Airborne Staphylococcus aureus in different environments-a review

Genomic epidemiology of Staphylococcus aureus from the Iberian Peninsula highlights the expansion of livestock associated-CC398 towards wildlife

Staphylococcus aureus is a versatile pathobiont, exhibiting a broad host range, including humans, other mammals, and avian species. Host specificity determinants, virulence, and antimicrobial resistance genes are often shared by strains circulating at the animal-human interface. While transmission dynamics studies have shown strain exchange between humans and livestock, knowledge of the source, genetic diversification, and transmission drivers of S. aureus in wildlife lag behind. In this work, we explore a wide array of S. aureus genomes from different sources in the Iberian Peninsula to understand population structure, gene content and niche adaptation at the human-livestock-wildlife nexus. Through Bayesian inference, we address the hypothesis that S. aureus strains in wildlife originate from humanized landscapes, either from contact with humans or through interactions with livestock. Phylogenetic reconstruction applied to whole genome sequence data was completed with a dataset of 450 isolates featuring multiple clones from the 1990-2022 period and a subset of CC398 strains representing the 2008-2022 period. Phylodynamic signatures of S. aureus from the Iberian Peninsula suggest widespread circulation of most clones among humans before jumping to other hosts. The number of transitions of CC398 strains within each host category (human, livestock, wildlife) was high (88.26 %), while the posterior probability of transitions from livestock to wildlife was remarkably high (0.99). Microbial genome-wide association analysis did not evidence genome rearrangements nor biomarkers suggesting S. aureus niche adaptation to wildlife, thus supporting recent spill overs. Altogether, our findings indicate that S. aureus isolates collected in the past years from wildlife most likely represent multiple introduction events from livestock. The clonal origin of CC398 and its potential to disseminate and evolve through different animal host species are highlighted, calling for management practices at the livestock-wildlife axis to improve biosecurity and thus restrict S. aureus transmission and niche expansion along gradients of human influence.

Distribution and survival of pathogens from different waste components and bioaerosol traceability analysis in household garbage room

Household garbage rooms release abundant bioaerosols and are an important source of pathogens; however, information on the distribution and survival patterns of pathogens in different waste components is limited. In this study, a culture method and 16S rRNA high-throughput sequencing were used to determine bacterial communities, culturable pathogens, and human bacterial pathogens (HBPs). The results showed that abundant culturable bacteria were detected in all waste types, and a large number of S. aureus was detected on the surface of recyclable wastes, whereas S. aureus, total coliforms, Salmonella, Enterococcus, and hemolytic bacteria were detected in food waste and other waste. The activities of these detected pathogenic bacteria decreased after 24 h of storage but re-activated within one week. Factors affecting the emergence of pathogens varied with different waste components. Sequencing results showed that Pseudomonas, Acinetobacter, and Burkholderia were abundant in the waste samples, whereas Achromobacter, Exiguobacteriums, Bordetella, and Corynebacterium were the primary pathogens in the bioaerosol and wall attachment. The results of traceability analysis showed that bioaerosol microbes were mainly derived from raw kitchen waste (5.98%) and plastic and paper contaminated with food waste (19.93%) in garbage rooms. In addition, bioaerosols were the main source of microflora in the wall attachment, which possessed high HBP diversity and required more attention. These findings will help in understanding the microbial hazards in different waste components and provide guidance for the control and risk reduction of bioaerosols during waste management and recycling.

Bioaerosolization behaviour of potential pathogenic microorganisms from wastewater treatment plants: Occurrence profile, social function and health risks

Wastewater treatment plants (WWTPs) are the leading sources of potential pathogenic bioaerosol that cause non-negligible health risks. However, bioaerosolization behaviour of potential pathogenic microorganisms (PPMs) migrating from wastewater to the atmosphere is still unclear. This study investigated the occurrence profile of PPMs in wastewater, sludge and bioaerosol, then analyzed bioaerosolization level, impact factors and social function. Staphylococcus aureus was selected as the target due to its pathogenicity, and the health risks of workers, engineers and researchers wearing various masks (N90, N95 and medical masks) were evaluated. The results showed that there were 38 and 64 PPMs in bioaerosol from plant A and B. Streptomyces in plant A (average bioaerosolization index, BI= 237.71) and Acinetobacter in plant B (average BI = 505.88) were more likely to migrate from wastewater to the atmosphere forming bioaerosol. Environmental factors (relative humidity, wind speed and temperature) affected both BI and microbial species of PPMs in different ways. PPMs related to fermentation, aerobic chemoheterotrophy, and chemoheterotrophy are the most abundant. Meanwhile microbial networks from plants A and B showed that PPMs were well-connected. Emission level of Staphylococcus aureus bioaerosol can reach 980 ± 309.19 CFU/m3 in plant A and 715.55 ± 44.17 CFU/m3 in plant B. For three exposure population, disease burden (DB) and annual probability infection (Py) of Staphylococcus aureus bioaerosol in two plants were both higher than the U.S.EPA benchmark (10-4 DALYs pppy). All three masks (N90,N95 and medical masks) can decrease Py and DB by at least one order of magnitude. This study illustrated the bioaerosolization behaviour of PPMs comprehensively, which provides a scientific basis for exposure risk prevention and control.

Isolation and characterization of novel Staphylococcus aureus bacteriophage Hesat from dairy origin

A novel temperate phage, named Hesat, was isolated by the incubation of a dairy strain of Staphylococcus aureus belonging to spa-type t127 with either bovine or ovine milk. Hesat represents a new species of temperate phage within the Phietavirus genus of the Azeredovirinae subfamily. Its genome has a length of 43,129 bp and a GC content of 35.11% and contains 75 predicted ORFs, some of which linked to virulence. This includes (i) a pathogenicity island (SaPln2), homologous to the type II toxin-antitoxin system PemK/MazF family toxin; (ii) a DUF3113 protein (gp30) that is putatively involved in the derepression of the global repressor Stl; and (iii) a cluster coding for a PVL. Genomic analysis of the host strain indicates Hesat is a resident prophage. Interestingly, its induction was obtained by exposing the bacterium to milk, while the conventional mitomycin C-based approach failed. The host range of phage Hesat appears to be broad, as it was able to lyse 24 out of 30 tested S. aureus isolates. Furthermore, when tested at high titer (108 PFU/ml), Hesat phage was also able to lyse a Staphylococcus muscae isolate, a coagulase-negative staphylococcal strain. KEY POINTS: • A new phage species was isolated from a Staphylococcus aureus bovine strain. • Pathogenicity island and PVL genes are encoded within phage genome. • The phage is active against most of S. aureus strains from both animal and human origins.

Interplay of xenobiotic-degrading and antibiotic-resistant microorganisms among the microbiome found in the air, handrail, and floor of the subway station

Investigating the quality of the subway environment, especially regarding antibiotic resistance genes (ARGs) and xenobiotics, conveys ecological and health impacts. In this study, compositions and relations of microorganisms harboring ARGs and xenobiotic degradation and metabolism genes (XDGs) in the Sukhumvit subway station (MRT-SKV) in Bangkok was assessed by analyzing the taxonomic and genetic diversity of the microbiome in the air and on the surfaces of floor and handrail. The major bacteria in the MRT-SKV (including Moraxella, which was abundant in the bioaerosol and handrail samples, and Staphylococcus, which was abundant in the bioaerosol samples) were found to contain both ARGs and XDGs. The co-abundance correlation network revealed notable relationships among bacteria harboring antibiotic resistance genes (ARGs) and xenobiotic degradation genes (XDGs). Significant associations were observed between ARGs linked to glycopeptide and fluoroquinolone resistance and genes associated with benzoate, styrene, and atrazine degradation pathways, as well as between ARGs related to cephamycin, cephalosporin, and MLS resistance and XDGs associated with the cytochrome P450-dependent drug metabolism pathway. These correlations suggested that selective pressure exerted by certain xenobiotics and antibiotics can simultaneously affect both ARGs and XDGs in the environment and should favor correlations and co-survival among ARG- and XDG-containing bacteria in the environments. The correlations may occur via shared mechanisms of resistance to both xenobiotics and antibiotics. Finally, different correlation pairs were seen in different niches (air, handrail, floor) of the subway environment or different geolocations. Thus, the relationship between ARG and XDG pairs most likely depends on the unique characteristics of the niches and on the prominent types of xenobiotics and antibiotics in the subway environment. The results indicated that interactions and connections between microbial communities can impact how they function. These microorganisms can have profound effects on accumulation of xenobiotics and ARGs in the MRT-SKV.

Biomimetic microfluidic chips for toxicity assessment of environmental pollutants

Various types of pollutants widely present in environmental media, including synthetic and natural chemicals, physical pollutants such as radioactive substances, ultraviolet rays, and noise, as well as biological organisms, pose a huge threat to public health. Therefore, it is crucial to accurately and effectively explore the human physiological responses and toxicity mechanisms of pollutants to prevent diseases caused by pollutants. The emerging toxicological testing method biomimetic microfluidic chips (BMCs) exhibit great potential in environmental pollutant toxicity assessment due to their superior biomimetic properties. The BMCs are divided into cell-on-chips and organ-on-chips based on the distinctions in bionic simulation levels. Herein, we first summarize the characteristics, emergence and development history, composition and structure, and application fields of BMCs. Then, with a focus on the toxicity mechanisms of pollutants, we review the applications and advances of the BMCs in the toxicity assessment of physical, chemical, and biological pollutants, respectively, highlighting its potential and development prospects in environmental toxicology testing. Finally, the opportunities and challenges for further use of BMCs are discussed.

