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Tuberculosis remains a global health challenge, with early diagnosis key to its reduction. Face-mask sampling detects exhaled Mycobacterium tuberculosis. We aimed to investigate bacillary output from patients with pulmonary tuberculosis and to assess the potential of face-mask sampling as a diagnostic method in active case-finding. We did a 24-h longitudinal study in patients from three hospitals in Pretoria, South Africa, with microbiologically confirmed pulmonary tuberculosis. Patients underwent 1 h of face-mask sampling eight times over a 24-h period, with contemporaneous sputum sampling. M tuberculosis was detected by quantitative PCR. We also did an active case-finding pilot study in inhabitants of an informal settlement near Pretoria. We enrolled individuals with symptoms of tuberculosis on the WHO screening questionnaire. Participants provided sputum and face-mask samples that were tested with the molecular assay Xpert MTB/RIF Ultra. Sputum-negative and face-mask-positive individuals were followed up prospectively for 20 weeks by bronchoscopy, PET-CT, and further sputum analysis to validate the diagnosis. Between Sept 22, 2015, and Dec 3, 2015, 78 patients with pulmonary tuberculosis were screened for the longitudinal study, of whom 24 completed the study (20 had HIV co-infection). M tuberculosis was detected in 166 (86%) of 192 face-mask samples and 38 (21%) of 184 assessable sputum samples obtained over a 24-h period. Exhaled M tuberculosis output showed no diurnal pattern and did not associate with cough frequency, sputum bacillary content, or chest radiographic disease severity. On May 16, 2018, 45 individuals were screened for the prospective active case-finding pilot study, of whom 20 had tuberculosis symptoms and were willing to take part. Eight participants were diagnosed prospectively with pulmonary tuberculosis, of whom six were exclusively face-mask positive at screening. Four of these participants (three of whom were HIV-positive) had normal findings on chest radiography but had treatment-responsive early tuberculosis-compatible lesions on PET-CT scans, with Xpert-positive sputum samples after 6 weeks. Face-mask sampling offers a highly efficient and non-invasive method for detecting exhaled M tuberculosis, informing the presence of active infection both with greater consistency and at an earlier disease stage than with sputum samples. The approach shows potential for diagnosis and screening, particularly in difficult-to-reach communities. Wellcome Trust, CARA (Council for At-Risk Academics), University of Leicester, the UK Medical Research Council, and the National Institute for Health Research. [Display omitted]

Disposable filtering face piece respirators (FFRs) are not approved for reuse as standard of care. However, lessons learnt from the SARS-CoV-2 pandemic, FFRs decontamination and reuse may be needed as crisis capacity strategy to ensure availability in medical facilities. We studied a decontamination methodology based on atmospheric pressure plasma technology, which allows for rapid, contact-free decontamination without utilisation of harmful chemicals, and suitable to access small pores and microscopic filters openings. Promising performances in terms of bioburden reduction (Log6) were achieved while imparting mainly transient chemical surface modifications to the masks filtering layers. The plasma decontamination process proposed was also considered in terms of the environmental impact of re-use technology for FFR medical devices in order to understand its sustainability. This study assessed the feasibility of an atmospheric pressure plasma approach for the decontamination of disposable filtering face piece respirators (FFR) or respiratory masks commonly used in hospital settings.

Based on the current knowledge of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) transmission, wearing a mask has been recommended during the COVID-19 pandemic. Bacterial filtration efficiency (BFE) measurements enable designing and regulating medical masks to prevent bioaerosol dissemination; however, despite the simplicity of these measurements, several scientific questions remain unanswered regarding BFE tests. Here, we investigated (1) the impact of substituting 100-mm Petri dishes with 90-mm disposable Petri dishes, (2) the impact of colony-counting methods on the bioaerosol aerodynamic size, and (3) the impact of colony-counting methods on the total viable particle counts. We demonstrated that disposable 90-mm Petri dishes can be used to replace the 100-mm dishes. We also showed that an automatic high-resolution colony counter can be used to directly count viable particles on collection substrates and to measure the bioaerosol size parameters. Our results enable possible modernization of the outdated testing methods recommended in the US and European standards for BFE measurements. Specifically, use of a modernized colony counter should be clearly regulated and permitted to avoid the counting of positive holes. The median aerodynamic diameter appears to be the most relevant parameter for characterizing bioaerosol size.

