Acinetobacter lwoffii

Acinetobacter lwoffii: A Comprehensive Reference on Its Biology, Research Evidence, and Emerging Interest as a Dietary and Therapeutic Ingredient

1. Identity and Taxonomy

Acinetobacter lwoffii, formerly known as Mima polymorpha or Acinetobacter calcoaceticus var. lwoffii, is a non-fermentative Gram-negative bacillus bacterium that is a member of the genus Acinetobacter. Bacteria of the genus Acinetobacter, Gram-negative cocci, belong to the family Moraxellaceae, order Pseudomonadales, class γ-Proteobacteria. Acinetobacter species are aerobic chemoorganotrophic saprophytes; they do not form spores and are not able to ferment glucose and carbohydrates.

It is important to note at the outset that A. lwoffii is not a botanical ingredient, a plant extract, or a traditionally classified dietary supplement in the conventional sense. It is a bacterium whose presence in food, soil, and on the human body has generated scientific inquiry into its potential immunomodulatory properties. Its characterization as a "dietary supplement ingredient" or "natural ingredient" is an emerging and commercially contested designation, and the preponderance of current evidence is preclinical (animal and in vitro). No regulatory body has formally approved it for use as a probiotic or dietary supplement ingredient as of the date of this article.

1.1 Synonymy and Nomenclatural History

Acinetobacter lwoffii, formerly known as Mima polymorpha or Acinetobacter calcoaceticus var. lwoffii, is a nonfermentative aerobic Gram-negative bacillus. The species was originally described by Audureau and subsequently formally reclassified by Brisou, and the type strain maintained in major culture collections bears the designation ATCC 15309 / CIP 64.10.

1.2 Physical and Microbiological Characteristics

Due to its ability to survive dry conditions, low pH, and a wide range of temperatures, A. lwoffii, along with A. johnsonii, has been found in frozen food, bacon, eggs, pasteurized milk, and fish. It is also resistant to many disinfectants, irradiation, and desiccation. Acinetobacter sp. have a fairly variable genome that contains various mobile genetic elements, such as IS elements, transposons, plasmids, and bacteriophages, which are often associated with antibiotic resistance.

2. Natural Sources and Ecological Distribution

A. lwoffii strains occur in a variety of natural and artificial environments such as forest and agricultural soils, animal and human skin and gut, and fresh and seawater. It is considered normal skin flora and can also inhabit the human oropharynx and perineum of up to 25% of the population.

The genus is able to survive on moist and dry surfaces and is present in foodstuffs and on healthy human skin. A. baumannii is the most frequently isolated species from humans, whereas A. lwoffii belongs to the predominant species found in food.

Particularly significant from an immunological research standpoint, A. lwoffii has been identified as a prevalent organism in agricultural cowsheds. The analysis of cowshed microflora from a farming environment in Bavaria (Germany) revealed one abundant bacterium, Acinetobacter lwoffii isolate F78, which was able to reduce allergic reactions in mice, activate mammalian cells in vitro, and induce a Th1-polarizing program in dendritic cells.

Only a few genomes of A. lwoffii strains isolated from natural environments have been reported, namely A. lwoffii ZS207 from a microbial mat in a gold mine, A. lwoffii M2a from a honey sample but probably originated from bee intestines, and A. lwoffii GC2 from petroleum-contaminated soil.

3. Historical and Traditional Context

A. lwoffii has no documented history of intentional use in traditional medicine systems such as Ayurveda, Traditional Chinese Medicine, or Western herbalism. It is not listed in any pharmacopeia, monograph, or official dietary supplement reference in relation to traditional use. The organism has been present in environments where humans have lived and worked for millennia, but its identity and biological roles were entirely unknown prior to modern microbiology.

The organism's presence in fermented and raw foods has a factual basis: due to its ability to survive dry conditions, low pH, and a wide range of temperatures, A. lwoffii has been found in frozen food, bacon, eggs, pasteurized milk, and fish. However, the suggestion that populations historically consuming fermented foods have intentionally benefited from A. lwoffii specifically is speculative and unsupported by documented evidence in the peer-reviewed literature.

