Monitoring Antimicrobial Resistance Dissemination in Aquatic Systems

A case study on pharmaceutical residues and antimicrobial resistance genes in Costa Rican rivers: A possible route of contamination for feline and other species

In this investigation, the presence of antibiotics and pharmaceuticals in Costa Rican surface waters, specifically in regions near feline habitats, was examined. The study revealed that 47% of the water samples contained detectable traces of at least one antibiotic. Ciprofloxacin and norfloxacin were the most frequently detected compounds, each with a detection rate of 27%. Other antibiotics, such as erythromycin, roxithromycin, and trimethoprim, were also found but at lower frequencies, around 14%. Notably, all antibiotic concentrations remained below 10 ng/L, with ciprofloxacin, norfloxacin, and erythromycin showing the highest concentrations. Furthermore, the investigation revealed the presence of non-antibiotic pharmaceutical residues in the water samples, typically at concentrations below 64 ng/L. Tramadol was the most frequently detected compound, present in 18% of the samples. The highest concentrations were observed for acetaminophen and tramadol, measuring 64 and 10 ng/L, respectively. Comparing these findings with studies conducted in treated wastewater and urban rivers, it became evident that the concentrations of antibiotics and pharmaceuticals were notably lower in this study. While previous research reported higher values, the limited number of studies conducted in protected areas raises concerns about the potential environmental impact on biodiversity. In summary, these results emphasize the importance of monitoring pharmaceutical residues and antimicrobial resistance genes ARGs in vulnerable ecosystems, especially those in close proximity to feline habitats in Costa Rica. Additionally, the study delved into the detection of (ARGs). All tested water samples were positive for at least one ARG, with the blaTEM gene being the most prevalent at 82%, followed by tetS at 64% and qnrB at 23%. Moreover, this research shed light on the complexity of evaluating ARGs in environmental samples, as their presence does not necessarily indicate their expression. It also highlighted the potential for co-selection and co-regulation of ARGs, showcasing the intricate behaviors of these genes in aquatic environments.

River rejuvenation in urban India for enhancing living conditions through integrated water resources management

India, being a developing country, faces big challenges in ensuring water, sanitation, and hygiene (WASH) for all. This case study presents the performance evaluation of a large wastewater management and sanitation-related infrastructure in a metropolitan city in North India. "Dravyavati River Project" is the major sanitation program of the water-stressed Jaipur city based on the concept of river rejuvenation of the long-lost Dravyavati River which flows across the city. The project envisages integrated urban water management such that it aims at the collection and treatment of wastewater (sewage network and treatment plants), safe disposal, ensuring continuous unpolluted flow, geological and ecological integrity to strengthen public health, to reduce the impact of water stress on the total water cycle by promoting groundwater recharge, and improvement in biodiversity. The technical assessment is based on the primary and secondary data collection of field samples and laboratory analysis of influent and effluent samples collected from the five sewage treatment plants (STPs). The results suggest that the project has largely delivered the envisaged environment, public well-being, and ecological and socioeconomic benefits, but there are substantial gaps in the conceived outputs and actual performance. The challenge lies in bridging these gaps and overcoming operational inefficiencies to ensure the sustainability of the Dravyavati River rejuvenation.

Effects of Dietary Supplementation with Bacillus amyloliquefaciens US573 on Intestinal Morphology and Gut Microbiota of European Sea Bass

Probiotics or direct-fed microbials (DFM) have proven strong potential for improving aquaculture sustainability. This study aims to evaluate the effects of dietary supplementation with the DFM Bacillus amyloliquefaciens US573 on growth performance, intestinal morphology, and gut microbiota (GM) of European sea bass. For this purpose, healthy fish were divided into two feeding trials in triplicate of 25 fish in each tank. The fish were fed with a control basal diet or a DFM-supplemented diet for 42 days. Results showed that, while no significant effects on growth performance were observed, the length and abundance of villi were higher in the DFM-fed group. The benefic effects of DFM supplementation included also the absence of cysts formation and the increase in number of goblet cells playing essential role in immune response. Through DNA metabarcoding analysis of GM, 5 phyla and 14 major genera were identified. At day 42, the main microbiome changes in response to B. amyloliquefaciens US573 addition included the significant decrease in abundance of Actinobacteria phylum that perfectly correlates with a decrease in Nocardia genus representatives which represent serious threat in marine and freshwater fish. On the contrary, an obvious dominance of Betaproteobacteria associated with the abundance in Variovorax genus members, known for their ability to metabolize numerous substrates, was recorded. Interestingly, Firmicutes, particularly species affiliated to the genus Sporosarcina with recent promising probiotic potential, were identified as the most abundant. These results suggest that B. amyloliquefaciens US573 can be effectively recommended as health-promoting DFM in European sea bass farming.

