The photo-based treatment technology simultaneously removes resistant bacteria and resistant genes from wastewater.

Because of the recent widespread usage of antibiotics, the acquisition and dissemination of antibiotic-resistance genes (ARGs) were prevalent in the majority of habitats. Generally, the biological wastewater treatment processes used in wastewater treatment plants have a limited efficiencies of antibiotics resistant bacteria (ARB) disinfection and ARGs degradation and even promote the proliferation of ARGs. Problematically, ARB and ARGs in effluent pose potential risks if they are not further treated. Photocatalytic oxidation is considered a promising disinfection technology, where the photocatalytic process generates many free radicals that enhance the interaction between light and deoxyribonucleic acid (DNA) for ARB elimination and subsequent degradation of ARGs. This review aims to illustrate the progress of photocatalytic oxidation technology for removing antibiotics resistant (AR) from wastewater in recent years. We discuss the sources and transfer of ARGs in wastewater. The overall removal efficiencies of ultraviolet radiation (UV)/chlorination, UV/ozone, UV/H2O2, and UV/sulfate-radical based system for ARB and ARGs, as well as the experimental parameters and removal mechanisms, are systematically discussed. The contribution of photocatalytic materials based on TiO2 and g-C3N4 to the inactivation of ARB and degradation of ARGs is highlighted, producing many free radicals to attack ARB and ARGs while effectively limiting the horizontal gene transfer (HGT) in wastewater. Finally, based on the reviewed studies, future research directions are proposed to realize specific photocatalytic oxidation technology applications and overcome current challenges.

The role of TiO2 and gC3N4 bimetallic catalysts in boosting antibiotic resistance gene removal through photocatalyst assisted peroxone process.

Antibiotics are extensively used in human medicine, aquaculture, and animal husbandry, leading to the release of antimicrobial resistance into the environment. This contributes to the rapid spread of antibiotic-resistant genes (ARGs), posing a significant threat to human health and aquatic ecosystems. Conventional wastewater treatment methods often fail to eliminate ARGs, prompting the adoption of advanced oxidation processes (AOPs) to address this growing risk. The study investigates the efficacy of visible light-driven photocatalytic systems utilizing two catalyst types (TiO2-Pd/Cu and g-C3N4-Pd/Cu), with a particular emphasis on their effectiveness in eliminating blaTEM, ermB, qnrS, tetM. intl1, 16 S rDNA and 23 S rDNA through photocatalytic ozonation and peroxone processes. Incorporating O3 into photocatalytic processes significantly enhances target removal efficiency, with the photocatalyst-assisted peroxone process emerging as the most effective AOP. The reemergence of targeted contaminants following treatment highlights the pivotal importance of AOPs and the meticulous selection of catalysts in ensuring sustained treatment efficacy. Furthermore, Polymerase Chain Reaction-Denaturing Gradient Gel Electrophoresis (PCR-DGGE) analysis reveals challenges in eradicating GC-rich bacteria with TiO2 and g-C3N4 processes, while slight differences in Cu/Pd loadings suggest g-C3N4-based ozonation improved antibacterial effectiveness. Terminal Restriction Fragment Length Polymorphism analysis highlights the efficacy of the photocatalyst-assisted peroxone process in treating diverse samples.

Breeding for brown plant hopper resistance in rice: recent updates and future perspectives.

Rice yield is often threatened by various stresses caused by biotic and abiotic agents. Many biotic stress factors are known to cause crop growth and yield from seedling to maturity. The brown plant hopper (BPH) can potentially reduce the rice yield to an extent of up to 80%. Intensive research efforts in 1972 led to a better understanding of pathogens/insect and host-plant resistance. This resulted in the identification of about 70 BPH-resistant genes and quantitative trait loci (QTLs) from diversified sources including wild germplasm. However, the BPH-resistant improved varieties with a single resistant gene lose the effectiveness of the gene because of the evolution of new biotypes. This review inferred that the level of resistance durable when incorporating multiple 'R' gene combinations when compared to a single gene. Breeding tools like wide hybridization, biparental crosses, marker-assisted introgression, pyramiding, and genetic engineering have been widely employed to breed rice varieties with single or combination of 'R' genes conferring durable resistance to BPH. Many other genes like receptor-like kinase genes, transcriptional factors, etc., were also found to be involved in the resistant mechanisms of 'R' genes. Due to this, the durability of the resistance can be improved and the level of resistance of the 'R' genes can be increased by adopting newer breeding tools like genome editing which hold promise to develop rice varieties with stable resistance.