Background Airborne microbial communities, although often challenging to study due to low biomass, play crucial roles in public health and pathogen transmission. Through shotgun metagenomics, this study utilizes non-invasive air sampling of face masks and aircraft cabin filters to investigate microbial diversity in environments with frequent human interactions, including hospitals and airplanes. A comprehensive sampling and analysis workflow was developed, incorporating environmental and enrichment protocols to enhance microbial DNA recovery and diversity profiling. Results Despite limitations in biomass, optimized extraction methods allowed for the successful identification of 407 species, with dominant taxa including Cutibacterium acnes , Staphylococcus epidermidis , Sphingomonas hankookensis , and Methylobacterium radiotolerans . Enrichment processing resulted in greater metagenome-assembled genome (MAG) recovery and higher antimicrobial resistance gene (ARG) identification. Conclusions The findings highlight the presence of ARGs in high-occupancy public spaces, suggesting the importance of monitoring and the potential for mitigating airborne transmission risks in such environments. This study demonstrates the utility of combining environmental and enrichment sampling to capture comprehensive microbial and ARG profiles in confined spaces, providing a framework for enhanced pathogen monitoring in public health contexts. 6abPKkDQuG-Sjfm7YhE_BL Video Abstract

Handlers can wear masks during food preparation to avoid contamination of the nose and mouth. However, if microorganisms can pass through mask layers and handlers touch their outer surfaces, their hands can contaminate the food being handled. This study evaluated the behavior of 31 food handlers wearing disposable masks in a food service kitchen. Next, the microorganisms on the external surface of food handler masks were identified using microbiological methods and matrix-associated laser desorption-time-of-flight (MALDI-TOF) mass spectrometry. Finally, the passage of microorganisms through mask layers was assessed in volunteers. Observations showed that 77.4% of the 31 food handlers touched their masks at least once per hour during food preparation. Microbiological analysis identified 14 bacterial species on all food handlers’ masks analyzed. The most frequent microorganisms found were coagulase-negative Staphylococcus , Staphylococcus aureus , and Bacillus spp. The external surfaces of uncontaminated masks showed contamination after volunteers used them for few hours. Furthermore, sterile gloved hands became contaminated after touching the external surfaces of these masks, indicating bacterial transference from the inner to the outer layers. Although masks can prevent direct microbial contamination from the nose and mouth if properly used, our findings indicate that masks may inadvertently become vectors of food cross-contamination if hands touch their external surfaces during food preparation. Since our study indicated that microorganisms can pass through mask layers, food handlers should avoid touching the external surfaces of masks. However, if it happens, they should carry out proper hand washing to prevent food cross-contamination during food preparation. Highlights Most food handlers wore masks inappropriately and touched its outside during food preparation. S. aureus and others 13 bacterial species were found on masks worn by the observed food handlers. The passage of microorganisms through disposable face masks worn by people was observed. The study demonstrated that microorganisms present in the masks can contaminate handlers’ hands. Food handlers must be trained and supervised on the correct use of masks and hand washing.

