Ambient dust pollution with all-cause, cardiovascular and respiratory mortality: A systematic review and meta-analysis.

A severe health crisis has been well-documented regarding dust particle exposure. We aimed to present the risk of all-cause, cardiovascular, and respiratory mortality due to particulate matter (PM) exposure during non-dust and dust storm events by performing a meta-analysis. A systematic review of the literature was conducted by an online search of the databases (Google Scholar, Web of Science, Scopus, and PubMed) with no restrictions according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines until December 2022. We performed a random-effects model to compute the pooled rate ratio (RR) of mortality with 95 % confidence intervals (CI). The Office of Health Assessment and Translation (OHAT) risk of bias rating tool was prepared to assess the quality of the individual study. The registration number in PROSPERO was CRD42023423212. We found a 16 % (95 % CI: 0.7 %, 24 %) increase in all-cause, 25 % (95 % CI: 14 %, 37 %) increase in cardiovascular, and 18 % (95 % CI: 13 %, 22 %) increase in respiratory mortality per 10 µg/m3 increment in dust exposure. Furthermore, the RRs per 10 µg/m3 increment in PM10-2.5 were 1.046 (95 % CI: 1.019, 1.072)¸ 1.085 (95 % CI: 1.045, 1.0124), and 1.089 (95 % CI: 0.939, 1.24) for all-cause, cardiovascular, and respiratory mortality, respectively. PM10 during dust days significantly increased the all-cause (1.013, 95 % CI: 1.007, 1.018) cardiovascular mortality risk (1.014, 95 % CI: 1.009, 1.02). We also found significant evidence for all-cause, cardiovascular, and respiratory mortality among females and the elderly age group due to dust particle (PM10-2.5 and PM10) exposure. Our results provided significant evidence about high concentrations of PM10-2.5 and PM10 during dust storm events related to mortality risk.

Estimation of health-related and economic impacts of PM2.5 in Arak, Iran, using BenMAP-CE.

Ambient air quality is one of the most critical threats to human health. In this study, the health and economic benefits of reducing PM2.5 were estimated in the city of Arak during the period of 2017-2019. The concentration data were obtained from the Environmental Protection Organization of Central Province, while the demographic data were obtained from the website of the Iran Statistics Center. The number of premature deaths from all causes, ischemic heart disease, chronic obstructive pulmonary disease, and lung cancer, attributable to PM2.5 pollution was estimated using the Environmental Benefits Mapping and Analysis Program-Comprehensive Version (BenMAP_CE) to limit the guidelines of the World Health Organization. The results showed that improving air quality in 2017, 2018, and 2019 in Arak could prevent the deaths of 729, 654, and 460 people, respectively. The number of years of life lost (YLL) in 2017, 2018, and 2019 was 11383, 10362, and 7260 years, respectively. The total annual economic benefits of reducing the PM2.5 concentration in Arak under the proposed scenarios in 2017, 2018, and 2019 were estimated to be 309,225,507, 262,868,727, and 182,224,053 USD, respectively, using the statistical life method (VSL). Based on the results of this study, there are significant health and economic benefits to reducing PM2.5 concentrations in Arak City. Therefore, planning and adopting control policies to reduce air pollution in this city are necessary.

Bacterial biofilm prevalence in dental unit waterlines: a systematic review and meta-analysis.

