Preparation of Photocatalytic TiO2-Polyacrylonitrile Nanofibers for Filtration of Airborne Microorganisms.

Background: We aimed to investigate the efficiency of neat polyacrylonitrile (PAN) nanofibers and photocatalytic PAN/TiO2 nanofibers for removal of airborne microorganisms. Methods: Nanofibers were fabricated from 16 wt% of PAN dissolved in dimethyl formamide through the electrospinning technique. The efficiency of media for removal of Staphylococcus epidermidis and Bacillus subtilis was investigated at different conditions such as face velocity, relative humidity, air temperature and UVC radiation intensity. as face velocity (0.1 and 0.3 m/s), relative humidity (35±5% and 60±5%), air temperature (22±3 °C and 30±3 °C) and the UVC radiation intensity (dark, 1±0.09 mW/cm2 and 1.8±0.07 mW/cm2) using air sampling from upstream and downstream of media by cascade impactor containing blood agar culture medium. Results: The mean diameter of electrospun fibers and coefficient of variation were 194 nm and 15%, respectively. The amount of immobilized TiO2 on the filter was 620±6.56 mg/m2. Photocatalytic nanofiber filter media presented the best performance for removal of airborne B. subtilis at 60±5% relative humidity, 0.1 m/s face velocity, air temperature 22 °C, and 1.8 ± 0.07 mW/cm2 UVC radiation. Conclusion: The filtration efficiency of photocatalytic media was significantly higher than neat ones. Lower efficiency of media was found in the higher air velocity for all bioaerosols. High UVC radiation intensity increased filtration efficiency. Moreover, the increase in air temperature and relative humidity (except for TiO2-coated media under UVC radiation) did not significantly affect the filtration efficiency of all media.

A comparison of biofiltration performance based on bacteria and fungi for treating toluene vapors from airflow.

With increasing concerns about industrial gas contaminants and the growing demand for durable and sustainable technologies, attentions have been gradually shifted to biological air pollution controls. The ability of Pseudomonas putida PTCC 1694 (bacteria) and Pleurotus ostreatus IRAN 1781C (fungus) to treat contaminated gas stream with toluene and its biological degradation was compared under similar operating conditions. For this purpose, a biofilter on the laboratory scale was designed and constructed and the tests were carried out in two stages. The first stage, bacterial testing, lasted 20 days and the second stage, fungal testing, lasted 16 days. Inlet loading rates (IL) for bacterial and fungal biofilters were 21.62 ± 6.04 and 26.24 ± 7.35 g/m3 h respectively. In general, fungal biofilter showed a higher elimination capacity (EC) than bacterial biofilter (18.1 ± 6.98 vs 13.7 ± 4.7 g/m3 h). However, the pressure drop in the fungal biofilter was higher than the bacterial biofilter (1.26 ± 0.3 vs 1 ± 0.3 mm water), which was probably due to the growth of the mycelium. Fungal biofiltration showed a better performance in the removal of toluene from the air stream.

First Detection and Characterization of Macrolide-Resistant Mycoplasma pneumoniae from People with Community-Acquired Pneumonia in Iran.

Objectives: Increasing macrolide resistance of Mycoplasma pneumoniae strains is becoming a public health concern worldwide. Nevertheless, no comprehensive genomic background of circulating isolates is available in our region. We aimed to study the genetic diversity of this microorganism using the multiple-locus variable-number tandem-repeat analysis method and to investigate the relationships between MLVA types and macrolide susceptibility profiles of the isolates. Materials and Methods: A total of 270 patients attending Tehran general university hospitals were included in this study. One throat swab was taken from each patient. M. pneumoniae was identified using culture and PCR assay. Macrolide resistance was determined using the broth microdilution method. The MLVA was performed by amplification of four variable-number tandem-repeat loci. Results: Of 270 specimens, M. pneumoniae was detected in 25.2% (n = 68) and 21.8% (n = 59) samples using PCR and culture, respectively. Approximately 56.9% of isolates were resistant to macrolides. Fifty-one of 59 M. pneumoniae isolates were divided into 6 distinct MLVA types. Conclusion: The macrolide-resistant M. pneumoniae (MRMP) rate in this study was relatively high and most of the MRMP isolates were assigned into the type 4/5/7/2. Since a significant association between MLVA type 4/5/7/2 and macrolide resistance of M. pneumoniae isolates was observed, further monitoring of genetic diversity of MRMP isolates might facilitate better understanding of epidemiology of this microorganism. Besides surveillance of the antibiotic susceptibility might be helpful to make necessary reconsiderations on guidelines for treatment of M. pneumoniae infection.