Healthcare-associated infections (HAIs) remain a critical public health issue, as they contribute to prolonged treatment duration, increased healthcare costs, and heightened risks of morbidity and mortality. In head and neck cancer patients undergoing radiotherapy, thermoplastic masks (TMs), which come into direct contact with the skin, represent a potential vector for infection. Additionally, the storage racks where these masks are kept may also facilitate microorganism transmission. Our study aimed to isolate and identify microorganisms from infective skin lesions secondary to radiation dermatitis in head and neck cancer patients, as well as from the TMs and storage racks, and to evaluate the antibiotic resistance profiles of the isolated microorganisms. The study included 71 locally advanced head and neck cancer patients who underwent radiotherapy between August 2022 and November 2023. Patients were monitored daily, and their skin evaluations were made according to Common Terminology Criteria for Adverse Events (CTCAE) version 4.0. Grade 2 and 3 radiodermatitis was observed in 29 of these 71 patients. Samples were collected using sterile swabs from the skin lesions on the head and neck area, the inner surfaces of the TM, and the storage rack from 29 patients. Samples were inoculated into enrichment and selective media. After the growing microorganisms were identified, antimicrobial susceptibility was evaluated using conventional methods and automated systems according to the European Committee on Antimicrobial Susceptibility Testing (EUCAST) criteria. At least one type of microorganism was isolated from the skin samples of infected patients, and double growth was detected in two patients. Among the samples, 2 were methicillin-resistant coagulase-negative Staphylococcus (MRCNS), 1 was methicillin-resistant Staphylococcus aureus (MRSA), 1 was Candida albicans ( C. albicans ), 15 were methicillin-sensitive coagulase-negative Staphylococcus (MSCNS), 1 was methicillin-sensitive Staphylococcus aureus (MSSA), 1 was Bacillus subspecies ( Bacillus spp.) and 3 were Corynebacterium diphtheriae ( C. diphtheriae ). Coagulase-negative Staphylococcus strains were isolated from the skin of 14 of 19 patients with grade 2 radiation dermatitis, whereas CNS strains were isolated from only 2 of 10 patients with grade 3 radiation dermatitis. Among the gram-negative bacteria, 3 Pseudomonas aeruginosa ( P. aeruginosa ), 2 Enterobacter cloacae ( E. cloacae ), 1 Klebsiella pneumoniae ( K. pneumoniae ) and 1 Moraxella catarrhalis ( M. catarrhalis ) strain were isolated. Sixteen (55.1%) of the TMs used in 29 patients and 20 (68.9%) of the storage racks harbored microorganisms, including HAI agents and flora bacteria. Bacteria colonize TMs and storage racks where they are risk factors for secondary skin infections in radiation dermatitis lesions that develop on the skin of head and neck cancer patients. Decontamination procedures should be meticulously applied to surfaces such as TMs and their storage racks during the course of radiotherapy.

Background Chlorhexidine (CHX) can lower the bacterial contamination on masks. This study explores how effectively CHX reduces the bacterial spectrum in the patient’s oral cavity and subsequently how this influences the contamination of masks. Methods Two intraoral samples were collected prior to any aerosol-generating treatment: the first before a 60-s CHX rinse and the second 10 min after. After dental treatment, the practitioner’s mask was imprinted onto agar plates. After cultivation, a Matrix-Assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry (MALDI-ToF) was used to identify the colony forming units. The identified species of the intraoral samples and mask imprints were then analysed based upon matches in bacterial species and quantity. Results A total of 108 unique patients were included, each receiving one aerosol-producing treatment. The total number of detected bacterial species in the oral cavity before the CHX rinse was 628, after 490. Staphylococcus aureus was found twice as often before the CHX rinse. The average amount of colony forming units on the mask’s imprints after the CHX rinse was 15.2. The bacterial species occurred in very similar proportions, with Staphylococcus species making up more than 50%. No species match between the oral samples and mask samples after the CHX rinse occurred most frequently (68.5%), followed by one match (25.9), two matches (3.7%) and three matches (1.9%). Conclusions A preprocedural CHX rinse reduces bacterial contamination on masks but has little effect on the spectrum of transmitted microorganisms. Our results suggest that the bacterial spectrum on the mask was not significantly influenced by the preprocedural change in the oral microbiota. Therefore, while CHX enhances clinical hygiene, it does not eliminate the risk of pathogenic transmission.

