Spread Of Antibiotic Resistance Research Articles

Effect of Mineral Fertilizers and Pesticides Application on Bacterial Community and Antibiotic-Resistance Genes Distribution in Agricultural Soils

Soils are a hotspot for the emergence and spread of antibiotic resistance. The effects of agrochemical treatments on the bacterial community of agricultural soils and the content of antibiotic-resistance genes (ARGs) were studied. Treatments included the following: control, mineral fertilizers (NPKs), pesticides, and the combined treatment of soils under soya (Glycine max), sunflower (Helianthus annuus L.), and wheat (Triticum aestivum). Bacterial community taxonomic composition was studied using 16S rRNA gene sequencing. The content of 10 ARGs and 3 integron genes (intI1, intI2, intI3) was determined using quantitative real-time PCR. The results showed that the treatments had little effect on the taxonomic composition and diversity of the soil bacterial community. The most significant factors determining differences in the microbial community were sampling time and soil physico-chemical parameters. A significant role of the bacterial community in ARG distribution in soils was demonstrated. Representatives of the Pseudomonas, Bacillus, Sphingomonas, Arthrobacter genera, and the Nocardioidaceae and Micrococcaceae families were likely ARG hosts. The presence of integron genes of all three classes was detected, the most numerous being intI3. This work provides important information on the role of agricultural soils in ARG transfer, and the findings may be useful for sustainable and safe agricultural development.

Macrolide Resistance in the Aerococcus urinae Complex: Implications for Integrative and Conjugative Elements

The recognition of the Aerococcus urinae complex (AUC) as an emerging uropathogen has led to growing concerns due to a limited understanding of its disease spectrum and antibiotic resistance profiles. Here, we investigated the prevalence of macrolide resistance within urinary AUC isolates, shedding light on potential genetic mechanisms. Phenotypic testing revealed a high rate of macrolide resistance: 45%, among a total of 189 urinary AUC isolates. Genomic analysis identified integrative and conjugative elements (ICEs) as carriers of the macrolide resistance gene ermA, suggesting horizontal gene transfer as a mechanism of resistance. Furthermore, comparison with publicly available genomes of related pathogens revealed high ICE sequence homogeneity, highlighting the potential for cross-species dissemination of resistance determinants. Understanding mechanisms of resistance is crucial for developing effective surveillance strategies and improving antibiotic use. Furthermore, the findings underscore the importance of considering the broader ecological context of resistance dissemination, emphasizing the need for community-level surveillance to combat the spread of antibiotic resistance within the urinary microbiome.

Current and emerging strategies to curb antibiotic-resistant urinary tract infections.

Rising rates of antibiotic resistance in uropathogenic bacteria compromise patient outcomes and prolong hospital stays. Consequently, new strategies are needed to prevent and control the spread of antibiotic resistance in uropathogenic bacteria. Over the past two decades, sizeable clinical efforts and research advances have changed urinary tract infection (UTI) treatment and prevention strategies to conserve antibiotic use. The emergence of antimicrobial stewardship, policies from national societies, and the development of new antimicrobials have shaped modern UTI practices. Future UTI management practices could be driven by the evolution of antimicrobial stewardship, improved and readily available diagnostics, and an improved understanding of how the microbiome affects UTI. Forthcoming UTI treatment and prevention strategies could employ novel bactericidal compounds, combinations of new and classic antimicrobials that enhance bacterial killing, medications that prevent bacterial attachment to uroepithelial cells, repurposing drugs, and vaccines to curtail the rising rates of antibiotic resistance in uropathogenic bacteria and improve outcomes in people with UTI.