Monitoring longitudinal antimicrobial resistance trends of Staphylococcus aureus strains worldwide over the past 100 years to decipher its evolution and transmission

Staphylococcus aureus inhabits diverse habitats including food waste and wastewater treatment plants. Cases of S. aureus-induced infection are commonly reported worldwide. The emergence of antimicrobial resistance (AMR) of S. aureus is a growing public health threat worldwide. Here, we longitudinally monitored global trends in antibiotic resistance genes (ARGs) of 586 S. aureus strains, isolated between 1884 and 2022. The ARGs in S. aureus exhibited a significant increase over time (P < 0.0001). Mobile genetic elements play a crucial role in the transfer of ARGs in S. aureus strains. The structural equation model results revealed a significant correlation between the human development index and rising antibiotic consumption, which subsequently leads to an indirect escalation of AMR in S. aureus strains. Lastly, a machine learning algorithm successfully predicted the AMR risk of global terrestrial S. aureus with over 70% accuracy. Overall, these findings provided valuable insights for managing AMR in S. aureus.

Environmental processes and health implications potentially mediated by dust-borne bacteria

Understanding microbial migration and survival mechanisms in dust events (DEs) can elucidate genetic and metabolic exchange between environments and help predict the atmospheric pathways of ecological and health-related microbial stressors. Dust-borne microbial communities have been previously characterized, but the impact and interactions between potentially active bacteria within transported communities remain limited. Here, we analysed samples collected during DEs in Israel, using amplicon sequencing of the 16S rRNA genes and transcripts. Different air trajectories and wind speeds were associated not only with the genomic microbial community composition variations but also with specific 16S rRNA bacterial transcripts. Potentially active dust-borne bacteria exhibited positive interactions, including carbon and nitrogen cycling, biotransformation of heavy metals, degradation of organic compounds, biofilm formation, and the presence of pathogenic taxa. This study provides insights into the potential interactive relationships and survival strategies of microorganisms within the extreme dust environment.

Methicillin-Resistant Staphylococcus aureus and Coagulase-Negative Staphylococcus from School Dining Rooms in Argentina

Methicillin-resistant Staphylococcus aureus (MRSA) constitutes an important cause for concern in the field of public health, and the role of the food chain in the transmission of this pathogen and in antimicrobial resistance (AMR) has not yet been defined. The objectives of this work were to isolate and characterize coagulase-positive Staphylococcus (CoPS) and coagulase-negative Staphylococcus (CoNS), particularly S. aureus, from school dining rooms located in Argentina. From 95 samples that were obtained from handlers, inert surfaces, food, and air in 10 establishments, 30 Staphylococcus strains were isolated. Four isolates were S. aureus, and the remaining ones (N = 26) belonged to 11 coagulase-negative species (CoNS). The isolates were tested for susceptibility to nine antibiotics. The presence of genes encoding toxins (luk-PV, sea, seb, sec, sed, and see), adhesins (icaA, icaD), and genes that confer resistance to methicillin (mecA) and vancomycin (vanA) was investigated. The resistance rates measured for penicillin, cefoxitin, gentamicin, vancomycin, erythromycin, clindamycin, levofloxacin, trimethoprim-sulfamethoxazole, and tetracycline were 73%, 30%, 13%, 3%, 33%, 17%, 13%, 7%, and 7% of the isolates, respectively. Seventeen AMR profiles were detected, and 11 isolates were multidrug resistant (MDR). Seven methicillin-resistant Staphylococcus isolates were detected in the hands of handlers from four establishments, two of them were MRSA. Two S. aureus isolates presented icaA and icaD, another one, only icaD. The gene vanA was found in two isolates. In relation to S. aureus, resistance to vancomycin but not to gentamicin was detected. School feeding plays a key role in the nutrition of children, and the consumption of food contaminated with MRSA and vancomycin-resistant S. aureus (VRSA) can be a serious threat to health. In particular, it was detected that the handlers were the source of MRSA, VRSA, MR-CoNS (methicillin-resistant coagulase-negative Staphylococcus), and MDR isolates. The results obtained indicate that the vigilance of this pathogen in school dining rooms should be extreme.

Kinship analysis of mecA gene of methicillin-resistant Staphylococcus aureus isolated from milk and risk factors from the farmers in Blitar, Indonesia

Background and Aim

There are numerous reports of subclinical mastitis cases in Blitar, which is consistent with the region's high milk production and dairy cattle population. Staphylococcus aureus, which is often the cause of mastitis cases, is widely known because of its multidrug-resistant properties and resistance to β-lactam antibiotic class, especially the methicillin-resistant S. aureus (MRSA) strains. This study aimed to molecular detection and sequence analysis of the mecA gene in milk and farmer's hand swabs to show that dairy cattle are reservoirs of MRSA strains.

Materials and Methods

A total of 113 milk samples and 39 farmers' hand swab samples were collected from a dairy farm for the isolation of S. aureus using Mannitol salt agar. The recovered isolates were further characterized using standard microbiological techniques. Isolates confirmed as S. aureus were tested for sensitivity to antibiotics. Oxacillin Resistance Screening Agar Base testing was used to confirm the presence of MRSA, whereas the mecA gene was detected by polymerase chain reaction and sequencing.

Results

A total of 101 samples were confirmed to be S. aureus. There were 2 S. aureus isolates that were multidrug-resistant and 14 S. aureus isolates that were MRSA. The mecA gene was detected in 4/14 (28.6%) phenotypically identified MRSA isolates. Kinship analysis showed identical results between mecA from milk and farmers' hand swabs. No visible nucleotide variation was observed in the two mecA sequences of isolates from Blitar, East Java.

Conclusion

The spread of MRSA is a serious problem because the risk of zoonotic transmission can occur not only to people who are close to livestock in the workplace, such as dairy farm workers but also to the wider community through the food chain.

Dynamic human exposure to airborne bacteria-associated antibiotic resistomes revealed by longitudinal personal monitoring data

Airborne antibiotic-resistant bacteria (ARB) can critically impact human health. We performed resistome profiling of 283 personal airborne exposure samples from 15 participants spanning 890 days and 66 locations. We found a greater diversity and abundance of airborne bacteria community and antibiotic resistomes in spring than in winter, and temperature contributed largely to the difference. A total of 1123 bacterial genera were detected, with 16 genera dominating. Of which, 7/16 were annotated as major antibiotic resistance gene (ARG) hosts. The participants were exposed to a highly dynamic collection of ARGs, including 322 subtypes conferring resistance to 18 antibiotic classes dominated by multidrug, macrolide-lincosamide-streptogramin, β-lactam, and fosfomycin. Unlike the overall community-level bacteria exposure, an extremely high abundance of specific ARG subtypes, including lunA and qacG, were found in some samples. Staphylococcus was the predominant genus in the bacterial community, serving as a primary bacterial host for the ARGs. The annotation of ARG-carrying contigs indicated that humans and companion animals were major reservoirs for ARG-carrying Staphylococcus. This study contextualized airborne antibiotic resistomes in the precision medicine framework through longitudinal personal monitoring, which can have broad implications for human health.

Bacterial indoor air contaminations in hospitals in MENA region: a systematic review

Poor indoor air quality in healthcare settings has been tied with the increase in hospital-acquired infections. Thus, this systematic review was conducted to assess the levels and compositions of bacteria in indoor hospital air in the Middle East and North Africa (MENA) region. We examined results provided by different search engines published between 2000 and 2021. Our data showed that most studies were conducted in Iran (80.9%) with a bacterial concentration mean of 172.9 CFU/m3. Comparing sensitive and non-sensitive areas of hospitals, no significant difference was detected in the mean bacterial concentration. The most investigated sensitive hospital areas were operating rooms and intensive care units with mean indoor bacterial concentrations of 180.3 CFU/m3 and 204.6 CFU/m3, respectively. Staphylococcaceae, Enterobacteriaceae, Pseudomonadaceae, and Bacillaceae were commonly identified bacterial families. In conclusion, the mean concentrations of the airborne bacteria were within the acceptable limit compared to WHO standards (300 CFU/m3) for the air in areas occupied by immunosuppressed people.

