Sequencing MRSA to Save Lives
Patrick Humphreys, Shona Anderson
Methodist College Belfast, Belfast, United Kingdom
I propose to sequence the genome of all nosocomial methicillin-resistant Staphylococcus Aureus (MRSA) infections, because it would facilitate the implementation of infection control measures within healthcare environments, allow scientists to better monitor the mutational evolution of MRSA and aid in the production of new, more advanced antibiotics. Since it was first identified in 1960 , MRSA has become a major healthcare problem globally, a problem which must be urgently addressed. Its resistance to ?-lactam-based antibiotics poses a significant threat to patients worldwide, as it is becoming increasingly difficult to treat.
In 2019/20, Public Health England recorded a total of 814 MRSA cases across all acute Trusts, of which 201 patients died within 30 days of diagnosis . While these numbers indicate a reduction in cases over the past decade, MRSA infection and antimicrobial resistance remain pressing issues, and I believe that whole genome sequencing of all nosocomial MRSA infections could reduce these problems.
Firstly, whole genome sequencing would aid in-depth analysis of MRSA strains which are present in hospital patients. This would allow healthcare providers to more easily determine the origin of such infections, which could prove vital in the implementation of appropriate infection control measures, because if MRSA is known to have been transmitted within a healthcare environment, the necessary measures could be put in place to prevent further spread. This has been proven by a research group studying MRSA transmission in the Cambridge University Hospitals NHS Foundation Trust, which used whole genome sequencing to demonstrate that several MRSA cases on a special care baby unit (SCBU) had originated from the same source . By applying this method to other healthcare environments, it would be possible to gain better insights into the transmission of MRSA and importantly, could reduce the detrimental impact of MRSA outbreaks. A joint research group from the University of Cambridge and the London School of Hygiene and Tropical Medicine also recently established a method by which whole genome sequencing of MRSA could be carried out in under 24 hours; this method could be used to significantly hasten the response of hospitals to MRSA outbreaks .
Furthermore, whole genome sequencing of MRSA infections could also prove vital in the production of antibiotics to combat novel strains of MRSA. It has been used previously to aid the development of treatments for pathogenic bacteria, such as tuberculosis (TB). It allowed scientists to identify several factors which contribute to TB’s antimicrobial resistance, including the exact molecular mechanism which is inhibited by bedaquiline, the active substance in some existing TB medications . It is therefore possible that whole genome sequencing could be applied to the production of MRSA antibiotics in a similar manner, providing novel insights into the mechanisms of resistance within different MRSA strains. In addition, there is evidence to suggest that MRSA can impair the function of the lymphatic system, which can lead to long-term immunodeficiency in patients who have recovered from MRSA infection . The development of more effective antibiotics for MRSA could not only result in reduced mortality, but also reduced post-infection morbidity.
Moreover, whole genome sequencing could be used to monitor the inheritance and evolution of genes which are already known to cause methicillin resistance, such as the mecA gene. For example, whole genome sequencing was previously used by a group of Dutch scientists  to demonstrate the key role of horizontal transfer in the dissemination of the mecA gene. Horizontal transfer is the movement of genetic material from one bacterium to another via mobile genetic elements (MGEs). This observation has had significant implications for our understanding of the epidemiology of MRSA, as it explains why methicillin resistance is able to spread quickly within populations of methicillin-susceptible S. aureus (MSSA).
In conclusion, whole genome sequencing of novel MRSA strains could have an enormously positive impact on the wider community. It could reduce the number of patients who die from the infection each year, by facilitating both development of new medications and contact tracing of infected individuals. Furthermore, by closely monitoring the transmission of MRSA within healthcare environments, it would be possible to minimise the spread of infection into the community, as patients could be properly treated before discharge. The potential role of whole genome sequencing of MRSA also shows promise for developing nations, as there is a possibility that more affordable antibiotics could be discovered. As a result, the impending threat of MRSA could be significantly reduced, and many lives could be saved in years to come.
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