BACKGROUNDS: Numerous studies have shown that dental unit water lines (DUWLs) are often contaminated by a wide range of micro-organisms (bacteria, fungi, protozoa) and various prevalence have been reported for it in previous studies. Therefore, this review study aims to describe the prevalence of bacterial biofilm contamination of DUWLs. METHODS: This is a systematic review and meta-analysis in which the related keywords in different international databases, including Medline (via PubMed) and Scopus were searched. The retrieved studies were screened and the required data were extracted from the included studies. Three standard methods including American Dental Association (ADA), The Center for Disease Control and Prevention (CDC) and contaminated > 100 CFU/ml(C-100) standards were used to assess the bacterial biofilm contamination of DUWLs. All studies that calculated the prevalence of bacterial biofilm contamination of DUWLs, and English full-text studies were included in the meta-analysis. Studies that did not have relevant data or used unusual laboratory methods were excluded. Methodological risk of bias was assessed by a related checklist and finally, the data were pooled by fixed or random-effect models. RESULTS: Seven hundred and thirty-six studies were identified and screened and 26 related studies were included in the meta-analysis. The oldest included study was published in 1976 and the most recent study was published in 2020. According to the ADA, CDC and C-100 standards, the prevalence of bacterial contamination was estimated to be 85.0% (95% confidence interval (CI): 66.0-94.0%), 77.0% (95%CI: 66.0-85.0%) and 69.0% (95%CI: 67.0-71.0%), respectively. The prevalence of Legionella Pneumophila and Pseudomonas Aeruginosa in DUWLs was estimated to be 12.0% (95%CI: 10.0-14.0%) and 8.0% (95%CI: 2.0-24.0%), respectively. CONCLUSION: The results of this review study suggested a high prevalence of bacterial biofilm in DUWLs; therefore, the use of appropriate disinfecting protocol is recommended to reduce the prevalence of contamination and reduce the probable cross-infection.

Quantitative and qualitative assessment of microbial aerosols in different indoor environments of a dental school clinic.

In the indoor environment of dental clinics, dental staff and patients are exposed to various types of infectious agents transported by aerosols and particles, generated during dental procedures, promoting an increased risk of cross-infection. The aim of this study was to determine the levels and diversity of microbial aerosol in relation to particle load in five different departments of a dental school clinic. The air samples were collected by an active single-stage Andersen sampler during the treatment procedure. The mean concentrations of airborne bacteria were in the range of 52-1030 and 8-844 CFU/m3 at the distances of 0.5 and 2 m, respectively. Bacterial aerosols in pediatric, endodontics, and restorative wards and fungal aerosols in all the sampling wards were significantly higher at the distances of 0.5 m. The dominant bacteria and fungi were identified as Micrococcus, Bacillus, Streptococcus, Staphylococcus, Penicillium, Cladosporium, Aspergillus, Rhizopus, and Alternaria. The positive associations were also obtained between bacteria and fungi levels and particulate matter (PM) concentrations.

Detection of antibiotic resistant Acinetobacter baumannii in various hospital environments: potential sources for transmission of Acinetobacter infections.

BACKGROUND: Antibiotic resistant Acinetobacter baumannii has emerged as one of the most problematic hospital acquired pathogens around the world. This study was designed to investigate the presence of antibiotic resistant A. baumannii in various hospital environments. METHODS: Air, water and inanimate surface samples were taken in different wards of four hospitals and analyzed for the presence of A. baumannii. Confirmed A. baumannii isolates were analyzed for antimicrobial susceptibility and also screened for the presence of three most common OXA- type carbapenemase-encoding genes. RESULTS: A. baumannii was detected in 11% (7/64) of air samples with the highest recovery in intensive care units (ICUs). A. baumannii was also detected in 17% (7/42) and 2% (1/42) of surface and water samples, respectively. A total of 40 A. baumannii isolates were recovered and analysis of antimicrobial susceptibility showed the highest resistance towards ceftazidime (92.5%, 37/40). 85% (34/40) and 80% (32/40) of the isolates were also resistant to imipenem and gentamicin, respectively. Resistance genes analysis showed that 77.5% (31/40) strains contained OXA-23 and 5% (2/40) strains contained OXA-24, but OXA-58 was not detected in any of the strains. CONCLUSION: Detection of antibiotic resistant A. baumannii in various samples revealed that hospital environments could act as a potential source for transmission of A. baumannii infections especially in ICUs. These results emphasize the importance of early detection and implementation of control measures to prevent the spread of A. baumannii in hospital environments.

Occurrence of airborne vancomycin- and gentamicin-resistant bacteria in various hospital wards in Isfahan, Iran.

