Pathogenic bacteria are microscopic organisms that can cause diseases in humans. These harmful microorganisms are a perennial threat to human health, leading to various illnesses and infections. Understanding the nature of pathogenic bacteria is crucial for developing effective remedies, and one such remedy that has gained prominence is mānuka oil.


The Origins of Mānuka Oil

manuka plants in New Zealand

Mānuka oil is a unique essential oil that originates from the mānuka tree, primarily found in New Zealand and parts of Australia. The oil is extracted from the leaves of the remarkable mānuka tree, through the process of steam distillation from the leaves and delicate branchlets of the mānuka shrub. 


What Are Pathogens?

Pathogens are microorganisms that can cause disease. The human body naturally contains various microbes, but these usually don’t pose a problem unless the immune system is weakened or they enter normally sterile body parts. Pathogens are different because they can potentially induce illness when they enter the body.

For pathogens to thrive, they only require a host. Once inside a host’s body, they evade the immune responses and utilise the body’s resources to replicate before exiting and spreading to new hosts.

Pathogens can be transmitted through various means, depending on their type. Transmission can occur through skin contact, bodily fluids, airborne particles, contact with feces, or by getting in contact with surfaces that an infected person has touched.


What Are The Types of Pathogens?

Various types of pathogens exist, with the focus here being on the four most common categories: viruses, bacteria, fungi, and parasites.



Viruses consist of genetic material, like DNA or RNA, enclosed within a protein coat. Once a person is infected, viruses infiltrate the host cells in their body. Inside these host cells, viruses use the cell’s machinery to reproduce, generating more viruses.

Once the replication process is complete, the newly formed viruses exit the host cell. This often results in damage to or destruction of the infected cells.

Certain viruses can remain dormant for a period before resuming their multiplication. During this phase, an individual may appear to have recovered from the viral infection but can become ill again.

It’s important to note that antibiotics are ineffective against viruses and cannot be used to treat viral infections. Antiviral medications may be considered, depending on the specific virus involved.



Bacteria are single-celled microorganisms that exhibit considerable diversity in shapes and characteristics. They can thrive in a wide range of environments, including both the inside and outside of the human body. Not all bacteria are responsible for causing infections; those with this capability are referred to as pathogenic bacteria.

When a virus weakens the immune system, susceptibility to bacterial infections can increase. A viral infection can create conditions that allow otherwise harmless bacteria to become pathogenic.

Antibiotics are employed to address bacterial infections. However, certain bacterial strains have developed resistance to antibiotics, rendering them challenging to treat. This resistance can occur naturally but is also exacerbated by the overuse of antibiotics, as highlighted by the World Health Organization (WHO).



The Earth hosts millions of fungal species, yet only around 300 are known to be capable of causing illnesses. Fungi are widespread in various environments, including both indoor and outdoor settings, as well as on human skin. Infections occur when fungi grow excessively, leading to an overgrowth situation.

The cells of fungi possess a nucleus and other components safeguarded by a membrane and a robust cell wall. This structural makeup can make them resilient and challenging to eradicate. Some emerging strains of fungal infections, like Candida auris, have proven to be particularly hazardous, prompting increased research into fungal infections.



Parasites are organisms that mimic tiny animals. They live inside or on a host and derive nourishment from or at the host’s expense. Although parasitic infections are more common in tropical and subtropical regions, they can occur anywhere.

Three primary types of parasites can induce diseases in humans:

  1. Protozoa: These are single-celled organisms capable of living and multiplying within your body.
  2. Helminths: These are larger, multi-celled organisms that can inhabit both the inside and outside of your body, commonly known as worms.
  3. Ectoparasites: These multi-celled organisms reside on or feed off the skin, including certain insects like ticks and mosquitoes.

Parasites can be transmitted through various means, including contaminated soil, water, food, blood, sexual contact, and insect bites.


How Do Pathogens Make You Sick?

Streptococcus bacteria Streptococcus species are responsible for pharyngitis, meningitis, bacterial pneumonia, endocarditis and necrotizing fasciitis

Pathogens can cause illness through various mechanisms. In some cases, they generate toxins that harm tissues, while in others, the pathogen triggers a robust immune response that damages not only infected tissue but also healthy tissue.

Pathogens also exploit this immune response to facilitate their spread. Actions like sneezing, coughing, and diarrhea are a few ways through which pathogens seek out new hosts to infect.

Pathogens can also be transmitted to food when handled with unclean hands during cooking. In the kitchen, pathogens from raw food can contaminate other food items. Additionally, the risk of pathogen transmission exists when changing a child’s diaper or after coming into contact with animals.


