Comparison of solid-phase cytometry and the plate count method for the evaluation of the survival of bacteria in pharmaceutical oils
Article first published online: 15 OCT 2008
© 2008 The Authors. Journal compilation © 2008 The Society for Applied Microbiology
Letters in Applied Microbiology
Volume 47, Issue 6, pages 571–573, December 2008
How to Cite
De Prijck, K., Peeters, E. and Nelis, H.J. (2008), Comparison of solid-phase cytometry and the plate count method for the evaluation of the survival of bacteria in pharmaceutical oils. Letters in Applied Microbiology, 47: 571–573. doi: 10.1111/j.1472-765X.2008.02464.x
- Issue published online: 19 NOV 2008
- Article first published online: 15 OCT 2008
- 2008/0545: received 30 March 2008, revised 31 July 2008 and accepted 6 August 2008
- carbol oil;
- jojoba oil;
- tea tree oil
Aim: To compare the survival of four bacterial strains (Escherichia coli, Proteus mirabilis, Staphylococcus aureus, Pseudomonas aeruginosa) in pharmaceutical oils, including jojoba oil/tea tree oil, carbol oil, jojoba oil and sesame oil.
Methods and Results: Oils were spiked with the test bacteria in a concentration of 104 CFU ml−1. Bacteria were extracted from oils with phosphate-buffered saline containing 0·5% Tween 20. Aliquots of the pooled water layers were analysed by solid-phase cytometry and plate counting. Plate counts dropped to zero for all test strains exposed for 24 h to three of the four oils. In contrast, significant numbers of viable cells were still detected by SPC, except in the jojoba oil/tea tree oil mixture and partly in sesame oil.
Conclusions: Exposure of bacteria for 24 h to the two oils containing an antimicrobial led to a loss of their culturability but not necessarily of their viability. The antibacterial activity of the jojoba oil/tea tree oil mixture supersedes that of carbol oil.
Significance and Impact of the Study: These in vitro data suggest that the jojoba oil/tea tree oil mixture more than carbol oil inhibits bacterial proliferation when used for intermittent self-catherization.