Eucalyptus for Antimicrobial

Eucalyptus, a genus of flowering trees and shrubs, has a long history of traditional use for its purported antimicrobial properties. Several clinical trials and randomized controlled trials (RCTs) have investigated the efficacy of eucalyptus-derived compounds in combating various microbial infections. This body of research aims to explore the potential of eucalyptus as a therapeutic intervention against microbial challenges, providing evidence-based support for its traditional applications.

Protocols Studied in Research

[1] Biogenic nanosilver-coated endotracheal tubes (ETT) to prevent ventilator-associated pneumonia (VAP). (Cited by: 3) (pmid: 36562803)

• Protocol: A randomized controlled trial in 47 veterinary patients compared AgNP-coated ETTs to uncoated ETTs. In vitro studies assessed antimicrobial activity against various microbes, including multi-drug resistant strains. A porcine VAP model was also used.
• Outcome: AgNP-coated ETTs significantly reduced microbial burden on the ETT surface and in lung tissue in both the porcine model and the clinical trial, demonstrating effective antimicrobial activity and safety.

[2] Cetylpyridinium chloride (CPC) lozenges of varying formulations for reducing oropharyngeal colony-forming units of *Staphylococcus aureus*, *Streptococcus pyogenes*, and *Candida albicans*. (Cited by: 1) (pmid: 8710750)

• Protocol: Six volunteers tested six different CPC lozenge formulations in vivo, measuring oropharyngeal bacterial/fungal reduction. In vitro tests assessed the effect of lozenge components (pH, other ingredients) on CPC activity against the same organisms.
• Outcome: Lozenge pH was the most significant factor influencing CPC's antimicrobial activity. Formulations with a pH above 5.5 demonstrated superior efficacy.

[3] Use of an essential oil-containing dentifrice for the effect on oral microbial flora and emergence of resistant microbial forms. (Cited by: 1) (pmid: 11763911)

• Protocol: A randomized, controlled trial comparing an essential oil-containing fluoride dentifrice to a control fluoride dentifrice without essential oils in 66 subjects. Plaque and saliva samples were collected at baseline, after prophylaxis, and at 3 and 6 months.
• Outcome: No significant differences in microbial flora were found between groups except for lower spirochete and "other" microorganism percentages in the essential oil group at 6 and 3 months, respectively. No evidence of bacterial resistance developed.

Research Interpretation: Summary and Conclusion

Three studies investigated the antimicrobial properties of eucalyptus-derived products, employing diverse methodologies. One study utilized silver nanoparticle-coated endotracheal tubes (ETT) in a veterinary setting and a porcine model, demonstrating a significant reduction in microbial burden. Another examined the impact of lozenge pH on the antimicrobial activity of cetylpyridinium chloride (CPC), finding formulations with pH above 5.5 superior. A third trial compared an essential oil-containing dentifrice to a control, revealing modest reductions in specific microbial groups (spirochetes and "other" microorganisms) without evidence of resistance. While the studies used different delivery methods and target organisms, a common thread is the demonstration of some antimicrobial effects from eucalyptus-related components or formulations. However, the magnitude of the effect varies significantly depending on the specific formulation and delivery method, highlighting the need for further research to optimize efficacy and identify the most effective applications of eucalyptus-derived antimicrobial agents.

Publications

[1] Lethongkam S; Sunghan J; Wangdee C; Durongphongtorn S; Siri R; Wunnoo S; Paosen S; Voravuthikunchai SP; Dejyong K; Daengngam C (2023). Biogenic nanosilver-fabricated endotracheal tube to prevent microbial colonization in a veterinary hospital Applied microbiology and biotechnology 107 (2-3) :623-638.

[2] Richards RM; Xing JZ; Weir LF (1996). The effect of formulation on the antimicrobial activity of cetylpyridinium chloride in candy based lozenges Pharmaceutical research 13 (4) :583-7.

[3] Charles CH; Vincent JW; Borycheski L; Amatnieks Y; Sarina M; Qaqish J; Proskin HM (2000). Effect of an essential oil-containing dentifrice on dental plaque microbial composition American journal of dentistry 13 (Spec No) :26C-30C.