Search Results (73)

Background/Objective: Sewage sludge (biosolids) is increasingly reused as a fertilizer to recycle nutrients and close material cycles; however, concerns persist regarding antibiotics and antimicrobial resistance. This study evaluated the agronomic safety and microbiological integrity of biosolid fertilization in soybean and maize systems, with particular attention to grain quality and food safety. Methods: Soybean and maize were cultivated in greenhouse microcosms under biosolid or mineral fertilization. Soil, roots, shoots, and grains were analyzed for antibiotic residues using LC–MS/MS and antibiotic-resistant bacteria (ARB) using culture-based assays. Minimum inhibitory concentrations for isolates from grains were compared with clinical breakpoints to verify phenotypic susceptibility. Multivariate analyses (PCA) integrating real-time antibiotic concentrations and updated resistance indicators were performed using centered and scaled data. Results: Fluoroquinolones were the predominant residues introduced by biosolids and exhibited consistent time-dependent declines across all treatments, although low concentrations remained detectable at 90 d in several soil–fertilizer–crop combinations. Tetracyclines, macrolides, and sulfonamides showed similar decreasing trends, with planted soils displaying faster dissipation than bulk control soils. Biosolid fertilization increased shoot biomass by 1.5–2.3-fold and nitrogen, phosphorus, and potassium uptake by 30–60% without impairing soybean nodulation or nitrogenase function. ARB was observed in all soils, including mineral and plant-free controls, indicating a natural background resistome. Ciprofloxacin-resistant isolates were detected in one simple sampling point, and MDR proportions were transient (67%), returning to their background levels by 45–90 days. PCA showed that crop presence, not fertilizer type, was the primary driver of microbial ordination, and that antibiotic concentrations and resistance indicators were only weakly aligned, indicating a limited selective pressure. No antibiotic residues or phenotypically resistant bacteria were detected in the soybean or maize grains. Conclusions: Updated residue, resistance, and multivariate data confirmed that biosolids did not induce, amplify, or transfer antibiotic resistance and maintained complete grain safety. Properly treated biosolids function as safe, agronomically beneficial fertilizers aligned with One Health goals, enhancing crop productivity without compromising food quality or increasing antimicrobial resistance. Full article

The phenotypic resistance of 56 Enterococcus faecalis isolates from Eurasian griffon vultures was subjected to surveillance testing with the microdilution method using a standardized panel of antimicrobials. Isolates were also characterized by MLST. Additionally, the genome of 19 isolates with phenotypic resistance to linezolid, ciprofloxacin, chloramphenicol and/or high-level resistance to gentamicin were sequenced to determine their antimicrobial resistance (ARGs) and virulence-associated genes and to identify mobile genetic elements (MGEs). Most isolates (82.1%) exhibited non-wild-type phenotypes to six antimicrobial agents, and multidrug resistance (MDR) was detected in 34% of the isolates. Most MDR isolates (53%) belonged to ST16, ST116 and ST35. ARGs were localized on the chromosome as well as on various MGEs previously reported in human, food and livestock isolates, suggesting that vultures may acquire antibiotic-resistant bacteria (ARBs) and/or ARGs as a consequence of anthropogenic pollution. Overall, 22 virulence-associated genes encoding cell surface and secreted factors were identified, some of which were located on MGEs that also carried ARGs. The significant proportion of E. faecalis isolates recovered from vultures that exhibited MDR phenotypes and harbored MGEs carrying ARGs and virulence-associated genes is cause for concern, since vultures may act as spreaders of these genes to the environment, domestic animals and humans. Full article