Rapid Detection of Mycoplasma pneumoniae by Loop-Mediated Isothermal Amplification (LAMP) in Clinical Respiratory Specimens.

BACKGROUND: Mycoplasma pneumoniae is a common cause of community-acquired pneumonia (CAP) worldwide, especially among children and debilitated populations. The present study aimed to investigate a loop-mediated isothermal amplification (LAMP) technique for rapid detection of M. pneumoniae in clinical specimens collected from patients with pneumonia. METHODS: Throat swabs were collected from 110 outpatients who suffered from pneumonia. Throat swab samples were obtained from patients referred to the hospital outpatient clinics of Tehran University hospitals, Iran in 2017. The presence of M. pneumoniae in the clinical specimens was evaluated by LAMP, PCR and culture methods. Sensitivity and specificity of the LAMP and PCR assays were also determined. RESULTS: Out of 110 specimens, LAMP assay detected M. pneumoniae in 35 specimens. Detection limit of the LAMP assay was determined to be 33fg /µL or ∼ 40 genome copies/reaction. Moreover, no cross-reaction with genomic DNA from other bacteria was observed. Only 25 specimens were positive by the culture method. The congruence between LAMP assay and culture method was 'substantial' (Ï°=0.77). Specificity and sensitivity of LAMP assay were 88.2%, 100% in compare with culture. However, the congruence between LAMP assay and PCR assay was 'almost perfect' (Ï°=0.86). Specificity and sensitivity of LAMP assay were 92.5%, 100% in compare with PCR. CONCLUSION: Overall, the LAMP assay is a rapid and cost-efficient laboratory test in comparison to other methods including PCR and culture. Therefore, the LAMP method can be applied in identification of M. pneumoniae isolates in respiratory specimens.

High frequency of Mycoplasma pneumoniae among patients with atypical pneumonia in Tehran, Iran.

INTRODUCTION: Mycoplasma pneumoniae is a major cause of atypical community-acquired pneumonia (CAP) with a prevalence range of 15-20% and up to 40% in adults and children, respectively. In Iran, the recorded frequency ranges between 1-6.15%. We aimed to investigate the frequency of M. pneumoniae among patients with atypical pneumonia acquired from the community. METHODS: Over a period of 5 months between January and June 2017, 520 patients with suspected CAP, who had been to the hospital outpatient clinics of Tehran University, were enrolled in this study. Throat swab specimens were obtained from 110 outpatients who presented with symptoms of atypical pneumonia. M. pneumoniae was identified via culture and biochemical tests, such as fermentation of glucose and arginine, hemolysis, and hemadsorption. For confirmation, PCR was performed to amplify the gene fragment coding for p1 adhesin. RESULTS: The major and minor clinical signs of the patients were dyspnea (67.3%) and nausea (15.5%), respectively. Out of 110 specimens, 25 (22.7%) and 29 (26.4%) isolates were identified to be M. pneumoniae via culture and molecular assay, respectively. Comparing the results of the two methods, the PCR showed better sensitivity and rapidity for the detection of M. pneumoniae. There was a high congruence between culture and the PCR assay; kappa level was 'almost perfect' (κ=0.90). CONCLUSION: This is the first report of high frequency of M. pneumoniae in our region. This finding can serve as baseline information for further investigation and confirmation of the potential epidemics of M. pneumoniae pneumonia in our community.