Comparative assessment of methicillin resistant Staphylococcus aureus diagnostic assays for use in resource-limited settings - PubMed (original) (raw)

Comparative Study

Comparative assessment of methicillin resistant Staphylococcus aureus diagnostic assays for use in resource-limited settings

A Ayebare et al. BMC Microbiol. 2019.

Abstract

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.

Keywords: Africa; Carriage; Chromogenic agar; MRSA; Methicillin-resistant Staphylococcus aureus; PCR.

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Conflict of interest statement

Cepheid donated the Cepheid Xpert SA Nasal Complete assays for use in this study, and Life Science donated the Hain GenoQuick MRSA kits used in this study. All authors declare no other competing interests.

Figures

Fig. 1

Fig. 1

Flow diagram of samples collected and results from all three testing methods

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