Search

Introduction: Protection of the respiratory system has been a vital, and for this purpose, various solutions have been proposed, including the use of masks. One of the most important parameters to measure the effectiveness of the mask against the penetration of microbial agents. The present study was conducted with the aim of evaluating the bacterial and particle filtration of medical masks. Material and Methods: To assess bacterial performance, the national standard 6138, compliant with EN14683, and Type I medical masks were utilized. Staphylococcus aureus bacterial suspension was prepared and passed through the mask using a nebulizer and through an impactor with a flow rate of 28.3 l/min. Plates containing soy agar were placed in the impactor. Subsequently, all plates were incubated, and the bacterial filtration efficiency (BFE) of the masks was determined by counting the bacterial colonies that passed through the mask’s media as a percentage of the total bacteria. It is worth noting that the pressure drop and particle filtration efficiency were also determined for all masks Results: Based on the results of the particle removal performance for the particle size of 3 µ, the masks were categorized into three groups with efficiency above 99%, above 95% and 90%. According to the standard, all masks had an acceptable pressure drop below 40 Pa. The acceptable bacterial filtration rate for type I masks should be above 95%. The results showed that type A and B masks have an acceptable bacterial filtration rate and there is a significant correlation between the types of masks examined in terms of bacterial and particle efficiency. Conclusion: The results showed that different types of masks under investigation have significant differences in terms of particle capture efficiency and bacterial filtration performance. In addition, there is a significant correlation between bacterial and particle filtration efficiency.

Introduction: Toluene is significant pollutants in the air. Long-term exposure to toluene can lead to adverse effects. Biofiltration is one of the air pollutant control methods. In this study, Pseudomonas putida was selected as a microorganism capable of hydrocarbon degradation and its ability to biodegrade toluene in a suspension growth reactor was also investigated. Material and Methods: Experiments were conducted in two days and in five hours. Each method consisted of three sample reactors (A, B, C) and one control reactor (D). In the first method, the amount of bacteria in the sample reactors is 0.5, 1 and 2 McFarland and the amount of toluene injection into the reactors is the same (0.5 microliters) and in the second method, the amount of toluene injection into the sample reactors is 0.5, 1 and 1.5 microliter and 1.5 microliter in the control reactor and the amount of bacteria in them was the same (1 McFarland).Toluene gas samples and carbon dioxide were periodically analyzed. Results: In the first method of toluene decomposition, there was a significant difference between the three reactors (p-value = 0.002). The results of the second method were also significantly different between the three reactors (p-value

Introduction: Volatile organic compounds are the most common pollutants in the air, and among them, toluene is the most common form, which is toxic resulting in liver and kidneys damages. Regarding the fact that this compound is widely used in various chemical industries, implementing an efficient method for controlling its concentration is of great importance. The comparative survey of the capability of virgin activated carbon with the one immobilized by pseudomonas putida PTCC, and also the performance of the biofiltration system involving pseudomonas putida bacteria immobilized on activated carbon for the adsorption and degradation of toluene from the air as well as regenerating the activated carbon were aimed in the present study. Material and Methods: The microbial growth process was initiated by incubation of pre-culture in a rotary shaker, at 150rpm overnight. After 4 days, the strain pseudomonas putida, PTCC No: 1694 was immobilized on a certain amount of activated carbon. Subsequently, an airstream containing toluene was introduced into the biofilter, and the inlet and outlet concentrations of toluene were measured. Results: The obtained results illustrated that the increase in the volume of the media and decrease in the gas flow rate significantly enhances efficiency. The great performance of the biofilter was confirmed by the high efficiency of the immobilized activated carbon which exhibited 89% yield during 14 hours. On the second cycle, the biofiltration system was able to adsorb toluene at an efficiency of 81%, while the virgin activated carbon exhibited far less efficiency with the value of 28%. Conclusion: The provided results demonstrated the feasibility and reusability of the biofilter system for toluene removal. The proposed technique also extends the activated carbon’s capacity, which could be a potential solution to re-use the activated carbon in industrial applications.

Background and Aim: Wound infections, as a common nosocomial infection, are contributing factors to mortality. Determining the prevalence of common pathogens causing wound infections and their antibiotic susceptibility patterns plays a key role in the rapid treatment and prevention of such infections. This study aimed to analyze wound infections in hospitalized patients in a university hospital in Tehran and determine the antimicrobial susceptibility patterns of the isolated bacteria. Materials and Methods: Data about 563 hospitalized patients from different wards of a university hospital, who had participated in the study from March 2017 to June 2019, were collected, and sample collection from the wounds was carried out. For the identification of pathogens, we used standard bacteriological techniques. The disk diffusion method was used to determine the antimicrobial susceptibility patterns of the isolates. Data were analyzed using SPSS 18. Results: Among five hundred and sixty-three samples, 382 (67.7%) had positive cultures. The most common isolated pathogens were Staphylococcus aureus (19.2%), Escherichia coli (17.7%), Acinetobacter spp. (14%), Pseudomonas aeruginosa (13.6%) and Klebsiella spp. (12.9%). Fifty percent of the Staphylococcus aureus isolates were resistant to cefoxitin. Escherichia coli and Acinetobacter spp. were resistant to most of the antibiotics. Conclusion: Our study found that pathogens causing wound infections were highly resistant to commonly prescribed antibiotics. Identifying the etiological agents of wound infection and their antibiotic susceptibility patterns is essential, especially for the treatment of elderly patients and those hospitalized in intensive care. This can assist in designing a therapeutic strategy for these types of infections.

