Microplastics and Antibiotic Resistance: The Magnitude of the Problem and the Emerging Role of Hospital Wastewater

Shallow shotgun sequencing of healthcare waste reveals plastic-eating bacteria with broad-spectrum antibiotic resistance genes

The burgeoning crises of antimicrobial resistance and plastic pollution are converging in healthcare settings, presenting a complex challenge to global health. This study investigates the microbial populations in healthcare waste to understand the extent of antimicrobial resistance and the potential for plastic degradation by bacteria. Our metagenomic analysis, using both amplicon and shallow shotgun sequencing, provided a comprehensive view of the taxonomic diversity and functional capacity of the microbial consortia. The viable bacteria in healthcare waste samples were analyzed employing full-length 16S rRNA sequencing, revealing a diverse bacterial community dominated by Firmicutes and Proteobacteria phyla. Notably, Proteus mirabilis VFC3/3 and Pseudomonas sp. VFA2/3 were detected, while Stenotrophomonas maltophilia VFV3/2 surfaced as the predominant species, holding implications for the spread of hospital-acquired infections and antimicrobial resistance. Antibiotic susceptibility testing identified multidrug-resistant strains conferring antimicrobial genes, including the broad-spectrum antibiotic carbapenem, underscoring the critical need for improved waste management and infection control measures. Remarkably, we found genes linked to the breakdown of plastic that encoded for enzymes of the esterase, depolymerase, and oxidoreductase classes. This suggests that specific bacteria found in medical waste may be able to reduce the amount of plastic pollution that comes from biological and medical waste. The information is helpful in formulating strategies to counter the combined problems of environmental pollution and antibiotic resistance. This study emphasises the importance of monitoring microbial communities in hospital waste in order to influence waste management procedures and public health policy. The findings highlight the need for a multidisciplinary approach to mitigate the risks associated with antimicrobial resistance and plastic waste, especially in hospital settings where they intersect most acutely.

Drivers of virulence and antimicrobial resistance in Gram-negative bacteria in different settings: A genomic perspective

The human gut presents a complex ecosystem harboring trillions of microorganisms living in close association with each other and the host body. Any perturbation or imbalance of the normal gut microbiota may prove detrimental to human health. Enteric infections and treatment with antibiotics pose major threats to gut microbiota health. Recent genomics-driven research has provided insights into the transmission and evolutionary dynamics of major enteric pathogens such as Escherichia coli, Klebsiella pneumoniae, Vibrio cholerae, Helicobacter pylori and Salmonella spp. Studies entailing the identification of various dominant lineages of some of these organisms based on artificial intelligence and machine learning point to the possibility of a system for prediction of antimicrobial resistance (AMR) as some lineages have a higher propensity to acquire virulence and fitness advantages. This is pertinent in the light of emerging AMR being one of the immediate threats posed by pathogenic bacteria in the form of a multi-layered fitness manifesting as phenotypic drug resistance at the level of clinics and field settings. To develop a holistic or systems-level understanding of such devastating traits, present methodologies need to be advanced with the high throughput techniques integrating community and ecosystem/niche level data across different omics platforms. The next major challenge for public health epidemiologists is understanding the interactions and functioning of these pathogens at the community level, both in the gut and outside. This would provide new insights into the dimensions of enteric bacteria in different environments and niches and would have a plausible impact on infection control strategies in terms of tackling AMR. Hence, the aim of this review is to discuss virulence and AMR in Gram-negative pathogens, the spillover of AMR and methodological advancements aimed at addressing it through a unified One Health framework applicable to the farms, the environment, different clinical settings and the human gut.