What can be said with more confidence is that, in the context of the "hygiene hypothesis," susceptibility to asthma and allergic diseases involves genetic variants and environmental exposure, alteration of the microbiome, and large-scale manipulation of the environment over the past century. These findings led to the hygiene hypothesis, which states that the tremendous increase in atopic diseases correlates with less contact to microbes and fewer infections in childhood. A number of epidemiological studies have shown that children who grow up in a farming environment will develop less atopic disorders later in life. A. lwoffii has been identified as a specific microbial component of such farming environments, and its role has been investigated scientifically since the mid-2000s.

4. Key Constituents and Active Compounds

Unlike plant-derived supplements with catalogued phytochemical profiles, A. lwoffii's putative bioactive properties are attributed to cellular structural components of the bacterium itself, most notably its lipopolysaccharide (LPS) and cell wall constituents.

4.1 Lipopolysaccharide (LPS)

The most thoroughly characterized bioactive component of A. lwoffii in the context of allergy research is the lipopolysaccharide (LPS) of strain F78. Evidence indicates that the allergy-protecting effects of A. lwoffii F78 are due to the activation of a T(H)1-polarizing program in human dendritic cells, and that the LPS of A. lwoffii F78 is responsible for these beneficial effects.

The structure of the LPS from A. lwoffii F78 is notable: structural and immunochemical analysis of the lipopolysaccharide from Acinetobacter lwoffii F78 identified an LPS outside Chlamydiaceae that contains a Chlamydia-specific LPS epitope in its core region — an epitope that had previously been identified only in chlamydial LPS.

The allergy-protective properties of Acinetobacter lwoffii F78 are imparted by its lipopolysaccharide, and it has been proposed that this substance should be considered as a "drug-like substance" for allergy protection.

4.2 Toll-Like Receptor (TLR) Ligands

A. lwoffii engages multiple pattern-recognition receptors. The innate immune system plays a central role in the initiation of effector responses, by signaling through pattern-recognition receptors, particularly Toll-like receptors (TLRs) and balancing the type of T-cell effector response, including TH-1, TH-2, and regulatory T cells. Specifically, the TLR-activating capacity of A. lwoffii F78 has been demonstrated in both maternal and offspring immune programming models.

4.3 Notch Ligands and Cytokine-Inducing Factors

Isolates were investigated with regard to their activation of pattern-recognition receptors, the maturation of human monocyte-derived dendritic cells, the upregulation of inflammatory cytokines, and the TH1-polarizing Notch ligand expression. A. lwoffii activates dendritic cells and induces highly Th1 polarizing immune responses including the enhanced expression of delta-4 mRNA and increased secretion of IL-12, as well as reduced mRNA expression for Jagged-1.

5. Mechanisms of Action

5.1 Th1/Th2 Immune Balance Modulation

The principal mechanism studied in relation to A. lwoffii's potential health-relevant effects is the shifting of the Th1/Th2 immune balance. Both bacterial isolates (F78 and Lactococcus lactis G121) were shown to reduce allergic reactions in mice, to activate mammalian cells in vitro, and to induce a TH1-polarizing program in dendritic cells. Th2-skewed immune responses are associated with atopic conditions such as asthma and allergic rhinitis; a shift toward Th1 signaling is proposed to suppress these responses.

5.2 Macrophage Polarization

Intranasal administration of Acinetobacter lwoffii alleviated Th2 inflammation through modulation of macrophage polarization: the lung macrophages tended to be M2b and less M2a, M2c. A. lwoffii also modulated innate lymphoid cells and T cells, resulting in a lowered type 2 immune response.

5.3 Interleukin-6 and Interleukin-10 Pathway

These experiments provide a novel mechanism of Acinetobacter lwoffii-induced asthma protection operating through IL-6-mediated epigenetic activation of IL-10 production and with associated effects on the intestinal microbiome. This study confirms that IL-6-deficient mice are resistant to the asthma-protective effect driven by Acinetobacter lwoffii. Downstream of IL-6, the asthma-blocking properties are mediated by IL-10, but not IL-17.

In mouse model studies, contact with the bacterium Acinetobacter lwoffii triggers a pro-inflammatory response. This reaction is controlled by the body's own messenger substances, the interleukins. Elevated levels of interleukin-6 then influence the body's immune cells.

