Risk assessment and disease burden of legionella presence in cooling towers of Iran's central hospitals

Applications of Quantitative Microbial Risk Assessment to Respiratory Pathogens and Implications for Uptake in Policy: A State-of-the-Science Review

BACKGROUND

Respiratory tract infections are major contributors to the global disease burden. Quantitative microbial risk assessment (QMRA) holds potential as a rapidly deployable framework to understand respiratory pathogen transmission and inform policy on infection control.

OBJECTIVES

The goal of this paper was to evaluate, motivate, and inform further development of the use of QMRA as a rapid tool to understand the transmission of respiratory pathogens and improve the evidence base for infection control policies.

METHODS

We conducted a literature review to identify peer-reviewed studies of complete QMRA frameworks on aerosol inhalation or contact transmission of respiratory pathogens. From each of the identified studies, we extracted and summarized information on the applied exposure model approaches, dose-response models, and parameter values, including risk characterization. Finally, we reviewed linkages between model outcomes and policy.

RESULTS

We identified 93 studies conducted in 16 different countries with complete QMRA frameworks for diverse respiratory pathogens, including SARS-CoV-2, Legionella spp., Staphylococcus aureus, influenza, and Bacillus anthracis. Six distinct exposure models were identified across diverse and complex transmission pathways. In 57 studies, exposure model frameworks were informed by their ability to model the efficacy of potential interventions. Among interventions, masking, ventilation, social distancing, and other environmental source controls were commonly assessed. Pathogen concentration, aerosol concentration, and partitioning coefficient were influential exposure parameters as identified by sensitivity analysis. Most (84%, n = 78 ) studies presented policy-relevant content including a) determining disease burden to call for policy intervention, b) determining risk-based threshold values for regulations, c) informing intervention and control strategies, and d) making recommendations and suggestions for QMRA application in policy.

CONCLUSIONS

We identified needs to further the development of QMRA frameworks for respiratory pathogens that prioritize appropriate aerosol exposure modeling approaches, consider trade-offs between model validity and complexity, and incorporate research that strengthens confidence in QMRA results. https://doi.org/10.1289/EHP12695.

Short-term exposure to some heavy metals carried with PM10 and cardiovascular system biomarkers during dust storm

This study aimed to evaluate the effect of short-term exposure to heavy metals (HM) extracted from PM10 on CB in workers' population in an outdoor space located in southern Iran during a dust storm. At first, 44 healthy and non-smoking workers were selected. Then PM10 and Blood samples were collected before and after the dust storm. Finally, HMs associated with PM10 measured by ICP-MS and its effect on the CB, including fibrinogen, CRP, TNF-α, and BP were estimated by ANOVA, Pearson correlation, and Odd Ratio (OR) in SPSS23. Based on the results, the concentration of PM10 and extracted HM such as Cr, As, and Cd was higher than the WHO/EPA standards in dust storms they increased the CB and BP remarkably. Moreover, the level of fibrinogen, blood pressure (BP) and TNF-α in dust storms were higher than in normal conditions (p < 0.05, OR > 3). In addition, As and Cd decreased fibrinogen concentration and systolic BP, respectively. Whereas, TNF-α was associated with concentration of Pb (R = - 0.85) on normal days. Consequently, the HM on PM10 such as As, interferes with the level of investigated CB. These results considered a potential risk for the residents in the southern regions of Iran.

Environmental Monitoring of Legionella in Hospitals in the Campania Region: A 5-Year Study

Legionella is a pathogen that colonizes soils, freshwater, and building water systems. People who are most affected are those with immunodeficiencies, so it is necessary to monitor its presence in hospitals. The purpose of this study was to evaluate the presence of Legionella in water samples collected from hospitals in the Campania region, Southern Italy. A total of 3365 water samples were collected from January 2018 to December 2022 twice a year in hospital wards from taps and showers, tank bottoms, and air-treatment units. Microbiological analysis was conducted in accordance with the UNI EN ISO 11731:2017, and the correlations between the presence of Legionella and water temperature and residual chlorine were investigated. In total, 708 samples (21.0%) tested positive. The most represented species was L. pneumophila 2-14 (70.9%). The serogroups isolated were 1 (27.7%), 6 (24.5%), 8 (23.3%), 3 (18.9%), 5 (3.1%), and 10 (1.1%). Non-pneumophila Legionella spp. represented 1.4% of the total. Regarding temperature, the majority of Legionella positive samples were found in the temperature range of 26.0-40.9 °C. An influence of residual chlorine on the presence of the bacterium was observed, confirming that chlorine disinfection is effective for controlling contamination. The positivity for serogroups other than serogroup 1 suggested the need to continue environmental monitoring of Legionella and to focus on the clinical diagnosis of other serogroups.

Legionella pneumophila Risk from Air–Water Cooling Units Regarding Pipe Material and Type of Water

Legionellosis is a respiratory disease related to environmental health. There have been manifold studies of pipe materials, risk installations and legionellosis without considering the type of transferred water. The objective of this study was to determine the potential development of the causative agent Legionella pneumophila regarding air–water cooling units, legislative compliance, pipe material and type of water. Forty-four hotel units in Andalusia (Spain) were analysed with respect to compliance with Spanish health legislation for the prevention of legionellosis. The chi-square test was used to explain the relationship between material–water and legislative compliance, and a biplot of the first two factors was generated. Multiple correspondence analysis (MCA) was performed on the type of equipment, legislative compliance, pipe material and type of water, and graphs of cases were constructed by adding confidence ellipses by categories of the variables. Pipe material–type of water (p value = 0.29; p < 0.05) and legislative compliance were not associated (p value = 0.15; p < 0.05). Iron, stainless steel, and recycled and well water contributed the most to the biplot. MCA showed a global pattern in which lead, iron and polyethylene were well represented. Confidence ellipses around categories indicated significant differences among categories. Compliance with Spanish health legislation regarding the prevention and control of legionellosis linked to pipe material and type of water was not observed.

The role of polymeric chains as a protective environment for improving the stability and efficiency of fluorogenic peptide substrates

We have faced the preparation of fully water-soluble fluorescent peptide substrate with long-term environmental stability (in solution more than 35 weeks) and, accordingly, with stable results in the use of this probe in determining the activity of enzymes. We have achieved this goal by preparing a co-polymer of the commercial N-vinyl-2-pyrrolidone (99.5% mol) and a fluorescent substrate for trypsin activity determination having a vinylic group (0.5%). The activity of trypsin has been measured in water solutions of this polymer over time, contrasted against the activity of both the commercial substrate Z-L-Arg-7-amido-4-methylcoumarin hydrochloride and its monomeric derivative, prepared ad-hoc. Initially, the activity of the sensory polymer was 74.53 ± 1.72 nmol/min/mg of enzyme, while that of the commercial substrate was 20.44 ± 0.65 nmol/min/mg of enzyme, the former maintained stable along weeks and the latter with a deep decay to zero in three weeks. The ‘protection’ effect exerted by the polymer chain has been studied by solvation studies by UV–Vis spectroscopy, steady-state & time resolved fluorescence, thermogravimetry and isothermal titration calorimetry.