Microbes within the building envelope-a case study on the patterns of colonization and potential sampling bias

Humans are exposed to diverse communities of microbes every day. With more time spent indoors by humans, investigations into the communities of microbes inhabiting occupied spaces have become important to deduce the impacts of these microbes on human health and building health. Studies so far have given considerable insight into the communities of the indoor microbiota humans interact with, but mainly focus on sampling surfaces or indoor dust from filters. Beneath the surfaces though, building envelopes have the potential to contain environments that would support the growth of microbial communities. But due to design choices and distance from ground moisture, for example, the temperature and humidity across a building will vary and cause environmental gradients. These microenvironments could then influence the composition of the microbial communities within the walls. Here we present a case study designed to quantify any patterns in the compositions of fungal and bacterial communities existing in a building envelope and determine some of the key variables, such as cardinal direction, distance from floor or distance from wall joinings, that may influence any microbial community composition variation. By drilling small holes across walls of a house, we extracted microbes onto air filters and conducted amplicon sequencing. We found sampling height (distance from the floor) and cardinal direction the wall was facing caused differences in the diversity of the microbial communities, showing that patterns in the microbial composition will be dependent on sampling location within the building. By sampling beneath the surfaces, our approach provides a more complete picture of the microbial condition of a building environment, with the significant variation in community composition demonstrating a potential sampling bias if multiple sampling locations across a building are not considered. By identifying features of the built environment that promote/retard microbial growth, improvements to building designs can be made to achieve overall healthier occupied spaces.

A comparison of passive and active dust sampling methods for measuring airborne methicillin-resistant Staphylococcus aureus in pig farms

Methicillin-resistant strains of Staphylococcus aureus (MRSA) are resistant to most β-lactam antibiotics. Pigs are an important reservoir of livestock-associated MRSA (LA-MRSA), which is genetically distinct from both hospital and community-acquired MRSA. Occupational exposure to pigs on farms can lead to LA-MRSA carriage by workers. There is a growing body of research on MRSA found in the farm environment, the airborne route of transmission, and its implication on human health. This study aims to directly compare two sampling methods used to measure airborne MRSA in the farm environment; passive dust sampling with electrostatic dust fall collectors (EDCs), and active inhalable dust sampling using stationary air pumps with Gesamtstaubprobenahme (GSP) sampling heads containing Teflon filters. Paired dust samples using EDCs and GSP samplers, totaling 87 samples, were taken from 7 Dutch pig farms, in multiple compartments housing pigs of varying ages. Total nucleic acids of both types of dust samples were extracted and targets indicating MRSA (femA, nuc, mecA) and total bacterial count (16S rRNA) were quantified using quantitative real-time PCRs. MRSA could be measured from all GSP samples and in 94% of the EDCs, additionally MRSA was present on every farm sampled. There was a strong positive relationship between the paired MRSA levels found in EDCs and those measured on filters (Normalized by 16S rRNA; Pearson's correlation coefficient r = 0.94, Not Normalized; Pearson's correlation coefficient r = 0.84). This study suggests that EDCs can be used as an affordable and easily standardized method for quantifying airborne MRSA levels in the pig farm setting.

Multi-Host Pathogen Staphylococcus aureus-Epidemiology, Drug Resistance and Occurrence in Humans and Animals in Poland

Staphylococcus aureus is a drug resistant pathogen with zoonotic potential commonly isolated from humans and animals. The aim of this study was to compare the occurrence of drug resistance, resistance genes, sequence types (STs), and genotypes of S. aureus isolated from humans, livestock, and wildlife in eastern Poland. A high percentage of isolates resistant to penicillin (63%), erythromycin (39%), clindamycin (37%), tetracycline (31%), and methicillin (MRSA-19%), an intermediate resistant to vancomycin (VISA-13%), and a multidrug resistant (MDR-39%) was obtained. Multilocus sequence typing analysis showed the presence of 35 different STs (with dominance ST 15, ST 45, ST 7, and ST 582 in human, and ST 398 and ST 8139 in porcine and cattle isolates, respectively), including 9 new ones that had never been reported before (ST 8133-8141). Identical genotypic patterns were detected among porcine and cattle isolates as well as from humans and cattle. A high percentage of MDR, MRSA, and VISA in humans and livestock combined with the presence of the same genotypes among S. aureus isolated from human and cattle indicates the circulation of strains common in the region and their zoonotic potential. There is a need to develop new strategies to counteract this phenomenon according to the One Health policy.

Prodigiosin as an antibiofilm agent against multidrug-resistant Staphylococcus aureus

Staphylococcus aureus is known for forming bacterial biofilms that confer increased antimicrobial resistance. Combining antibiotics with antibiofilm agents is an alternative approach, but the antibiofilm ability of prodigiosin (PG), a potential antibiotic synergist, against antimicrobial-resistant (AMR) S. aureus remains to be understood. The antibiofilm activity of PG against 29 clinical AMR S. aureus strains was evaluated using crystal violet staining, and its synergistic effects with vancomycin (VAN) was confirmed using the checkerboard test. The viability and metabolic activity of biofilms and planktonic cells were also assessed. The results revealed that PG exhibited promising inhibitory activity against biofilm formation and synergistic activity with VAN. It effectively reduced the metabolic activity of biofilms and suppressed the production of exopolysaccharides, which might be attributed to the downregulation of biofilm-related genes such as sarA, agrA, and icaA. These findings suggest that PG could be used as a preventive coating or adjuvant against biofilms in clinical settings.

Complete Genome Sequences of Bioluminescent Staphylococcus aureus Strains Xen31 and Xen36, Derived from Two Clinical Isolates

Here, we report complete genome sequences of two clinical isolates of Staphylococcus aureus, namely, Xen31 and Xen36, which have been genetically modified to express an optimized Photorhabdus luminescens luciferase operon. Xen31 and Xen36 are bioluminescent strains used widely for investigation of bacterial pathogenesis, drug discovery, and development of novel therapies.

Microbiological monitoring of coagulase-negative Staphylococcus in public drinking water fountains: Pathogenicity factors, antimicrobial resistance and potential health risks

The presence of opportunistic bacteria such as coagulase-negative Staphylococcus (CoNS) in drinking water poses public health concerns because of its potential to cause human infection and due to its antimicrobial resistance (AMR) diversity. This study evaluated the occurrence, virulence markers and AMR of CoNS in 468 drinking water samples from 15 public fountains located in four urban parks of São Paulo city (Brazil). Out of 104 samples positive for the presence of Staphylococcus genus, we detected CoNS in 75 of them (16%), which did not meet the Brazilian sanitary standards for residual chlorine. All isolates were of concern to public health for being responsible for infection in humans from low to high severity, nine of them are considered the most of concern due to 63.6% being multiresistant to antimicrobials. The results demonstrated that CoNS in drinking water must not be neglected. It is concluded that the presence of resistant staphylococci in drinking water is a potential health risk, which urges feasible and quick control measures to protect human health, especially in crowded public places.

Correlating the physico-chemical properties of two conventional glazed porcelain stoneware tiles in relation to cleanability and sanitization

Keeping surfaces clean can reduce the spread of infections. In particular, to decrease the potential for SARS CoV-2 contamination, performing disinfection of high-touching surfaces. Several ceramic tiles and porcelain stoneware tiles with antimicrobial properties are already available on the market. However, the widespread use of antimicrobial glazed stoneware tiles may require to replace the ceramic surfaces already present in many buildings. The unfeasibility of such replacement can be due to both product durability (lifetime of a tile is usually long) and/or monetary restrictions. Furthermore, as porcelain stoneware per se does not have antimicrobial activity, these materials are fabricated by adding chemical agents able to provide antimicrobial properties. This approach requires a compatibility between the antimicrobial agents and the glaze formulation, as well as a careful control of the firing cycle and the final properties of the ceramic products. It follows that the final cost of antimicrobial tiles is not competitive with that of conventional tiles. In the latter, the persistence of potential pathogens on the surfaces is a crucial problem to face: the longer a pathogen survives on a surface, the longer it may be a source of transmission and thus endanger susceptible subjects. In this work, bacteria's capacity to adhere and to be effectively removed from two conventional glazed porcelain stoneware tiles (under dirty and clean conditions) was investigated. Two different glazes were tested, one mainly glassy (glossy) and the other mainly crystalline (matt). The sanitization procedures were carried out by chemical and chemo-mechanical procedures. The results showed that chemo-mechanical sanitization was the most effective, and the best results could be obtained on the stoneware tiles coated with the mainly glassy glaze, with the lowest porosity and the lower roughness values and water contact angles, especially under clean conditions.

Bats Are Carriers of Antimicrobial-Resistant Staphylococcaceae in Their Skin

Bats have emerged as potential carriers of zoonotic viruses and bacteria, including antimicrobial-resistant bacteria. Staphylococcaceae has been isolated from their gut and nasopharynx, but there is little information about Staphylococcaceae on bat skin. Therefore, this study aimed to decipher the Staphylococci species in bat skin and their antimicrobial susceptibility profile. One hundred and forty-seven skin swabs were collected from bats during the spring and summer of 2021 and 2022. Bats were captured in different areas of the Metropolitan Region of São Paulo, Brazil, according to the degree of anthropization: Area 1 (Forested), Area 2 (Rural), Area 3 (Residential-A), Area 4 (Slum-- up to two floors), Area 5 (Residential-B-condo buildings), and Area 6 (Industrial). Swabs were kept in peptone water broth at 37 °C for 12 h when bacterial growth was streaked in Mannitol salt agar and incubated at 37 °C for 24 h. The disc-diffusion test evaluated antimicrobial susceptibility. Staphylococcaceae were isolated from 42.8% of bats, mostly from young, from the rural area, and during summer. M. sciuri was the most frequent species; S. aureus was also isolated. About 95% of isolates were resistant to at least one drug, and most strains were penicillin resistant. Eight isolates were methicillin resistant, and the mecA gene was detected in one isolate (S. haemolyticus). Antimicrobial resistance is a One Health issue that is not evaluated enough in bats. The results indicate that bats are carriers of clinically meaningful S. aureus and antimicrobial-resistant bacteria. Finally, the results suggest that we should intensify action plans to control the spread of resistant bacteria.