Analysis of chlorhexidine, antibiotics and bacterial community composition in water environments from Brazil, Cameroon and Madagascar during the COVID-19 pandemic

The widespread of chlorhexidine and antibiotics in the water bodies, which grew during the global COVID-19 pandemic, can increase the dispersion of antibiotic resistance. We assessed the occurrence of these pharmaceutical compounds as well as SARS-CoV-2 and analysed the bacterial community structure of hospital and urban wastewaters from Brazil, Cameroon, and Madagascar. Water and wastewater samples (n = 59) were collected between January–June 2022. Chlorhexidine, azithromycin, levofloxacin, ceftriaxone, gentamicin and meropenem were screened by Ultra-High-Performance Liquid Chromatography coupled with mass spectrometer. SARS-CoV-2 was detected based on the nucleocapsid gene (in Cameroon and Madagascar), and envelope and spike protein-encoding genes (in Brazil). The total community-DNA was extracted and used for bacterial community analysis based on the 16S rRNA gene. To unravel likely interaction between pharmaceutical compounds and/or SARS-CoV-2 with the water bacterial community, multivariate statistics were performed. Chlorhexidine was found in hospital wastewater effluent from Brazil with a maximum concentration value of 89.28 μg/L. Additionally, antibiotic residues such as azithromycin and levofloxacin were also present at concentrations between 0.32–7.37 μg/L and 0.11–118.91 μg/L, respectively. In Cameroon, azithromycin was the most found antibiotic present at concentrations from 1.14 to 1.21 μg/L. In Madagascar instead, ceftriaxone (0.68–11.53 μg/L) and levofloxacin (0.15–0.30 μg/L) were commonly found. The bacterial phyla statistically significant different (P < 0,05) among participating countries were Proteobacteria, Patescibacteria and Dependentiae which were mainly abundant in waters sampled in Africa and, other phyla such as Firmicutes, Campylobacterota and Fusobacteriota were more abundant in Brazil. The phylum Caldisericota was only found in raw hospital wastewater samples from Madagascar. The canonical correspondence analysis results suggest significant correlation of azithromycin, meropenem and levofloxacin with bacteria families such as Enterococcaceae, Flavobacteriaceae, Deinococcaceae, Thermacetogeniaceae and Desulfomonilaceae, Spirochaetaceae, Methanosaetaceae, Synergistaceae, respectively. Water samples were also positive for SARS-CoV-2 with the lowest number of hospitalized COVID-19 patients in Madagascar (n = 7) and Brazil (n = 30). Our work provides new data about the bacterial community profile and the presence of pharmaceutical compounds in the hospital effluents from Brazil, Cameroon, and Madagascar, whose limited information is available. These compounds can exacerbate the spreading of antibiotic resistance and therefore pose a risk to public health.

Impact of earthworms on antibiotic resistance genes removal in ampicillin-contaminated soil through bacterial community alteration.

The emergence of antibiotic resistance genes (ARGs) as contaminants in soil poses a significant threat to public health. Earthworms (Eisenia foetida), which are common inhabitants of soil, have been extensively studied for their influence on ARGs. However, the specific impact of earthworms on penicillin-related ARGs remains unclear. In this study, we investigate the role of earthworms in mitigating ARGs, specifically penicillin-related ARGs, in ampicillin-contaminated soil. Utilizing high-throughput quantitative PCR (HT-qPCR), we quantified a significant reduction in the relative abundance of penicillin-related ARGs in soil treated with earthworms, showing a decrease with a p-value of <0.01. Furthermore, high-throughput 16S rRNA gene sequencing revealed that earthworm intervention markedly alters the microbial community structure, notably enhancing the prevalence of specific bacterial phyla such as Proteobacteria, Firmicutes, Chloroflexi, and Tenericutes. Our findings not only demonstrate the effectiveness of earthworms in reducing the environmental load of penicillin-related ARGs but also provide insight into the alteration of microbial communities as a potential mechanism. This research contributes to our understanding of the role of earthworms in mitigating the spread of antibiotic resistance and provides valuable insights for the development of strategies to combat this global health issue.

A novel high-throughput screening method for identifying compounds that inhibit plasmid conjugation

Plasmid conjugation is an important contributing factor to the spread of antibiotic resistance among bacteria, posing a significant global health threat. Our method introduces an innovative high-throughput screening approach to identify compounds that inhibit or reduce conjugation, addressing the need for new strategies against the spread of antimicrobial resistance.Using Escherichia coli strains as donor and recipient, we screened 3500 compounds from a library provided by ABAC Therapeutics. Each 96 –well plate was loaded with 88 different compounds and bacterial cultures. Every plate also included negative and positive controls of conjugation. After an hour, cultures from wells were spotted on agar plates and assessed visually. Compounds that showed a visible effect on conjugation were retested. Six compounds targeting conjugation were found, showing promise for further analysis.

