MRSA: An Overview

Because of its pronounced virulence and resistance, methicillin-resistant Staphylococcus aureus (MRSA) is a highly successful pathogen [1]. It was first identified in the 1880s in the fluid emerging from a leg abscess [2]. Despite the invention of penicillin treatments in the 1940s, resistant MRSA strands evolved [2]. It continued to spread, but the pace of transmission did not pick up until the 1990s, at which point the pathogen was present in various regions of the world [2]. Today, MRSA is a major global concern [3]. Accordingly, it is pivotal for clinicians to be well-acquainted with the epidemiology, transmission, and treatment of MRSA.

In terms of epidemiology, the primary characteristic of MRSA is its role in initiating the emergence of resistant epidemic strains [2]. A sole pandemic strain does not exist; rather, the pathogen has led to multiple waves of infection, each characterized by different predominant strains [2]. Some of these strains include CA-MRSA USA300, which was prevalent in North America, and HA-MRSA clonal complex 30 (CC30), which was commonly found in Europe and North America [2]. This adaptability has enabled the pathogen to be the “most common cause of community-spread bacterial infections” in the United States [4].

Unlike many other dominant pathogens, the rate of nasal colonization is very low [4]. In fact, nasal transmission is estimated to account for only about 0.4% of infections [4]. Instead, the pathogen is primarily spread when people come into contact with infected individuals [4]. Beyond these two avenues, animals have also been linked to certain outbreaks [4]. For instance, in Europe, the MRSA clone ST398 was found in both pigs and pig farmers more than a decade ago [4].

Moreover, it can be transmitted in both community and healthcare settings [2]. Healthcare-acquired (HA) MRSA occurs in hospital settings among patients who have a pronounced risk of infection, such as the immunocompromised [4]. By contrast, community-acquired MRSA, or CA-MRSA, is spread between healthy and non-healthy individuals [4]. While it often presents in the form of a soft tissue or skin infection, it can also lead to the development of life-threatening infections [4]. These life-threatening infections include pyomyositis, purpura fulminans, necrotizing pneumonia, necrotizing fasciitis, and sepsis [1].

Managing MRSA infections is challenging because of pathogen resistance. Current protocols involve multifaceted approaches combining adjunctive care and novel antimicrobials [2]. Therefore, management including a mixture of echocardiography, source control, and infectious disease consultation are common [2]. With regards to pharmacotherapy, many antimicrobials are in the midst of clinical testing, including delafloxacin, ceftobiprole, and dalbavancin [2]. Depending on accessibility, progress, and resistance, these medications may be useful resources for clinicians treating these patients.

If a patient’s infection is minor, topical and local therapy could suffice [5]. In the event of a more serious infection, clinicians should first identify the site of infection, risk factors, comorbidities, local strain profiles, and susceptibility to prior antibiotics [2, 3]. After that information has been determined, physicians must consider which treatments are appropriate for the patient.

In the future, MRSA can be better controlled by investing in measures of community control and increased support for healthcare workers [1, 6]. Communities could lower their rates of MRSA infection by allocating more resources toward screening, surveillance, and prevention [1]. In hospital settings, better educational programs, more space for isolation, clarified isolation protocols, and improved communication could help substantially lower the risk of contamination [6]. Through a combined effort, this epidemic could eventually be controlled.

References

[1] M. Hawkes et al., “Community-associated MRSA: Superbug at our doorstep,” Canadian Medical Association Journal, vol. 176, no. 1, p. 54-56, January 2007. [Online]. Available: https://doi.org/10.1503/cmaj.061370.

[2] N. A. Turner et al., “Methicillin-resistant Staphylococcus aureus: an overview of basic and clinical research,” Nature Reviews Microbiology, vol. 17, p. 203-218, February 2019. [Online]. Available: https://doi.org/10.1038/s41579-018-0147-4.

[3] A. Hassoun, P. K. Linden, and B. Friedman, “Incidence, prevalence, and management of MRSA bacteremia across patient populations—a review of recent developments in MRSA management and treatment,” Critical Care, vol. 21, no. 211, p. 1-10, August 2017. [Online]. Available: https://doi.org/10.1186/s13054-017-1801-3.

[4] A. D. Kennedy and F. R. DeLeo, “Epidemiology and Virulence of Community-Associated MRSA,” Clinical Microbiology Newsletter, vol. 31, no. 20, p. 153-160, October 2009. [Online]. Available: https://doi.org/10.1016/j.clinmicnews.2009.09.004.

[5] L. Nicolle, “Community-acquired MRSA: a practitioner’s guide,” Canadian Medical Association Journal, vol. 175, no. 2, p. 145-146, July 2006. [Online]. Available: https://doi.org/10.1503/cmaj.060457.

[6] D. J. Seibert et al., “Preventing transmission of MRSA: A qualitative study of health care workers’ attitudes and suggestions,” American Journal of Infection Control, vol. 42, no. 4, p. 405-411, April 2014. [Online]. Available: https://doi.org/10.1016/j.ajic.2013.10.008.