Quantitative microbial risk assessment with nasal/oral breathing pattern for S. aureus bioaerosol emission from aeration tanks and residual sludge storage yard in a wastewater treatment plant

A large number of pathogenic bioaerosols are generated during the treatment process of wastewater treatment plants (WWTPs), and they can pose potential risks to human health. Therefore, this study systematically analyzed the emission characteristics of Staphylococcus aureus bioaerosols released from an inverted umbrella aeration tank, a microporous aeration tank, and a residual sludge storage yard in a WWTP, and quantitatively evaluated the health risks of four kinds of exposed populations with nasal/oral breathing patterns under optimistic and conservative estimations. The results displayed that the bioaerosol concentration in inverted umbrella aeration tank was higher than that in microporous aeration tank and residual sludge storage yard. Aerosolization ratio in residual sludge storage yard was an order of magnitude lower than that in aeration tanks. Sludge workers were at higher health risks than the other three exposed populations. The health risks of nasal breathers (infection risk: 1.62 × 10^-5-2.56 × 10^-3 pppy; disease burden: 4.24 × 10^-8-6.72 × 10^-6 DALYs pppy) were 0.61-0.63 times higher than those of oral breathers (infection risk: 9.95 × 10^-6-1.59 × 10^-3 pppy; disease burden: 2.61 × 10^-8-4.18 × 10^-6 DALYs pppy). For female field engineers using oral breathing, laboratory technicians, and researchers without personal protective equipment (PPE), infection risk and disease burden had the opposite results, which indicated that satisfying one certain benchmark did not mean absolute safety. In addition, health risks of exposed populations were reduced by an order of magnitude after wearing PPE. This study can provide a reliable theoretical basis for the risk prevention of bioaerosols and supply data support for the strategies of health risk control perspectives for local sewage utilities.

Emergent crisis of antibiotic resistance: A silent pandemic threat to 21st century

Antibiotic resistance has become an indispensably alarming menace to the global community. The primary factors are overuse and abuse of antibiotics, lack of novel medicines under development, the health care industry's focus on profit, and the absence of diagnostic testing prior to the prescription of antibiotics. Additionally, over the past few decades, the main factors contributing to the global spread of antibiotic resistance have been the overuse of antibiotics in livestock and other animals, drug efficacy, development of fewer new vaccines, environmental toxicity, transmission through travel, and lack of funding for healthcare research and development. These factors have accelerated resistance in microorganisms through structural and functional modifications in bacteria such as reduced drug permeability, increased efflux pumps, enzymatic antibiotic modification, and change in drug target, intracellular infection, and biofilm creation. There has been an increase in resistance during the pandemic and among cancer patients due to improper prescriptions. A number of modern therapeutic alternatives have been developed to curb widespread antibiotic resistance such as nanoparticle, bacteriophage, and antimicrobial biochemical approaches. It is high time to explore new alternatives to curtail enormous increase in resistant pathogens which could be an incurable global confrontation. This review highlights the complete insight on the global drivers of resistance along with the modes of action and impacts, finally discussing the latest therapeutic alternatives.

A comparative study on antibiotic resistance and virulence properties of Staphylococcus aureus isolated from hospitalized patients and hospital environment

BACKGROUND

We compared the characteristics of clinical Staphylococcus aureus and S. aureus isolated from environmental surfaces in 3 hospitals.

METHODS

Clinical S. aureus isolates were collected from hospitalized patients. Environmental surfaces were sampled from the rooms of patients infected with S. aureus. After identifying rooms with the target organism, 3-5 high-touch surfaces in patient care areas were sampled using swabs before room cleaning by environmental services. S. aureus isolates were subjected to genotyping, antimicrobial susceptibility testing, and virulence determinant screening. The isolates were analyzed for integron content and sequences of variable region amplification products.

RESULTS

There were epidemiologically unrelated 79 clinical and 62 environmental S. aureus isolates. Overall, 11.4% of clinical and 59.7% of environmental isolates were methicillin-resistant. The environmental and clinical S. aureus exhibited very different virulence profiles: 79% of the environmental isolates were negative for virulence genes compared to 2.5% of clinical isolates (P < .001). Environmental isolates were more resistant to antibiotics compared to clinical isolates. Class 1 integrons were only detected in 7 of 62 environmental isolates, of which 3 isolates had integrons with cysteine synthase cassette, 1 had aadA1, and 1 had an unknown cassette.

CONCLUSION

These data indicate the different characteristics between environmental and clinical S. aureus, which may reflect different reservoirs from which the 2 groups acquired the strains.

Bioaerosols emission characteristics from wastewater treatment aeration tanks and associated health risk exposure assessment during autumn and winter

Aeration tanks from activated sludge wastewater treatment plants (WWTPs) can release a large amount of bioaerosols that can pose health risks. However, risk characterization of bioaerosols emissions form wastewater treatment plants is currently not systematically carried out and still in its infancy. Therefore, this study investigated emission characteristic of two indicator model bioaerosols Staphylococcus aureus and Escherichia coli, emitted from aeration tanks of a municipal WWTP. Monte Carlo simulation was then used to quantitatively assess microbial risk posed by different aeration modes under optimistic and conservative estimates. Further to this, two different exposure scenarios were considered during 3 days sampling campaign in autumn and winter. Results showed that the bioaerosol concentration from microporous aeration tank (20-262 CFU m^-3) was one order of magnitude lower than rotating disc aeration tank. Average aerosolization rate was 7.5 times higher with mechanical aeration mode. Health risks of exposed populations were 0.4 and 9.6 times higher in winter than in autumn for E. coli and S. aureus bioaerosol, respectively. Health risks of staff members were 10 times higher than academic visitors. Interesting results were observed for academic visitors without personal protective equipment (PPE) respectively exposed to S. aureus and E. coli bioaerosol in autumn and winter: while the derived infection risk met the United States Environmental Protection Agency (U.S. EPA) benchmark under optimistic estimation, the disease risk burden was over the World Health Organization (WHO) benchmark under conservative estimation. These revealed that only satisfying one of the two benchmarks didn't mean absolute acceptable health risk. This study could facilitate the development of better understanding of bioaerosol quantitative assessment of risk characterizations and corresponding appropriate risk control strategies for wastewater utilities.

What are the disease burden and its sensitivity analysis of workers exposing to Staphylococcus aureus bioaerosol during warm and cold periods in a wastewater treatment plant?

Biological treatment in wastewater treatment plants releases high amounts of pathogenic bioaerosols. Quantitative microbial risk assessment is a framework commonly used for quantitative risk estimation for occupational exposure scenarios. However, the quantitative contributions of health-risk-estimate inputted parameters remain ambiguous. Therefore, this research aimed to study the disease burden of workers exposed to Staphylococcus aureus bioaerosol during warm and cold periods and strictly quantify the contributions of the inputted parameters by sensitivity analysis on the basis of Monte Carlo simulation. Results showed that the disease health risk burden of workers in the warm period was 1.15-6.11 times higher than that of workers in the cold period. The disease health risk burden of workers without personal protective equipment was 23.83-36.55 times higher than that of workers with personal protective equipment. Sensitivity analysis showed that exposure concentration and aerosol ingestion rate were the first and second predominant factors, respectively; the sensitivity partitioning coefficient of the former was 1.17-1.35 times the value of the latter. In addition, no remarkable differences were revealed in the sensitivity percentage ratio between warm and cold periods. The findings could contribute to the mitigation measures for the management of public health risks.

Inactivation of airborne SARS-Co-V2 using NTP-UVGI hybrid process

Indoor environments such as healthcare centers are known as one of the key centers in the outbreak of viral infectious diseases. In the present study, the pathogenic agents' treatment system (PATS) was designed by the combination of non-thermal plasma (NTP) with the ultraviolet germicidal irradiation (UVGI) processes. Then, the treatment efficiency of PATS was measured for the "SARS-Co-V2." The exhaled air of the confirmed case of "COVID-19" was considered as the viral source of "SARS-Co-V2" and directed to the upstream of PATS. The treatment process was done by passing directed air through two steps of treatment (NTP and UVGI). The treatment efficiency of PATS was measured by sampling at the sampling points (before and after the treatment process). According to the energy emission pattern (corona discharge, UV rays) in the designed system, during two steps, the high efficiency of treatment for the collected pathogens was achieved. Based on the real-time polymerase chain reaction (RT-PCR) results, the CT value was lower than 29 (CTs < 29), and after the treatment using PATS was upper than 40 (CTs > 40) confirming the highest removal efficiency of "SARS-Co-V2." Also, the treatment efficiency of each reactor in individual operation was at the optimum level. The findings suggested, the present PATS may eliminate the viral pathogens with hospital sources and also, be applicable in the other intensive care unit (ICU) wards with the same risk thus, significantly reducing the possible exposure risk of healthcare and sick companions, and preventing the outbreak of infectious diseases.

