Methicillin-resistant Staphylococcus aureus (MRSA)—changing epidemiology and workplace considerations

Until the mid-2000s, methicillin-resistant Staphylococcus aureus (MRSA) infections were predominately hospital acquired (HA-MRSA) and seen mainly in patients and health care personnel. However, since 2005, community-acquired MRSA (CA-MRSA) infections—a different genotype from HA-MRSA—have increased dramatically in BC.[1,2,3] Recent annual surveillance data indicate that CA-MRSA accounted for about 25% of MRSA in BC, with the remainder mostly HA-MRSA.[2] Therefore, acquisition of MRSA in both occupational and non-occupational (community) settings should be considered, including in health care workers.

One-third of the population is estimated to be asymptomatic carriers of staphylococcus aureus, with MRSA nasal carriage estimated from 0% to 8%, varying by population, geography, and region.[1,2,4,5] MRSA is not reportable in BC.[6]

HA-MRSA can be distinguished from CA-MRSA based on genetic, epidemiologic, or microbiological profiles.[3] Three genotypes of MRSA account for 90% of all genotypes throughout Canada.[1,2] MRSA-2 is usually associated with HA-MRSA; MRSA-7 and MRSA-10 are usually associated with CA-MRSA. A third grouping of MRSA, called livestock-acquired MRSA (LA-MRSA), has been recently identified in Canada and can potentially affect livestock workers,[7] but to date, no known human infections have been associated with these strains in BC (written communication with D.M. Patrick and L.M. Hoang, BC Centre for Disease Control, 2 February 2018).

Known reservoirs for staphylococcus aureus are humans and livestock, and survival outside of the host is highly variable—ranging from 30 minutes to 60 days.[8] The incubation period is variable and indefinite—ranging from 1 to 10 days for infection to develop once it enters compromised skin or mucous membrane. The communicable period is as long as a purulent lesion is present or carrier state persists.[8,9] With respect to HA-MRSA, both MRSA-carrier and/or infected patients and health care workers can act as vectors for transmission in hospital settings, with hands being the most important means of transmission. HA-MRSA risk factors for patients include hospitalization, surgery, or dialysis in the past 12 months; presence of an indwelling catheter; and residence in a long-term care home.[3,6,8,9,10,11]

Although anyone can acquire CA-MRSA, populations at increased risk include those with risk factors summarized as the 5Cs: crowding, frequent skin contact, compromised skin, sharing contaminated personal items, and lack of cleanliness.[4,6,8,10,11] These factors may also need to be considered in certain workplaces, such as child care services, military living quarters, or shelters.

In a health care worker with a confirmed MRSA infection, work circumstances, possible direct contact or exposure to an infected patient, and incubation period, along with the risk factors outlined above, are considered by WorkSafeBC when adjudicating a claim.

HA-MRSA results in respiratory tract, urinary tract, bloodstream, and postsurgical infections, whereas CA-MRSA predominantly causes skin and soft tissue infections such as furuncles, carbuncles, or abscesses.[3,6,10]

Management of HA-MRSA and CA-MRSA is based on clinical presentation. Physicians can refer to the BCCDC and IDSA Guidelines for both management and exposure control for HA-and CA-MRSA carriers and those with clinical infection.[6,12] MRSA bacteria is resistant to ß-lactam agents, including cephalosporins and carbapenems. After treating active infections and reinforcing hygiene and appropriate wound care, decolonization is not usually required in carriers but may be considered for those with recurrent skin and soft tissue infections or ongoing transmission among household members or close contacts, or for colonized health care workers who have been identified as likely sources of transmission.[4,6,12]

Unless directed by a health care provider or an employer’s infection control policy, workers with MRSA infections should not be routinely excluded from going to work. Exclusion should be reserved for those with wound drainage that cannot be properly covered and contained with a clean, dry bandage, and for those who cannot maintain good hygiene practices. Workers with active infections should be excluded from activities where skin-to-skin contact with the affected skin area is likely to occur until their infections are healed.[4]

If you require further information regarding an MRSA claim, contact the Occupational Disease Services Client Services Manager at 604 231-8842.
—Olivia Sampson, MD, CCFP, MPH, FRCPC, ABPM
—Lorri Galbraith, MD, MScOH, FCBOM, CIME
WorkSafeBC Medical Advisors, Occupational Disease Services

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This article is the opinion of WorkSafeBC and has not been peer reviewed by the BCMJ Editorial Board.

References

1.    Public Health Agency of Canada. Methicillin-resistant Staphylococcus aureus in Canadian acute-care hospitals: Surveillance Report January 1, 2008 to December 31, 2012. Accessed 5 March 2018. www.ammi.ca/Guideline/25.ENG.pdf.

2.    Public Health Agency of Canada. Canadian antimicrobial resistance surveillance system – Report 2016. p. 30-37. Accessed 5 March 2018. www.canada.ca/content/dam/phac-aspc/documents/services/publications/drugs-health-products/antibiotic-resistance-antibiotique/antibiotic-resistance-antibiotique-2016-eng.pdf.

3.    Loewen K, Schreiber Y, Kiriew M, et al. Community-associated methicillin-resistant Staphylococcus aureus infection: Literature review and clinical update. Can Fam Phys 2017;63:512-520.

4.    National Institute for Occupational Safety and Health (NIOSH). MRSA and the workplace. Accessed 5 March 2018. www.cdc.gov/niosh/topics/mrsa.

5.    Provincial Infection Control Network of British Columbia (PICNet). Annual surveillance report of health-care associated infections in BC healthcare facilities: Fiscal year 2016/17. Accessed 5 March 2018. www.picnet.ca/wp-content/uploads/PICNet-Annual-Surveillance-Report-2016-2017.pdf.

6.    BC Centre for Disease Control. Guidelines for the management of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) – related skin and soft tissue infections in primary care. Accessed 5 March 2018. www.bccdc.ca/resource-gallery/Documents/Statistics and Research/Statistics and Reports/Epid/Antibiotics/MRSAguidelineFINALJuly7.pdf.

7.    Golding GR, Bryden L, Levett PN, et al. Livestock-associated Methicillin-Resistant Staphylococcus aureus Sequence Type 398 in Humans, Canada. Emerg Inf Dis 2010;16:587-594.

8.    Government of Canada. Pathogen safety data sheets: Infectious substances – Staphylococcus aureus. Accessed 5 March 2018. www.canada.ca/en/public-health/services/laboratory-biosafety-biosecurity/pathogen-safety-data-sheets-risk-assessment/staphylococcus-aureus.html.

9.    Harbarth S. Staphylococcus Diseases. In: Heymann DL, ed. Control of communicable diseases manual: an official report of the American Public Health Association. 20th ed. Washington, DC: American Public Health Association, 2015. p. 573.

10.    Patrick DM, Henry B, Gamage B. Management of community-associated methicillin-resistant Staphylococcus aureus infections in primary care. BCMJ 2006: 48:114-115.

11.    Cimolai N. Methicillin-resistant Staphylococcus aureus in Canada: A historical perspective and lessons learned. Can J Micrbiol 2010;56:89-120.

12.    Liu C, Cosgrove SE, Daum RS, et al. Clinical Practice Guidelines by the Infectious Disease Society of America for the treatment of methicillin-resistant Staphylococcus aureus infections in adults and children. CID 2011;52:e18-55.