Genomic evidence for the evolution of Streptococcus equi : host restriction, increased virulence, and genetic exchange with human pathogens

The continued evolution of bacterial pathogens has major implications for both human and animal disease, but the exchange of genetic material between host-restricted pathogens is rarely considered. Streptococcus equi subspecies equi (S. equi) is a host-restricted pathogen of horses that has evolved from the zoonotic pathogen Streptococcus equi subspecies zooepidemicus (S. zooepidemicus). These pathogens share approximately 80% genome sequence identity with the important human pathogen Streptococcus pyogenes. We sequenced and compared the genomes of S. equi 4047 and S. zooepidemicus H70 and screened S. equi and S. zooepidemicus strains from around the world to uncover evidence of the genetic events that have shaped the evolution of the S. equi genome and led to its emergence as a host-restricted pathogen. Our analysis provides evidence of functional loss due to mutation and deletion, coupled with pathogenic specialization through the acquisition of bacteriophage encoding a phospholipase A(2) toxin, and four superantigens, and an integrative conjugative element carrying a novel iron acquisition system with similarity to the high pathogenicity island of Yersinia pestis. We also highlight that S. equi, S. zooepidemicus, and S. pyogenes share a common phage pool that enhances cross-species pathogen evolution. We conclude that the complex interplay of functional loss, pathogenic specialization, and genetic exchange between S. equi, S. zooepidemicus, and S. pyogenes continues to influence the evolution of these important streptococci.Publisher PDFPeer reviewe

Extending the reach and task-shifting ophthalmology diagnostics through remote visualisation

Driven by the global increase in the size and median age of the world population, sight loss is becoming a major public health challenge. Furthermore, the increased survival of premature neonates in low- and middle-income countries is causing an increase in developmental paediatric ophthalmic disease. Finally, there is an ongoing change in health-seeking behaviour worldwide, with consequent demand for increased access to healthcare, including ophthalmology. There is therefore the need to maximise the reach of resource-limited ophthalmology expertise in the context of increasing demand. Yet, ophthalmic diagnostics critically relies on visualisation, through optical imaging, of the front and of the back of the eye, and teleophthalmology, the remote visualisation of diagnostic images, shows promise to offer a viable solution.In this chapter, we first explore the strategies at the core of teleophthalmology and, in particular, real-time vs store-and-forward remote visualisation techniques, including considerations on suitability for different tasks and environments. We then introduce the key technologies suitable for teleophthalmology: anterior segment imaging, posterior segment imaging (retinal imaging) and, briefly, radiographic/tomographic techniques. We highlight enabling factors, such as high-resolution handheld imaging, high data rate mobile transmission, cloud storage and computing, 3D printing and other rapid fabrication technologies and patient and healthcare system acceptance of remote consultations. We then briefly discuss four canonical implementation settings, namely, national service provision integration, field and community screening, optometric decision support and virtual clinics, giving representative examples. We conclude with considerations on the outlook of the field, in particular, on artificial intelligence and on robotic actuation of the patient end point as a complement to televisualisation