A Bioavailability Model to Predict the Impact of pH and Dissolved Organic Carbon on Ciprofloxacin Ecotoxicity to the Cyanobacterium Microcystis aeruginosa

Ciprofloxacin (CIP) is a pseudopersistent antibiotic detected in freshwater worldwide. As an ionizable chemical, its fate in freshwater is influenced by water chemistry factors such as pH, hardness, and dissolved organic carbon (DOC) content. We investigated the effect of pH, DOC, and Ca²⁺ levels on the toxicity of CIP to Microcystis aeruginosa and developed a bioavailability model on the basis of these experimental results. We found that the zwitterion (CIP^+/- ) is the most bioavailable species of CIP to M. aeruginosa, whereas DOC is the most dominant factor reducing CIP toxicity, possibly via binding of both CIP^+/- and CIP⁺ to DOC. pH likely also regulates CIP-DOC binding indirectly through its influence on CIP speciation. In addition, higher tolerance to CIP by M. aeruginosa was observed at pH < 7.2, but the underlying mechanism is yet unclear. Calcium was identified as an insignificant factor in CIP bioavailability. When parameterized with the data obtained from toxicity experiments, our bioavailability model is able to provide accurate predictions of CIP toxicity because the observed and predicted total median effective concentrations deviated by <28% from each other. Our model predicts that changes in pH and DOC conditions can affect CIP toxicity by up to 10-fold, suggesting that CIP in many natural environments is likely less toxic than in standard laboratory toxicity experiments. Environ Toxicol Chem 2022;41:2835-2847. © 2022 SETAC.

Establishing a marine monitoring programme to assess antibiotic resistance: A case study from the Gulf Cooperation Council (GCC) region

The World Health Organization considers antimicrobial resistance as one of the most pressing global issues which poses a fundamental threat to human health, development, and security. Due to demographic and environmental factors, the marine environment of the Gulf Cooperation Council (GCC) region may be particularly susceptible to the threat of antimicrobial resistance. However, there is currently little information on the presence of AMR in the GCC marine environment to inform the design of appropriate targeted surveillance activities. The objective of this study was to develop, implement and conduct a rapid regional baseline monitoring survey of the presence of AMR in the GCC marine environment, through the analysis of seawater collected from high-risk areas across four GCC states: (Bahrain, Oman, Kuwait, and the United Arab Emirates). 560 Escherichia coli strains were analysed as part of this monitoring programme between December 2018 and May 2019. Multi-drug resistance (resistance to three or more structural classes of antimicrobials) was observed in 32.5% of tested isolates. High levels of reduced susceptibility to ampicillin (29.6%), nalidixic acid (27.9%), tetracycline (27.5%), sulfamethoxazole (22.5%) and trimethoprim (22.5%) were observed. Reduced susceptibility to the high priority critically important antimicrobials: azithromycin (9.3%), ceftazidime (12.7%), cefotaxime (12.7%), ciprofloxacin (44.6%), gentamicin (2.7%) and tigecycline (0.5%), was also noted. A subset of 173 isolates was whole genome sequenced, and high carriage rates of qnrS1 (60/173) and bla _CTX-M-15 (45/173) were observed, correlating with reduced susceptibility to the fluoroquinolones and third generation cephalosporins, respectively. This study is important because of the resistance patterns observed, the demonstrated utility in applying genomic-based approaches to routine microbiological monitoring, and the overall establishment of a transnational AMR surveillance framework focussed on coastal and marine environments.