5.4 Toll-Like Receptor Signaling in Prenatal Protection

Maternal intranasal exposure to A. lwoffii F78 protected against the development of experimental asthma in the progeny. Maternally, A. lwoffii F78 exposure resulted in a transient increase in lung and serum proinflammatory cytokine production and up-regulation of lung TLR messenger RNA. Conversely, suppression of TLRs was observed in placental tissue.

5.5 Gut Microbiome Remodeling

It is particularly notable that far-reaching physical changes are triggered by contact with the bacterium. As a result of bacterial stimulation of immune cells, such as T cells, scientists were able to observe changes in the natural gut flora, known as the gut microbiome. In IL-6-deficient mice, exposure to A. lwoffii increases Muribaculaceae and Sutterellaceae, and decreases Lachnospiraceae and Bacillaceae, compared to unexposed mice, restoring the status quo observed in wild-type littermate mice.

5.6 Epigenetic Mechanisms

Although most of the focus has been on postnatal microbial effects, there is emerging evidence of intrauterine effects. Human studies also show that allergy protection by in utero microbial exposure in rural farming environments is associated with enhanced neonatal Treg function, FOXP3 expression, and associated epigenetic effects (hypomethylation) of the FOXP3 gene. Non-pathogenic microbial strains (Acinetobacter lwoffii) have been isolated from these environments and their effects examined further in animal models.

6. Scientific Evidence by Area of Use

6.1 Allergy and Atopic Disease Prevention

Context and Epidemiological Basis: An increasing number of epidemiological studies show that exposure to a farming environment during early childhood strongly influences the development of allergic reactions later in life — a concept known as the "hygiene hypothesis."

Key Preclinical Study (Debarry et al., 2007, J Allergy Clin Immunol): Of a number of bacterial species identified in cowsheds of farms, two were selected, isolated, and characterized — namely Acinetobacter lwoffii F78 and Lactococcus lactis G121. The isolates were investigated with regard to their activation of pattern-recognition receptors, the maturation of human monocyte-derived dendritic cells, the upregulation of inflammatory cytokines, and TH1-polarizing Notch ligand expression. It was shown that both bacterial isolates were able to reduce allergic reactions in mice, activate mammalian cells in vitro, and induce a TH1-polarizing program in dendritic cells. These data strongly support the hygiene hypothesis, which states that an environment rich in microbiologic structures, such as a farming environment, might protect against the development of allergies. This work provides the first data on a potential application of cowshed bacteria in allergy protection.

Mechanistic Study on LPS (Debarry et al., 2010, Allergy): In a follow-up study, A. lwoffii F78's impact on human monocyte-derived dendritic cells was investigated with respect to T helper cell polarization capacity, using ELISA and real-time PCR experiments as well as confocal microscopy. The responsible molecule was further characterized using blocking experiments. It was shown that A. lwoffii F78 induced a T(H)1-polarizing program in human dendritic cells.

Prenatal Protection Study (Conrad et al., 2009, J Exp Med): Using the cowshed-derived bacterium Acinetobacter lwoffii F78 together with a mouse model of experimental allergic airway inflammation, this study investigated the hygiene hypothesis, maternal (prenatal) microbial exposure, and the involvement of TLR signaling in prenatal protection from asthma. Maternal intranasal exposure to A. lwoffii F78 protected against the development of experimental asthma in the progeny. Although prenatal A. lwoffii F78 treatment appears to positively influence antibody titers, its effect may not be strong enough to override the effects of the adjuvant used. Additionally, it is possible that the protection produced by prenatal A. lwoffii F78 treatment occurs in a B cell-independent manner. If this was the case, it would indicate that treatment does not prevent sensitization per se but rather initiates mechanisms that prevent or dampen the elicitation of the inflammatory response to allergen challenge.

Evidence Strength: All allergy/asthma protection data for A. lwoffii are currently at the preclinical stage (mouse models and cell-culture experiments). No randomized controlled trials in humans have been published demonstrating allergy prevention attributable specifically to A. lwoffii supplementation. The epidemiological data supporting the hygiene hypothesis is robust, but the link between A. lwoffii exposure specifically — as opposed to the broader farming-environment microbiome — and allergy protection in humans has not been established in a clinical trial.