Respiratory protection is key in infection prevention of airborne diseases, as highlighted by the COVID-19 pandemic for instance. Conventional technologies have several drawbacks (i.e., cross-infection risk, filtration efficiency improvements limited by difficulty in breathing, and no safe reusability), which have yet to be addressed in a single device. Here, we report the development of a filter overcoming the major technical challenges of respiratory protective devices. Large-pore membranes, offering high breathability but low bacteria capture, were functionalized to have a uniform salt layer on the fibers. The salt-functionalized membranes achieved high filtration efficiency as opposed to the bare membrane, with differences of up to 48%, while maintaining high breathability (> 60% increase compared to commercial surgical masks even for the thickest salt filters tested). The salt-functionalized filters quickly killed Gram-positive and Gram-negative bacteria aerosols in vitro, with CFU reductions observed as early as within 5 min, and in vivo by causing structural damage due to salt recrystallization. The salt coatings retained the pathogen inactivation capability at harsh environmental conditions (37 °C and a relative humidity of 70%, 80% and 90%). Combination of these properties in one filter will lead to the production of an effective device, comprehensibly mitigating infection transmission globally.

Although tuberculosis is transmitted by the airborne route, direct information on the natural output of bacilli into air by source cases is very limited. We sought to address this through sampling of expelled aerosols in face masks that were subsequently analyzed for mycobacterial contamination. In series 1, 17 smear microscopy positive patients wore standard surgical face masks once or twice for periods between 10 minutes and 5 hours; mycobacterial contamination was detected using a bacteriophage assay. In series 2, 19 patients with suspected tuberculosis were studied in Leicester UK and 10 patients with at least one positive smear were studied in The Gambia. These subjects wore one FFP30 mask modified to contain a gelatin filter for one hour; this was subsequently analyzed by the Xpert MTB/RIF system. In series 1, the bacteriophage assay detected live mycobacteria in 11/17 patients with wearing times between 10 and 120 minutes. Variation was seen in mask positivity and the level of contamination detected in multiple samples from the same patient. Two patients had non-tuberculous mycobacterial infections. In series 2, 13/20 patients with pulmonary tuberculosis produced positive masks and 0/9 patients with extrapulmonary or non-tuberculous diagnoses were mask positive. Overall, 65% of patients with confirmed pulmonary mycobacterial infection gave positive masks and this included 3/6 patients who received diagnostic bronchoalveolar lavages. Mask sampling provides a simple means of assessing mycobacterial output in non-sputum expectorant. The approach shows potential for application to the study of airborne transmission and to diagnosis.

Whether in the field of medical care, or in people’s daily life and health protection, the importance of masks has been paid more and more attention. Acne, the most common complication after wearing masks, which is also called maskne, has been successfully introduced into the common language as a common topic of dermatologist consultations. This study aims to study the changes of microflora in maskne patients and healthy controls before and after wearing masks. In the summer of 2023, we collected a total of 50 samples from 15 maskne patients and 10 healthy controls before and after wearing surgical masks for a long time. 16 S ribosomal DNA sequencing and identification technology with V3-V4 variable region were adopted to explore the microbiome changes caused by mask wearing, analyze the changes in microbial diversity, and make interaction network. LDA effect size analysis was used to identify which bacteria showed significant changes in their relative abundance from phylum to genus. After wearing a mask, the microbiome of the maskne patients changed significantly more than that of the healthy controls, with both α diversity and β diversity lower than those of maskne patients before wearing masks and those of healthy controls after wearing masks. Co-occurrence network analysis showed that compared with other groups, the network of maskne patients after wearing masks for a long time had the lowest connectivity and complexity, but the highest clustering property, while the opposite was true for healthy controls. Many microbes that are potentially beneficial to the skin decreased significantly after wearing a mask. There was almost no difference in healthy controls before and after wearing a mask.