Antibiotic resistomes in water supply reservoirs sediments of central China: main biotic drivers and distribution pattern

Water supply reservoirs form one of the critical drinking water resources. Their water quality directly affects human health. However, reservoir sediments have not received adequate attention in antibiotic resistance genes (ARGs) dissemination, though they reflect long-term ARGs contamination of water supply reservoirs. Moreover, the physicochemical parameters in water supply reservoir sediments are generally better than those in the other media. Thus, the main ARGs biotic drivers of the media would demonstrate their unique characteristics. In this study, sediment samples were collected from 10 water supply reservoirs in central China, and the antibiotic resistomes were determined with the metagenomic method. As revealed from the results, 174 ARGs (18 ARG types) were detected in the reservoir sediment. Besides, multidrug-, sulfonamide-, and vancomycin-ARGs were the dominant ARGs in the sediment samples. The macrolide-resistant Microcystis was prevalent (100% detection frequency with 0.35% average percentage) in reservoir sediments and posed potential risks to human health. Furthermore, the results of the Mantel test and VPA demonstrated that mobile genetic elements (MGEs) were the more essential biotic drivers in ARG contents of reservoir sediments rather than the bacteria community.

The role of antibiotics and heavy metals on the development, promotion, and dissemination of antimicrobial resistance in drinking water biofilms

Antimicrobial resistance (AMR), as well as the development of biofilms in drinking water distribution systems (DWDSs), have become an increasing concern for public health and management. As bulk water travels from source to tap, it may accumulate contaminants of emerging concern (CECs) such as antibiotics and heavy metals. When these CECs and other selective pressures, such as disinfection, pipe material, temperature, pH, and nutrient availability interact with planktonic cells and, consequently, DWDS biofilms, AMR is promoted. The purpose of this review is to highlight the mechanisms by which AMR develops and is disseminated within DWDS biofilms. First, this review will lay a foundation by describing how DWDS biofilms form, as well as their basic intrinsic and acquired resistance mechanisms. Next, the selective pressures that further induce AMR in DWDS biofilms will be elaborated. Then, the pressures by which antibiotic and heavy metal CECs accumulate in DWDS biofilms, their individual resistance mechanisms, and co-selection are described and discussed. Finally, the known human health risks and current management strategies to mitigate AMR in DWDSs will be presented. Overall, this review provides critical connections between several biotic and abiotic factors that influence and induce AMR in DWDS biofilms. Implications are made regarding the importance of monitoring and managing the development, promotion, and dissemination of AMR in DWDS biofilms.

The Requirement of Genetic Diagnostic Technologies for Environmental Surveillance of Antimicrobial Resistance

Antimicrobial resistance (AMR) is threatening modern medicine. While the primary cost of AMR is paid in the healthcare domain, the agricultural and environmental domains are also reservoirs of resistant microorganisms and hence perpetual sources of AMR infections in humans. Consequently, the World Health Organisation and other international agencies are calling for surveillance of AMR in all three domains to guide intervention and risk reduction strategies. Technologies for detecting AMR that have been developed for healthcare settings are not immediately transferable to environmental and agricultural settings, and limited dialogue between the domains has hampered opportunities for cross-fertilisation to develop modified or new technologies. In this feature, we discuss the limitations of currently available AMR sensing technologies used in the clinic for sensing in other environments, and what is required to overcome these limitations.

Prevalence and Traits of Mobile Colistin Resistance Gene Harbouring Isolates from Different Ecosystems in Africa

The mobile colistin resistance (mcr) gene threatens the efficacy of colistin (COL), a last-line antibiotic used in treating deadly infections. For more than six decades, COL is used in livestock around the globe, including Africa. The use of critically important antimicrobial agents, like COL, is largely unregulated in Africa, and many other factors militate against effective antimicrobial stewardship in the continent. Currently, ten mcr genes (mcr-1 to mcr-10) have been described. In Africa, mcr-1, mcr-2, mcr-3, mcr-5, mcr-8, and mcr-9 have been detected in isolates from humans, animals, foods of animal origin, and the environment. These genes are harboured by Escherichia coli, Klebsiella, Salmonella, Citrobacter, Enterobacter, Pseudomonas, Aeromonas, Alcaligenes, and Acinetobacter baumannii isolates. Different conjugative and nonconjugative plasmids form the backbone for mcr in these isolates; however, mcr-1 and mcr-3 have also been integrated into the chromosome of some African strains. Insertion sequences (ISs) (especially ISApl1), either located upstream or downstream of mcr, class 1 integrons, and transposons, are drivers of mcr in Africa. Genes coding multi/extensive drug resistance and virulence are colocated with mcr on plasmids in African strains. Transmission of mcr to/among African strains is nonclonal. Contact with mcr-habouring reservoirs, the consumption of contaminated foods of animal/plant origin or fluid, animal-/plant-based food trade and travel serve as exportation, importation, and transmission routes of mcr gene-containing bacteria in Africa. Herein, the current status of plasmid-mediated COL resistance in humans, food-producing animals, foods of animal origin, and environment in Africa is discussed.