Antibiotics have revolutionized medicine and animal production, yet their extensive use has accelerated the emergence and spread of antimicrobial resistance (AMR). Beyond clinical contexts, livestock and aquaculture are now recognized as major contributors to the global resistome. This review synthesizes evidence across cattle, poultry, swine, sheep and goats, and aquaculture, highlighting how antimicrobial usage shapes resistance at the human–animal–environment interface. A substantial proportion of administered drugs is excreted unmetabolized, leading to the accumulation of unmetabolized antimicrobial residues, antibiotic-resistant bacteria (ARB), and antibiotic resistance genes (ARGs) in soils, manures, waters, sediments, and air. These reservoirs function as long-term sources and dissemination pathways through runoff, leaching, bioaerosols, effluents, and biological vectors. Despite different production systems, similar ARG families dominate, particularly those conferring resistance to tetracyclines, sulfonamides, and β-lactams. Mobile genetic elements and co-selectors such as heavy metals, disinfectants, and microplastics reinforce their persistence. Aquaculture, where water serves both as habitat and vector, emerges as a critical hotspot, while small ruminant systems remain under-researched despite their importance in many low- and middle-income countries. This synthesis highlights convergent patterns across sectors: antimicrobial use drives ARG enrichment; manures, litters, sediments, and effluents act as persistent reservoirs; and dissemination routes connect farms, ecosystems, and human populations. Within a One Health framework, mitigation requires preventive strategies—vaccination, biosecurity, and optimized waste management—supported by harmonized stewardship policies and integrated environmental surveillance. Full article

Wastewater treatment plants (WWTPs) are recognized hotspots for the convergence and dissemination of antimicrobial-resistant bacteria (ARB) and antimicrobial resistance genes (ARGs) into the environment. Among ARB, carbapenem-resistant Enterobacterales (CR-E) and extended-spectrum β-lactamase-producing Escherichia coli and Klebsiella pneumoniae (ESBL-Ec/Kp) are of particular concern due to their clinical relevance. We characterized 30 CR-E and 176 ESBL-Ec/Kp isolates (two of them were both ESBL-producing and carbapenem-resistant) recovered from influent, intermediate, effluent, sludge, and downstream river samples collected from two WWTPs in northern Spain. Isolates were evaluated for resistance phenotypes against 12 antimicrobials, and β-lactamase-encoding genes were assessed by PCR and sequencing. Notably, among CR-E isolates, bla_KPC-2 was the most prevalent (93%), followed by bla_OXA-48-like, detected in two isolates from non-treated and pasteurized sludge; both isolates also carried bla_CTX-M-15, a finding not previously reported specifically in sludge samples. Among ESBL-Ec/Kp, a broad diversity of ESBL genes was identified, including bla_{CTX-M group 1} (variants 1, 3, 15, 32, 55), bla_{CTX-M group 9} (variants 14, 27, 65, 97), bla_SHV-12 and bla_TEM-169. The most prevalent ESBL gene was bla_CTX-M-15 (48.3%), followed by bla_CTX-M-14, bla_CTX-M-32, and bla_SHV-12, detected in 10.8%, 8.5%, and 6.8% of isolates, respectively. CR-E and ESBL-Ec/Kp were found in all sample types and were still detectable at terminal stages, indicating persistence throughout treatment. These findings support the need to improve and optimize current wastewater treatment methods and underscore the importance of integrating culture-based and molecular methods into routine WWTP monitoring for early detection of microbiological hazards, although further research is still needed. Full article

The One Health approach is used to assess health-associated risks resulting from human exposure to antibiotic-resistant bacteria (ARB) that pose a significant public health risk. In this approach, wastewater treatment plants (WWTPs) play an important role in reducing bacteria and antibiotic-resistant genes (ARGs) in the environment. The ESKAPE (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp.) are of significant concern due to their ability to evade the effects of multiple antibiotics, including last-resort treatments such as carbapenems and glycopeptides. This study aimed to investigate the environmental surveillance of ESKAPE bacteria in wastewater and their adjacent receiving water bodies in Limpopo Province, South Africa. Methodology: Over a period of 6 months, all isolates were identified phenotypically, and genomic DNA was extracted using the QIAamp 96 DNA QIAcube^® HT Kit. Species-specific PCR was performed, followed by Sanger sequencing. The relevant sequences were compared to NCBI GenBank references using BLAST for confirmation and to assess the potential human health-associated risks. Results: ESKAPE organisms identified phenotypically were confirmed using PCR in both WWTP samples. Bacteria such as Acinetobacter baumannii and Enterobacter spp. were not detected in upstream or downstream river samples, particularly during August and September. In December and January, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, and Pseudomonas aeruginosa were not detected in effluent samples at both sites. Phylogenetic analysis revealed a diverse range of clinically significant genera, including Pseudomonas, Klebsiella, Enterobacter, and Staphylococcus, with strains closely related to global clinical isolates. Many of the isolates were associated with resistance to carbapenems, fluoroquinolones, and aminoglycosides. In addition, some strains clustered with both methicillin-sensitive and methicillin-resistant lineages. Conclusions: The findings emphasise the urgent need for increased genomic surveillance in environmental settings affected by wastewater discharge and highlight the importance of integrated antimicrobial resistance monitoring that connects clinical and environmental health sectors. Full article

