Vitek 2 id gn cards

Eight clinical CR-GNB (two CR Escherichia coli, two CR Klebsiella spp., two CR Acinetobacter baumannii, and two CR Pseudomonas aeruginosa), collected as part of a national surveillance study in Singapore from 2009–2011, and four American Type Culture Collection (ATCC) strains (E. coli ATCC25922, A. baumannii ATCC19606, P. aeruginosa ATCC27853, and Klebsiella pneumoniae ATCC13883), were used. Genus identities of the clinical isolates were determined by the individual hospitals, using Vitek 2 ID-GN cards (bioMérieux Inc., Marcy-l’Étoile, France) and matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry analysis. Susceptibility to carbapenems was determined by disk diffusion and interpreted using the Clinical and Laboratory Standards Institute (CLSI) guidelines [17 ]. The isolates were stored at −80 °C and fresh isolates were sub-cultured twice on 5% blood agar plates (Thermo Scientific, Waltham, MA, USA) for 24 h at 35 °C before each experiment.

Clinical strains of carbapenem-resistant (CR) A. baumannii (n = 30), P. aeruginosa (n = 30) and K. pneumoniae (n = 40) were collected from Singapore hospitals from 2009–13 to develop the ATP bioluminescence assay. Genus identity was determined using Vitek 2 ID-GN cards (bioMerieux, Inc., Hazelwood, MO). Carbapenem susceptibility was determined using disk diffusion and interpreted in accordance to the Clinical and Laboratory Standards Institute (CLSI) guidelines [11 ]. MICs to multiple antibiotics were performed using custom-made microbroth dilution panels (Trek Diagnostics, East Grinstead, UK), and susceptibility defined based on CLSI breakpoints [11 ]. All isolates were stored at -80°C in CryoCare bacteria preservers (Key Scientific Products, Round Rock, TX), and fresh isolates were sub-cultured twice on 5% blood agar plates (Biomedia-Bloxwich, Malaysia) for 24 h at 35°C prior to each experiment.

Nonclonal clinical strains of CR E. coli were previously collected as part of a nationwide surveillance study from 2011 to 2012 and were obtained from the largest tertiary hospital in Singapore (1700 beds). Genus identities were determined using Vitek 2 ID-GN cards (bioMérieux, Inc., Hazelwood, MO, USA). CR E. coli strains were stored at −80 °C in Cryobank (Thermo Scientific, Singapore) storage vials. Fresh isolates were sub-cultured twice on 5% sheep blood agar plates (Thermo Scientific, Singapore) for 24 h at 35 °C before each experiment.