|
Author
Bellsolà Liarte, Joana
|
Abstract
Objectives: Antibiotic resistance is an increasingly important public health problem. Its extensive and inappropriate use has caused bacteria to become drug resistant, causing infections in humans that are difficult to treat, increasing medical costs, prolonging hospital stays and increasing mortality. The objective of this project is to study UV LED lamps as a method of elimination of Eschericia coli bacteria (which is an indicator of microbiological contamination in wastewater) as well as the analysis of the most effective wavelength and the comparison of the results according whether the bacteria are sensitive or resistant to antibiotics.
Methods: Escherichia coli bacteria from a wastewater located in the province of Barcelona are isolated and seeded on a Chromocult selective medium plates with the presence of three antibiotics (Sulfamethoxazole (SMX), Ampicilin (AMP) and Ciprofloxacin (CPR)) and without the presence of antibiotics. Sensitive and resistant bacteria are exposed to the UV-LED apparatus at a distance of 30 cm and different exposure times and wavelengths are applied. The results are plotted to observe the differences between the two bacteria in order to observe the logarithms of inactivation in each specific case.
Results: The wavelength that provides the most bacterial inactivation is 265nm while the most effective wavelength is 285nm.The combination of wavelengths that has been able to inactivate more bacteria is 265nm + 285nm. It is also considered to be the most effective combination as it is able to eliminate the most elevated number of bacteria in the shortest period of time. When comparing the results obtained according to whether the bacteria are resistant or sensitive to antibiotics, it has been observed that when combining different wavelengths there are more logarithms of bacterial inactivation in bacteria resistant to antibiotic than sensitive to antibiotic.
Conclusions: The results show that UV-LED technology is a good method for disinfecting surfaces. The disinfection process is determined by the exposure time, the irradiance, and the irradiation distance. The wavelength of 265nm is the one that eliminates the most elevated number of bacteria, this result agrees with the absorption peak of bacterial DNA. The combination of wavelengths that has been more successful in inactivating bacteria is 265nm+285nm. More number of resistant bacteria were eliminated than sensitive bacteria when combining different wavelengths, while when irradiating with a single wavelength no significant differences were found between antibiotic sensitive and antibiotic resistant bacteria.
Key words: Escherichia coli, wastewater, UVLED, antibiotic resistant bacteria, antibiotic sensitive bacteria, WWTP, Chromocult.
|
|
