1. Investigación

Influenza A virus (IAV) infection triggers quantitative and qualitative modifications in lung and intestinal microbiota composition, which contain an important reservoir of antibiotic resistance genes. Analysis of genetic changes is a common practice in studies that analyze microbiota modifications. However, there is little evidence of functional changes linked to such microbiota modifications. This study evaluates some cecal microbiota’s functional changes, comparing sublethal IAV with mock-infected mice. Community-wide phenotypic metabolic profile (Biolog EcoPlatesTM) and relative antibiotic resistance changes to clinically relevant antibiotics (cenoantibiogram) have been performed in this context. Results reveal a temporal association between IAV infection and alterations in nutrient substrate profile usage as well as changes in antibiotic resistance of cecal microbiota. Alterations are transient and predominantly occur at early time points post-IAV infection. There is a functional rebalance in nutrient substrate usage and antibiotic resistance under the established culture conditions, accompanied by a decrease in microbial density of the cecal community on days 5 and 7 after the IAV infection. Our data underline that active IAV infections altering microbial populations are associated with changes in nutrient usage preferences and affectaffectaffectcommunity behaviors toward specific antibiotics. These findings could have implications including activation of nutrient-related metabolic stress at the microbiota community level and additional antibiotic resistance selection mechanisms of clinically relevant infections.

Bacteriophages are types of viruses that infect bacteria. They are the most abundant and diverse entities in the biosphere, and influence the evolution of most bacterial species by promoting gene transfer, sometimes in unexpected ways. Although pac-type phages can randomly package and transfer bacterial DNA by a process called generalized transduction, some mobile genetic elements have developed elegant and sophisticated strategies to hijack the phage DNA-packaging machinery for their own transfer. Moreover, phage-like particles (gene transfer agents) have also evolved, that can package random pieces of the producing cell's genome. The purpose of this review is to give an overview of some of the various ways by which phages and phage-like particles can transfer bacterial genes, driving bacterial evolution and promoting the emergence of novel pathogens.

Bacteriophage-mediated horizontal gene transfer is one of the primary driving forces of bacterial evolution. The pac-type phages are generally thought to facilitate most of the phage-mediated gene transfer between closely related bacteria, including that of mobile genetic elements-encoded virulence genes. In this study, we report that staphylococcal cos-type phages transferred the Staphylococcus aureus pathogenicity island SaPIbov5 to non-aureus staphylococcal species and also to different genera. Our results describe the first intra- and intergeneric transfer of a pathogenicity island by a cos phage, and highlight a gene transfer mechanism that may have important implications for pathogen evolution.

Genetic transduction is a major evolutionary force that underlies bacterial adaptation.Here we report that the temperate bacteriophages ofStaphylococcusaureusengage in adistinct form of transduction we term lateral transduction. Staphylococcal prophagesdo not follow the previously described excision-replication-packaging pathway but insteadexcise late in their lytic program. Here, DNA packaging initiates in situ from integratedprophages, and large metameric spans including several hundred kilobases of theS.aureusgenome are packaged in phage heads at very high frequency. In situ replication beforeDNA packaging creates multiple prophage genomes so that lateral-transducing particles formduring normal phage maturation, transforming parts of theS.aureuschromosome intohypermobile regions of gene transfer.