A Nanocomposite with Extracellular Vesicles from Lactobacillus paracasei as a Bioinspired Nanoantibiotic Targeting Staphylococcus aureus

The utilization of biomimetic materials that merge functional nanoparticles (NPs) with a cell-derived nanosized membrane is a state-of-the-art approach to harnessing cellular properties for biomedical applications. However, the development of biocompatible and species-selective biomimetic agents against hazardous pathogens threatening human health is still in its early stages. Herein, we report the synthesis and functional analysis of a novel nanoplatform in which a PEGylated MoS2-ZnO (MZ) nanocomposite was cloaked with a generally regarded as safe (GRAS)-grade Lactobacillus paracasei-derived extracellular vesicle (LPEV) for MZ-LPEV nanocomposite and evaluated its activity against Staphylococcus aureus. The MZ nanocomposite was characterized via X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. The coating of MZ with LPEV was confirmed through nanoparticle tracking analysis and zeta potential measurements. MZ-LPEV exhibited 5- to 20-fold higher antibacterial activity than that of ZO NPs and MZ nanocomposite against S. aureus. Reactive oxygen species (ROS) production and bacterial membrane disruption were confirmed as antibacterial mechanisms of MZ-LPEV. Finally, MZ-LPEV exhibited enhanced biocompatibility and selectivity for S. aureus. All our results showed that LPEV could be utilized for developing synergistic nanoantibiotics against S. aureus.

Limited evidence of patient-to-patient transmission of Staphylococcus aureus strains between children with cystic fibrosis, Queensland, Australia

OBJECTIVES

Here we used whole genome sequencing (WGS) to understand strain diversity and potential for patient-to-patient transmission of Staphylococcus aureus among children with cystic fibrosis (CF) in Queensland, Australia.

METHODS

S. aureus isolates (n = 401) collected between January 2018 and April 2019 from 184 patients with CF (n = 318 isolates) and 76 patients without CF (n = 83 isolates) were subjected to WGS and subsequent multilocus sequence typing (MLST), and a phylogeny was constructed from core genome single nucleotide polymorphism (SNP) analysis. The subsequent data was compared with available patient information.

RESULTS

WGS revealed that patients with CF were essentially colonised by the same genotypes as those seen in patients without CF. Sequence types (ST) for our patients with CF were predominantly ST5 (20.1%), ST30 (7.3%), ST15 (6.3%) and ST8 (5.3%). Two Australian clones, ST93 and ST239, typically seen in skin infections and health-care settings, respectively, were notably absent from our patients with CF. Based on a SNP distance threshold of 14 SNPs, 20 cluster types involving 50/260 patients were evident; of these, 6 clusters contained only patients found to be siblings or otherwise living in the same household. Epidemiological relationships could not be determined for a remaining 14 cluster types involving 38 patients, comprising 2-7 (median 2) patients each. Multiple S. aureus genotypes were observed in 19/73 CF patients who provided more than one sample.

CONCLUSION

These results show that WGS is a useful tool for surveillance of S. aureus strains in children with CF and that the strains in our CF cohort were largely consistent with those circulating in patients without CF. Overall, this confirms previous findings and indicates that S. aureus acquisition in children with CF is similar to that of other patient groups, with limited evidence of potential patient-to-patient transmission within this patient group.

Microbial Indoor Air Quality and Associated Factors in Jimma Town Prison Administration, Southwestern Ethiopia

Indoor air quality determines the well-being of occupants. It has been linked to sick building syndrome and building-related diseases which lead to many socio-economic problems including reduced productivity and impaired learning. Indoor air quality problem is more serious for prisoners, due to their confinement and exposure condition. However, it has not been studied in our study setting. Thus, this study aimed to determine the indoor air microbial quality and associated factors in Jimma town prison administration, Southwestern Ethiopia. A cross-sectional study design was employed in August 2021. Data on the general condition of the prison rooms and occupancy were collected by trained data collectors using an observational checklist. The microbial sample was collected using a sterilized Petri dish. A total of 19 triplicate air samples were collected using Mannitol salt agar and Sabouroad dextrose agar media for the growth of S. aureus and fungi respectively. Data were analyzed using SPSS version 23 and presented using tables and a graph. The effect of predictor variables on the microbial load was also analyzed by using linear regression. The finding of this study revealed that the microbial load of indoor air at Jimma town prison administration ranged from 891 to 15 439 and 315 to 3067 CFU/m³ for S. aureus and fungi respectively. Both S. aureus and the fungal load of the indoor environment were positively affected by the temperature of the room. Whereas, the floor space per inmate affects the concentration of S. aureus alone. Almost all rooms of the prison administration had microbial load beyond the acceptable limit. Higher temperature, less floor space per inmate, bad floor cleanness conditions, inadequate ventilation, and dampness were contributing factors to the high load of S. aureus and fungus. Thus, additional rooms are required to reduce overcrowding and keep room temperature.

Recent advances in airborne pathogen detection using optical and electrochemical biosensors

The world is currently facing an adverse condition due to the pandemic of airborne pathogen SARS-CoV-2. Prevention is better than cure; thus, the rapid detection of airborne pathogens is necessary because it can reduce outbreaks and save many lives. Considering the immense role of diverse detection techniques for airborne pathogens, proper summarization of these techniques would be beneficial for humans. Hence, this review explores and summarizes emerging techniques, such as optical and electrochemical biosensors used for detecting airborne bacteria (Bacillus anthracis, Mycobacterium tuberculosis, Staphylococcus aureus, and Streptococcus pneumoniae) and viruses (Influenza A, Avian influenza, Norovirus, and SARS-CoV-2). Significantly, the first section briefly focuses on various diagnostic modalities applied toward airborne pathogen detection. Next, the fabricated optical biosensors using various transducer materials involved in colorimetric and fluorescence strategies for infectious pathogen detection are extensively discussed. The third section is well documented based on electrochemical biosensors for airborne pathogen detection by differential pulse voltammetry, cyclic voltammetry, square-wave voltammetry, amperometry, and impedance spectroscopy. The unique pros and cons of these modalities and their future perspectives are addressed in the fourth and fifth sections. Overall, this review inspected 171 research articles published in the last decade and persuaded the importance of optical and electrochemical biosensors for airborne pathogen detection.

Antimicrobial resistance in commensal Staphylococcus aureus from wild ungulates is driven by agricultural land cover and livestock farming

Staphylococcus aureus is a human pathobiont (i.e., a commensal microorganism that is potentially pathogenic under certain conditions), a nosocomial pathogen and a leading cause of morbidity and mortality in humans. S. aureus is also a commensal and pathogen of companion animals and livestock. The dissemination of antimicrobial resistant (AMR) S. aureus, particularly methicillin-resistant (MRSA), has been associated to its ability for establishing new reservoirs, but limited attention has been devoted to the role of the environment. To fill this gap, we aimed to characterize animal carrier status, AMR phenotypes, predominant clonal lineages and their relationship with clinical and food-chain settings, as well as to find predictors of AMR occurrence. Nasal swabs (n = 254) from wild boar (n = 177), red deer (n = 54) and fallow deer (n = 23) hunted in Portugal, during the season 2019/2020, yielded an overall carrier proportion of 35.8%, ranging from 53.7% for red deer and 32.2% for wild boar to 21.7% for fallow deer. MRSA from wild boar and phenotypically linezolid-resistant S. aureus from wild boar and red deer were isolated, indicating that resistance to antimicrobials restricted to clinical practice also occurs in wildlife. The most prevalent genotypes were t11502/ST2678 (29.6%) and t12939/ST2678 (9.4%), previously reported in wild boar from Spain. Clonal lineages reported in humans and livestock, like CC1, CC5 or CC8 (19.1%) and ST425, CC133 or CC398 (23.5%), respectively, were also found. The sequence type ST544, previously restricted to humans, is described in wildlife for the first time. We also identified that land use (agricultural land cover), human driven disturbance (swine abundance) and host-related factors (sex) determine resistance occurrence. These findings suggest that antibiotics used in clinical settings, agriculture and livestock farming, spill over to wildlife, leading to AMR emergence, with potential biological, ecological, and human health effects. This work is one of the most comprehensive surveys in Europe of S. aureus occurrence and determinants among widely distributed wild ungulates.