Arctic plasmidome analysis reveals distinct relationships among associated antimicrobial resistance genes and virulence genes along anthropogenic gradients.

Polar regions are relatively isolated from human activity and thus could offer insight into anthropogenic and ecological drivers of the spread of antibiotic resistance. Plasmids are of particular interest in this context given the central role that they are thought to play in the dissemination of antibiotic resistance genes (ARGs). However, plasmidomes are challenging to profile in environmental samples. The objective of this study was to compare various aspects of the plasmidome associated with glacial ice and adjacent aquatic environments across the high Arctic archipelago of Svalbard, representing a gradient of anthropogenic inputs and specific treated and untreated wastewater outflows to the sea. We accessed plasmidomes by applying enrichment cultures, plasmid isolation and shotgun Illumina sequencing of environmental samples. We examined the abundance and diversity of ARGs and other stress-response genes that might be co/cross-selected or co-transported in these environments, including biocide resistance genes (BRGs), metal resistance genes (MRGs), virulence genes (VGs) and integrons. We found striking differences between glacial ice and aquatic environments in terms of the ARGs carried by plasmids. We found a strong correlation between MRGs and ARGs in plasmids in the wastewaters and fjords. Alternatively, in glacial ice, VGs and BRGs genes were dominant, suggesting that glacial ice may be a repository of pathogenic strains. Moreover, ARGs were not found within the cassettes of integrons carried by the plasmids, which is suggestive of unique adaptive features of the microbial communities to their extreme environment. This study provides insight into the role of plasmids in facilitating bacterial adaptation to Arctic ecosystems as well as in shaping corresponding resistomes. Increasing human activity, warming of Arctic regions and associated increases in the meltwater run-off from glaciers could contribute to the release and spread of plasmid-related genes from Svalbard to the broader pool of ARGs in the Arctic Ocean.

Koncept “Jedno zdravlje” u prevenciji pojave ostataka β-laktamskih antibiotika u mlijeku i okolišu

The One Health concept emerged with the aim of balancing the lives of humans, animals, and plants on Earth, while also preserving theenvironment. Its aim is to improve overall living conditions on Earth and one of these issues is the overuse of antibiotics for therapeutic purposes and the use of antibiotics to promote livestock breeding on farms, which has led to a rapid spread of antibiotic resistance among microorganisms. Additionally, residual antibiotics are found in food of animal origin, and in the environment where they pollute soil and water. The most widely used group of antimicrobial agents are the β-lactam antibiotics. Due to their powerful antimicrobial effect and low toxicity, they are used to treat bacterial infections in both human and animal medicine. β-lactam antibiotics are major antibiotics used for treating mastitis, the most common infection occurring in milk-producing cows. Across EU Member States, testing and identifying the residues of β-lactam antibiotics in milk samples is included in national antibiotic residue monitoring plans for food of animal origin. The development of sophisticated methods with high sensitivity and precision, based on liquid chromatography coupled to mass spectrometry, enables the simultaneous control of different antibiotic classes for the official control of residues in foods of animal origin. According to the literature, β-lactam antibiotics are frequently detected antibiotic residues in EU Member States, with penicillin G as the most common compound.

Fraxetin Targeting to Sortase A Decreases the Pathogenicity of Streptococcus agalactiae to Nile Tilapia.

