Rapid<i>Burkholderia pseudomallei</i>identification and antibiotic resistance determination by bacteriophage amplification and MALDI-TOF MS

Abstract

Phage amplification detected by MALDI-TOF MS was investigated for rapid and simultaneous <i>Burkholderia pseudomallei</i> identification and ceftazidime resistance determination. <i>B. pseudomallei</i> ceftazidime susceptible and resistant Δ<i>purM</i> mutant strains Bp82 and Bp82.3 were infected with broadly targeting <i>B. pseudomallei</i> phage ϕX216 and production of the m/z 37.6 kDa phage capsid protein observed by MALDI-TOF MS over the course of 3 h infections. This allowed for repoducible phage-based bacterial ID within 2 h of the onset of infection. MALDI-TOF MS-measured time to detection correlated with in silico modeling, which predicted an approximate 2 h detection time. Ceftazidime susceptible strain Bp82, while detectable in the absence of the drug, owing to the reliance of phage amplification on a viable host, was not detectable when 10 μg/mL ceftazidime was added at the onset of infection. In contrast, resistant strain Bp82.3 was detected in the same 2 h timeframe both with and without the addition of ceftazidime.