In Episode 263 of the This Week in Microbiology Podcast, the hosts discussed the recent findings of two 2022 papers. The manuscripts are entitled: The elimination effects of lavender essential oil on Listeria monocytogenes biofilms developed at different temperatures and the induction of VBNC state (Han et al.) and Inhibiting host-protein deposition on urinary catheters reduces associated urinary tract infections (Andersen et al.).
Han et al. investigated the effects of lavender essential oil on biofilm formation of Listeria monocytogenes, a foodborne pathogen that can enter a non-culturable state. The researchers evaluated the elimination effects of four common antimicrobial agents, lavender oil, lactic acid, sodium hypochlorite and hydrogen peroxide, on mature biofilms of L. monocytogenes at different temperatures, 10°C (cold biofilms) and 32°C (warm biofilms). The results showed that lavender oil and sodium hypochlorite (75%) were the best agents for disrupting the biofilms, with lavender oil being able to remove up to 83% of the biofilm at four times the minimum inhibitory concentration. The authors focused on lavender oil due to past literature documenting the oil’s effect on Staphylococcus aureus2 and Campylobacter jejuni3. The authors were also interested in understanding the effects of lavender oil on mature biofilms at the different biofilm temperatures? mentioned earlier. The study also discovered that lavender oil was more efficient in lowering the number of viable cells, and that biofilms created at 10 °C were less vulnerable to the sanitizers than those formed at 32°C. Overall, among the evaluated antimicrobial agents, lavender oil was found to have the most significant eradication impact on Listeria biofilms.
Andersen et al. conducted a study to examine the inhibition of host-protein fibrinogen deposition and biofilm formation on catheters in a mouse model. They looked at different catheter materials coated with liquid-infused silicon (LIS) and soaked in medical-grade silicon oil. The study determined that LIS inhibits fibrinogen binding to a range of different UTI-causing pathogens, such as uropathogenic E. coli (UPEC) and Pseudomonas aeruginosa. The researchers used an in vitro model to show that fibrinogen promotes the initial binding of uropathogens to LIS catheters and found that colonization of LIS catheters was significantly reduced. They also demonstrated that LIS modification successfully reduced the fibrinogen-microbial binding platform and disrupted uropathogen biofilm formation on catheters and colonization of the bladder in vivo. The study suggests that disrupting the uropathogen-fibrinogen interaction can reduce the ability ofpathogens to bind and colonize on the catheter surface and bladder.
In the Han et al. paper, the authors did not explore the effects of lactic acid and hydrogen peroxide on metabolic activity, viable and culturable cells, and the observation via confocal laser scanning microscopy of the cold and warm biofilms. Also, the potential for antimicrobial resistance of lavender oil as a treatment for L. monocytogenes infections was not discussed. In the discussion about the Andersen et al. paper, one of the hosts, Dr. Petra Levin mentioned that E. coli exhibits a pilus adhesion protein called FimH that can potentially bind to fibrinogen. During my first rotation, I worked with UPEC to understand if different carbon sources alter the morphology of UPEC colony biofilms. It would be interesting to see how the LIS catheter will manage bacteria that are grown in different sugars and concentrations, like mannose, which can inhibit bacteria by interacting with the E. coli type 1 pilus adhesion protein, FimH. I concluded that mannose alters the rugosity and genetically manipulates UTI89 and VUTI137 when introduced into the sugar environment. Therefore, I suggest that introducing sugar fed UPEC isolates into the murine bladder could make it harder to get rid of the adhesion properties of FimH and the uropathogen. It would be interesting to see how the LIS catheter would work in this scenario.
Cited Articles
- Han, X., Chen, Q., Zhang, X., Peng, J., Zhang, M., & Zhong, Q. (2022). The elimination effects of lavender essential oil on Listeria monocytogenes biofilms developed at different temperatures and the induction of VBNC state. Letters in applied microbiology, 74(6), 1016–1026. https://doi.org/10.1111/lam.13681
- Brożyna, M., Paleczny, J., Kozłowska, W., Chodaczek, G., Dudek‐Wicher, R., Felińczak, A., Gołębiewska, J., Górniak, A. and et al. (2021) The antimicrobial and antibiofilm in vitro activity of liquid and vapour phases of selected essential oils against Staphylococcus aureus. Pathogens 10, 1207–1232.
- Ramić, D., Bucar, F., Kunej, U., Dogša, I., Klančnik, A. and Možina, S.S. (2021) Antibiofilm Potential of Preparations against Campylobacter jejuni. Appl Environ Microbiol 87, 1099–1021.
- Marissa Jeme Andersen, ChunKi Fong, Alyssa Ann La Bella, Jonathan Jesus Molina, Alex Molesan, Matthew M Champion, Caitlin Howell, Ana L Flores-Mireles (2022) Inhibiting host-protein deposition on urinary catheters reduces associated urinary tract infections eLife 11:e75798. https://doi.org/10.7554/eLife.75798
