Because of the focus on β-lactamase, the current study has concentrated on β-lactam based probe constructs. However, the approach represents an optical platform using photoactivatable constructs that can be adapted for several targets that might confer antibiotic resistance. An interesting area of exploration is the use of the same technology for therapy where the constructs could be modified to specifically

target β-lactamase resistant bacteria [49], in a variation of photodynamic therapy [74, 75] that has shown promise in several indications of infections. Acknowledgements We thank Dr. Mary Jane Ferraro (Microbiology Labs, selleck chemicals Massachusetts General Hospital, Boston, MA, USA) for very helpful discussions and for providing the S. aureus clinical isolates. We are grateful to Dr. Robert L. Skov (Statens Serum Institut, Copenhagen, Denmark) for providing this website some of the genotype data. We would also like to thank Dr. Akilan Palanisami and Dr. Sarika Verma for involved discussions and input, and Dr.

S. Sibel Erdem for help in drawing chemical structures and proofreading. This research was funded by the Department of Defense/Air Force Office of Research (DOD/AFOSR) (Grant number FA9550-11-1-0331), and NIH/NIBIB (National Institute of Biomedical Imaging and Bioengineering) (Point of Care Technology in Primary Care) through CIMIT (Centre for Integration of Medicine and Innovation Technology) (Grant number U54 EB015408).

Electronic supplementary material Additional file 1: Figure S1: β-LEAF cleavage rates for ATCC control strains and bacteria free controls. Data from the two ATCC S. aureus control strains [known β-lactamase producer ATCC 29213 (#1) and non-producer ATCC 25923 (#2)] and PBS only control, with three antibiotics (cefazolin, cefoxitin and Doxorubicin order cefepime) is presented. The different samples were incubated with β-LEAF (probe) alone or β-LEAF and respective antibiotic, and fluorescence was monitored over 60 min. The y-axis represents the cleavage rate of β-LEAF (measured as fluorescence change rate – milliRFU/min) (Bacterial O.D. is not accounted for here). Results are presented as the average of four independent experiments (each experiment contained samples in triplicates) and error bars represent the standard error. (JPEG 75 KB) Additional file 2: Figure S2: Standard Disk diffusion assay to determine cefazolin susceptibility and zone edge test for β-lactamase detection. Representative Disk diffusion plates for the control strains S. aureus ATCC 29213 (#1) and ATCC 25923 (#2) are shown, with the cefazolin disk at the centre of the plate. The clear zone of inhibition and zone edges are indicated. #1 was used as a positive control for the zone edge test (sharp edge) and #2 as a negative control (fuzzy edge), following CLSI guidelines.