Detection of Microplastics in Human Breast Milk and Its Association with Changes in Human Milk Bacterial Microbiota

Background: Presently, there is increasing public consciousness regarding the contamination and detection of microplastics (MPs) within the human body, and studies on the detection and characterization of MPs in human breast milk are limited. Objectives: This study aims to investigate the prevalence and characteristics of MPs found in human breast milk and examine the relationship between maternal hygiene practices, complications that may arise during breastfeeding, and the composition of the bacterial microbiota. Methods: Postpartum breast milk was analyzed for MPs using Raman micro-spectroscopy. The relationship between MP detection, maternal hygiene, breastfeeding complications, and bacterial microbiota was examined. In order to identify correlations and differences between groups that had detected and non-detected MPs, statistical analyses were performed, which involved demographic comparisons and correlation network analysis. Results: The mean age of the 59 postpartum women was 28.13 years. We found MPs in 38.98% of breast milk samples (23 of 59), exhibiting diverse morphological and chemical characteristics. Most MP polymers were polypropylene, polyethylene, polystyrene, and polyvinyl chloride. Maternal hygiene and breastfeeding complications differed between the MPs-detected and non-detected groups. Maternal behaviors may influence the presence of microplastics in breast milk, which were associated with these differences. Bacterial microbiota analysis revealed significant taxonomic differences between the MPs-detected and non-detected groups. Staphylococcus and Streptococcus dominated the MPs-detected group, while Enterobacter, Escherichia, Pseudomonas, and Acinetobacter dominated the non-detected group. The MPs-detected group had a more even bacterial distribution, especially Bacteroides. Conclusions: This study found MPs in 38.98% of breast milk samples using Raman micro-spectrometry, with PP, PE, and PVC being the most common. Significant differences in maternal hygiene and breastfeeding complications were found between the groups with and without MPs. Breast milk microbiota may be linked to MP detection. Further study should be conducted to identify the possible maternal-child health.

Expanding the focus of the One Health concept: links between the Earth-system processes of the planetary boundaries framework and antibiotic resistance

The scientific community warns that our impact on planet Earth is so acute that we are crossing several of the planetary boundaries that demarcate the safe operating space for humankind. Besides, there is mounting evidence of serious effects on people's health derived from the ongoing environmental degradation. Regarding human health, the spread of antibiotic resistant bacteria is one of the most critical public health issues worldwide. Relevantly, antibiotic resistance has been claimed to be the quintessential One Health issue. The One Health concept links human, animal, and environmental health, but it is frequently only focused on the risk of zoonotic pathogens to public health or, to a lesser extent, the impact of contaminants on human health, i.e., adverse effects on human health coming from the other two One Health "compartments". It is recurrently claimed that antibiotic resistance must be approached from a One Health perspective, but such statement often only refers to the connection between the use of antibiotics in veterinary practice and the antibiotic resistance crisis, or the impact of contaminants (antibiotics, heavy metals, disinfectants, etc.) on antibiotic resistance. Nonetheless, the nine Earth-system processes considered in the planetary boundaries framework can be directly or indirectly linked to antibiotic resistance. Here, some of the main links between those processes and the dissemination of antibiotic resistance are described. The ultimate goal is to expand the focus of the One Health concept by pointing out the links between critical Earth-system processes and the One Health quintessential issue, i.e., antibiotic resistance.

Microplastics: Omnipresent and an ongoing challenge for medical science

Micro- and nanoplastics are omnipresent not only in the environment, but have also been detected in human body fluids and tissue. The subsequent commentary provides a perspective about potential risks for human health as well as resulting challenges for medical science.

Emerging Issues on Antibiotic-Resistant Bacteria Colonizing Plastic Waste in Aquatic Ecosystems