Sortase A (SrtA) is responsible for anchoring surface proteins to the cell wall, and has been identified as a promising target developing anti-infective drugs of Gram-positive bacteria. The aim of the study was to identify inhibitors of Streptococcus agalactiae (S. agalactiae) SrtA from natural compounds to overcome the spread of antibiotic resistance in aquaculture. Here, we found that the MIC of fraxetin against S. agalactiae was higher than 256 μg/mL, indicating that fraxetin had no anti- S. agalactiae activity. But fraxetin could dose-dependently decrease the activity of SrtA in vitro at concentrations ranging between 4-32 μg/mL by a fluorescence resonance energy transfer (FRET) assay. Moreover, the inhibition of SrtA by fraxetin decreased the anchoring of surface proteins with the LPXTG motif to the cell wall by detecting the immunofluorescence change of serine-rich repeat protein 1 (Srr1) on the bacterial cell surface. The results of fibronectin binding and cell adhesion assays indicated that fraxetin could significantly decrease the adhesion ability of S. agalactiae in a dose-dependent manner. The results were further proven by immunofluorescence staining. Animal challenge results showed that treatment with fraxetin could reduce the mortality of tilapia infected with S. agalactiae to 46.67%, indicating that fraxetin could provide a significant amount of protection to tilapia by inactivating SrtA. Taken together, these findings provided a novel inhibitor of S. agalactiae SrtA and a promising candidate for treating S. agalactiae infections in aquaculture.

[Silencing of Resistance Mechanism in Vancomycin-Resistance Enterococci Using Antisense RNA of vanA Gene].

The World Health Organization has included the problem of antibiotic resistance among the top 10 important health problems in the world. Treatment of infectious diseases has become more difficult due to the spread of antibiotic resistance between bacteria via transposable elements. Vancomycin-resistant enterococci (VRE) are of critical medical and public health importance due to their association with serious nosocomial infections and high risk of death. One of the most important features of VREs is that they have multiple antibiotic resistance and treatment options are reduced. Therefore, new treatment methods are needed. The vanA gene constitutes the building block of the vancomycin resistance mechanism and causes high resistance to vancomycin. In this study, it was aimed to investigate the neutralization of the vancomycin resistance mechanism by creating vanA antisense RNA (asRNA). The vanA positive VRE50 strain in our culture collection which was isolated from the clinical sample, was used to amplify the vanA gene by polymerase chain reaction (PCR). The amplified vanA amplicon was inserted inversely into the pUC19 plasmid by means of the enzyme cutting sites in the primers used. The resulting plasmid was combined with the pAT392 plasmid which can replicate in gram-positive bacteria and a fusion plasmid was created. The fusion plasmid whose orientation was confirmed, was transferred to the wild strain VRE50 by electroporation method. Minimum inhibitory concentration (MIC) values of transformed VRE (tVRE50) and wild type VRE50 strains used as control were determined by the E-Test method. The vancomycin MIC value of the wild type VRE50 strain was determined as 1024 µg/mL and that of the tVRE50 strain was 32 µg/mL and it was determined that the vancomycin resistance of the tVRE50 strain decreased with asRNA (antisense RNA). Antisense RNA technology is an important method for neutralizing the expression of genes. This study showed that neutralization of the vancomycin resistance gene may provide a lower MIC value in a vancomycin-resistant enterococcus strain and lead to increased susceptibility. This new approach provides a new method for VRE treatment by neutralizing the vancomycin resistance mechanism. The result obtained in this study needs to be supported by in vivo tests.

A Review of the Impact of Streptococcal Infections and Antimicrobial Resistance on Human Health.

Streptococcus pneumoniae, Streptococcus pyogenes (GAS), and Streptococcus agalactiae (GBS) are bacteria that can cause a range of infections, some of them life-threatening. This review examines the spread of antibiotic resistance and its mechanisms against antibiotics for streptococcal infections. Data on high-level penicillin-resistant invasive pneumococci have been found in Brazil (42.8%) and Japan (77%). The resistance is caused by mutations in genes that encode penicillin-binding proteins. Similarly, GAS and GBS strains reported from Asia, the USA, and Africa have undergone similar transformations in PBPs. Resistance to major alternatives of penicillins, macrolides, and lincosamides has become widespread among pneumococci and streptococci, especially in Asia (70-95%). The combination of several emm types with erm(B) is associated with the development of high-level macrolide resistance in GAS. Major mechanisms are ribosomal target modifications encoded by erm genes, ribosomal alterations, and active efflux pumps that regulate antibiotic entry due to mefA/E and msrD genes. Tetracycline resistance for streptococci in different countries varied from 22.4% in the USA to 83.7/100% in China, due to tet genes. Combined tetracycline/macrolide resistance is usually linked with the insertion of ermB into the transposon carrying tetM. New quinolone resistance is increasing by between 11.5 and 47.9% in Asia and Europe. The mechanism of quinolone resistance is based on mutations in gyrA/B, determinants for DNA gyrase, or parC/E encoding topoisomerase IV. The results for antibiotic resistance are alarming, and urgently call for increased monitoring of this problem and precautionary measures for control to prevent the spread of resistant mutant strains.