Multidrug-Resistant Bacteria and Enterobacteriaceae Count in Abattoir Wastes and Its Receiving Waters in Limbe Municipality, Cameroon: Public Health Implications

The release of untreated wastes from abattoirs into the environment and nearby water bodies poses a significant threat to public health. Such litters may contain pathogens, including antibiotic-resistant bacteria. This study investigated 80 samples collected from butchering tables, slaughter slabs, meat rinsing points, and abattoir wastes receiving water from two abattoirs (A and B). Total Enterobacteriaceae count (TEC) for each sample was determined, and Escherichia coli (E. coli), Salmonella spp., Shigella spp., and Staphylococcus aureus (S. aureus) were isolated and identified. Antimicrobial susceptibility testing was done on all bacterial isolates against nine locally used antibiotics. Overall, 118 bacterial isolates, comprising E. coli (42.5%), Salmonella spp. (27.5%), Shigella spp. (37.5%), and S. aureus (40.0%), were recovered. Of the 118 bacterial isolates, 104 (88.1%) were multidrug-resistant, including 58 (55.8%) from abattoir A and 46 (44.2%) from abattoir B; however, this difference was not statistically significant (p = 0.6837). Of the 32 S. aureus isolates, 29 (90.6%) were multidrug-resistant. All S. aureus were 100% sensitive to vancomycin, kanamycin, and amikacin. Similarly, 31 (91.2%) of the 34 E. coli isolates recovered in this study were multidrug-resistant. Salmonella spp. and Shigella spp. also showed high levels of multidrug resistance corresponding to 81.8% and 86.7%, respectively. All isolates of E. coli, Salmonella, and Shigella were 100% resistant to ampicillin and 100% sensitive to ciprofloxacin. Minimum and maximum mean values for TEC were 3.62-5.83 log CFU/mL for abattoir A and 4.08–5.56 log CFU/mL for abattoir B. The highest and lowest TEC counts were from slaughter slab and upstream water, respectively, in each abattoir. Our results indicate a predominance of multidrug-resistant bacteria in abattoir wastes and their receiving waters in the study sites. Hence, we recommend the treatment of abattoir wastes before disposal and improved hygiene and sanitation practices to enhance public health.

Estimating acceptable exposure time for bioaerosols emission in a wastewater treatment plant by reverse quantitative microbial risk assessment based on various risk benchmarks

Populations exposed to bioaerosols over time in wastewater treatment plants (WWTPs) will be infected. Then, the reverse quantitative microbial risk assessment (QMRA) provides a quantitative framework for the estimation of acceptable exposure time to protect people from excessive exposure and then manage their health risk. In this study, the acceptable exposure time for staffs and visiting researchers exposed to S. aureus or E. coli bioaerosols emitted from aeration ponds in WWTPs was estimated and analyzed by Monte Carlo simulation-based reverse QMRA (using the 1E-4 pppy suggested by the US EPA or 1E-6 DALYs pppy suggested by the WHO as benchmarks). The 1E-3 and 1E-2 pppy were selected as a series of loose annual infection risk benchmarks to calculate a practical acceptable exposure time. The results showed that for the acceptable exposure time in each specific exposure scenario, the exposure of females was consistently 0.3-0.4 times longer than that of males; the exposure of staffs was 3.6-3.9 times shorter than that of visiting researchers; the exposures of populations in the rotating-disc aeration mode were consistently 6.3-6.6 and 2.8-3.1 times longer than those in the microporous aeration mode for S. aureus and E. coli bioaerosols, respectively. The acceptable exposure time with the use of personal protective equipment (PPE) was 33.4-35.0 times as long as that without PPE. The US EPA benchmark is stricter than the WHO benchmark with regard to the estimation of the acceptable exposure time of S. aureus or E. coli bioaerosols. The 1E-3 pppy is more appropriate and practical than the US EPA benchmark, but the 1E-2 pppy is notably too loose for health risk management. This research can assist managers of WWTPs to formulate a justified exposure time and develop applicable administrative and personal intervention strategies. The results can enrich the knowledge bases of reverse QMRA to elect a series of loose health-based target risk benchmarks for health risk management.

Methicillin-Resistant Staphylococcus aureus from Peninsular Malaysian Animal Handlers: Molecular Profile, Antimicrobial Resistance, Immune Evasion Cluster and Genotypic Categorization

Staphylococcus aureus (S. aureus) infections, particularly methicillin-resistant Staphylococcus aureus (MRSA) in humans and animals, have become a significant concern globally. The present study aimed to determine the prevalence and antibiogram of S. aureus isolated from animal handlers in Peninsular Malaysia. Furthermore, the genotypic characteristics of S. aureus isolates were also investigated. Nasal and oral swab samples were collected from 423 animal handlers in Peninsular Malaysia. The antibiogram profiles of S. aureus against 18 antibiotics were established using a Kirby–Bauer test. The genotypic profile of S. aureus, including the presence of antimicrobial resistance (AMR), virulence genes and spa genotypes, was investigated using molecular techniques. The overall carriage rate of S. aureus, MRSA and MDRSA was 30.5%, 1.2% and 19.4%, respectively. S. aureus was highly resistant against penicillin (72.3%) and amoxicillin (52.3%). Meanwhile, gentamicin and linezolid were fully effective against all the isolated S. aureus from animal handlers. It was observed that animal handlers with close exposure to poultry were more likely to carry S. aureus that is resistant to tetracycline and erythromycin. S. aureus isolates harboured tetracycline resistance (tetK, tetL and tetM), erythromycin resistance (ermA, ermB, ermC and msrA) and immune evasion cluster (IEC) genes (scn, chp, sak, sea and sep). Seventeen different spa types were detected among the 30 isolates of MDRSA, with t189 (16.7%) and t4171 (16.7%) being the predominant spa type, suggesting wide genetic diversity of the MDRSA isolates. The present study demonstrated the prevalence of S. aureus strains, including MRSA and MDRSA with various antimicrobial resistance and genetic profiles from animal handlers in Peninsular Malaysia.

Role of Bioaerosols on the Short-Distance Transmission of Multidrug-Resistant Methicillin-Resistant Staphylococcus aureus (MRSA) in a Chicken Farm Environment

Methicillin-resistant Staphylococcus aureus (MRSA) is a dynamic and tenacious pathogenic bacterium which is prevalent in livestock farming environments. This study investigated the possibility of MRSA spread via bioaerosol transmission from an indoor chicken farm environment to outdoors downwind (up to 50 m). The concentration of total airborne bacteria colony formation units (CFUs) was decreased with increasing sampling distance ranging from 9.18 × 10¹ to 3.67 × 10³ per air volume (m³). Among the 21 MRSA isolates, 15 were isolated from indoor chicken sheds and exposure square areas, whereas 6 were isolated from downwind bioaerosol samples. Molecular characterization revealed that all of them carried the staphylococcal cassette chromosome mec (SCCmec) VIII, and they were remarkably linked with the hospital-associated MRSA group. Spa typing analysis determined that all MRSA isolates belonged to spa type t002. Virulence analysis showed that 100% of total isolates possessed exfoliative toxin A (eta), whereas 38.09% and 23.80% strains carried exfoliative toxin B (etb) and enterotoxin A (entA). Additionally, all of these MRSA isolates carried multidrug resistance properties and showed their resistance against chloramphenicol, ciprofloxacin, clindamycin, tetracycline, and erythromycin. In addition, chi-squared statistical analysis displayed a significant distributional relationship of gene phenotypes between MRSA isolates from chicken farm indoor and downwind bioaerosol samples. The results of this study revealed that chicken farm indoor air might act as a hotspot of MRSA local community-level outbreak, wherein the short-distance dispersal of MRSA could be supported by bioaerosols.

Antibacterial activities against Staphylococcus aureus and Escherichia coli of extracted Piper betle leaf materials by disc diffusion assay and batch experiments

The use of contaminated water by bacteria may cause many diseases, and thus clean water is needed. Chlorine is normally used for the disinfection of wastewater treatment; however, it produces unwanted odors. Using extracted Piper betle (P. betle) is an interesting choice because it is a good chemical compound for bacterial inhibitions. This study attempted to extract P. betle leaf and synthesize P. betle beads (PBB) to characterize materials and investigate antibacterial efficiencies by disc diffusion assay, batch tests, adsorption isotherms, kinetics, and material reusability. The results demonstrated the successful extraction and synthesis of the materials of P. betle. P. betle powder (PBP) had porous and rough surfaces, whereas PBB had a spherical shape with a coarse surface. The four main chemical elements and functional groups of PBP and PBB were carbon, oxygen, calcium, chlorine, and O–H, C–H, N–H, C–O, respectively. The extraction yield and total phenolic, flavonoid, and tannin contents of P. betle were 11.30%, 201.55 ± 0.31 mg GAE per g, 56.86 ± 0.14 mg RE per g, and 41.76 ± 1.32 mg CE per g, respectively. The six main compounds of eugenol, quercetin, apigenin, kaempferol, ascorbic acid, and hydroxychavicol were detected by HPLC analysis. The results of the disc diffusion assay confirmed antibacterial efficiencies of PBB, and the batch tests examined high antibacterial efficiencies of PBB for 100% on Staphylococcus aureus and Escherichia coli. The adsorption isotherms and kinetics of PBB corresponded to Freundlich model and pseudo-second order kinetic model, and the desorption experiments confirmed the reusability of PBB. Therefore, PBB can be possibly applied for an antibacterial purpose in wastewater treatment systems.

The alternative antibacterial material (PBB) is presented with high efficiency and reusability to apply for the disinfection of wastewater systems.

