Exploring the Antimicrobial Properties of Methylene Blue Dye: An In Vitro Study

Dear Editor, The pathogenic fungi and bacteria developed resistance to multiple antibiotics, making them difficult to treat with standard therapies. Hence, using alternative strategies such as dyes is urgent.[1] Methylthioninium chloride, commonly called methylene blue (MB), is a salt used as a dye and a medication used to treat methemoglobinemia by converting/chemically reducing the ferric iron in hemoglobin to ferrous iron.[2] Candida albicans has served as the leading causal agent of life-threatening invasive infections with mortality rates approaching 40% despite treatment.[3]Pseudomonas aeruginosa is the most common Gram-negative rod infection, especially in severely sick and vulnerable individuals.[4]Staphylococcus aureus continues to be one of the most involved bacteria in human diseases. S. aureus have both intrinsic and acquired antibiotic resistance, making clinical management of infection a real challenge, particularly in patients with comorbidity.[5] In the current study, a total of 30 S. aureus and P. aeruginosa were isolated from wounds by culturing the specimens in three media (blood agar, McConkey agar, and Mannitol salt agar). C. albicans was isolated from three sites (Vagina, oral, and urine) in 30 patients and cultured in sabouraud dextrose agar and confirmed by germ tube test.[6] The well diffusion method is used to evaluate the activity of MB; the diameter of the inhibited growth is measured in millimeters. It is considered sensitive when the inhibition zone is ≥ 13 mm. All the statistical analysis was conducted by using SPSS 26 software.[7] In the current study, the activity of MB against C. albicans isolates was 100%, while it was 81% on bacterial infections (S. aureus and P. aeruginosa) [Figure 1].Figure 1: Percentage of methylene blue activityIn this study, the median comparison of C. albicans and bacteria for MB activity was shown in Table 1. The sensitivity of C. albicans was 26 (26–28) mm and P. aeruginosa was 6 (0 –22) mm to MB with a significant difference (P = <0.0001). Activity of MB to C. albicans was 26 (26–28) mm, while for S. aureus 22 (21 –22) mm with significant differences (P = 0.001). This mean MB was active against C. albicans then against S. aureus and had less activity against p. aeruginosa.Table 1: Comparison medians of MB activity for candida and bacteriaMB is employed as a medication for the treatment of methemoglobinemia, which can arise from the ingestion of certain pharmaceuticals, toxins, or broad beans. Normally, through the NADH or NADPH-dependent methemoglobin reeducates enzymes; methemoglobin is reduced back to hemoglobin.[8] A study mentation MB is known to have antibacterial activity. Numerous studies have found that MB has activity alone or in combination with various other compounds. For example, Sauer and co-workers showed that in combination with sodium citrate MB had in vitro activity against P. aeruginosa, S. aureus, Staphylococcus epidermidis, and C. albicans.[9] In conclusion: MB has more activity against yeast fungal infection 100% (C. albicans) than bacterial isolates 81% activity with statistically significant differences (P < 0.01). Data availability Data is available and shall be shared on reasonable request. Author contribution Author 1 and 2 conceptualized the study and designed the experiments. Author 1 and 2 developed the theory and performed the computations and verified the analytical methods. Author 1 carried out the experiment and collected data and analyse data. Author 1 and 2 wrote the manuscript. All authors discussed the results and contributed to the final manuscript. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.