BACKGROUND: Airborne transmission of pathogenic resistant bacteria is well recognized as an important route for the acquisition of a wide range of nosocomial infections in hospitals. The aim of this study was to determine the prevalence of airborne vancomycin and gentamicin (VM and GM) resistant bacteria in different wards of four educational hospitals. MATERIALS AND METHODS: A total of 64 air samples were collected from operating theater (OT), Intensive Care Unit (ICU), surgery ward, and internal medicine ward of four educational hospitals in Isfahan, Iran. Airborne culturable bacteria were collected using all glass impingers. Samples were analyzed for the detection of VM- and GM-resistant bacteria. RESULTS: The average level of bacteria ranged from 99 to 1079 CFU/m(3). The highest level of airborne bacteria was observed in hospital 4 (628 CFU/m(3)) and the highest average concentration of GM- and VM-resistant airborne bacteria were found in hospital 3 (22 CFU/m(3)). The mean concentration of airborne bacteria was the lowest in OT wards and GM- and VM-resistant airborne bacteria were not detected in this ward of hospitals. The highest prevalence of antibiotic-resistant airborne bacteria was observed in ICU ward. There was a statistically significant difference for the prevalence of VM-resistant bacteria between hospital wards (P = 0.012). CONCLUSION: Our finding showed that the relatively high prevalence of VM- and GM-resistant airborne bacteria in ICUs could be a great concern from the point of view of patients' health. These results confirm the necessity of application of effective control measures which significantly decrease the exposure of high-risk patients to potentially airborne nosocomial infections.

Hospital air: A potential route for transmission of infections caused by ß-lactam-resistant bacteria.

BACKGROUND: The emergence of bacterial resistance to ß-lactam antibiotics seriously challenges the treatment of various nosocomial infections. This study was designed to investigate the presence of ß-lactam-resistant bacteria (BLRB) in hospital air. METHODS: A total of 64 air samples were collected in 4 hospital wards. Detection of airborne bacteria was carried out using culture plates with and without ß-lactams. BLRB isolates were screened for the presence of 5 common ß-lactamase-encoding genes. Sequence analysis of predominant BLRB was also performed. RESULTS: The prevalence of BLRB ranged between 3% and 34%. Oxacillin-resistant bacteria had the highest prevalence, followed by ceftazidime- and cefazolin-resistant bacteria. The frequency of ß-lactamase-encoding genes in isolated BLRB ranged between 0% and 47%, with the highest and lowest detection for OXA-23 and CTX-m-32, respectively. MecA had a relatively high frequency in surgery wards and operating theaters, whereas the frequency of blaTEM was higher in intensive care units and internal medicine wards. OXA-51 was detected in 4 wards. Acinetobacter spp, Acinetobacter baumannii, and Staphylococcus spp were the most predominant BLRB. CONCLUSIONS: The results revealed that hospital air is a potential route of transmission of BLRB, such as Acinetobacter and Staphylococcus, 2 important causative agents of nosocomial infections. Therefore, improvement of control measures against the spreading of airborne bacteria in hospital environments is warranted.

Monitoring of airborne bacteria and aerosols in different wards of hospitals - Particle counting usefulness in investigation of airborne bacteria.

INTRODUCTION AND OBJECTIVE: The presence of airborne bacteria in hospital environments is of great concern because of their potential role as a source of hospital-acquired infections (HAI). The aim of this study was the determination and comparison of the concentration of airborne bacteria in different wards of four educational hospitals, and evaluation of whether particle counting could be predictive of airborne bacterial concentration in different wards of a hospital. MATERIALS AND METHOD: The study was performed in an operating theatre (OT), intensive care unit (ICU), surgery ward (SW) and internal medicine (IM) ward of four educational hospitals in Isfahan, Iran. A total of 80 samples were analyzed for the presence of airborne bacteria and particle levels. RESULTS: The average level of bacteria ranged from 75-1194 CFU/m (3) . Mean particle levels were higher than class 100,000 cleanrooms in all wards. A significant correlation was observed between the numbers of 1-5 µm particles and levels of airborne bacteria in operating theatres and ICUs. The results showed that factors which may influence the airborne bacterial level in hospital environments should be properly managed to minimize the risk of HAIs especially in operating theaters. CONCLUSIONS: Microbial air contamination of hospital settings should be performed by the monitoring of airborne bacteria, but particle counting could be considered as a good operative method for the continuous monitoring of air quality in operating theaters and ICUs where higher risks of infection are suspected.