DIY spectrophotometry: Rapid, low-cost RGB approach for vis-spectroscopy, OD600, and fluorescence quantification in profiling nosocomial antibiotic resistance (MRSA)

Abstract

Problem: Existing spectrophotometric assays are prohibitively expensive and incompatible with resource-limited settings (i.e. developing countries, citizen science and field testing), thereby necessitating a viable, economical alternative capable of yielding accurate and reproducible results. The increasing prevalence of multi-drug resistance has made the rapid & accurate determination of antibiotic susceptibility an imperative. In particular, Methicillin-resistant S. aureus (MRSA), a nosocomial pathogen, is responsible for significant inpatient morbidity and mortality [3.2 cases/1000 inpatient days]. Aim: Herein, an affordable, high-throughout, semi-automated method of determining S. aureus antibiotic susceptibility via RGB analysis is described. OD600 (MIC) values from broth microdilution, and endpoint fluorescence values from strain-typing (PCR) were quantified, yielding absorbance readings comparable to commercial spectrophotometers (R2 correlation coefficient = 0.9931, 0.9539 respectively). [Peer Assessment Review]