The Effects of UV B and C Radiation and Led Light on Selected Pathogenic Oral Bacteria With and Without Antibiotic Resistance

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This research looks at how to solve the issue of bacterial resistance to antibiotics. This is accomplished by the presentation of an alternate approach focused on recent literature on the sensitivity of pathogenic microbes to specific wavelengths of light to which they are vulnerable. This  is based on the hypothesis, which this research intends to test, that bacteria are vulnerable to light exposure, which can function as a mutant. As a result, the thesis will analyze and test various studies on the various mutational effects of light exposure on pathogenic bacteria. The study will sample a specimen of pathogens of a chosen species and use the UV B and C and LED light to photosensitize them and observe the interactions that happen. The orientation of the study preempts an experimental study methodology that will be based on manipulation of variables. Appropriate sampling, data analysis and statistical decoding will aid the process of interpreting the results.


There has been increasing scholarly and expert in research on the exposure of light to microorganisms. This is in the wake of the medical problem of microbial antibiotic resistance and exposure to light makes the pathogenic bacteria and other microorganism in general to be inactive (Maclean et al., 2009, 1935). There has been some research already conducted on multiple bearings of this issue and literature is in existence that demonstrates the milestones, problems and interactions so far as it regards to this area of medical study. This section will introduce some of the issues that have been revealed through prior-researches, explain the various interactions about it with regard to the issue of light and radiation exposure to microbial pathogens and establish the essence of this kind of investigation, its implications and rationale.

Ultraviolet (UV) light and Visible Light Exposure

Ultraviolet (UV) light has been known and accepted for years as an inactivation treatment that is based on light exposure. Experiments has shown that the effects of such exposure grossly range between inducing damage to DNA, when DNA absorbs UV emitted at wavelengths of between 240nm to 280nm, and occasioning damage, though to sub-lethal extents, to systems that help to repair DNA (Nitzan et al., 2004, 21). On the other hand, researches that have resulted to the development of modern cancer therapies have also helped to establish inactivation of visible-light as a treatment for some notorious bacterial pathogens only that with this, photosensitizing molecules are usually integrated and which leads to the process being termed as photodynamic inactivation (PDI) (Ashkenazi et al., 2003, 21). With the concerns over microbial antibiotic resistance, it has led to the consideration of better alternatives of curbing them. This is when PDI has received close scholarly and expert research attention as having potential to offer an alternative to counter microbial resistance and even serve as the ultimate antimicrobial treatment (Hamblin & Hasan, 2004, 445). However, the present research does not look at the photo-inactivation of bacteria or microorganisms by adding a photosensitizer. It only considers the overall effects of the exposure to visible light in form of UV B and C as well as LED light on bacterial pathogens.

Previous Research and Inactivation

Based on what previous research has shown, certain species of bacteria become in active when they are exposed to visible light. This is especially the case with blue-light wavelengths. Some of the bacterial species that are affected in this manner encompass particular oral pigmented bacteria, propionobacterium acnes, and Helicobacter pylori (Science Buddies Staff, 2015). The mechanism of inactivation usually relies on the presence of oxygen and the effect happens due to the photoexcitation of endogenous porphyrins that occur naturally and whose action within the bacterial cells has an endogenous photosensitizing effect. As a result of photoexcitation of porphyrins, the occasioning of energy transfer happens that yields "highly cytoxic, oxygen derived species, most notably, singlet oxygen" (Rongies et al., 2011, 91). From previous work, it has been indicated that staphylococcus aureus, a bacterial species, when exposed to 400 to 420 nm visible-light, can be photodynamically inactivated provided the visible-light can be at an optimum of 405nm and in a process that is oxygenated. The mechanism is porphyrin-facilitated.

Influence of Visible-Light Exposure

However, a review of previous work has been quite limited since they most were narrow spectrum as they were confined to the 450nm visible-light wavelength (Song et al., 2013, 72). The inactivation process in the researches seem not to have investigate the mechanism of attaining the inactivation effect. As such, experimentations do not accurately describe the mechanism of inactivation given the wavelength of visible-light exposure (Friedberg et al., 2001, 103). Whether the inactivation resulted from molecules of endogenous porphyrin being photo-stimulated is not clearly elaborated in the studies. In investigating the influence of the UV B, C and LED light, it would have aided the current study if previous studies had yielded insights elucidating the exact role of porphyrins in the process of inactivation (Wang et al., 2005, 2921). This would help estimate the other possible influences that visible-light exposure can have to various bacterial species that is the target of the current study.

Uncertainties in Previous Research

Based on the fact that previous works have not comprehensively addressed all that is important to know about the effect of visible-light exposure to pathogenic bacteria, various uncertainties still exist. One is with respect to being able to explain the interactions that happen to create the influences on bacteria given the voids in existing research revelations (Maclean et al., 2008, 230). It is possible that the current research may perpetuate the same voids of similar work which leads to the uncertainty that this study will satisfactorily connect all the dots to offer a consistent elucidation of the mechanism of inactivation or other influences and effects on bacteria due to exposure to visible-light (Zeina et al., 2001, 276). However, such uncertainty will not bar the investigative expedition that this research still has a determination to accomplish. This is because of the significance of the findings that will result from this study given the amount of interest in the medical circles.