Oxygen vacancy-dependent synergistic disinfection of antibiotic-resistant bacteria by BiOBr nanoflower induced H2O2 activation.

Antibiotic-resistant bacteria (ARB) and antibiotic-resistant genes (ARGs) pose a significant threat to both ecosystems and human health. Owing to the excellent catalytic activity, eco-safety, and convenience for defect engineering, BiOBr with oxygen vacancies (OVs) of different density thus were fabricated and employed to activate H2O2 for ARB disinfection/ARGs degradation in present study. We found that BiOBr with OVs of appropriate density induced via ethanol reduction (BOB-E) could effectively activate H2O2, achieving excellent ARB disinfection and ARGs degradation efficiency. Moreover, this disinfection system exhibited remarkable tolerance to complex water environments and actual water conditions. In-situ characterization and theoretical calculations revealed that OVs in BOB-E could effectively capture and activate aqueous H2O2 into HO· and O2·-. The generated reactive oxygen species combined with electron transfer could damage the cell membrane system and degrade genetic materials of ARB, leading to effective disinfection. The impressive reusability, high performance achieved in two immobilized reaction systems (packed column and baffled ditch reactor), excellent degradation of emerging organic pollutants supported the feasibility of BOB-E/H2O2 system towards practical water decontamination. Overall, this study not only provides insights into fabrication of bismuth-based catalysts for efficient ARB disinfection/ARGs degradation via OVs regulation, but also paves the way for their practical applications.

A Review of the Dissemination of Antibiotic Resistance through Wastewater Treatment Plants: Current Situation in Sri Lanka and Future Perspectives.

The emergence of antibiotic resistance (AR) poses a significant threat to both public health and aquatic ecosystems. Wastewater treatment plants (WWTPs) have been identified as potential hotspots for disseminating AR in the environment. However, only a limited number of studies have been conducted on AR dissemination through WWTPs in Sri Lanka. To address this knowledge gap in AR dissemination through WWTP operations in Sri Lanka, we critically examined the global situation of WWTPs as hotspots for transmitting antibiotic-resistant bacteria (ARB) and antibiotic-resistant genes (ARGs) by evaluating more than a hundred peer-reviewed international publications and available national publications. Our findings discuss the current state of operating WWTPs in the country and highlight the research needed in controlling AR dissemination. The results revealed that the impact of different wastewater types, such as clinical, veterinary, domestic, and industrial, on the dissemination of AR has not been extensively studied in Sri Lanka; furthermore, the effectiveness of various wastewater treatment techniques in removing ARGs requires further investigation to improve the technologies. Furthermore, existing studies have not explored deeply enough the potential public health and ecological risks posed by AR dissemination through WWTPs.

Response and disease resistance evaluation of sorghum seedlings under anthracnose stress.

Sorghum is the world's fifth-largest cereal crop, and anthracnose (Colletotrichum sublineola) is the main disease affecting sorghum. However, systematic research on the cellular structure, physiological and biochemical, and genes related to anthracnose resistance and disease resistance evaluation in sorghum is lacking in the field. Upon inoculation with anthracnose (C. sublineola) spores, disease-resistant sorghum (gz93) developed a relative lesion area (RLA) that was significantly smaller than that of the disease-susceptible sorghum (gz234). The leaf thickness, length and profile area of leaf mesophyll cells, upper and lower epidermal cells decreased in the lesion area, with a greater reduction observed in gz234 than in gz93. The damage caused by C. sublineola resulted in a greater decrease in the net photosynthetic rate (Pn) in gz234 than in gz93, with early-stage reduction due to stomatal limitation and late-stage reduction caused by lesions. Overall, the activities of superoxide dismutase (SOD) and catalase (CAT), the content of proline (Pro), abscisic acid (ABA), jasmonic acid (JA), salicylic acid (SA), and gibberellic acid (GA3), are higher in gz93 than in gz234 and may be positively correlated with disease resistance. While malondialdehyde (MDA) may be negatively correlated with disease resistance. Disease-resistant genes are significantly overexpressed in gz93, with significant expression changes in gz234, which is related to disease resistance in sorghum. Correlation analysis indicates that GA3, MDA, peroxidase (POD), and disease-resistance genes can serve as reference indicators for disease severity. The regression equation RLA = 0.029 + 8.02 × 10-6 JA-0.016 GA3 can predict and explain RLA. Principal component analysis (PCA), with the top 5 principal components for physiological and biochemical indicators and the top 2 principal components for disease-resistant genes, can explain 82.37% and 89.11% of their total variance, reducing the number of evaluation indicators. This study provides a basis for research on the mechanisms and breeding of sorghum with resistance to anthracnose.