Phenotypic and Genotyping Identification of Extended Spectrum Beta-Lactamase (ESBL) Producing Enterobacteriaceae Obtained from Animal Fecal Samples within Owerri Metropolis

Background: One of the major means for the spread or distribution of antibiotic resistance is through animal, either by consumption or as companions. Most of the antibiotic resistant bacteria investigated have been reported to exhibit multidrug resistance which can either be acquired or natural. The present study was targeted at investigating the epidemiology of extended spectrum beta-lactamase-producing Enterobacteriaceae. Using stratified randomized sample design, three hundred (n = 300) fecal samples [of cattle, and goats (n = 150 for each)] were collected from various abattoir in Owerri metropolis. The isolation, purification, and antibiotic sensitivity were carried out using standard procedures. The resistant genes were investigated using forward and reverse primers specific for the following genes blaTEM, blaCTX-M, and blaSHV.&#x0D; Results: The result showed 97.67 % growth of Enterobacteriaceae. The highest Enterobacteriaceae isolated was in cattle fecal sample (61.00 %), while 2.33 % of the total samples did not show any growth for Enterobacteriaceae. Only three Enterobacteriaceae species were identified: Escherichia coli, Proteus vulgaris, and Klebsiella pneumonia. Escherichia coli was the most abundant Enterobacteriaceae (42.32 %) and P. vulgaris was the least abundant (23.89 %). The isolates showed multiple resistances to most of the antibiotics tested. All the isolates were susceptible to Imipenem (IPM). The molecular characterization showed the presence of the three genes (blaTEM, blaCTX-M, and blaSHV) investigated. The blaCTX gene-band was the most prevalent (72.22 %) while the blaSHV gene-band was the lowest prevalent resistant gene (61.11 %).&#x0D; Conclusion: It was concluded that the genes: blaTEM, blaCTX-M, and blaSHV were present in Enterobacteriaceae species (K. pneumoniae, P. vulgaris, and E. coli) isolated from abattoir in Owerri metropolis, Imo State.

CRISPR-Cas System: A New Dawn to Combat Antibiotic Resistance.

Antimicrobial resistance (AMR) can potentially harm global public health. Horizontal gene transfer (HGT), which speeds up the emergence of AMR and increases the burden of drug resistance in mobile genetic elements (MGEs), is the primary method by which AMR genes are transferred across bacterial pathogens. New approaches are urgently needed to halt the spread of bacterial diseases and antibiotic resistance. Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR), an RNA-guided adaptive immune system, protects prokaryotes from foreign DNA like plasmids and phages. This approach may be essential in limiting horizontal gene transfer and halting the spread of antibiotic resistance. The CRISPR-Cas system has been crucial in identifying and understanding resistance mechanisms and developing novel therapeutic approaches. This review article investigates the CRISPR-Cas system's potential as a tool to combat bacterial AMR. Antibiotic-resistant bacteria can be targeted and eliminated by the CRISPR-Cas system. It has been proven to be an efficient method for removing carbapenem-resistant plasmids and regaining antibiotic susceptibility. The CRISPR-Cas system has enormous potential as a weapon against bacterial AMR. It precisely targets and eliminates antibiotic-resistant bacteria, facilitates resistance mechanism identification, and offers new possibilities in diagnostics and therapeutics.