Introduction: Air pollution is now recognized as an important environmental and health concern. Biological control processes, due to their durable, cost-effective and eco-friendly, have become a good alternative to physic-chemical methods. Biotechnology is based on the activity of microorganisms. The aim of this study was to compare the capability of Pseudomonas Putida PTCC 1694 (bacteria) and Polarotus Stratus IRAN 1781C (mushroom) in the removal of toluene from the air stream and its biodegradation under same operating conditions. Material and Methods: To this purpose, a bio filter containing two parallel columns was designed and constructed on a laboratory scale and the experiments were carried out based on measuring the removal efficiency (RE), elimination capacity (EC) and pressure drop in these two columns. Thus, the bacteria were inoculated in one of the columns and in the other the fungus was inoculated. Results: The bacterial testing lasted for 20 days and the fungal testing lasted for 16 days. The contaminant loading rates (LR) for bacterial and fungal bio filters were 11.65±2.26 and 11.94±2.56 g/m3.h, respectively. The results showed that the fungal bio filter was more capable of eliminating of toluene vapor than bacterial bio filter (9.65±3.53 vs 9.18±2.6 g/m3.h). However, the pressure drop in the bacterial bio filter was lower than the fungal bio filter (1±0.28 vs 1.1±0.32 cm water). Conclusion: According to the results, fungal bio filtration appeared to be more successful than bacterial bio filtration in the removal of toluene.

Introduction: Indoor air environments contain a wide variety of microorganisms such as bacteria, fungi, and viruses in which some of them can affect the human health. Filtration is considered as one of the most common methods to remove microorganisms in these environments. The purpose of current study was to investigation the neat and photocatalytic HEPA filters performance at different face velocities and various intensity of UVC light source on the reduction of airborne microorganisms. Material and Method: After installation of the neat and photocatalytic HEPA filters in a closed–loop chamber, suspension of Staphylococcus epidermidis and Bacillus subtilis bacteria with a concentration of 107 CFU / ml were sprayed into the closed–loop chamber by nebulizer. Sampling of penetrated microorganisms from filters were performed using the NIOSH 0800 method under ambient temperature 22±3oC, relative humidity 35±5%, and different air velocity (0.1 m/s and 0.3 m/s) and UVC different radiation intensity (1 mW/cm2, 1.8 mW/cm2 and no radiation (dark)) at 30 minutes time period. penetrated microorganisms density from filters was determined in term of CFU/m3. Result: There were no significant differences in the penetration rates of microorganisms at the dark mode between the two neat and photocatalytic HEPA filters (p>0.05). The penetration rate of bacteria was significantly decreased in the neat and photocatalytic HEPA filters at UVC radiation mode with various intensities than dark mode (p

Introduction: Nowadays, HEPA filters is used in hospitals, clean rooms, microbiology hoods, ventilation of surgery rooms, and Pharmacy for removing microorganisms and reduce health hazard. The aim of this study is to increase the efficiency of HEPA filters with UVC radiation to reduce the density of airborne microorganisms. Material and Method: The closed–loop chamber was made to evaluate Staphylococcus epidermidis, Bacillus subtilis bacteria and Aspergillus Niger, Penicillium fungi. The concentration of fungi and bacteria suspension Respectively was 106, 107 CFU/ml. After the suspension was prepared, it was sprayed into the closed loop chamber by nebulizer. Sampling was done with UVC radiation (1.8 mW/cm2 Illuminance) and no radiation (dark) that included time periods 60, 90 and 120 minutes. Microorganisms density was determined in term of CFU/m3. Result: The result showed that there was a significant difference between UVC radiation and dark section for all the microorganisms (epidermidis, subtilis, Niger and Penicillium) at each time periods (P value< 0.05). This indicates that concentration of four microorganisms were decreased at all the time periods. UVC radiation could change the essential molecular substances for cellular factor. UVC can penetrate the cell walls of microorganisms. thus nucleic acids and other cellular vital material affected and will cause the destruction or inactivation of microorganisms. Conclusion: UVC radiation is effectiveness to decrease concentration of four microorganisms. because UVC radiation could remove both bacteria and fungi. While the other studies in other countries, UVA radiation is only effective in reducing bacteria. Therefore, achieved greater efficiencies of HEPA filters, using HEPA filters with UVC will have a significant effect on reducing the density of microorganisms.