Genomic insights of the emerging human pathogen Proteus appendicitidis sp. nov.

Objectives: Proteus are known as opportunistic human pathogens that can cause a variety of infections. Proteus appendicitidis is a novel Proteus species associated with appendicitis, whereas their genomic characteristics and virulence potential remain understudied. This study aims to compare the genomic features of P. appendicitidis to that of the close Proteus species, and to assess its virulence-factor encoding capacity as an emerging pathogen. Methods: Genomes similar to that of P. appendicitidis HZ0627T were retrieved from the PATRIC-v3.6.10 web-server using the implanted Similar Genome Finder tool. Average nucleotide identity (ANI) between HZ0627T and the retrieved genomes was calculated using FastANI-v1.33. Core-genome sequences were extracted using Roary-v3.13.0, and core-genomic tree was constructed using FastTree-v2.1.11. Virulence-factor encoding capacity was predicted using PathoFact-v1.0. Results: Two previously unclassified Proteus sp. strains were reclassified as P. appendicitidis. Strains phylogenomically close to P. appendicitidis were clustered into five species, three of which were previously categorized under P. vulgaris biogroup 3. Remarkably, Proteus genomosp. 6 was identified as the closest species to P. appendicitidis, exhibiting ANI values ranging from 94.45 % to 94.95 % against HZ0627T. Genome annotation revealed shared genomic features and antimicrobial resistance (AMR) genes between P. appendicitidis and its phylogenetic neighbors. Additionally, P. appendicitidis is hypothesized to share infection mechanisms with Proteus genomosp. 6, as evidenced by the encoding of numerous virulence factors implicated in cell lysis and membrane pore-formation in the genome of both species. Conclusions: This study provides genomic insights of P. appendicitidis sp. nov. and its taxonomic relatives, shedding light on their evolutionary relationships, pathogenic mechanisms, and AMR profiles. The findings are significant for the development of targeted therapeutic interventions against infections caused by this emerging pathogen.

Genetic Adaptations and Mechanistic Insights Into Bacterial Bioremediation in Ecosystems.

Metal pollution poses significant threats to the ecosystem and human health, demanding effective remediation strategies. Bioremediation, which leverages the unique metal-resistant genes found in bacteria, offers a cost-effective and efficient solution to heavy metal contamination. Genes such as Cad, Chr, Cop, and others provide pathways to improve the detoxification of the ecosystem. Through multiple techniques, genetic engineering makes bacterial genomes more capable of improving metal detoxification; nonetheless, there are still unanswered questions regarding the nature of new metal-resistant genes. This article examines bacteria's complex processes to detoxify toxic metals, including biosorption, bioaccumulation, bio-precipitation, and bioleaching. It also explores essential genes, proteins, signaling mechanisms, and bacterial biomarkers involved in breaking toxic metals.

Advances and solutions in biological treatment for antibiotic wastewater with resistance genes: A review.