Antibiotic-resistant bacteria (ARB) adhesion onto plastic substrates is a potential threat to environmental and human health. This current research investigates the prevalence of two relevant human pathogens, Staphylococcus spp. and Klebsiella spp., and their sophisticated equipment of antibiotic-resistant genes (ARGs), retrieved from plastic substrates submerged into an inland water body. The results of microbiological analysis on selective and chromogenic media revealed the presence of colonies with distinctive phenotypes, which were identified using biochemical and molecular methods. 16S rDNA sequencing and BLAST analysis confirmed the presence of Klebsiella spp., while in the case of Staphylococcus spp., 63.6% of strains were found to be members of Lysinibacillus spp., and the remaining 36.3% were identified as Exiguobacterium acetylicum. The Kirby-Bauer disc diffusion assay was performed to test the susceptibility of the isolates to nine commercially available antibiotics, while the genotypic resistant profile was determined for two genes of class 1 integrons and eighteen ARGs belonging to different classes of antibiotics. All isolated bacteria displayed a high prevalence of resistance against all tested antibiotics. These findings provide insights into the emerging risks linked to colonization by potential human opportunistic pathogens on plastic waste commonly found in aquatic ecosystems.

Climate warming, environmental degradation and pollution as drivers of antibiotic resistance

Antibiotic resistance is a major challenge to public health, but human-caused environmental changes have not been widely recognized as its drivers. Here, we provide a comprehensive overview of the relationships between environmental degradation and antibiotic resistance, demonstrating that the former can potentially fuel the latter with significant public health outcomes. We describe that (i) global warming favors horizontal gene transfer, bacterial infections, the spread of drug-resistant pathogens due to water scarcity, and the release of resistance genes with wastewater; (ii) pesticide and metal pollution act as co-selectors of antibiotic resistance mechanisms; (iii) microplastics create conditions promoting and spreading antibiotic resistance and resistant bacteria; (iv) changes in land use, deforestation, and environmental pollution reduce microbial diversity, a natural barrier to antibiotic resistance spread. We argue that management of antibiotic resistance must integrate environmental goals, including mitigation of further increases in the Earth's surface temperature, better qualitative and quantitative protection of water resources, strengthening of sewage infrastructure and improving wastewater treatment, counteracting the microbial diversity loss, reduction of pesticide and metal emissions, and plastic use, and improving waste recycling. These actions should be accompanied by restricting antibiotic use only to clinically justified situations, developing novel treatments, and promoting prophylaxis. It is pivotal for health authorities and the medical community to adopt the protection of environmental quality as a part of public health measures, also in the context of antibiotic resistance management.

A thorough analysis of the occurrence, removal and environmental risks of organic micropollutants in a full-scale hybrid membrane bioreactor fed by hospital wastewater

The Urban Wastewater Treatment Directive recent draft issued last October 2022 pays attention to contaminants of emerging concern including organic micropollutants (OMPs) and requires the removal of some of them at large urban wastewater treatment plants (WWTPs) calling for their upgrading. Many investigations to date have reported the occurrence of a vast group of OMPs in the influent and many technologies have been tested for their removal at a lab- or pilot-scale. Moreover, it is well-known that hospital wastewater (HWW) contains specific OMPs at high concentration and therefore its management and treatment deserves attention. In this study, a 1-year investigation was carried out at a full-scale membrane bioreactor (MBR) treating mainly HWW. To promote the removal of OMPs, powdered activated carbon (PAC) was added to the bioreactor at 0.1 g/L and 0.2 g/L which resulted in the MBR operating as a hybrid MBR. Its performance was tested for 232 target and 90 non-target OMPs, analyzed by UHPLC-QTOF-MS using a direct injection method. A new methodology was defined to select the key compounds in order to evaluate the performance of the treatments. It was based on their frequency, occurrence, persistence to removal, bioaccumulation and toxicity. Finally, an environmental risk assessment of the OMP residues was conducted by means of the risk quotient approach. The results indicate that PAC addition increased the removal of most of the key OMPs (e.g., sulfamethoxazole, diclofenac, lidocaine) and OMP classes (e.g., antibiotics, psychiatric drugs and stimulants) with the highest loads in the WWTP influent. The hybrid MBR also reduced the risk in the receiving water as the PAC dosage increased mainly for spiramycin, lorazepam, oleandomycin. Finally, uncertainties and issues related to the investigation being carried out at full-scale under real conditions are discussed.

