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Evaluation of Short-Term Exposure to 2.4 Ghz Radiofrequency Radiation GMJ.2020;9:e1580 www.gmj.ir Received 2019-04-24 Revised 2019-07-14 Accepted 2019-08-06 Evaluation of Short-Term Exposure to 2.4 GHz Radiofrequency Radiation Emitted from Wi-Fi Routers on the Antimicrobial Susceptibility of Pseudomonas aeruginosa and Staphylococcus aureus Samad Amani 1, Mohammad Taheri 2, Mohammad Mehdi Movahedi 3, 4, Mohammad Mohebi 5, Fatemeh Nouri 6 , Alireza Mehdizadeh3 1 Shiraz University of Medical Sciences, Shiraz, Iran 2 Department of Medical Microbiology, Faculty of Medicine, Hamadan University of Medical Sciences, Hamadan, Iran 3 Department of Medical Physics and Medical Engineering, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran 4 Ionizing and Non-ionizing Radiation Protection Research Center (INIRPRC), Shiraz University of Medical Sciences, Shiraz, Iran 5 School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran 6 Department of Pharmaceutical Biotechnology, School of Pharmacy, Hamadan University of Medical Sciences, Hamadan, Iran Abstract Background: Overuse of antibiotics is a cause of bacterial resistance. It is known that electro- magnetic waves emitted from electrical devices can cause changes in biological systems. This study aimed at evaluating the effects of short-term exposure to electromagnetic fields emitted from common Wi-Fi routers on changes in antibiotic sensitivity to opportunistic pathogenic bacteria. Materials and Methods: Standard strains of bacteria were prepared in this study. An- tibiotic susceptibility test, based on the Kirby-Bauer disk diffusion method, was carried out in Mueller-Hinton agar plates. Two different antibiotic susceptibility tests for Staphylococcus au- reus and Pseudomonas aeruginosa were conducted after exposure to 2.4-GHz radiofrequency radiation. The control group was not exposed to radiation. Results: Our findings revealed that by increasing the duration of exposure to electromagnetic waves at a frequency of 2.4 GHz, bacte- rial resistance increased against S. aureus and P. aeruginosa, especially after 24 hours (P<0.05). Conclusion: The use of electromagnetic waves with a frequency of 2.4 GHz can be a suitable method for infection control and treatment. [GMJ.2020;9:e1580] DOI:10.31661/gmj.v9i0.1580 Keywords: Pseudomonas aeruginosa; Staphylococcus aureus; Radiofrequency; Drug Resis- tance Introduction communication (GSM), several changes have occurred in the natural environment. Wi-Fi uring the last decades, due to the increase radiation, as a part of non-ionizing radiation Din the telecommunication systems uses, in the electromagnetic spectrum, usually pro- such as wireless fidelity (Wi-Fi) and mobile duce radiofrequency waves with a frequency GMJ Correspondence to: Dr. Alireza Mehdizadeh, Ph.D. in Medical Physics, Copyright© 2020, Galen Medical Journal. This is School of Medicine, Shiraz University of Medical Sci- an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International ences, Shiraz, Iran License (http://creativecommons.org/licenses/by/4.0/) Telephone Number: 0711-2349332 Email:[email protected] Email Address: [email protected] Amani S, et al. Antimicrobial Susceptibility after Wi-Fi Exposure Antimicrobial Susceptibility after Wi-Fi Exposure Amani S, et al. of 2.4 GHz [1]. It is evident that electromag- posure of Wi-Fi emitted from routers, on the netic radiation either ionizing or non-ionizing susceptibility of S. aureus and P. aeruginosa, can affect biological systems via thermal or as opportunistic microorganisms, to various non-thermal effects [2]. As a result, the elec- antibiotics. tromagnetic effects on the biological functions of living microorganisms represent an inter- Materials and Methods esting area of research regarding the environ- mental impacts on human health. It has been Antimicrobial Agents reported that electromagnetic field (EMFs) In this study, the following antibiotics were can either negatively [3-6] or positively [5, 7, evaluated against P. aeruginosa; levofloxacin 8] affect cell growth and viability, as well as (5 μg), piperacillin (100 μg), aztreonam (30 bacterial sensitivity to antibiotics, depending μg), ciprofloxacin (5 μg), imipenem (10 μg), on its physical parameters, such as frequen- amikacin (30 μg), cefotaxime (30 μg), and cy, exposure time, intensity and magnetic flux ceftriaxone (30 μg). Also, ampicillin (10 μg), density and bacterial strain. The non-thermal vancomycin (30 μg), cotrimoxazole (30 μg), effects of Wi-Fi exposure on different strains tetracycline (30 μg), amikacin (30 μg), levo- of bacteria have been studied [5–11]. Overall, floxacin (5 μg), piperacillin (100 μg), and cef- the effects of EMFs on the biological systems triaxone (30 μg) were used for S. aureus. The have been investigated in several