Significance and Rationale

The rapid development in antibiotic resistance and the need for rapid but aggressive response provides a staunch rationale for this study. Essentially, all efforts to find a way of curbing the resistance needs to utilize all information that can be found as it can be put together to lead to a possible medical breakthrough that will offer hope for millions of patients. This is because control of bacterial pathogens is still in very formative stages and this is evident in the cancer endemic that remains a puzzle for many medical experts and professionals across the globe (Goodson, 2016). What is required is information that utilizes existing works and achievements in this area to render an improved version of elucidation of interactions of visible-light exposure to pathogenic micro-organisms and bacteria in particular (Jori & Coppelloti, 2007, 129). It has to be known that the inactivation effect that is the widely researched and vastly discussed has a promise of being applied to create decontamination systems to rid the air, various disposing surfaces and even instruments used for medical functions of pathogenic microbial microorganisms (Maclean, 2006). This could especially lead to the safer clinical environments that will aver infections that happen in hospitals where the presence of pathogenic microbial organisms predispose patients and staff. By extension, it could be applied to control of food-borne pathogens and bacteria that lead to food spoilage and other adaptations such as water treatment and industrial decontamination and disinfection.


The study will adopt the experimental approach. This approach is usually employed in studies where cause precedes effect (Patton, 1990, 81). In this case, the experiment is testing the effect of visible-light effect of UV B and C and LED light, which is the cause, on pathogenic bacteria. The influence can only be determined through manipulation of variables in this case, visible-light being the independent variable and bacteria being the dependent variable. The one effect that will be tested as such is bacterial inactivation where the visible-light will be exposed to the bacteria staphylococcus aureus to observe the mechanism of effect of the light on the bacteria. Basic thing about experimentation is that it is used not just to determine effect but to explain the process of causation which in this study is referred to as the mechanism or interactions that happen following exposure of the bacteria to visible-light (Bernard & Green, 1957, 71). Data collected will be used to estimate the possible influences of the exposure besides inactivation as well as attempt to offer an explanation of the way that the effect is achieved. This will elucidate the mechanism or interaction aspect of the study.

Statistical Analysis

Statistical tests will show the amount of samples that can be impacted on by exposure to visible-light radiation at 405nm in one instance. It will show the variation in samples, wavelength exposure and the resultant extent of effect of inactivation or other influence as will be observed. The statistics will be essential for easy interpretation of the data and decoding of meaning that is assigned to the values (Patton, 1990, 121). In order to achieve reliability, the research questions will be keenly developed such as for them to guide an objective flow of experimental procedure, presentation for variables and focus on the interactions and their ultimate influences on the sample. With good research questions that are based on a sound research problem background, the study will best fine-tune methodological execution ranging from the choice of experimental tools to statistical measures. The sample size will be based on specimens that will be determined based on randomization and assigned to both the experimental and control groups (Mugenda, 1999, 140). This will ensure that the exposure to the visible-light is likely to be done to the available strains or types of bacteria specimens in the population. Blinding will be used where the researcher will not attempt to know the strains of bacteria and their likely response under the experimental conditions which will also help in eliminating bias.

Results and Interpretation

The research will upon completion decode the results in form of statistical data. This will be cast on either the SPSS software or simply fitted into the computer and use computer worksheets to generate graphical representations. This representation will be useful in enabling easier transcoding and assignment of meaning to the collected data (Bernard & Green, 1957, 93). In addition, software will also render data in ways that can be understood even by those who may not be conversant with the issues covered under the topic area. As a result, this will help to better disseminate the data and connect the interactions assigning meaning to results.


The study involves exposure to radiation in the form of UV B and C which has ethical implications on the extent of responsibility and discretion that has to be exercised (Young, 2006). As such, all human participants that will be involved in the study will be informed of the vital information, objective of the study so that they participate out on the basis of willingness and from a point of information. Every effort shall be made to ensure that the safety and health of participants do no subordinate the attainment of study objectives.

Risk Assessment

For purposes of safety, a risk assessment shall have to be conducted by consulting relevant authorities. This will include efforts to ensure that compliance with various experimental and research regulations is adhered to. Besides, the risk assessment will help to prepare for any eventualities so that nothing gets out of hand or goes a miss to lead to release of hazards into the environment or endanger life. For risk management and even prevention, the study will have to establish the best way to perform the experiment, the safest environment that minimizes risk and even provide necessary protective gear for participants based on the results of the risk assessment and the advice of research risk experts (Ganz et al., 2005, 262).


The project is based on facts that the researcher can relate to. The researcher has enlightened himself in the most of research methods, reviewed various research projects and works and actually participated in large scale researches. He therefore understands the issues that are involved in a project of this magnitude. It is however important to point out the choice of research was based on a pre-analysis of the methodology, procedure, materials and tools that are be required. It was also motivated by looking at the sorts of projects that others have done previously and from a comparative evaluation of the current study, it is feasible. It does not occasion huge budgetary implications, requires material that is at the disposal of the researcher to procure as well does not call for advanced level of expertise to tailor it. While it has large implications on the medical field, it offers an opportunity for a study to be carried out at small scale yet offer benefits that may be instrumental in mitigating a real problem in the medical circles. It is however a reprieve that whatever complexities and technicalities the study has, which as far as the researcher is concerned are possible to surmount, there is the time until its eventual tailoring to reflect, prepare and plan on how best to perform the project.


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Bernard, C. and Greene, H.C., 1957. An introduction to the study of experimental medicine. Courier Corporation.

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Science Buddies Staff. (2015, February 19). Death Rays: What Duration of Ultraviolet Exposure Kills Bacteria?. Retrieved March 5, 2017 from

Song, H., Lee, J., Um, H., Chang, B., Lee, S. and Lee, M. (2013). Phototoxic effect of blue light on the planktonic and biofilm state of anaerobic periodontal pathogens. Journal of Periodontal & Implant Science, 43(2), p.72.

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December 08, 2022

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