Microplastics as an emerging contaminant of concern to our environment: a brief overview of the sources and implications

Over the years, it has become evident that microplastics are one of the most important contaminants of concern requiring significant attention. The large abundance of microplastics that are currently in the environment poses potential toxicity risks to all organisms that are exposed to them. Microplastics have been found to affect the physiological and biological processes in marine and terrestrial organisms. As well as being a contaminant of concern in itself, microplastics also have the ability to act as vectors for other contaminants. The potential for microplastics to carry pollutants and transfer them to other organisms has been documented in the literature. Microplastics have also been linked to hosting antibiotic resistant bacteria and antibiotic resistance genes which poses a significant risk to the current health system. There has been a significant increase in research published surrounding the topic of microplastics over the last 5 years. As such, it is difficult to determine and find up to date and relevant information. This overview paper aims to provide a snapshot of the current and emerging sources of microplastics, how microplastics can act as a contaminant and have toxic effects on a range of organisms and also be a vector for a large variety of other contaminants of concern. The aim of this paper is to act as a tool for future research to reference relevant and recent literature in this field.

The Role of Stakeholders' Understandings in Emerging Antimicrobial Resistance: A One Health Approach

The increasing misuse of antibiotics in human and veterinary medicine and in agroecosystems and the consequent selective pressure of resistant strains lead to multidrug resistance (AMR), an expanding global phenomenon. Indeed, this phenomenon represents a major public health target with significant clinical implications related to increased morbidity and mortality and prolonged hospital stays. The current presence of microorganisms multi-resistant to antibiotics isolated in patients is a problem because of the additional burden of disease it places on the most fragile patients and the difficulty of finding effective therapies. In recent decades, international organizations like the World Health Organization (WHO) and the European Centre for Disease Prevention and Control (ECDC) have played significant roles in addressing the issue of AMR. The ECDC estimates that in the European Union alone, antibiotic resistance causes 33,000 deaths and approximately 880,000 cases of disability each year. The epidemiological impact of AMR inevitably also has direct economic consequences related not only to the loss of life but also to a reduction in the number of days worked, increased use of healthcare resources for diagnostic procedures and the use of second-line antibiotics when available. In 2015, the WHO, recognising AMR as a complex problem that can only be addressed by coordinated multi-sectoral interventions, promoted the One Health approach that considers human, animal, and environmental health in an integrated manner. In this review, the authors try to address why a collaboration of all stakeholders involved in AMR growth and management is necessary in order to achieve optimal health for people, animals, plants, and the environment, highlighting that AMR is a growing threat to human and animal health, food safety and security, economic prosperity, and ecosystems worldwide.

The use of honey bee (Apis mellifera L.) as biological monitors for pathogenic bacteria and antimicrobial resistance: A systematic review

The phenomenon of antimicrobial resistance (AMR) is an increasingly real and relevant health problem. It is essential to verify the spread of this phenomenon in the environment. The European honey bee, Apis mellifera L., is a globally managed pollinator continuously used for biomonitoring thanks to its morphological and behavioural characteristics. During their foraging activities, a large number of honey bees move in the area surrounding the hive within a 1.5 km of radius. Besides, their body covered with hair and bristles are able to intercept pollen and minute particles, such as atmospheric particles, contaminants and microorganisms. For these reasons, A. mellifera L. is widely used as an environmental sentinel, especially for detecting pollutants, pesticides, microorganisms, and AMR. This systematic review aimed to collect and summarize the role of honey bee colonies as a biological monitor of AMR pathogenic bacteria and the environmental spread of antimicrobial resistance genes (ARGs). From honey bees were isolated a wide range of pathogenic and environmental bacteria strains, harbouring AMR and ARGs. However, AMR and ARGs were detected not only in environmental bacteria but also in symbiotic bacteria colonizing the bee gut. This systematic review highlights the employment of potential use of honey bees as AMR sentinel helpful for ecosystem health to implement possible control measures for humans, animals and plants, in the context of the "One-Health" approach.