6.2 Asthma and Airway Inflammation

Macrophage Polarization Study (Kang et al., 2022, Clinical & Experimental Allergy): Although lung macrophages are directly exposed to external stimuli, their exact immunologic roles in asthma are still largely unknown. The aim of this study was to investigate the anti-asthmatic effect of Acinetobacter lwoffii in terms of lung macrophage modulation. Intranasal A. lwoffii exposure was found to suppress asthma development by suppressing the type 2 response via modulating lung macrophage activation, shifting M2a and M2c macrophages to M2b macrophages. This study used a mouse model (6-week-old female BALB/c mice sensitized and challenged with ovalbumin), with flow cytometry performed to assess the phenotype of macrophages, innate lymphoid cells, and T cells. It does not constitute human clinical evidence.

IL-6 Mechanism Study (Alashkar Alhamwe et al., 2023, Allergy): Early-life exposure to certain environmental bacteria including Acinetobacter lwoffii (AL) has been implicated in protection from chronic inflammatory diseases including asthma later in life. However, the underlying mechanisms at the immune-microbe interface remain largely unknown. The effects of repeated intranasal AL exposure on local and systemic innate immune responses were investigated in wild-type and IL-6-, IL-10-, and IL-17-deficient mice exposed to ovalbumin-induced allergic airway inflammation. Those investigations were expanded by microbiome analyses.

Acinetobacter baumannii-induced alleviation of allergic airway inflammation is not an isolated observation in the Acinetobacter species, since it has been previously shown that intranasal treatment of mice with A. lwoffii F78, a non-pathogenic Acinetobacter isolate cultured from farm cowsheds, also suppressed airway eosinophilia and airway hyperresponsiveness.

Evidence Strength: Evidence for anti-asthmatic effects is exclusively preclinical (mouse models). The mechanistic pathways (IL-6/IL-10, macrophage polarization, TLR signaling) are increasingly well characterized in animal and cell-culture systems, but translation to human clinical outcomes has not yet been demonstrated.

6.3 Gut Microbiome Modulation

In IL-6-deficient mice, exposure to A. lwoffii increases Muribaculaceae and Sutterellaceae, and decreases Lachnospiraceae and Bacillaceae, compared to unexposed mice, restoring the status quo observed in wild-type littermate mice. This suggests that A. lwoffii's immunological actions may be partly transduced through secondary changes in the commensal gut microbiota, though the clinical significance in humans has not been established.

It should be noted that some literature has categorized A. lwoffii as a potentially pro-inflammatory gut organism. Some reports suggest that Acinetobacter lwoffii is among those species considered pathogenic bacteria with a "pro-inflammatory" effect in gut microbiota classification schemes. This apparent contradiction — where the organism may be anti-inflammatory in the airway/systemic context but pro-inflammatory in the gut — reflects the strain- and context-specific nature of its effects and the incompleteness of current knowledge.

6.4 Immunomodulation in the Hygiene Hypothesis Framework

Most recently, Acinetobacter lwoffii and Lactococcus lactis have been identified in the environment of traditional farms, further supporting the concept that environmental components play a decisive role in programming early immune responses. Several approaches clearly demonstrate that the route of exposure, the time of exposure, and the dose are critical variables that determine the outcome of downstream immune responses. The innate immune system plays a central role in the initiation of effector responses, by signaling through pattern recognition receptors, particularly Toll-like receptors (TLRs) and balancing the type of T-cell effector response, including TH-1, TH-2, and regulatory T cells.

6.5 Pharmaceutical Applications Under Investigation

The potential for deliberate pharmaceutical use of A. lwoffii is reflected in patent activity. One US patent describes the use of bacteria of the species Lactococcus and/or Acinetobacter as naturally occurring, non-genetically manipulated organisms. The use of these bacteria in isolated form is specified — either a Lactococcus species or an Acinetobacter species, preferably Acinetobacter lwoffii, particularly preferably Acinetobacter lwoffii strain F28, or a mixture of the two species, are employed in a pharmaceutical composition for protection from allergies and inflammatory disorders. This represents an investigational rather than approved therapeutic application.

