Integration of Bdellovibrio spp. with SODIS and Moringa oleifera flocculation to target multi-drug resistant Klebsiella pneumoniae and Pseudomonas aeruginosa

Combination treatments using Bdellovibrio bacteriovorus PF13 and/or TWPF pre-treatment; solar disinfection (SODIS); and Moringa oleifera flocculation, were investigated for the reduction of antibiotic resistant Klebsiella pneumoniae and Pseudomonas aeruginosa. After the various stages of treatment, culture- and molecular-based methods were employed to quantify the respective bacteria. Results indicated that pre-treatment with the B. bacteriovorus strains did not reduce the P. aeruginosa cell concentration. The subsequent exposure of the pre-treated and non-pre-treated samples to SODIS (6 h) then significantly reduced the P. aeruginosa cell counts and gene copies (EMA-qPCR) by up to 7.50 logs, and 4.37 logs, respectively. In contrast, pre-treatment using both B. bacteriovorus strains (PF13 and TWPF) in combination with SODIS significantly reduced the K. pneumoniae cell counts (8.46 logs) and gene copies (4.40 logs) to below detection limit. While significant log reductions were obtained for the K. pneumoniae samples pre-treated with B. bacteriovorus PF13 or TWPF, and SODIS only (no pre-treatment), K. pneumoniae still persisted. Furthermore, flocculation treatment following SODIS did not significantly reduce the concentration of K. pneumoniae or P. aeruginosa. The antibiogram of the target organisms was compared before and after each treatment stage using the VITEK® 2 Compact System. No difference in the organisms’ susceptibility to the tested antibiotics was observed, with both K. pneumoniae and P. aeruginosa maintaining their MDR and XDR status, respectively. It is thus recommended that the interaction and predation kinetics of employing multiple predatory bacteria as a pre-treatment to SODIS is explored, as these treatments eradicated the MDR K. pneumoniae.