Non-human primates (NHPs) are close relatives of humans and can serve as hosts for many zoonotic pathogens. They play crucial role in spreading antimicrobial resistant bacteria (AMR) to humans across various ecological niches. The spread of antimicrobial resistance in NHPs may complicate wildlife conservation efforts, as it may threaten domestic livestock, endangered species as well as human’s health. This review analyses the existing literature on the prevalence of AMR in NHP species, including Rhinopithecus roxellana, Macaca fascicularis, and Sapajus nigritus, to create awareness in all stake holders involve in the fight against AMR on the serious potential threats that these primates pose. Methods: We performed a comprehensive literature search using the PubMed (National Library of Medicine-NLM), Scopus (Elsevier), Web of Science Core Collection (Clarivate Analytics), Springer Link (Springer), and Science Direct (Elsevier) databases until January, 2025. The search strategy combined terms from the areas of non-human primates, antibiotic resistance, antimicrobial resistance, and antibacterial resistance genes (ARGs). Studies that isolated bacteria from NHPs and assessed phenotypic resistance to specific antibiotics as well as studies that identified ARGs in bacteria isolated from NHPs were included. Data were synthesised thematically across all included studies. Results: A total of 37 studies were included (explained as Cercopithecidae (n = 23), Callithrix (n = 6), Cebidae (n = 4), Hominidae (n = 3), and Atelidae (n = 1)). The results showed that the most common ARB across the various NHPs and geographical settings was Staphylococcus spp. (45.95%) and Escherichia spp. (29.73%). The tested antibiotics that showed high levels of resistance in NHPs included Tetracycline (40.54%), Ciprofloxacin (32.43%), and Erythromycin (24.34%), whereas ermC, tetA, tetM, aadA, aph (3″)-II, and qnrS1 were the most widely distributed antibiotic resistance genes in the studies. Conclusion: NHPs are potential natural reservoirs of AMR, therefore global policy makers should consider making NHPs an indicator species for monitoring the spread of ARB. Full article

The increasing presence of heavy metals in wastewater is a growing environmental and public health concern, particularly due to their role in promoting the spread of antibiotic-resistant bacteria (ARB) through co-selection mechanisms. This review explores recent advances in real-time detection of heavy metals and some other pollutants using chemical sensors as a strategic tool to limit ARB proliferation. It provides an overview of sensor types, including electrochemical, optical, biosensors, and molecularly imprinted polymer (MIP) sensors, and assesses their suitability for monitoring pollutants in complex wastewater matrices. Emphasis is placed on the integration of these technologies with Internet of Things (IoT) platforms, portable and autonomous systems, and data-driven approaches for multi-metal detection, selectivity enhancement, and predictive analysis. The review also discusses current challenges such as sensor stability, interference, and cost-efficiency, and outlines future directions in real-time environmental monitoring and antibiotic resistance control. Overall, chemical sensor-based monitoring offers a promising, scalable solution for safeguarding ecosystems and public health in the face of growing antimicrobial resistance. Full article

