better quantify their contribution to global carbon fluxes. We document - at pantropical scale - the extent of these forests and their changes (degradation, deforestation and recovery) over the last three decades. We estimate that 17% of the tropical moist forests have disappeared since 1990 with a remaining area of 1060 million ha in 2019, from which 8.5% are degraded. Our study underlines the importance of the degradation process in such ecosystems, in particular as precursor of deforestation and in the recent increase of the tropical moist forest disturbances. Without reduction of the present disturbance rates, undisturbed forests will disappear entirely in large tropical humid regions by 2050. Our study suggests reinforcing actions to prevent the first disturbance scar that leads to forest clearance in 45% of the cases.

ecology↗

bioRxiv2020

Genotypic diversity between surgical and nasal Staphylococcus aureus isolates

Staphylococcus aureus is a common organism in periprosthetic joint infection (PJI). Little is known about S. aureus genetic diversity in PJI as compared to nasal carriage. We hypothesized PJI S. aureus strains would be associated with increased virulence as compared to those from nasal carriage. Whole genome sequencing and multilocus sequence typing (MLST) was performed to genotype these two populations at high resolution. MLST revealed a variety of genotypes in both populations but many belonged to the most common clonal complexes. In nasal cultures, 69% of strains were of clonal complexes CC5, CC8, and CC30. In PJI cultures, only 51% could be classified in these common clonal complexes. Remaining strains were atypical, and these atypical strains in PJI were associated with poor host status and compromised immune conditions. Mutations in genes involved in fibronectin binding (ebh, fnbA, clfA, clfB) systematically distinguished later PJI isolates from the first PJI isolate from each patient. S. aureus isolated from nasal carriage and PJI specimens differ significantly, with the latter being more diverse. Strains associated with lower pathogenicity tended to be found in immunocompromised patients, suggesting the host immune system plays an important role in preventing PJI. Repeated mutations in S. aureus genes associated with extracellular matrix binding were identified suggesting an adaptive, parallel evolution in S. aureus during the development of PJI.

microbiology↗