Antimicrobial and antibiofilm effect of cannabinoids from Cannabis sativa against methicillin-resistant Staphylococcus aureus (MRSA) causing bovine mastitis.

Antimicrobial resistance (AMR) poses a serious threat to human, animal, and plant health on a global scale. Search and elimination techniques should be used to effectively counter the spread of methicillin-resistant Staphylococcus aureus (MRSA) infections. With only a few novel drugs in clinical development, the quest for plant-based alternatives to prevent the spread of antibiotic resistance among bacteria has accelerated. Treatment of MRSA infections is challenging owing to rapidly emerging resistance mechanisms coupled with their protective biofilms. In the present research, we examined the antibacterial properties of ten plant-derived ethanolic leaf extracts. The most effective ethanolic leaf extract against MRSA in decreasing order of zone of inhibition, Cannabis sativa L. > Syzygium cumini > Murraya koenigii > Eucalyptus sp. > while Aloe barbadensis, Azadirachta indica, had very little impact. Mangifera indica, Curcuma longa, Tinospora cordifolia, and Carica papaya did not exhibit inhibitory effects against MRSA; hence, Cannabis was selected for further experimental study. The minimal inhibitory concentration (MIC) of Cannabis sativa L. extract was 0.25mgml-1 with 86% mortality. At a sub-MIC dosage of 0.125mgml-1, the biofilm formation was reduced by 71%. The two major cannabinoids detected were cannabidiol and delta-9-tetrahydrocannabinol (Δ9-THC), which were majorly attributed to substantial inhibitory action against MRSA. The time-kill kinetics demonstrated a bactericidal action at 4 MIC over an 8-20-h time window with a 90% reduction in growth rate. The results from SEM, and light microscopy Giemsa staining revealed a reduction in cells in the treated group with increased AKP activity, indicating bacterial cell membrane breakdown. These findings suggested cannabinoids may be a promising alternative to antibiotic therapy for bovine biofilm-associated MRSA.

Current Epidemiological Status and Antibiotic Resistance Profile of Serratia marcescens.

The spread of antibiotic resistance represents a serious worldwide public health issue, underscoring the importance of epidemiology research in determining antimicrobial strategies. The purpose of this research was to investigate antibiotic resistance in Serratia marcescens isolates from clinical samples over seven years at the University Hospital "San Giovanni di Dio e Ruggi d'Aragona" in Salerno, Italy. S. marcescens is an important opportunistic pathogen associated with a wide spectrum of clinical diseases, including pneumonia, keratitis, meningitis, and urinary tract and wound infections. Outbreaks of nosocomial infections by S. marcescens strains have been documented in high-risk settings, mainly affecting immunocompromised patients and newborns. The primary objective of this study is to assess the rates of antibiotic resistance over the years to deal with a future emergency which includes the failure of various therapies due to antibiotic resistance. During the investigation, a total of 396 species of S. marcescens were isolated from various clinical samples, mainly from broncho-aspirates and sputum (31.6%) and blood cultures (21.5%). Antibiotics that showed the greatest susceptibility included ceftazidime/avibactam, amikacin, trimethoprim/sulfamethoxazole, and selected members of the cephalosporin class. However, a disconcerting trend of increasing rates of carbapenem resistance was outlined over the observation period. The absence of effective countermeasures, combined with growing antibiotic resistance that negates the effectiveness of multiple antibiotics, highlights the potential for S. marcescens infections to trigger serious clinical complications and increased mortality rates. The surveillance of Serratia marcescens infections constitutes a pivotal element in refining empiric therapy to mitigate the dissemination of antimicrobial resistance.