Biological treatment represents a fundamental component of wastewater treatment plants (WWTPs). The transmission of antibiotic resistance bacteria (ARB) and resistance genes (ARGs) occurred through the continuous migration and transformation, attributed to the residual presence of antibiotics in WWTPs effluent, posing a significant threat to the entire ecosystem. It is necessary to propose novel biological strategies to address the challenge of refractory contaminants, such as antibiotics, ARGs and ARB. This review summarizes the occurrence of antibiotics in wastewater, categorized by high and low concentrations. Additionally, current biological treatments used in WWTPs, such as aerobic activated sludge, anaerobic digestion, sequencing batch reactor (SBR), constructed wetland, membrane-related bioreactors and biological aerated filter (BAF) are introduced. In particular, because microorganisms are the key to those biological treatments, the effect of high and low concentration of antibiotics on microorganisms are thoroughly discussed. Finally, solutions involving functional bacteria, partial nitrification (PN)-Anammox and lysozyme embedding are suggested from the perspective of the entire biological treatment process. Overall, this review provides valuable insights for the simultaneous removal of antibiotics and ARGs in antibiotics wastewater.

Exploring the antimicrobial efficacy of Manuka honey against multidrug-resistant and extensively drug-resistant Salmonella Typhi causing septicemia in Pakistan.

Aim: To determine the efficacy of manuka honey against multidrug-resistant (MDR) and extensively drug-resistant (XDR) clinical strains of Salmonella Typhi. Materials & methods: Clinical isolates were processed using the Bactec blood culture system, identification and antibiogram by Vitek 2 and antibiotic resistance genes through polymerase chain reaction (PCR). Microbroth dilution assays evaluated the antibacterial activity of manuka honey. Results: MDR and XDR-S. Typhi was susceptible to azithromycin. These strains carried the H58, gyrA, gyrB, blaCTX-M-15 , and blaTEM-1 genes. At 100% honey, the zone of inhibition for MDR (15-23 mm) and XDR (15-24 mm) strains. 18/50 MDR and 14/50 XDR strains inhibited at 3.125 v/v% killed at 6.25 v/v% concentration respectively. Conclusion: Manuka honey could be an alternative option for treating S. Typhi infections.

Typhoid fever is a life-threatening bacterial infection caused by the Salmonella Typhi. These bacteria are transmitted through contaminated water and food and cause fever, abdominal pain, headache, vomiting, and diarrhea mainly in children under 5. There are around 9 million people get infected with S. Typhi, with an increased death of 1,10,000 annually. Bees that collect nectar from the blossoms of the Manuka tree in Australia and New Zealand produce a type of honey known as manuka honey. This honey is famous for its antibacterial activity, and potential health benefits. Therefore, we aimed to determine its antibacterial activity against S. Typhi. Our finding shows that the commonly available antibiotics did not kill S. Typhi because their DNA was drug-resistant. After applying the manuka honey, these bacteria were killed and given a clear zone ranging from 15­24mm on the agar plate. Further analysis revealed that at low concentrations of manuka honey, 3.1% and 6.25%, most of the S. Typhi stopped growing and killed, respectively. This study suggested that manuka honey, which is affordable and readily available, could be used as a treatment option to treat infections produced by these harmful bacteria after further analysis.

The bacterial microbiome and resistome of house dust mites in Irish homes.

Dust samples were collected from Irish homes. House Dust Mite and storage mites were separated from the dust. The microbiome and resistome of mites and originating dust were assessed using a culture-independent approach. The bacterial microbiome of mites and dust were predominantly populated by Staphylococci. There was a highly significant (P = 0.005; Spearman's rank test) correlation between the bacterial microbiome of mites and the dust. One-hundred and eighteen antimicrobial resistance genes (ARGs) were associated with mites and 176 with dust. Both contained ARGs encoding resistance for multi drug resistances, macrolide-lincosamide-streptogramin B, mobile genetic elements, Beta-lactam, Tetracycline and Aminoglycosides. By contrast, 15 ARGs were found for a laboratory-grown strain of Dermatophagoides pteronyssinus. A significant difference (P = 0.03; t test) was found in means between the resistome of mites and the household dust from which they emanated. No significant correlations (P = 0.23 and P = 0.22; Mantel test) were observed between the microbiome and resistome of mite and dust samples. There was not a significant difference (P = 0.54; t-test) between the means of ARGs for homes with and without a history of antibiotic use.

Opposite Effects of Planting on Antibiotic Resistomes in Rhizosphere Soil with Different Sulfamethoxazole Levels.