Antibiotic resistance in the environment

Antibiotic resistance is a global health challenge, involving the transfer of bacteria and genes between humans, animals and the environment. Although multiple barriers restrict the flow of both bacteria and genes, pathogens recurrently acquire new resistance factors from other species, thereby reducing our ability to prevent and treat bacterial infections. Evolutionary events that lead to the emergence of new resistance factors in pathogens are rare and challenging to predict, but may be associated with vast ramifications. Transmission events of already widespread resistant strains are, on the other hand, common, quantifiable and more predictable, but the consequences of each event are limited. Quantifying the pathways and identifying the drivers of and bottlenecks for environmental evolution and transmission of antibiotic resistance are key components to understand and manage the resistance crisis as a whole. In this Review, we present our current understanding of the roles of the environment, including antibiotic pollution, in resistance evolution, in transmission and as a mere reflection of the regional antibiotic resistance situation in the clinic. We provide a perspective on current evidence, describe risk scenarios, discuss methods for surveillance and the assessment of potential drivers, and finally identify some actions to mitigate risks.

Staphylococcus aureus in Substrates for Black Soldier Fly Larvae (Hermetia illucens) and Its Dynamics during Rearing

Black soldier fly larvae (BSFL; Hermetia illucens) are promising insects for the conversion of organic waste streams into valuable biomolecules. Such waste streams can contain foodborne pathogens. To assess this risk factor, this study evaluated the presence of Staphylococcus aureus in waste streams as a substrate ingredient for BSFL production as well as in the rearing process. First, the general microbiological quality and the occurrence of S. aureus were investigated for different waste streams. Staphylococcus aureus was abundantly present. Control of pH and water activity should avoid pathogens, which cannot grow in single-substrate ingredients, redeveloping when mixing streams for optimal substrate conditions for BSFL production. Next, it was investigated whether S. aureus present in the substrate was ingested and/or eradicated by BSFL. In inoculation trials, with S. aureus added to chicken feed as the substrate at 3 or 7 log CFU/g, the larvae showed a reducing effect on S. aureus. After 6 days, S. aureus counts were below the detection limit (2.0 log CFU/g) in all larvae samples and decreased in the substrate to <2.0 and <3.1 log CFU/g for inoculation levels of 3 and 7 log CFU/g, respectively. While this is promising, it is still recommended to monitor and control this pathogen in BSFL rearing. Intriguingly, screening of antimicrobial activity of dominant microorganisms associated with BSFL showed a clear activity of Trichosporon isolates against S. aureus. Future research should explore whether Trichosporon, which is frequently observed in BSFL, plays a role in controlling specific microorganisms, such as S. aureus. IMPORTANCE Given the increasing need for (more sustainable) methods to upcycle organic waste streams, the interest to rear insects, like black soldier fly larvae (BSFL), on such streams is increasing. This study reveals that S. aureus is abundantly present in such waste streams, which might be a point of attention for insect producers. At the same time, it reveals that when S. aureus was inoculated in chicken feed as the substrate, it was not detected in the larvae and was reduced in the substrate after 6 days. Future inoculation trials should investigate whether this reduction is substrate dependent or not. Toward the future, the role of the BSFL microbiota in controlling intestinal bacterial community homeostasis should be explored, because one of the dominant microorganisms associated with BSFL, Trichosporon spp., showed clear activity against S. aureus.

In Vitro Evaluation of Biological Activities and Phytochemical Analysis of Different Solvent Extracts of Punica granatum L. (Pomegranate) Peels

Antimicrobial resistance is a public health concern resulting in high rates of morbidity and mortality worldwide. Furthermore, a high incidence of food poisoning diseases besides harmful implications of applying synthetic food additives in food preservation necessitates fabrication of safe food preservatives. Additionally, damaging effects of free radicals on human health has been reported to be involved in the incidence of serious diseases, including cancer, diabetes and cardiovascular diseases; hence, finding safe sources of antioxidants is vital. Therefore, the present study was carried out to assess the antibacterial, antiradical and carcinopreventive efficacy of different solvent extracts of pomegranate peels. Agar disk diffusion assay revealed that Staphylococcus aureus, MRSA, E. coli and S. typhimurium were highly susceptible to methanolic fraction of Punica granatum L. peels recording inhibition zones of 23.7, 21.8, 15.6 and 14.7 mm respectively. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the methanolic fraction of Punica granatum L. peels against S. aureus were 0.125 and 0.250 mg/mL, respectively. In addition, the pomegranate acetonic and methanolic fractions revealed an impressive antiradical efficiency against DPPH (2,2-diphenyl-1-picrylhydrazyl) radical recording radical scavenging activity percentages of 86.9 and 79.4%, respectively. In this regard, the acetonic fraction of pomegranate peels revealed the highest anti-proliferative efficiency after 48 h incubation against MCF7 cancer cells recording IC₅₀ of 8.15 µg/mL, while the methanolic extract was highly selective against transformed cancer cells compared to normal cell line recording selectivity index of 5.93. GC-MS results demonstrated that 5-Hydroxymethylfurfural was the main active component of methanolic and acetonic extracts of pomegranate peels recording relative percentages of 37.55 and 28.84% respectively. The study recommends application of pomegranate peel extracts in the biofabrication of safe food preservatives, antioxidants and carcinopreventive agents.

Seasonal fluctuation of aerosolization ratio of bioaerosols and quantitative microbial risk assessment in a wastewater treatment plant

Wastewater treatment plants (WWTPs) play a vital role in public health because it can emit a large quantity of bioaerosols. Exposure to bioaerosols from WWTPs is a potential health risk to WWTP workers and surrounding residents. In this study, the seasonal fluctuation of aerosolization ratios of several bioaerosols and quantitative health risks of the WWTP workers and the surrounding residents exposed to total coliform, fecal coliform, and enterococcal bioaerosols were analyzed. Results showed that the aerosolization ratio of airborne bacteria was higher in the cold seasons and lower in the warm seasons, whereas the aerosolization ratio of airborne fungi was the highest in summer. The aerosolization ratio of airborne fungi was evidently higher than that of other bioaerosols. Moreover, the aerosolization ratio under the inverted umbrella aerator mode was generally higher than that under the microporous aerator mode. For each exposure scenario, the health risks of males were generally 7.2-26.7% higher than those of females. The health risks of the exposure population exposed to total coliform and enterococcal bioaerosols were generally higher in warm seasons, whereas those of the population exposed to fecal coliform bioaerosol were the highest in winter. Additionally, the health risks of exposure population without masks under the imprudent/conservative estimate all exceeded the benchmarks. However, when equipped with masks, all the exposure populations' health risks decreased 1-2 orders of magnitude and approached acceptable levels. This research methodically provides new scientific data on the aerosolization ratio of microorganism bioaerosols in a WWTP and promotes the comprehension of their quantitative health risks under imprudent/conservative estimates.

Antimicrobial Resistance of Coagulase-positive Staphylococcus Isolated From Healthy Crioulo Horses and Associated Risk Factors

Antimicrobial resistance (AMR) is a global concern that must be addressed from a one health perspective. Horses are companion animals and their contact with humans facilitates exchange of resistant bacteria. This study aimed to evaluate AMR of coagulase-positive Staphylococcus (CoPS), including Staphylococcus aureus, isolated from healthy Crioulo horses. Swab samples from nostrils (n = 214) and skin (n = 107) of 107 horses from Porto Alegre, South Brazil, were used for CoPS isolation. The isolates were evaluated for AMR and a multivariate logistic regression was applied to identify the risk factors associated to this outcome, using information on horses' management and installations where they were maintained. A total of 143 CoPS were isolated from 79 horses (73.8%), of which 8 (5.6%) were S. aureus. The isolates showed resistance to seven of 10 tested antimicrobials and 38.5% (55/143) of them were resistant to at least one antimicrobial. One isolate (0.7%; 1/143) was classified as multidrug-resistant. Regarding S. aureus, 62.5 % (5/8) showed AMR, but none were methicillin-resistant. The risk factors associated with CoPS' antimicrobial resistance were lower frequency of bed changing (OR = 6.40; P = .001) and nonaccumulation of bed materials (OR = 3.47; P = .002). The results point that healthy horses have antimicrobial-resistant CoPS and S. aureus in their microbiota, which may be of concern for animal and human health. Moreover, bed management was associated with AMR, which can serve as a guide for best practices to be adopted to avoid the occurrence of resistant bacteria in these animals.

The Influence of the Use of Face Masks During the COVID-19 Pandemic on the Human Microbiome – A Mini-Review

The aim of this study was to draw attention to the possible consequences of improper, unhygienic use of mouth and nose covers in the context of prophylaxis against the spread of COVID-19 from the point of view of a family physician and focus on the risk of respiratory infections and skin lesions in patients, in different age groups. The use of protective masks may reduce the likelihood of infection but will not eliminate the risk of infection. However, it should be remembered that any mask, no matter how effective the filtration is or how well it seals, will have little effect if not used in conjunction with other preventive measures, including isolation of infected people, immunization, proper respiratory culture, regular, frequent replacement of masks, and hand hygiene. Additionally, certain risks associated with this form of prophylaxis should be taken into account, which, unfortunately, may also aggravate or even constitute a source of serious respiratory infections and lead to the development and aggravation of skin problems. Moreover, educating society not only on hand hygiene but also on the topic of the value of nose and mouth covers, as well as the frequency of their replacement and/or disinfection, is becoming a significant issue.