The persistence of antibiotics and antibiotic-resistant bacteria (ARB) in aquatic environments poses a significant risk to both the environment and public health. Conventional wastewater treatment systems are often inefficient in completely removing these emerging contaminants, highlighting the need for advanced and integrative treatment approaches. Electrocoagulation (EC) has emerged as a promising electrochemical method due to its operational simplicity, low chemical demand, and versatility in treating a wide range of wastewater types. This review critically analyzes the efficiency of EC, both as a standalone process and in combination with complementary technologies such as electrooxidation, membrane filtration, advanced oxidation processes (AOPs), and biological treatments. Emphasis is placed on the removal mechanisms, influencing parameters (pH, current density, electrode material), and the synergistic effects that enhance the degradation of antibiotics and the inactivation of ARB. Additionally, the review discusses the limitations of EC, including electrode passivation and energy consumption. The integration of EC with other technologies demonstrates improved pollutant removal and process robustness, offering a viable alternative for treating complex wastewater streams. This work provides a perspective on the current state and future potential of EC-based hybrid systems in mitigating the environmental impact of antibiotic pollutants and antimicrobial resistance. Full article

Antimicrobial-resistant bacteria (ARB) in the ESKAPE group include Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp. These pathogens continue to pose a global threat to human health. Urban and non-urban rivers affected by anthropogenic activities such as farming can act as reservoirs for ARB. The influx of wastewater from animal farms and irrigation processes can affect the normal microbiota in surrounding waterbodies. New bacteria, such as those in the ESKAPE family, may be introduced into these waterbodies, since most ESKAPE pathogens are domiciled in humans and animals. There is a dearth of information on the persistence of ESKAPE isolates and their associated health hazards in non-nosocomial settings. Therefore, this review aimed to collect data on the global distribution of ESKAPE pathogens in aquatic systems. PubMed and Google Scholar were searched for articles published from 2009 to 2025. A total of 76 studies published in peer-reviewed journals were included. Data were collected from 21 papers for E. faecium/faecalis, 12 for S. aureus, 15 for K. pneumoniae, 11 for A. baumannii, 8 for P. aeruginosa, and 9 for Enterobacter spp. The findings in this review will increase public health awareness on the significance of ESKAPE pathogens in aquatic systems. Full article

Background/Objectives: The increasing presence of antimicrobial residues and antibiotic-resistant bacteria (ARB) in effluents from wastewater treatment plants (WWTP) has become a critical concern for environmental and public health. This study aimed to investigate the occurrence, concentrations, and ecological risks of commonly used antimicrobials as well as the prevalence of clinically relevant ARB in treated effluents. Methods: A five-month monitoring campaign was conducted at a major WWTP in Curitiba, Brazil. Thirteen antibiotics were quantified using LC-MS/MS, resistant bacteria were identified via phenotypic profiling, and ecotoxicological assays were performed with Desmodesmus subspicatus. Risk assessments included hazard quotient (HQ) calculations for ecotoxicity and resistance selection as well as multivariate and correlation analyses. Results: All antibiotics were consistently detected over five months, with total concentrations ranging from 1730 to 2840 ng L⁻¹. Clinically relevant ARB (Escherichia coli, Klebsiella pneumoniae, and Enterobacter cloacae) resistant to high-priority antibiotics were also isolated. Ecotoxicological tests showed moderate growth inhibition only in undiluted effluent. HQ values for ecotoxicity were <1, but HQ for resistance selection exceeded 1 for all compounds. Multivariate analyses showed strong associations between fluoroquinolone and macrolide concentrations and ARB detection. Conclusions: Although WWTPs reduce pollutant loads, conventional processes may not fully eliminate antimicrobials and ARB, highlighting the need for advanced treatments. Culture-based detection may have underestimated the resistance diversity. These findings support the integration of resistance-based discharge thresholds into regulations, and provide a replicable model for AMR surveillance in tropical urban systems. Full article