Diseases Caused by Pathogens

  • Chickenpox/s
  • Common cold
  • Dengue fever
  • Flu
  • Hingles
  • HIV and AIDS
  • Hepatitis A, B, C, D, E
  • Measles
  • Meningitis
  • Oral and genital herpes
  • Viral gastroenteritis, including norovirus and rotavirus
  • Warts, including genital warts
  • Yellow fever
  • Bacterial gastroenteritis, such as salmonella food poisoning or E.coli infection
  • Bacterial meningitis
  • Cellulitis
  • Lyme disease
  • Gonorrhea
  • Strep throat
  • Tuberculosis
  • Urinary Tract Infection (UTI)
  • Athlete’s foot
  • Jock itch
  • Fungal nail infection (onychomycosis)
  • Ringworm
  • Thrush
  • Vaginal yeast infection
  • Giardiasis
  • Intestinal worms
  • Malaria
  • Pubic lice
  • Toxoplasmosis
  • Trichomoniasis

Mānuka Oil’s Antimicrobial Properties: The Battle Against Pathogenic Bacteria

Mānuka oil contains triketones, which are organic chemical compounds known for their remarkable antibacterial and antimicrobial properties. When applied, these triketones demonstrate the ability to effectively combat and eliminate pathogenic bacteria, contributing to their potential to promote health and hygiene. 

This unique quality of mānuka oil makes it a valuable natural resource in various applications, particularly in the field of wellness and skincare, where its antibacterial properties can be harnessed to address a range of concerns related to bacterial pathogens.


Why Is Mānuka Oil Powerful Against Pathogenic Bacteria?

Pathogenic bacteria do not easily develop resistance to potent essential oil antimicrobials such as mānuka oil for several compelling reasons:

  1. Complexity of Essential Oils: Unlike antibiotics with just one or two active ingredients, antimicrobial essential oils such as mānuka leaf oil comprise a complex blend of natural antibacterial constituents, each with multiple mechanisms of action. For example, β-triketones like leptospermone, isoleptospermone, grandiflorone, and flavesone, as well as sesquiterpenes including calamenene, aromadendrene, and selinene in mānuka oil possess potent antibacterial properties. This complexity makes it difficult, if not impossible, for pathogenic bacteria to develop multiple resistance mechanisms against all these bioactive compounds.
  2. Quorum Sensing Inhibition: Essential oils can sometimes reverse antimicrobial resistance in bacteria by inhibiting bacterial communication systems known as “quorum sensing.” This prevents bacteria from becoming virulent, including rapid multiplication, biofilm formation, and the secretion of bacterial toxins. When bacteria are in a quiescent state, they often do not pose a significant threat to health, even though they haven’t been entirely eliminated.
  3. Genetic Mutations and Cell Functioning: Resistance in bacteria to antibiotics typically arises through genetic mutations that are rapidly passed to other bacteria. However, envisioning a single genetic mutation or a series of mutations that render microbial membranes impervious to essential oils while allowing normal cell functioning is challenging. Any potential mutations that confer resistance to essential oils are likely to adversely impact overall microbial growth and survival.
  4. Efflux Pump Inhibition: Drug efflux is a crucial antimicrobial resistance mechanism in gram-negative bacteria, enabling them to expel antibiotics before causing fatal cell damage. Phenolic compounds such as eugenol have been demonstrated to turn off efflux pumps in some bacteria, thus eliminating their resistance to antibiotics.
  5. Enhanced Absorption: Some essential oil components, such as monoterpenes, p-cymene and myrcene, may not have direct antibacterial effects but significantly enhance the absorption of antimicrobial substances into bacteria. East Cape mānuka oil contains small amounts of these terpenes.

These factors collectively contribute to the effectiveness of mānuka oil as a potent antimicrobial agent with a reduced likelihood of bacteria developing resistance.


The Science Behind Mānuka Oil vs Pathogenic Bacteria

white manuka flowers

There exists an ongoing and pressing demand for efficacious antimicrobial treatments aimed at addressing skin and oral infections, particularly those stemming from multidrug-resistant pathogens such as Methicillin-Resistant Staphylococcus aureus (MRSA). The excessive application of topical antimicrobial agents in the management of skin infections has been identified as a key factor exacerbating the concerning issue of antimicrobial resistance (AMR). Furthermore, the global impact of AMR has been heightened by the Covid-19 pandemic, as it has led to an increased production and utilisation of antibiotics, over-the-counter products, sanitisers, and chemicals.

In response to the imminent threat posed by AMR, researchers are diligently investigating plant essential oils as promising candidates for developing safe and effective antimicrobial solutions characterised by multiple mechanisms of action. Substantive evidence has emerged to indicate that East Cape mānuka oil, rich in β-triketones, exhibits remarkable efficacy against a diverse spectrum of pathogens, including MRSA and Herpes Simplex Virus Type 1 (HSV-1).