Molecular detection and antibiogram of Staphylococcus aureus in rabbits, rabbit handlers, and rabbitry in Terengganu, Malaysia

Objectives

This study aims to investigate the prevalence and antibiogram of Staphylococcus aureus and methicillin-resistance S. aureus (MRSA) in rabbits, rabbit handlers, and rabbitry environments in Terengganu.

Materials and Methods

Swab samples from 183 rabbits (183 oral and 183 ear swabs), 45 rabbit handlers (45 oral and 45 nasal), and environmental (n = 180) samples from rabbitries were collected from 10 rabbit farms in Terengganu. The associated S. aureus isolates from the swabs were isolated using phenotypic microbiology tests. The bacteria were confirmed by polymerase chain reaction targeting nuc (S. aureus) and mecA (MRSA) genes. The antibiogram of all S. aureus isolates was determined using the Kirby-Bauer test.

Results

Staphylococcus aureus was detected in 19% of rabbits, 26.7% of rabbit handlers, and 8.8% of swabs from the rabbitry environment. However, MRSA (0%) could not be detected. Antibiotic susceptibility test revealed that S. aureus from rabbits showed low resistance (<20%) against 15 different antibiotics while fully susceptible to 4 antibiotics. Meanwhile, S. aureus from rabbit handlers showed high resistance against penicillin (86%), oxacillin (64%), and amoxicillin (50%).

Conclusions

This study suggests the emergence of antibiotic-resistant S. aureus in rabbit farms settings. Therefore, careful selection of antimicrobial agents will be essential to preserve the effectiveness of treatments toward S. aureus infections.

Molecular Evaluation of Traditional Chicken Farm-Associated Bioaerosols for Methicillin-Resistant Staphylococcus aureus Shedding

The outbreak of airborne pathogens, such as methicillin-resistant Staphylococcus aureus (MRSA) through bioaerosol, and their molecular characterization around domestic poultry farming areas, was not completely understood. This imposes risk of a MRSA-associated health threat for the relevant livestock food production units. To address this issue, the present study investigated the role of bioaerosol in transmitting MRSA strains in poultry house settings by combining molecular typing, phylogenetic classification, antibiotic susceptibility, and virulence gene distribution patterns. The present study highlights that all 18 bioaerosol and stool samples collected were MRSA positive, with a unique set of virulence factors. Out of 57 isolated MRSA isolates, 68.4% and 19.3% consisted of SCCmec I and IV elements, respectively, which are commonly linked with hospital-acquired and livestock-associated MRSA strains. It is worth noting that the exfoliative toxin eta and etb genes were carried by 100% and 70.2% of all isolates, respectively. Only 17.5% of strains showed the presence of enterotoxin entC. These MRSA isolates were resistant to chloramphenicol (C), ciprofloxacin (CIP), clindamycin (DA), erythromycin (E), and tetracycline (T), signifying their multi-drug resistance traits. A cluster of phylogenetic analysis described that 80.7% and 15.8% of total isolates belonged to Staphylococcus aureus protein A (spa) type t002 and t548. Whereas 3.5% were reflected as a new spa type. Additionally, as per the chi-squared test score value, these two spa types (t002 and t548) have a distribution correlation with HA-MRSA and LA-MRSA in all the samples (p < 0.005, chi-squared test; degree of freedom = 1). Ultimately, this study highlights the prevalence of MRSA colonization in the conventional poultry farm environment, showing the risk of bioaerosol transmission, which needs epidemiological attention and prevention strategies.

Bacteria and Their Antibiotic Resistance Profiles in Ambient Air in Accra, Ghana, February 2020: A Cross-Sectional Study

Inappropriate use of antibiotics has led to the presence of antibiotic-resistant bacteria in ambient air. There is no published information about the presence and resistance profiles of bacteria in ambient air in Ghana. We evaluated the presence and antibiotic resistance profiles of selected bacterial, environmental and meteorological characteristics and airborne bacterial counts in 12 active air quality monitoring sites (seven roadside, two industrial and three residential) in Accra in February 2020. Roadside sites had the highest median temperature, relative humidity, wind speed and PM₁₀ concentrations, and median airborne bacterial counts in roadside sites (115,000 CFU/m³) were higher compared with industrial (35,150 CFU/m³) and residential sites (1210 CFU/m³). Bacillus species were isolated in all samples and none were antibiotic resistant. There were, however, Pseudomonas aeruginosa, Escherichia coli, Pseudomonas species, non-hemolytic Streptococci, Coliforms and Staphylococci species, of which six (50%) showed mono-resistance or multidrug resistance to four antibiotics (penicillin, ampicillin, ciprofloxacin and ceftriaxone). There was a positive correlation between PM₁₀ concentrations and airborne bacterial counts (r_s = 0.72), but no correlations were found between PM₁₀ concentrations and the pathogenic bacteria nor their antibiotic resistance. We call for the expansion of surveillance of ambient air to other cities of Ghana to obtain nationally representative information.

Assessment of Pediatric Admissions for Kawasaki Disease or Infectious Disease During the COVID-19 State of Emergency in Japan

IMPORTANCE

The development of Kawasaki disease (KD) has been suggested to be associated with droplet- or contact-transmitted infection; however, its triggers and transmission modes remain to be determined. Under an epidemic of SARS-CoV-2, the COVID-19 state of emergency in Japan served as a nationwide social experiment to investigate the impact of quarantine or isolation on the incidence of KD.

OBJECTIVE

To assess the role of droplet or contact transmission in the etiopathogenesis of KD.

DESIGN, SETTING, AND PARTICIPANTS

This multicenter, longitudinal, cross-sectional study was conducted from 2015 to 2020 at Fukuoka Children's Hospital and 5 adjacent general hospitals. The number of admissions for KD and infectious diseases were analyzed. Participants were pediatric patients admitted to the participating hospitals for KD or infectious diseases.

EXPOSURES

Quarantine and isolation owing to the COVID-19 state of emergency.

MAIN OUTCOMES AND MEASURES

The primary end points were the ratios of patients with KD to patients with respiratory tract or gastrointestinal infections admitted from April to May in 2015 to 2019 and 2020. A Poisson regression model was used to analyze them.

RESULTS

The study participants included 1649 patients with KD (median [interquartile range] age, 25 [13-43] months; 901 boys [54.6%]) and 15 586 patients with infectious disease (data on age and sex were not available for these patients). The number of admissions for KD showed no significant change between April and May in 2015 to 2019 vs the same months in 2020 (mean [SD], 24.8 [5.6] vs 18.0 [4.0] admissions per month; 27.4% decrease; adjusted incidence rate ratio [aIRR], 0.73; 95% CI, 0.48-1.10; P = .12). However, the number of admissions for droplet-transmitted or contact-transmitted respiratory tract infections (mean [SD], 157.6 [14.4] vs 39.0 [15.0] admissions per month; 75.3% decrease; aIRR, 0.25; 95% CI, 0.17-0.35; P < .001) and gastrointestinal infections (mean [SD], 43.8 [12.9] vs 6.0 [2.0] admissions per month; 86.3% decrease; aIRR, 0.14; 95% CI, 0.04-0.43; P < .001) showed significant decreases between April and May in 2015 to 2019 vs the same months in 2020 (total, 12 254 infections). Thus, the ratio of KD to droplet- or contact-transmitted respiratory tract and gastrointestinal infections incidence in April and May 2020 was significantly increased (ratio, 0.40 vs 0.12; χ21 = 22.76; P < .001).

CONCLUSIONS AND RELEVANCE

In this study, the significantly increased incidence of KD compared with respiratory tract and gastrointestinal infections during the COVID-19 state of emergency suggests that contact or droplet transmission is not a major route for KD development and that KD may be associated with airborne infections in most cases.

Bacterial Contamination in Health Care Centers: Differences between Urban and Rural Settings

This study aims to assess the airborne bioburden of rural and urban Portuguese Primary Health Care Centers (PHCC) using active and passive sampling methods and identify the potential differences in airborne microbiota between both environments. The highest total aerobic mesophilic bacterial load in indoor air were found in the Vaccination Room (448 CFU.m−3) in the Rural PHCC and in the Waiting Room (420 CFU.m−3) for Urban PHCC. The total coliforms contamination level in indoor air was detected only in the Cleaning Supplies Room (4 CFU.m−3) in the Urban PHCC. The most frequent bacteria genera identified was Micrococcus (21% Rural PHCC; 31% Urban PHCC). The surface samples showed a highest total aerobic mesophilic bacterial contamination in the Treatment Room (86 × 103 CFU.m−2) from the Rural PHCC and in the Front Office (200 × 103 CFU.m−2) from the Urban PHCC. The electrostatic dust cloth (EDC) samples showed a highest bacterial load in the Urban PHCC. Total aerobic mesophilic bacterial load in settled dust and in the Heating, Ventilating and Air Conditioning (HVAC) filter samples in the Urban PHCC (8 CFU.g−1 and 6 × 103 CFU.m−2) presented higher values compared with the Rural PHCC (1 CFU.g−1 and 2.5 × 103 CFU.m−2). Urban PHCC presented higher bacterial airborne contamination compared with the Rural PHCC for the majority of sampling sites, and when compared with the indoor air quality (IAQ) Portuguese legislation it was the Rural PHCC in two sampling places who did not comply with the established criteria.