Abstract:A qualitative detection method for Pseudomonas aeruginosa in bottled water developed and its performance was evaluated. Appropriate cultivation conditions and meat-based enrichment broth were selected according to the inoculation results at low bacterial concentrations. Moreover, a single-factor test was performed to optimize the enrichment medium formula for inoculation at low bacterial concentrations. Thereafter, a multiple comparison test was conducted to optimize the solid medium for selection and separation. Commercially available bottled water was used and spiked with different concentrations of reference strains, followed by ozone addition for 0, 30, 60 and 90 min. The pre-treated water was then tested using the proposed qualitative detection method. More specifically, 4 g/L mannitol was added to tryptic soy broth (TSB). The bacteria were cultivated in liquid media at 42 ℃ for 6~8 h. Next, sodium 0.20 g/L pyruvate was added to CN agar and cultured at 42 ℃ for 24~48 h. Finally, MALDI-TOF MS was adopted to ensure accurate, rapid, and high-throughput detection of potentially pathogenic bacteria, including P. aeruginosa. The results were compared to those obtained via the GB 8538-2022 method in terms of sensitivity, selectivity, and specificity. Different types of samples were also selected to evaluate the wide range of applications that can be assessed using the proposed method. The results demonstrated that the proposed method can identify P. aeruginosa at concentrations as low as 3 CFU/250 mL. Moreover, it identified interfering bacteria at a concentration range of 1 000~10 000 CFU/250 mL. The detection and identification performances for different samples were statistically significant (x2=25.45, P<0.05). Thus, the method established in this study exhibits high sensitivity and specificity, ease of use, and high efficiency compared to existing methods.