The use of untreated livestock manure in urban agriculture sustains soil fertility but risks disseminating antimicrobial resistance (AMR) in resource-limited settings. This study characterized antibiotic-resistant bacteria (ARB) prevalence across manure–soil–vegetable pathways in Blantyre, Malawi. Using a cross-sectional design, we collected 35 samples (poultry/pig manure, farm/home soils, Brassica rapa subsp. chinensis, Brassica rapa, and Amaranthus spp.) from five livestock farms. Microbiological analysis with API 20E identification and disk diffusion testing revealed clear differences in contamination: Escherichia coli dominated pig manure (52%) and farm soil (35%), with detection in vegetables suggesting possible transfer (e.g., 20% in Brassica rapa subsp. chinensis), while Klebsiella pneumoniae contaminated all sample types (peak: 60% vegetables and 67% home soils). All manure isolates exhibited sulfamethoxazole–trimethoprim resistance, with 50% of pig manure E. coli showing cefotaxime resistance. Soil isolates mirrored these patterns (100% ampicillin resistance in K. pneumoniae and 77% cefotaxime resistance in farm soil E. coli). Vegetables displayed severe multidrug resistance (100% E. coli and 80% K. pneumoniae resistant to ≥3 classes), including critical gentamicin resistance (100% E. coli). Composting for ≤6 weeks, as practiced on the studied farms, did not eliminate ARBs, suggesting that longer durations may be needed. Notably, this study provides the first phenotypic evidence of presumptive Pasteurella-like organisms on edible leafy vegetables, specifically 45% in Amaranthus spp. and 6.1% in Brassica rapa, suggesting a potential zoonotic transmission route from livestock farms that requires molecular confirmation. These findings demonstrate manure-amended farms as AMR reservoirs, necessitating extended composting and antibiotic stewardship to mitigate One Health risks. Full article

Background: The emergence and spread of antimicrobial-resistant bacteria (ARB) has become an urgent global concern as a silent pandemic. When taking measures to reduce the impact of antimicrobial resistance (AMR) on the environment, it is important to consider appropriate treatment of wastewater from medical facilities. Methods: In this study, a continuous-flow wastewater treatment system using ozone and ultraviolet light, which has excellent inactivation effects, was implemented in a hospital in an urban area of Japan. Results: The results showed that 99% (2 log₁₀) of Gram-negative rods and more than 99.99% (>99.99%) of ARB comprising ESBL-producing Enterobacterales were reduced by ozone treatment from the first day after treatment, and ultraviolet light-emitting diode (UV-LED) irradiation after ozone treatment; UV-LED irradiation after ozonation further inactivated the bacteria to below the detection limit. Inactivation effects were maintained throughout the treatment period in this study. Metagenomic analysis showed that the removal of these microorganisms at the DNA level tended to be gradual in ozone treatment; however, the treated water after ozone/UV-LED treatment showed a 2 log₁₀ (>99%) removal rate at the end of the treatment. The residual antimicrobials in the effluent were benzylpenicillin, cefpodoxime, ciprofloxacin, levofloxacin, azithromycin, clarithromycin, doxycycline, minocycline, and vancomycin, which were removed by ozone treatment on day 1. In contrast, the removal of ampicillin and cefdinir ranged from 19% to 64% even when combined with UV-LED treatment. Conclusions: Our findings will help to reduce the discharge of ARB and antimicrobials into rivers and maintain the safety of aquatic environments. Full article

Antimicrobial resistance (AMR) is a growing global health threat, with wild birds increasingly recognized as potential reservoirs of resistant pathogens and as sentinels of environmental AMR. This study investigated the occurrence and AMR profiles of Gram-negative bacteria isolated from wild birds that died at the Wildlife Rescue Center in Vanzago, Lombardy, in 2024. Cloacal swabs were collected from 112 birds representing various ecological categories. A total of 157 Gram-negative bacteria were isolated and identified, including clinically relevant genera and species, such as Escherichia coli, Klebsiella pneumoniae, Enterobacter spp., Salmonella spp., Pseudomonas aeruginosa, and Acinetobacter baumannii. Antimicrobial susceptibility testing revealed resistance to first-line and critically important antimicrobials, including those exclusively authorized for human use. Notably, a phenotype compatible with Extended-Spectrum Beta-Lactamase (ESBL) production was detected in four out of ten (40%) K. pneumoniae isolates. In addition, 20 out of the 157 (12.7%) isolated bacteria phenotypically exhibited a resistance profile indicative of AmpC beta-lactamase (AmpC) production, including Enterobacter spp. and P. aeruginosa. Resistance patterns were particularly interesting in birds with carnivorous, scavenging, or migratory-associated behaviors. These findings highlight the role of wild birds in the ecology and dissemination of antimicrobial-resistant bacteria (ARB) and highlight the need for wildlife-based AMR monitoring programs as part of a One Health approach. Full article

