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

Megan Kode, Monique Waso-Reyneke, Brandon Reyneke, Julia Denissen, Tanya Clements-Decker, Benjamin Havenga, Sehaam Khan, Wesaal Khan

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2 Citations (Scopus)


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.

Original languageEnglish
Article number107962
JournalJournal of Environmental Chemical Engineering
Issue number3
Publication statusPublished - Jun 2022


  • AOPs advanced oxidation processes
  • ARW artificial rainwater
  • AST antimicrobial susceptibility testing
  • Abbreviations ABR antibiotic resistant
  • B. bacteriovorus Bdellovibrio bacteriovorus
  • BDL below detection limit
  • CLSI Clinical and Laboratory Standards Institute
  • DBPS disinfection by-products
  • DNB diluted nutrient broth
  • EMA ethidium monoazide bromide
  • EUCAST European Committee on Antimicrobial Susceptibility Testing
  • GC gene copies
  • K. pneumonia Klebsiella pneumoniae
  • M. oleifera Moringa oleifera
  • MDR multi-drug resistant
  • P. aeruginosa Pseudomonas aeruginosa
  • PBS phosphate buffered saline
  • PCR polymerase chain reaction
  • PFU/mL plaque forming units per millilitre
  • SODIS solar disinfection
  • XDR extensively drug resistant
  • qPCR quantitative PCR

ASJC Scopus subject areas

  • Chemical Engineering (miscellaneous)
  • Waste Management and Disposal
  • Pollution
  • Process Chemistry and Technology


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