Achieving consensus about the rhizosphere effect on soil antibiotic resistomes is challenging due to the variability in antibiotic concentrations, sources, and the elusory underlying mechanisms. Here, we characterized the antibiotic resistomes in both the rhizosphere and bulk soils of soybean plants grown in environments with varying levels of antibiotic contamination, using sulfamethoxazole (SMX) as a model compound. We also investigated the factors influencing resistome profiles. Soybean cultivation altered the structure of antibiotic-resistant genes (ARGs) and increased their absolute abundance. However, the rhizosphere effect on the relative abundance of ARGs was dependent on SMX concentrations. At low SMX levels, the rhizosphere effect was characterized by the inhibition of antibiotic-resistant bacteria (ARBs) and the promotion of sensitive bacteria. In contrast, at high SMX levels, the rhizosphere promoted the growth of ARBs and facilitated horizontal gene transfer of ARGs. This novel mechanism provides new insights into accurately assessing the rhizosphere effect on soil antibiotic resistomes.

Introgression of blast and bacterial blight disease resistance genes in a rice genotype ADT43 through marker assisted back cross breeding.

Bacterial Leaf Blight (Xanthomonas oryzae pv. oryzae) and blast (Magnaporthe oryzae) are the major biotic stresses around the rice-growing zones of the world. The development of resistant varieties through Marker Assisted Backcross Breeding is the utmost economical and eco-friendly method for achieving stable yield. Amongst the resistance genes recognized, Xa21 and Pi54 possess broad-spectrum resistance to many Xoo and blast strains around the world. In the present study, we have effectively introgressed a Bacterial Blight resistance gene (Xa21) and a blast resistance gene (Pi54) into susceptible variety ADT43 from RP-Bio-Patho-2 coupled with phenotypic selection for agronomic, cooking quality and grain traits through MABC. MABC was sustained till BC2F2 generation with specific markers pTA248 for Xa21 and Pi54MAS for Pi54 resistance genes. A set of SSR markers for parental polymorphism were utilized for maximum regaining of recurrent parent genome in each backcrossing. "Positive plants" from BC2F1 were selfed to generate BC2F2 and the homozygous lines for bacterial leaf blight and blast resistance genes were identified for further assessment.

Dynamics of antimicrobial resistance and susceptibility profile in full-scale hospital wastewater treatment plants.

Drug resistance has become a matter of great concern, with many bacteria now resist multiple antibiotics. This study depicts the occurrence of antibiotic-resistant bacteria (ARB) and resistance patterns in five full-scale hospital wastewater treatment plants (WWTPs). Samples of raw influent wastewater, as well as pre- and post-disinfected effluents, were monitored for targeted ARB and resistance genes in September 2022 and February 2023. Shifts in resistance profiles of Escherichia coli, Pseudomonas aeruginosa, and Acinetobacter baumannii antimicrobial-resistant indicators in the treated effluent compared to that in the raw wastewater were also worked out. Ceftazidime (6.78 × 105 CFU/mL) and cefotaxime (6.14 × 105 CFU/mL) resistant species showed the highest concentrations followed by ciprofloxacin (6.29 × 104 CFU/mL), and gentamicin (4.88 × 104 CFU/mL), in raw influent respectively. WWTP-D employing a combination of biological treatment and coagulation/clarification for wastewater decontamination showed promising results for reducing ARB emissions from wastewater. Relationships between treated effluent quality parameters and ARB loadings showed that high BOD5 and nitrate levels were possibly contributing to the persistence and/or selection of ARBs in WWTPs. Furthermore, antimicrobial susceptibility tests of targeted species revealed dynamic shifts in resistance profiles through treatment processes, highlighting the potential for ARB and ARGs in hospital wastewater to persist or amplify during treatment.

Enhanced removal of ciprofloxacin and associated antibiotic-resistant genes from wastewater using a biological aeration filters in combination with Fe3O4-modified zeolite.

