Conceptualization, R.J., J.R.T., A.L.V. and J.D.F.H.; methodology, R.J. and A.L.V.; formal analysis, A.L.V.; investigation, A.L.V. and R.J.; writing—original draft preparation, R.J.; writing—review and editing, R.J., A.L.V., J.D.F.H. and J.R.T.; project administration, R.J. All authors have read and agreed to the published version of the manuscript.

Figure 1. Schematic diagram of M. luteus Q24 pilot trials on skin. Images created using MS PowerPoint.

Figure 1. Schematic diagram of M. luteus Q24 pilot trials on skin. Images created using MS PowerPoint.

Figure 2. Effect of storage conditions on the microbial stability (viable cell count) of M. luteus Q24 serum. Data points are means (n = 3 ± SD).

Figure 2. Effect of storage conditions on the microbial stability (viable cell count) of M. luteus Q24 serum. Data points are means (n = 3 ± SD).

Figure 3. Participant tolerability assessment for each attribute: Itching, Burning, Irritation, and Erythema. The distribution percent (%) of scores is plotted against each trial. Score 1 = none, 2 = slight, 3 = moderate, 4 = severe.

Figure 3. Participant tolerability assessment for each attribute: Itching, Burning, Irritation, and Erythema. The distribution percent (%) of scores is plotted against each trial. Score 1 = none, 2 = slight, 3 = moderate, 4 = severe.

Figure 4. Influence of M. luteus Q24 dosage level on the subsequent colonisation levels of the probiotic detected after 24 h following one-off application on the forearms of adult participants (n = 13) Data points are means ± SD. Dots on the graphs represents distribution of individual data points.

Figure 4. Influence of M. luteus Q24 dosage level on the subsequent colonisation levels of the probiotic detected after 24 h following one-off application on the forearms of adult participants (n = 13) Data points are means ± SD. Dots on the graphs represents distribution of individual data points.

Figure 5. Influence of M. luteus Q24 dosage level on the subsequent colonisation levels of the probiotic detected 24 h post last dose following one week pre sleep application on the forearms of adult participants (n = 11). Data points are means ± SD. Only groups showing a significant difference (p ≤ 0.05) are indicated with * on the graph.

Figure 5. Influence of M. luteus Q24 dosage level on the subsequent colonisation levels of the probiotic detected 24 h post last dose following one week pre sleep application on the forearms of adult participants (n = 11). Data points are means ± SD. Only groups showing a significant difference (p ≤ 0.05) are indicated with * on the graph.

Figure 6. Influence of M. luteus Q24 dosage level on the subsequent colonisation levels of (a) M. luteus Q24and (b) presumptive staphylococci, detected 24h post last dose following one week of pre-sleep application on the face of adult participants (n = 9). Low dose group (n = 5) High dose group (n = 4). Data points are means ± SD. Only groups showing a significant difference are indicated on the graph with one * indicates p ≤ 0.05 and ** indicates p ≤ 0.01.

Figure 6. Influence of M. luteus Q24 dosage level on the subsequent colonisation levels of (a) M. luteus Q24and (b) presumptive staphylococci, detected 24h post last dose following one week of pre-sleep application on the face of adult participants (n = 9). Low dose group (n = 5) High dose group (n = 4). Data points are means ± SD. Only groups showing a significant difference are indicated on the graph with one * indicates p ≤ 0.05 and ** indicates p ≤ 0.01.

Figure 7. Effect of M. luteus Q24 serum formulation (1% w/w) on the (a) detection levels of M. luteus Q24 like colonies and (b) percentage of participants colonized 24 h post the last dose of twice daily application for 4 weeks on the face of adult participants (n = 13). Only groups showing a significant difference (p ≤ 0.05) are indicated with * in the graph.

Figure 7. Effect of M. luteus Q24 serum formulation (1% w/w) on the (a) detection levels of M. luteus Q24 like colonies and (b) percentage of participants colonized 24 h post the last dose of twice daily application for 4 weeks on the face of adult participants (n = 13). Only groups showing a significant difference (p ≤ 0.05) are indicated with * in the graph.

Figure 8. Self-reported Skin health assessment.

Figure 8. Self-reported Skin health assessment.

Figure 9. Improvement in the appearance of dry scaling patch on the forearm (left) and increase in M. luteus Q24 count and decrease in presumptive pathogenic staphylococci count (right) after application of M. luteus Q24 oil serum for 28 days.

Figure 9. Improvement in the appearance of dry scaling patch on the forearm (left) and increase in M. luteus Q24 count and decrease in presumptive pathogenic staphylococci count (right) after application of M. luteus Q24 oil serum for 28 days.

Table 1. Summary of M. luteus Q24 clinical trials.

Table 1. Summary of M. luteus Q24 clinical trials.

TrialBody SiteFormulationStudy Design/Population/Dose DurationPilot trial 1:
One-off multidoseForearmActive: M. luteus Q24: 0.1%, 0.5%, 1%, 5%, or 10% w/w in aqueous cream
Placebo: Aqueous creamRandomised placebo-controlled, open label
Healthy adults 18–75 y (n = 13) (5 Female, 8 Male)
Dose: 0.1g (1 × 107, 1 × 109, CFU/dose)/one off at night on the left forearm (2 cm × 2 cm) and 5 × 107, 1 × 108, 5 × 108 on the right forearm (4 cm × 6 cm).
Placebo: Aqueous cream 0.1g on the left forearm (2 cm × 2 cm).Pilot trial 2:
One-week repeated multidoseForearmActive: M. luteus Q24: 1% or 5% w/w in aqueous creamRandomised controlled, single blind.
Healthy adults 18–75 y (n = 11) (3 Female, 8 Male)
Dose: 0.1g (1 × 108 CFU/dose)/7 days at night on the left forearm (2 cm × 2 cm) and (5 × 108 CFU/dose)/7 days at night on the right forearm (2 cm × 2 cm)Pilot trial 3:
One-week repeated multidoseFace (cheeks only)Active: M. luteus Q24: 0.1%, 0.5%, 1%, or 2.5% w/w in aqueous creamRandomised controlled, single blind.
Healthy adults 18–75 y (n = 12) (6 Female, 6 Male)
Dose: 0.1 g, Duration: 7 nights, Application: 2 cm × 2 cm area on the face
Group 1 (low dose): 1 × 107 CFU/dose) on the left side of face and (5 × 107 CFU/dose) on the right side of face (n = 6).
Group 2 (high dose): 1 × 108 CFU/dose on the left side of the face and 2.5 × 108 CFU/dose on the right side of the face (n = 6).Pilot trial 4:
Four weeks repeated doseFace (entire)Active: M. luteus Q24: 1% w/w in oil serumRandomised controlled single blind.
Healthy adults 18–75 y (n = 13) (5 Female, 8 Male)
Dose: 0.1 g (1 × 108 CFU/dose)/30 days at night on the full face.
Skin health questionnaire for cosmetic evaluation.

Table 2. Antibiotic susceptibility of M. luteus Q24.

Table 2. Antibiotic susceptibility of M. luteus Q24.

Antimicrobial AgentM. luteus Q24 Culture
(Control)
MIC µg/mLM. luteus Q24 Freeze Dried Raw Ingredient
MIC µg/mLInterpretation *Ampicillin≤2≤2SClindamycin0.50.5IE **Erythromycin0.50.5N/A ***Gentamicin≤0.5≤0.5IE **Tetracycline
(Doxycycline)≤0.5≤0.5IE **Vancomycin≤0.5≤0.5IE **