Identification of Acinetobacter baumannii and its carbapenem-resistant gene bla(OXA-23-like) by multiple cross displacement amplification combined with lateral flow biosensor

Acinetobacter baumannii is a frequent cause of the nosocomial infections. Herein, a novel isothermal amplification technique, multiple cross displacement amplification (MCDA) is employed for detecting all A. baumannii strains and identifying the strains harboring bla(OXA-23-like) gene. The duplex MCDA assay, which targets the pgaD and bla(OXA-23-like) genes, could identify the A. baumannii isolates and differentiate these isolates harboring bla(OXA-23-like) gene. The disposable lateral flow biosensors (LFB) were used for analyzing the MCDA products. A total of sixty-eight isolates, include fifty-three A. baumannii strains and fifteen non-A. baumannii strains, were employed to optimize MCDA methods and determine the sensitivity, specificity and feasibility. The optimal reaction condition is found to be 63 °C within 1 h, with limit of detection at 100 fg templates per tube for pgaD and bla(OXA-23-like) genes in pure cultures. The specificity of this assay is 100%. Moreover, the practical application of the duplex MCDA-LFB assay was evaluated using clinical samples, and the results obtained from duplex MCDA-LFB method were consistent with conventional culture-based technique. In sum, the duplex MCDA-LFB assay appears to be a reliable, rapid and specific technique to detect all A. baumannii strains and identify these strains harboring bla(OXA-23-like) gene for appropriate antibiotic therapy.