Evolving Threat of Community Acquired Methicillin Resistant Staphylococcus aureus Upper Extremity Infections in the South Pacific: 2011–2015

Background: Community Acquired Methicillin Resistant Staphylococcus aureus (CA-MRSA) rates have been increasing worldwide and contribute to a growing “global health security threat” as reported by the WHO. Our group previously reported an overall rate of 7% in CA-MRSA upper extremity infections between 2004–2009 at the Auckland Regional Hand Unit. This fell below the Center for Disease Control (CDC) recommendation for empiric antimicrobial cover once local rates exceed 10–15%. We examined prevalence and characteristics of CA-MRSA upper extremity infections in our region over a subsequent 5-year period.

Methods: One thousand two hundred and fifty-two patients with upper extremity infections requiring operative management between 2011 and 2015 inclusive were included in this study. Associated clinical characteristics were recorded including ethnicity, cultured organisms, antibiotic sensitivities, infection rate, and treatment practice.

Results: One hundred and fifty (12%) of patients had culture positive CA-MRSA upper extremity infections. There was an increasing annual trend. Of note, rates of CA-MRSA in the Maori and Pacific Island ethnic subpopulations exceeded 15% in 2014 and 2015. Susceptibilities, associated factors and patient demographics are reported.

Conclusions: Our unit enjoys significantly lower rates of CA-MRSA upper extremity infections than has been reported internationally. However, trends are increasing relative to our prior 6-year report, and the threshold for empiric treatment has been met within the Maori and Pacific Island ethnic subpopulations. This evolving threat is also highlighted by increasing cases of multi-drug resistant CA-MRSA. Evolving regional guidelines for empiric coverage of CA-MRSA among high-risk ethnic subpopulations identified by this study are underway.