The use of &lt;i&gt;Quercus cortex&lt;/i&gt; extract and chlortetracycline in the diet: feed digestibility, slaughter traits and the content of chemicals in organism of broilers

In the poultry industry, feed additives with positive effects on the condition of the poultry are constantly used. Antimicrobials are used for this purpose. However, the indiscriminate use of antibiotics accelerates the spread of antibiotic resistance among bacteria. Hence, researchers have increased interest in finding alternative feed additives. Plant extracts are of considerable interest in this matter as they have a wide range of biological properties including antibacterial activity. Phytobiotics, have been found to increase productivity, feed conversion ratio, safety and meat quality. Among the potential phytobiotics, oak bark extract (Quercus cortex) should be emphasized, the activity of which is associated with the content of more active substances. With this in mind, the purpose of this work was formulated to study the effect of Quercus cortex extract and the feed antibiotic Biovit 200 based on 20% chlorotetracycline on feed digestibility, its slaughter properties and the content of chemicals in the body of broilers.The results obtained during the study suggest that the use of Quercus cortex extract (at a dose of 0,2 ml/kg) both alone and in combination with Biovit 200 (at a dose of 0,63 g/kg w.m./day contributed to an increase in the EIP index, digestibility coefficients. An excess in slaughter yield in I, II and III groups over the control group was recorded.

Chlorite and bromate alter the conjugative transfer of antibiotic resistance genes: Co-regulation of oxidative stress and energy supply

The widespread use of disinfectants during the global response to the 2019 coronavirus pandemic has increased the co-occurrence of disinfection byproducts (DBPs) and antibiotic resistance genes (ARGs). Although DBPs pose major threats to public health globally, there is limited knowledge regarding their biological effects on ARGs. This study aimed to investigate the effects of two inorganic DBPs (chlorite and bromate) on the conjugative transfer of RP4 plasmid among Escherichia coli strains at environmentally relevant concentrations. Interestingly, the frequency of conjugative transfer was initially inhibited when the exposure time to chlorite or bromate was less than 24h. However, this inhibition transformed into promotion when the exposure time was extended to 36h. Short exposures to chlorite or bromate were shown to impede the electron transport chain, resulting in an ATP shortage and subsequently inhibiting conjugative transfer. Consequently, this stimulates the overproduction of reactive oxygen species (ROS) and activation of the SOS response. Upon prolonged exposure, the resurgent energy supply promoted conjugative transfer. These findings offer novel and valuable insights into the effects of environmentally relevant concentrations of inorganic DBPs on the conjugative transfer of ARGs, thereby providing a theoretical basis for the management of DBPs. Environmental ImplicationDisinfection by-products (DBPs) and antibiotic resistance genes (ARGs) are harmful contaminants with widespread distribution in water environments. Our study demonstrated that the conjugative transfer of ARGs is initially suppressed and subsequently enhanced by environmental concentrations of chlorite and bromate exposure. Our results highlighted the potential risks of low-concentration inorganic DBPs on the spread of antibiotic resistance. Further, our findings contributed to advancing our understanding of the effective management and control of DBPs in water environments, especially considering the selection of chlorine dioxide and ozone to mitigate the formation of chorine-derived DBPs.

Effect of a probiotic and an antibiotic on the mobilome of the porcine microbiota.

Introduction: To consider the growing health issues caused by antibiotic resistance from a "one health" perspective, the contribution of meat production needs to be addressed. While antibiotic resistance is naturally present in microbial communities, the treatment of farm animals with antibiotics causes an increase in antibiotic resistance genes (ARG) in the gut microbiome. Pigs are among the most prevalent animals in agriculture; therefore, reducing the prevalence of antibiotic-resistant bacteria in the pig gut microbiome could reduce the spread of antibiotic resistance. Probiotics are often studied as a way to modulate the microbiome and are, therefore, an interesting way to potentially decrease antibiotic resistance. Methods: To assess the efficacy of a probiotic to reduce the prevalence of ARGs in the pig microbiome, six pigs received either treatment with antibiotics (tylvalosin), probiotics (Pediococcus acidilactici MA18/5M; Biopower® PA), or a combination of both. Their faeces and ileal digesta were collected and DNA was extracted for whole genome shotgun sequencing. The reads were compared with taxonomy and ARG databases to identify the taxa and resistance genes in the samples. Results: The results showed that the ARG profiles in the faeces of the antibiotic and combination treatments were similar, and both were different from the profiles of the probiotic treatment (p < 0.05). The effects of the treatments were different in the digesta and faeces. Many macrolide resistance genes were detected in a higher proportion in the microbiome of the pigs treated with antibiotics or the combination of probiotics and antibiotics. Resistance-carrying conjugative plasmids and horizontal transfer genes were also amplified in faeces samples for the antibiotic and combined treatments. There was no effect of treatment on the short chain fatty acid content in the digesta or the faeces. Conclusion: There is no positive effect of adding probiotics to an antibiotic treatment when these treatments are administered simultaneously.