studies [1, antibiotic susceptibility pattern was performed 9]. However, the results have been controver- according to the Clinical and Laboratory Stan- sial, and different cell responses have been dards Institute guidelines. The Kirby-Bauer reported. In this regard, our previous study disc diffusion method was applied in Muel- reported that Wi-Fi exposure could not only ler-Hinton Agar (MHA; Biolife, Italy). The change the antibacterial susceptibility but also antibiotic disks were purchased by ROSCO cause changes in the growth rate of pathogenic Diagnostica (DK-2630 Taastrup, Denmark). bacteria such as Listeria monocytogenes and Escherichia coli [10]. Another study revealed Antimicrobial Susceptibility Testing that Wi-Fi radiation significantly enhanced The two bacterial strains, including P. aeru- the susceptibility of Klebsiella pneumoniae ginosa ATCC 27853, and S. aureus ATCC to various antibiotics [11]. Accordingly, it 25923 were obtained. Fresh bacterial cultures is necessary to evaluate the EMF effects on (0.5 McFarland turbidity, 1.5×108 CFU) were the bacteria and also find strategies to con- prepared separately. Each bacterial suspension trol antibacterial susceptibility in the clinical was poured on the plate. Afterward, different laboratories or even in the environment [12, types of antibiotic disks were placed on the 13]. Pseudomonas aeruginosa is a Gram-neg- plates for each bacterium and kept in incuba- ative, oxidase-positive, non-stimulating, aer- tors at 37°C. The test group was exposed to a obic bacterium. It accounts for 11% to 23% Wi-Fi router at 2.4 GHz in a 14.5 cm distance of hospital infections, especially in patients (far field) [18], while the control group had no with cystic fibrosis, burn or immune deficien- exposure to such radiation. In the test group, cy, and dependence on respiratory equipment Wi-Fi exposure was achieved at intervals of 2, [14]. The development of multi-drug resistant 4, 6, 8, 10, and 24 hours. The antibiotic sus- (MDR) strains of P. aeruginosa is critical in ceptibility results were measured and record- the acquisition and development of resis- ed before and after exposure to waves emitted tance in Gram-negative bacteria [15, 16]. On from the Wi-Fi router. The inhibition zone di- the other hand, Staphylococcus aureus is a ameters were also recorded (mm). Gram-positive bacterium and also one of the most common pathogens in human communi- Statistical Analysis ties and hospitals. Despite the availability of The inhibition zone diameters in the exposed effective antibiotics, this pathogen considered and non-exposed groups were analyzed using the most common cause of skin and surgi- IBM SPSS Inc. version 22. The tests were car- cal wound infections [17]. The present study ried out in triplicate, and the non-parametric aimed to evaluate the effects of short-term ex- Mann-Whitney U test was performed for data 2 GMJ.2020;9:e1580 www.gmj.ir Antimicrobial Susceptibility after Wi-Fi Exposure Amani S, et al. analysis. P-value<0.05 was considered as sig- cin, aztreonam; and finally after 24 hours of nificant differences. exposure with all antibiotics. All of the ob- served changes were statistically significant Results (P<0.05). The mean inhibition zone diameters of P. aeruginosa are presented in Figure-1. Effects of Radiation Emitted from Wi-Fi Rout- According to this Figure, bacteria, which were ers on P. aeruginosa exposed to radiofrequency radiation, showed In P. aeruginosa bacteria, the inhibition zone remarkable changes in susceptibility to anti- diameters decreased significantly compared to biotics in comparison with the control group with the control group at the following times: at different exposure intervals. As shown in after two hours of Wi-Fi exposure emitted Figure-1, reduction in the inhibition zone di- from the Wi-Fi router for ceftriaxone; after ameter was related to increased resistance to four hours of treatment with ceftriaxone and antibiotics; therefore, after 24 hours of expo- cefotaxime; after six hours of treatment with sure to 2.4-GHz radiation, resistance patterns ceftriaxone, cefotaxime, and piperacillin; af- were determined for all antibiotics; changes ter eight and ten hours of treatment with cef- in antibacterial susceptibility to ciprofloxacin triaxone, cefotaxime, piperacillin, ciprofloxa- were evident (Figure-2). Figure 1. The mean inhibition zone diameter of P. aeruginosa bacteria before and after exposure to Wi-Fi radiation. Figure 2. The mean inhibition zone diameter of P. aeruginosa after 24 hours of exposure to Wi-Fi radiation. 2 GMJ.2020;9:e1580 GMJ.2020;9:e1580 3 www.gmj.ir www.gmj.ir Amani S, et al. Antimicrobial Susceptibility after Wi-Fi Exposure Antimicrobial Susceptibility after Wi-Fi Exposure Amani S, et al. Effects of Wi-Fi Router
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