Antimicrobial resistance (AMR) has emerged as a planetary health emergency, driven not only by the clinical misuse of antibiotics but also by diverse environmental dissemination pathways. This review critically examines the role of environmental compartments—water, soil, and air—as dynamic reservoirs and transmission routes for antibiotic-resistant bacteria (ARB) and resistance genes (ARGs). Recent metagenomic, epidemiological, and mechanistic evidence demonstrates that anthropogenic pressures—including pharmaceutical effluents, agricultural runoff, untreated sewage, and airborne emissions—amplify resistance evolution and interspecies gene transfer via horizontal gene transfer mechanisms, biofilms, and mobile genetic elements. Importantly, it is not only highly polluted rivers such as the Ganges that contribute to the spread of AMR; even low concentrations of antibiotics and their metabolites, formed during or after treatment, can significantly promote the selection and dissemination of resistance. Environmental hotspots such as European agricultural soils and airborne particulate zones near wastewater treatment plants further illustrate the complexity and global scope of pollution-driven AMR. The synergistic roles of co-selective agents, including heavy metals, disinfectants, and microplastics, are highlighted for their impact in exacerbating resistance gene propagation across ecological and geographical boundaries. The efficacy and limitations of current mitigation strategies, including advanced wastewater treatments, thermophilic composting, biosensor-based surveillance, and emerging regulatory frameworks, are evaluated. By integrating a One Health perspective, this review underscores the imperative of including environmental considerations in global AMR containment policies and proposes a multidisciplinary roadmap to mitigate resistance spread across interconnected human, animal, and environmental domains. Full article

Background: Antimicrobial resistance (AMR) is a growing global health concern, driven in part by the environmental release of antimicrobial-resistant bacteria (ARB) and antimicrobial resistance genes (ARGs). Aquatic systems, particularly those exposed to urban, agricultural, and industrial activity, are recognized as hotspots for AMR evolution and transmission. In Chile, the Aconcagua River—subject to multiple anthropogenic pressures—offers a representative model for studying the environmental dimensions of AMR. Methods: Thirteen surface water samples were collected along the Aconcagua River basin in a single-day campaign to avoid temporal bias. Samples were filtered through 0.22 μm membranes and cultured on MacConkey agar, either unsupplemented or supplemented with ceftazidime (CAZ) or ciprofloxacin (CIP). Isolates were purified and identified using MALDI-TOF mass spectrometry. Antibiotic susceptibility was evaluated using the Kirby–Bauer disk diffusion method in accordance with CLSI guidelines. Carbapenemase activity was assessed using the Blue-Carba test, and PCR was employed for the detection of the bla_VIM, bla_KPC, bla_NDM, and bla_IMP genes. Results: A total of 104 bacterial morphotypes were isolated; 80 were identified at the species level, 5 were identified at the genus level, and 19 could not be taxonomically assigned using MALDI-TOF. Pseudomonas (40 isolates) and Aeromonas (25) were the predominant genera. No growth was observed on CIP plates, while 24 isolates were recovered from CAZ-supplemented media, 87.5% of which were resistant to aztreonam. Five isolates exhibited resistance to carbapenems; two tested positive for carbapenemase activity and carried the bla_VIM gene. Conclusions: Our results confirm the presence of clinically significant resistance mechanisms, including bla_VIM, in environmental Pseudomonas spp. from the Aconcagua River. These findings highlight the need for environmental AMR surveillance and reinforce the importance of adopting a One Health approach to antimicrobial stewardship and wastewater regulation. Full article