This work was supported by National Institutes of Health Research Training Grant #R25 TW009337 funded by the Fogarty International Center and the National Institute of Mental Health and National Institutes of Health (to LMB); T32 Ruth L. Kirschstein National Research Service Award #5T32AI007433–22 (to LMB); KL2/Catalyst Medical Research Investigator Training award (an appointed KL2 award) from Harvard Catalyst | The Harvard Clinical and Translational Science Center (National Center for Advancing Translational Sciences, National Institutes of Health Award KL2 TR001100, LMB); Massachusetts General Hospital Department of Anesthesia, Critical Care and Pain Medicine (to LMB, PGF); and support from the National Institutes of Mental Health #MH K23099916 (to MJS).
Bacterial pathogens -- Research
Background: The rise of methicillin-resistant Staphylococcus aureus(MRSA) is a global health concern. Paucity of data on MRSA carriage prevalence and diagnostic methods in resource-limited settings hampers efforts to define the problem and plan an appropriate response. Additionally, high variability in cost and logistical characteristics of MRSA screening methods may impede infection control efforts. We compared the performance of locally-available chromogenic agar BD CHROMagar MRSA II and two PCR-based assays (Hain GenoQuick MRSA and Cepheid Xpert SA Complete) for the detection of asymptomatic MRSA carriage in nasal swabs.
Results: During 2015, we enrolled 500 patients from five hospital wards at a Ugandan regional referral hospital. We found 30% prevalence of methicillin-sensitive Staphylococcus aureus (MSSA) nasal carriage, and 5.4% MRSA nasal carriage prevalence. Compared to a composite reference standard defined as a positive test result on any one of the three assays, Hain GenoQuick MRSA demonstrated the highest sensitivity (96%) followed by direct plating on CHROMagar at (70%), with the lowest sensitivity observed with Xpert SA Complete (52%). Cepheid Xpert provided the most rapid results (< 1 h) but was the most expensive (US $45–50/test). Substantially more labor was required for the Hain GenoQuick MRSA compared to Xpert SA Complete or CHROMagar tests.
Conclusion: MRSA nasal carriage prevalence rates were low, and high diagnostic sensitivity was achieved using Hain GenoQuick MRSA. Chromogenic media had significantly lower sensitivity, but may represent a viable local option given its lower cost compared to PCR-based assays.
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Ayebare, A., Bebell, L. M., Bazira, J., Ttendo, S., Katawera, V., Bangsberg, D. R., ... & Boum II, Y. (2019). Comparative assessment of methicillin resistant Staphylococcus aureus diagnostic assays for use in resource-limited settings. BMC Microbiology, 19(1), 1-6.