Evolutionary trade-offs occur when selection on one trait has detrimental effects on other traits. In pathogenic microbes, it has been hypothesized that antibiotic resistance trades off with fitness in the absence of antibiotic. Although studies of single resistance mutations support this hypothesis, it is unclear whether trade-offs are maintained over time, due to compensatory evolution and broader effects of genetic background. Here, we leverage natural variation in 39 extraintestinal clinical isolates of Escherichia coli to assess trade-offs between growth rates and resistance to fluoroquinolone and cephalosporin antibiotics. Whole-genome sequencing identifies a broad range of clinically relevant resistance determinants in these strains. We find evidence for a negative correlation between growth rate and antibiotic resistance, consistent with a persistent trade-off between resistance and growth. However, this relationship is sometimes weak and depends on the environment in which growth rates are measured. Using in vitro selection experiments, we find that compensatory evolution in one environment does not guarantee compensation in other environments. Thus, even in the face of compensatory evolution and other genetic background effects, resistance may be broadly costly, supporting the use of drug restriction protocols to limit the spread of resistance. Furthermore, our study demonstrates the power of using natural variation to study evolutionary trade-offs in microbes.

The objective of this investigation was to present a case of masquerade syndrome secondary to primary CNS lymphoma in a Northern Ontario community. Masquerade syndrome of primary CNS lymphoma in the eye can often be misinterpreted as an immune-mediated process, owing to its tendency to first present with only vitreous cell, or chronic uveitis. Correct diagnosis of intraocular primary CNS lymphoma requires clinical suspicion and ophthalmologists should have a low threshold for triggering a diagnostic work-up of older and immunocompromised patients with a characteristic presentation.

Most people with coronavirus disease 2019 (COVID-19) recover completely within a few weeks. But some people continue to experience symptoms after the initial recovery. This condition is called post-COVID-19 syndrome or long COVID-19. They are threatened by the development of various diseases.We tried to answer some of these questions in our research. The study was conducted in 49 patients with ophthalmic pathologies who had previously undergone COVID-19. On the one hand, ocular pathologies are important because they allow in a non-traumatic way to obtain lifetime visualization of the state of blood vessels and capillaries as well as to assess the effect of the virus on the central nervous system.