In a study conducted by Takarada (2004), the antibacterial effects of essential oils, including manuka, tea tree, eucalyptus, lavender, and rosemary, were investigated on several oral bacteria strains. These strains included Porphyromonas gingivalis, Actinobacillus actinomycetemcomitans, Fusobacterium nucleatum, Streptococcus mutans, and Streptococcus sobrinus. Among the essential oils tested, mānuka oil exhibited the highest efficacy in inhibiting the growth and eradicating all tested oral bacteria, regardless of whether they were gram-positive or gram-negative. This finding is significant because mānuka oil is typically more effective against gram-positive bacteria. The study also observed that mānuka oil demonstrated bactericidal properties, capable of killing bacteria, as well as bacteriostatic properties, which can halt bacterial growth. Remarkably, gum disease-causing bacterial strains were eliminated after only 30 seconds of exposure to a 0.2% concentration of mānuka oil. Additionally, mānuka oil displayed significant inhibitory activity against the adhesion of P. gingivalis and S. mutans to surfaces.

Research by Reichling et al. (2005) demonstrated the effectiveness of East Cape mānuka oil against HSV1 and HSV2. 

Herpes simplex virus (HSV) is a highly contagious pathogen that commonly leads to recurrent skin lesions, primarily occurring in and around the oral cavity. However, these lesions can also manifest in the eyes, nose, pharynx, esophagus, and the genital region. Epidermal lesions in the orofacial area, known as herpes labialis, are primarily attributed to Herpes simplex virus type 1 (HSV-1), while genital lesions, referred to as herpes genitalis, are caused by HSV-2. It is estimated that in industrialised countries, over 90% of the population is infected with HSV-1, and 20-30% are infected with HSV-2.

Schnitzler et al. (2008) further confirmed its efficacy against drug-resistant HSV1, positioning mānuka oil as an ideal topical treatment for HSV infections, especially in patients experiencing frequent recurrences. 

Reichling et al. (2009), indicate that mānuka oil exhibits more potent antiviral properties compared to tea tree oil, peppermint oil, sandalwood oil, and thyme oil against both HSV1 and HSV2. This study suggests that mānuka oil inactivates HSV viruses either by interfering with the virus envelope or by masking essential viral components required for entry into host cells.

In a study conducted by Song et al. (2013),  the effectiveness of mānuka oil against strains of S. pseudintermedius, collected from dogs with skin and ear infections in Korea between 2009 and 2011, was investigated. The in vitro antimicrobial activity of mānuka oil was assessed by measuring minimum inhibitory concentrations (MICs) against 39 methicillin-resistant S. pseudintermedius (MRSP) strains and 11 methicillin-susceptible S. pseudintermedius (MSSP) strains. The results demonstrated that mānuka oil exhibited excellent activity against all tested S. pseudintermedius isolates.

In addition to the bacterial species mentioned, Malassezia pachydermatis is a commensal fungus commonly present in the microflora of healthy dogs. However, it can also act as an opportunistic pathogen, leading to skin and ear infections in dogs. A study conducted by Bismark et al. (2020) investigated the effectiveness of essential oils against M. pachydermatis isolates from canine ears and found that mānuka oil exhibited strong antifungal efficacy.


Benefits of Mānuka Oil Beyond Bacteria

Mānuka oil’s applications extend beyond bacterial warfare. It is revered in skincare and has remarkable benefits and uses:

  1. Reduce Infections: Mānuka oil effectively inhibits bacterial growth, reducing and preventing infections.
  2. Manage Acne: Its antibacterial and anti-inflammatory properties make it highly effective in preventing and treating acne-prone skin.
  3. Wound Healing: Mānuka oil alleviates inflammation, discomfort, and the risk of wound infection, expediting the healing process for cuts, bites, and stings.
  4. Combat Nail Fungus: It acts as an antifungal agent, helping to combat nail fungus, athlete’s foot, ringworm, and other fungal infections.
  5. Stress Reduction through Aromatherapy: Adding mānuka oil to a warm bath promotes calm, reduces stress, and enhances well-being through aromatherapy.
  6. Alleviate Allergy Symptoms: Mānuka oil acts as a natural antihistamine, relieving allergy symptoms without known allergens.
  7. Hair and Scalp Health Improvement: It benefits hair and scalp health by reducing dandruff, soothing irritation, eradicating lice, and improving hair strength and shine.
  8. Use as a Deodorant: Due to its antibacterial properties, mānuka oil is an excellent ingredient for natural deodorants.
  9. Use as a Household Cleaning Agent: Mānuka oil has various household applications, including as an insect repellent, herbicide, disinfectant, deodoriser, and mould/mildew remover, among others.

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