Antibiotics release into the water environment through sewage discharge is a significant environmental concern. In the present study, we investigated the removal of ciprofloxacin (CIP) in simulated sewage by biological aeration filter (BAF) equipped with Fe3O4-modified zeolite (Fe3O4@ZF). Fe3O4@ZF were prepared with impregnation method, and the Fe3O4 particles were successfully deposited on the surface of ZF in an amorphous form according to the results of XPS and XRD analysis. The modification also increased the specific surface area (from 16.22 m²/g to 22 m²/g) and pore volume (from 0.0047 cm³/g to 0.0063 cm³/g), improving the adsorption efficiency of antibiotics. Fe3O4 modified ZF improved the treatment performance significantly, and the removal efficiency of CIP in BAF-Fe3O4@ZF was 79%±2.4%. At 10ml/L CIP, the BAF-Fe3O4@ZF reduced the relative abundances of antibiotics resistance genes (ARGs) int, mexA, qnrB and qnrS in the effluent by 57.16%, 39.59%, 60.22%, and 20.25%, respectively, which effectively mitigate the dissemination risk of ARGs. The modification of ZF increased CIP-degrading bacteria abundance, such as Rhizobium and Deinococcus-Thermus, and doubled bacterial ATP activity, promoting CIP degradation. This study offers a viable, efficient method to enhance antibiotic treatment and prevent leakage via sewage discharge.

Genomic insights of S. aureus associated with bovine mastitis in a high livestock activity region of Mexico.

IMPORTANCE: Bovine mastitis, predominantly associated with gram-positive Staphylococcus aureus, poses a significant threat to dairy cows, leading to a decline in milk quality and volume with substantial economic implications. OBJECTIVE: This study investigated the incidence, virulence, and antibiotic resistance of S. aureus associated with mastitis in dairy cows. METHODS: Fifty milk-productive cows underwent a subclinical mastitis diagnosis, and the S. aureus strains were isolated. Genomic DNA extraction, sequencing, and bioinformatic analysis were performed, supplemented by including 124 S. aureus genomes from cows with subclinical mastitis to enhance the overall analysis. RESULTS: The results revealed a 42% prevalence of subclinical mastitis among the cows tested. Genomic analysis identified 26 sequence types (STs) for all isolates, with Mexican STs belonging primarily to CC1 and CC97. The analyzed genomes exhibited multidrug resistance to phenicol, fluoroquinolone, tetracycline, and cephalosporine, which are commonly used as the first line of treatment. Furthermore, a similar genomic virulence repertoire was observed across the genomes, encompassing the genes related to invasion, survival, pathogenesis, and iron uptake. In particular, the toxic shock syndrome toxin (tss-1) was found predominantly in the genomes isolated in this study, posing potential health risks, particularly in children. CONCLUSION AND RELEVANCE: These findings underscore the broad capacity for antibiotic resistance and pathogenicity by S. aureus, compromising the integrity of milk and dairy products. The study emphasizes the need to evaluate the effectiveness of antibiotics in combating S. aureus infections.

Screening of vancomycin resistance-associated genes in methicillin-resistant Staphylococcus aureus isolates from cattle, sheep and goats in northwestern Iran.

Staphylococcus aureus is an important pathogen causing a wide range of diseases in both humans and animals. The aim of this research was to screen the vancomycin resistance-associated genes in methicillin-resistant Staphylococcus aureus (MRSA) isolates from animals. A total of 400 nasal swab samples were collected from cattle, goats and sheep between February and August 2022 from both industrial and traditional livestock farms in West Azerbaijan province, Iran. Then, nasal swabs were cultured on mannitol salt agar and molecular analysis was performed after bacteriological examination to confirm the presence of S. aureus. The MecA gene was used to detect MRSA isolates, and two important vancomycin resistance-associated genes, namely vanA and vanB, were searched in the isolates. Out of 400 nasal swabs, 69 samples had S. aureus; of which seven isolates were resistant against methicillin. No vancomycin resistance-associated genes were detected in the MRSA isolates. Based on these findings, vancomycin could be used to treat infections caused by this bacterium.

Integrative and conjugative elements of Pasteurella multocida: Prevalence and signatures in population evolution.