Spread of antibiotic-resistant actinobacteria in soils exposed to various types of anthropogenic impact

The work investigated the spectra of resistance to a certain set of antibiotics and the frequency of occurrence of resistant strains among typical soil bacteria – actinomycetes. Equal samples of isolates from sod-podzolic soil were used,  selected at sites typifying various types of economic activity, namely: the production areas of a plywood factory and a chemical plant, the territory of a medical institution, and a solid waste collection and storage site. A total of 58 isolates with features characteristic of actinomycetes of the genus Streptomyces of the sections Cinereus, Helvolo-Flavus and Albus were obtained. It has been established that various types of economic activity lead to specific changes in the antibiotic resistance, which characterizes the soil of a natural grass-grass meadow (back-ground). Isolates with resistance to nalidixic  acid, amoxicillin and ceftriaxone were found in the sample taken on the territory of the chemical plant more often than in the soil of the background site. The proportion of strains resistant to nalidixic acid, lincomycin and azithromycin was significantly (P&lt;0.05) higher in the soil samples  taken at the MSW collection site and the territory of the medical institution, while those resistant  to nalidixic acid and amoxicillin were in the sample from the plywood factory Groups of antibiotics (quinolones – nalidixic acid, and  β-lactams – amoxicillin and ceftriaxone) were identified, the resistance to which in streptomyces isolates from soils involved in economic activity  was significantly higher than in soil isolates from the background territory. The data obtained in  the work indicate the need to monitor the spread of antibiotic resistance in soils that are not only at risk of accumulation of residual concentrations of antibiotics, but also other  consequences of anthropogenic influences.

Oxygen mediated mobilization and co-occurrence of antibiotic resistance in lab-scale bioreactor using metagenomic binning.

Sub-lethal levels of antibiotic stimulate bacteria to generate reactive oxygen species (ROS) that promotes emergence and spread of antibiotic resistance mediated by mobile genetic elements (MGEs). Nevertheless, the influence of dissolved oxygen (DO) levels on mobility of antibiotic resistance genes (ARGs) in response to ROS-induced stress remains elusive. Thus, the study employs metagenomic assembly and binning approaches to decipher mobility potential and co-occurrence frequency of ARGs and MGEs under hyperoxic (5.5-7 mgL- 1), normoxic (2.5-4 mgL- 1), and hypoxic (0.5-1 mgL- 1) conditions in lab-scale bioreactor for 6 months. Among 163 high-quality metagenome-assembled genomes (MAGs) recovered from 13 metagenomes, 42 MAGs harboured multiple ARGs and were assigned to priority pathogen group. Total ARG count increased by 4.3 and 2.5% in hyperoxic and normoxic, but decreased by 0.53% in hypoxic conditions after 150 days. On contrary, MGE count increased by 7.3-1.3% in all the DO levels, with only two ARGs showed positive correlation with MGEs in hypoxic compared to 20 ARGs under hyperoxic conditions. Opportunistic pathogens (Escherichia, Klebsiella, Clostridium, and Proteus) were detected as potential hosts of ARGs wherein co-localisation of critical ARG gene cassette (sul1, dfr1,adeF, and qacC) were identified in class 1 integron/Tn1 family transposons. Thus, enhanced co-occurrence frequency of ARGs with MGEs in pathogens suggested promotion of ARGs mobility under oxidative stress. The study offers valuable insights into ARG dissemination and hosts dynamics that is essential for controlling oxygen-related stress for mitigating MGEs and ARGs in the environment.