Azole antifungal resistance in fungal isolates from wastewater treatment plant effluents

Wastewater treatment plants (WWTPs) can be significant sources of antifungal resistant fungi, which can disseminate further in the environment by getting into rivers together with effluents discharged from WWTPs and pose a risk for human health. In this study, the presence of azole resistance was determined in fungal isolates from treated effluents of two WWTPs using the standard microdilution method from Clinical and Laboratory Standards Institute (CLSI). A total of 41 fungal isolates representing 23 fungal species and 16 fungal genera were obtained. Fungal genera related to the known human and/or plant pathogens such as Aspergillus, Fusarium, and Candida were detected. Among the observed species, the susceptibility of Aspergillus fumigatus and Fusarium oxysporum was tested against fluconazole (FCZ), ketoconazole (KTZ), itraconazole (ITZ), and voriconazole (VCZ). The isolate A. fumigatus was susceptible to KTZ, ITZ, and VCZ, while it showed resistance against FCZ. On the contrast, the isolate F. oxysporum showed resistance to KTZ, ITZ, and VCZ. Comparatively, VCZ showed highest activity against both A. fumigatus and F. oxysporum. Analysis of the gene Cyp51A for the A. fumigatus isolate showed no evidence of drug resistance that could be related to point mutations and/or tandem repeats in the gene. To the best of our knowledge, this is the first susceptibility test study on A. fumigatus and F. oxysporum isolates from the WWTPs of South Africa. In conclusion, this study indicated an urgent need for thorough investigation with larger group of fungal isolates from different regions of South Africa to broadly understand the role of WWTPs in the dissemination of azole antifungal drug resistance.

Spatiotemporal Changes of Antibiotic Resistance and Bacterial Communities in Drinking Water Distribution System in Wrocław, Poland

Antibiotic resistance of bacteria is an emerging problem in drinking water treatment. This paper presents the comparison of antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) prevalence during the summer and winter season in a full-scale drinking water distribution system (DWDS) supplied by two water treatment plants (WTPs). The effect of distance from WTP and physical–chemical water parameters on its microbial properties was also tested. Bacterial consortia dwelling in bulk tap water were additionally compared by means of denaturating gradient gel electrophoresis (DGGE). The results showed that among ARB, bacteria resistant to ceftazidime (CAZ) were the most abundant, followed by bacteria resistant to amoxicillin (AML), ciprofloxacin (CIP), and tetracycline (TE). Numerous ARGs were detected in tested tap water samples. Only CAZ resistant bacteria were more prevalent in the season of increased antibiotic consumption, and only AML resistant bacteria relative abundances increase was statistically significant with the distance from a WTP. The investigated tap water meets all legal requirements. It is therefore safe to drink according to the law. Nevertheless, because antibiotic resistance could pose a threat to consumer health, it should be further monitored in DWDSs.

Country Income Is Only One of the Tiles: The Global Journey of Antimicrobial Resistance among Humans, Animals, and Environment

Antimicrobial resistance (AMR) is one of the most complex global health challenges today: decades of overuse and misuse in human medicine, animal health, agriculture, and dispersion into the environment have produced the dire consequence of infections to become progressively untreatable. Infection control and prevention (IPC) procedures, the reduction of overuse, and the misuse of antimicrobials in human and veterinary medicine are the cornerstones required to prevent the spreading of resistant bacteria. Purified drinking water and strongly improved sanitation even in remote areas would prevent the pollution from inadequate treatment of industrial, residential, and farm waste, as all these situations are expanding the resistome in the environment. The One Health concept addresses the interconnected relationships between human, animal, and environmental health as a whole: several countries and international agencies have now included a One Health Approach within their action plans to address AMR. Improved antimicrobial usage, coupled with regulation and policy, as well as integrated surveillance, infection control and prevention, along with antimicrobial stewardship, sanitation, and animal husbandry should all be integrated parts of any new action plan targeted to tackle AMR on the Earth. Since AMR is found in bacteria from humans, animals, and in the environment, we briefly summarize herein the current concepts of One Health as a global challenge to enable the continued use of antibiotics.