7. Body Systems Associated with Acinetobacter lwoffii Research

• Immune System: Th1/Th2 polarization, dendritic cell maturation, macrophage activation, innate immune TLR signaling, IL-6/IL-10 cytokine axis.
• Respiratory / Pulmonary System: Airway hyperresponsiveness, eosinophilia, asthma models, lung macrophage phenotype.
• Gastrointestinal / Microbiome: Gut microbiome composition changes secondary to immune cell stimulation.
• Skin: Commensal colonization of healthy skin; research into skin microbiome interactions.
• Epigenetic Programming: FOXP3 gene methylation, neonatal immune system programming through prenatal exposure.

8. Dosage Forms and Doses Reported in Research

No standardized human dosage for A. lwoffii as a dietary supplement has been established, and no clinical trials in humans reporting dose-response data have been published. The following dosage-related information derives exclusively from preclinical and patent sources:

• Mouse model — intranasal administration: In A. lwoffii studies, treatment started 10 days before antigen sensitization and continued every second day throughout the whole sensitization and challenge phases of the study. The bacterial preparation was delivered intranasally in these murine experiments.
• Pharmaceutical patent — oral dosage form: The patent specifies use of naturally occurring, non-genetically manipulated isolated organisms, preferably A. lwoffii strain F28, in a pharmaceutical composition. Specific CFU (colony-forming unit) counts for A. lwoffii specifically are not enumerated in this patent.
• Tolerability in animal models: Acute and chronic exposure to A. lwoffii F78 was well tolerated by treated animals. After intranasal microbial application, mice exhibited normal behavior and, throughout the study, did not show signs of weight loss or lethargy. Chronic treatment with the nonpathogenic A. lwoffii F78 did not result in infection, as histological lung sections from chronically treated mice showed no signs of inflammation.

9. Safety Considerations

9.1 Commensal Status in Healthy Individuals

Being a ubiquitous bacterium in nature, it is seen as a member of the normal flora that inhabits the oropharynx, human skin, and the perineum in approximately 20 to 25% of healthy individuals. When patients have their immune system impaired or compromised, the bacteria turn into opportunistic pathogens that can cause nosocomial infections.

In general, Acinetobacter spp. are considered to be nonpathogenic to healthy individuals but may cause infections in debilitated and immunocompromised people.

9.2 Pathogenic Potential in Vulnerable Populations

While A. baumannii is the most clinically important Acinetobacter species causing infections, A. lwoffii has been increasingly reported as a hospital pathogen associated with nosocomial infections like septicemia, pneumonia, meningitis, urinary tract infections, skin infections, gastroenteritis, and wound infections.

It can cause infections in human hosts, particularly catheter-associated infections in immunocompromised patients. It has also been associated with at least one case of gastroenteritis.

Results confirm that catheter-related A. lwoffii bacteremia in immunocompromised hosts is associated with a low risk for death. However, this study identified A. lwoffii MDR strains that cause bacteremia in immunocompromised catheterized patients.

9.3 Antibiotic Resistance Profile

A multidrug-resistant clinical isolate of A. lwoffii, designated WJ10621, carries a plasmid with the NDM-1 resistance gene, one of the most clinically significant carbapenemase genes. This finding is of considerable concern because it indicates horizontal gene transfer capacity between A. lwoffii and other drug-resistant organisms.

Studies have indicated that new clinical isolates of A. lwoffii showed increased resistance to irradiation in comparison with isolates from the 1970s, which raises concerns about the persistence of A. lwoffii on medical devices that are sterilized by irradiation, especially in intensive care units (ICU).

The emerging pathogen A. lwoffii is the leading cause of Acinetobacter-derived bloodstream infections in England and Wales, followed by the extensively studied A. baumannii. However, A. baumannii has developed widespread multidrug resistance, while A. lwoffii has remained sensitive to almost all antibiotics. While research into A. baumannii is increasing and more is known about its antibiotic resistance, there remains a knowledge gap in understanding the emerging opportunistic pathogen, A. lwoffii.

A. lwoffii isolates were less likely to be multidrug resistant than A. baumannii, but MDR strains have been isolated and documented.

9.4 Resistance to Environmental Stressors

A. lwoffii is resistant to many disinfectants, irradiation, and desiccation. Acinetobacter can live on wet and dry surfaces for weeks and can be aerosolized after an infected patient coughs. Its propensity to survive on various surfaces creates ample opportunities for patients to contract the bacteria.