Pasteurella multocida (P. multocida) is a bacterial pathogen responsible for a range of infections in humans and various animal hosts, causing significant economic losses in farming. Integrative and conjugative elements (ICEs) are important horizontal gene transfer elements, potentially enabling host bacteria to enhance adaptability by acquiring multiple functional genes. However, the understanding of ICEs in P. multocida and their impact on the transmission of this pathogen remains limited. In this study, 42 poultry-sourced P. multocida genomes obtained by high-throughput sequencing together with 393 publicly available P. multocida genomes were used to analyse the horizontal transfer of ICEs. Eighty-two ICEs were identified in P. multocida, including SXT/R391 and Tn916 subtypes, as well as three subtypes of ICEHin1056 family, with the latter being widely prevalent in P. multocida and carrying multiple resistance genes. The correlations between insertion sequences and resistant genes in ICEs were also identified, and some ICEs introduced the carbapenem gene blaOXA-2 and the bleomycin gene bleO to P. multocida. Phylogenetic and collinearity analyses of these bioinformatics found that ICEs in P. multocida were transmitted vertically and horizontally and have evolved with host specialization. These findings provide insight into the transmission and evolution mode of ICEs in P. multocida and highlight the importance of understanding these elements for controlling the spread of antibiotic resistance.

Leaching of antibiotic resistance genes and microbial assemblages following poultry litter applications in karst and non-karst landscapes.

Antibiotic resistance is increasingly recognized as a critical challenge affecting human, animal, and environmental health. Yet, environmental dynamics and transport of antibiotic resistance genes (ARGs) and microbial communities in karst and non-karst leachate following poultry litter land applications are not well understood. This study investigates impacts of broiler poultry litter application on the proliferation of ARGs (tetW, qnrS, ermB, sulI, and blaCTX-M-32), class 1 integron (intI1 i), and alterations in microbial communities (16S rRNA) within karst derived soils, which are crucial and under-researched systems in the global hydrological cycle, and non-karst landscapes. Using large, intact soil columns (45 cm diam. × 100 cm depth) from karst and non-karst landscapes, the role of preferential flow and ARG transport in leachate was enumerated following surface application of poultry litter and simulated rain events. This research demonstrated that in poultry litter amended karst soils, ARG (i.e., ermB and tetW) abundance in leachate increased 1.5 times compared to non-karst systems (p < 0.05), highlighting the influence of geological factors on ARG proliferation. Notably, microbial communities in karst soil leachate exhibited increased diversity and abundance, suggesting a potential linkage between microbial composition and ARG presence. Further, our correlation and network analyses identified relationships between leachate ARGs, microbial taxa, and physicochemical properties, underscoring the complex interplay in these environmentally sensitive areas. These findings illuminate the critical role of karst systems in shaping ARG abundance and pollutant dispersal and microbial community dynamics, thus emphasizing the need for landscape-specific approaches in managing ARG dissemination to the environment. This study provides a deeper understanding of hydrogeological ARG dynamics but also lays the groundwork for future research and strategies to mitigate ARG dissemination through targeted manure applications across agricultural landscapes.

Deciphering Multidrug-Resistant Plasmids in Disinfection Residual Bacteria from a Wastewater Treatment Plant.

Current disinfection processes pose an emerging environmental risk due to the ineffective removal of antibiotic-resistant bacteria, especially disinfection residual bacteria (DRB) carrying multidrug-resistant plasmids (MRPs). However, the characteristics of DRB-carried MRPs are poorly understood. In this study, qPCR analysis reveals that the total absolute abundance of four plasmids in postdisinfection effluent decreases by 1.15 log units, while their relative abundance increases by 0.11 copies/cell compared to investigated wastewater treatment plant (WWTP) influent. We obtain three distinctive DRB-carried MRPs (pWWTP-01-03) from postdisinfection effluent, each carrying 9-11 antibiotic-resistant genes (ARGs). pWWTP-01 contains all 11 ARGs within an ∼25 Kbp chimeric genomic island showing strong patterns of recombination with MRPs from foodborne outbreaks and hospitals. Antibiotic-, disinfectant-, and heavy-metal-resistant genes on the same plasmid underscore the potential roles of disinfectants and heavy metals in the coselection of ARGs. Additionally, pWWTP-02 harbors an adhesin-type virulence operon, implying risks of both antibiotic resistance and pathogenicity upon entering environments. Furthermore, some MRPs from DRB are capable of transferring and could confer selective advantages to recipients under environmentally relevant antibiotic pressure. Overall, this study advances our understanding of DRB-carried MRPs and highlights the imminent need to monitor and control wastewater MRPs for environmental security.