9.5 Regulatory and Safety Status as a Supplement

No regulatory authority — including the US FDA, the European Food Safety Authority (EFSA), or the WHO — has evaluated or approved Acinetobacter lwoffii as a probiotic or dietary supplement ingredient. No qualified presumption of safety (QPS) status has been granted by EFSA for Acinetobacter species. The bacterium is explicitly noted for laboratory research use only in major culture collections such as the ATCC, and the product is intended for laboratory research use only and is not intended for any animal or human therapeutic use, any human or animal consumption, or any diagnostic use.

10. Summary of Evidence Quality

The following table summarizes the current state of evidence for A. lwoffii in health-related research:

• Allergy/atopy prevention: Evidence is preclinical only (murine models, cell culture). Epidemiological association via hygiene hypothesis is consistent but indirect. No human RCTs.
• Asthma/airway inflammation: Preclinical only (murine ovalbumin challenge models). Mechanistic detail is increasing but human data are absent.
• Gut microbiome modulation: Secondary observation from murine immunological studies. No independent human microbiome intervention data.
• General immunomodulation: Cell-culture and animal data support Th1-polarizing effects; no human clinical validation.
• Safety in healthy adults: Commensal status suggests low risk in immunocompetent individuals, but deliberate oral administration has not been assessed in clinical trials. MDR strains carrying NDM-1 have been documented.

References

• Wikipedia — Acinetobacter lwoffii
• Genome Analysis of Acinetobacter lwoffii Strains Isolated from Permafrost Soils — PMC/NCBI
• Whole-Genome Sequence of a Multidrug-Resistant Clinical Isolate of Acinetobacter lwoffii — PMC/NCBI (Journal of Bacteriology)
• Draft Genome Sequence and Complete Plasmid Sequence of Acinetobacter lwoffii F78, an Isolate with Strong Allergy-Protective Properties — PMC/NCBI (Genome Announcements)
• Acinetobacter lwoffii and Lactococcus lactis strains isolated from farm cowsheds possess strong allergy-protective properties — Journal of Allergy and Clinical Immunology, 2007
• The allergy-protective properties of Acinetobacter lwoffii F78 are imparted by its lipopolysaccharide — PubMed (Allergy, 2010)
• Maternal TLR signaling is required for prenatal asthma protection by the nonpathogenic microbe Acinetobacter lwoffii F78 — PMC/NCBI (Journal of Experimental Medicine, 2009)
• Intranasal administration of Acinetobacter lwoffii in a murine model of asthma induces IL-6-mediated protection — Allergy (Wiley), 2023
• Effect of Acinetobacter lwoffii on the modulation of macrophage activation and asthmatic inflammation — PubMed (Clinical & Experimental Allergy, 2022)
• Contact with the bacterium Acinetobacter lwoffii protects against asthma — Deutsches Zentrum für Lungenforschung (DZL)
• The role of epigenetic dysregulation in the epidemic of allergic disease — PMC/NCBI
• Acinetobacter baumannii Infection Inhibits Airway Eosinophilia and Lung Pathology in a Mouse Model of Allergic Asthma — PLOS ONE, 2011
• Clinical and Microbiological Characteristics of Acinetobacter lwoffii Bacteremia Compared With Acinetobacter baumannii — Open Forum Infectious Diseases, Oxford Academic
• Catheter-related Bacteremia and Multidrug-resistant Acinetobacter lwoffii — CDC Emerging Infectious Diseases, 2007
• Acinetobacter — StatPearls, NCBI Bookshelf, NIH
• Differential development of antibiotic resistance and virulence between Acinetobacter species — mSphere, ASM, 2024
• Effect of baicalin on eradicating biofilms of bovine milk derived Acinetobacter lwoffii — PMC/NCBI
• US Patent 9950017 — Pharmaceutical composition for protection from allergies and inflammatory disorders (Acinetobacter lwoffii F28)
• The Immunological Basis of the Hygiene Hypothesis — Springer Nature
• Acinetobacter lwoffii — ScienceDirect Topics (Immunology and Microbiology)