Antimicrobials and Antibiotic-Resistant Bacteria: A Risk to the Environment and to Public Health

Novel Fluoroquinolones with Possible Antibacterial Activity in Gram-Negative Resistant Pathogens: In Silico Drug Discovery

Antibiotic resistance is a global threat to public health, and the search for new antibacterial therapies is a current research priority. The aim of this in silico study was to test nine new fluoroquinolones previously designed with potential leishmanicidal activity against Campylobacter jejuni, Escherichia coli, Neisseria gonorrhoeae, Pseudomonas aeruginosa, and Salmonella typhi, all of which are considered by the World Health Organization to resistant pathogens of global concern, through molecular docking and molecular dynamics (MD) simulations using wild-type (WT) and mutant-type (MT) DNA gyrases as biological targets. Our results showed that compound 9FQ had the best binding energy with the active site of E. coli in both molecular docking and molecular dynamics simulations. Compound 9FQ interacted with residues of quinolone resistance-determining region (QRDR) in GyrA and GyrB chains, which are important to enzyme activity and through which it could block DNA replication. In addition to compound 9FQ, compound 1FQ also showed a good affinity for DNA gyrase. Thus, these newly designed molecules could have antibacterial activity against Gram-negative microorganisms. These findings represent a promising starting point for further investigation through in vitro assays, which can validate the hypothesis and potentially facilitate the development of novel antibiotic drugs.

A South African Perspective on the Microbiological and Chemical Quality of Meat: Plausible Public Health Implications

Meat comprises proteins, fats, vitamins, and trace elements, essential nutrients for the growth and development of the body. The increased demand for meat necessitates the use of antibiotics in intensive farming to sustain and raise productivity. However, the high water activity, the neutral pH, and the high protein content of meat create a favourable milieu for the growth and the persistence of bacteria. Meat serves as a portal for the spread of foodborne diseases. This occurs because of contamination. This review presents information on animal farming in South Africa, the microbial and chemical contamination of meat, and the consequential effects on public health. In South Africa, the sales of meat can be operated both formally and informally. Meat becomes exposed to contamination with different categories of microbes, originating from varying sources during preparation, processing, packaging, storage, and serving to consumers. Apparently, meat harbours diverse pathogenic microorganisms and antibiotic residues alongside the occurrence of drug resistance in zoonotic pathogens, due to the improper use of antibiotics during farming. Different findings obtained across the country showed variations in prevalence of bacteria and multidrug-resistant bacteria studied, which could be explained by the differences in the manufacturer practices, handling processes from producers to consumers, and the success of the hygienic measures employed during production. Furthermore, variation in the socioeconomic and political factors and differences in bacterial strains, geographical area, time, climatic factors, etc. could be responsible for the discrepancy in the level of antibiotic resistance between the provinces. Bacteria identified in meat including Escherichia coli, Listeria monocytogenes, Staphylococcus aureus, Campylobacter spp., Salmonella spp., etc. are incriminated as pathogenic agents causing serious infections in human and their drug-resistant counterparts can cause prolonged infection plus long hospital stays, increased mortality and morbidity as well as huge socioeconomic burden and even death. Therefore, uncooked meat or improperly cooked meat consumed by the population serves as a risk to human health.

Within-Host Diversity of Coagulase-Negative Staphylococci Resistome from Healthy Pigs and Pig Farmers, with the Detection of cfr-Carrying Strains and MDR-S. borealis

The ecology and diversity of resistome in coagulase-negative staphylococci (CoNS) from healthy pigs and pig farmers are rarely available as most studies focused on the livestock-associated methicillin-resistant S. aureus. This study aims to characterize the antimicrobial resistance (AMR) mechanisms, intra-host species diversity (more than one species in a host), and intra-species AMR diversity (same species with more than one AMR profile) in CoNS recovered from the nasal cavities of healthy pigs and pig farmers. One-hundred-and-one CoNS strains previously recovered from 40 pigs and 10 pig farmers from four Spanish pig farms were tested to determine their AMR profiles. Non-repetitive strains were selected (n = 75) and their AMR genes, SCCmec types, and genetic lineages were analyzed by PCR/sequencing. Of the non-repetitive strains, 92% showed a multidrug resistance (MDR) phenotype, and 52% were mecA-positive, which were associated with SCCmec types V (46.2%), IVb (20.5%), and IVc (5.1%). A total of 28% of the pigs and pig farmers had intra-host species diversity, while 26% had intra-species AMR diversity. High repertoires of AMR genes were detected, including unusual ones such as tetO, ermT, erm43, and cfr. Most important was the detection of cfr (in S. saprophyticus and S. epidermidis-ST16) in pigs and pig farmers; whereas MDR-S. borealis strains were identified in pig farmers. Pig-to-pig transmission of CoNS with similar AMR genes and SCCmec types was detected in 42.5% of pigs. The high level of multidrug, within-host, and intra-species resistome diversity in the nasal CoNS highlights their ability to be AMR gene reservoirs in healthy pigs and pig farmers. The detection of MDR-S. borealis and linezolid-resistant strains underscore the need for comprehensive and continuous surveillance of MDR-CoNS at the pig farm level.

Are hospital wastewater treatment plants a source of new resistant bacterial strains?

To understand which type of hospital waste may contain the highest amount of antibiotic resistant microorganisms that could be released into the environment, the bacterial strains entering and leaving a hospital wastewater treatment plant (HWTP) were identified and tested for their antibiotic susceptibility. To achieve this goal, samples were collected from three separate sites, inlet and outlet wastewater positions, and sludge generated in a septic tank. After microbiological characterization according to APHA, AWWA, and WEF protocols, the relative susceptibility of the bacterial strains to various antibiotic agents was assessed according to the Clinical and Laboratory Standards Institute guidelines, to determine whether there were higher numbers of resistant bacterial strains in the inlet wastewater sample than in the outlet wastewater and sludge samples. The results showed more antibiotic resistant bacteria in the sludge than in the inlet wastewater, and that the Enterobacteriaceae family was the predominant species in the collected samples. The most antibiotic-resistant families were found to be Streptococcacea and non-Enterobacteriaceae. Some bacterial strains were resistant to all the tested antibiotics. We conclude that the studied HWTP can be considered a source of resistant bacterial strains. It is suggested that outlet water and sludge generated in HWTPs should be monitored, and that efficient treatment to eliminate all bacteria from the different types of hospital waste released into the environment is adopted.

The VxrAB two-component system is important for the polymyxin B-dependent activation of the type VI secretion system in Vibrio cholerae O1 strain A1552

The type VI secretion system (T6SS) is used by bacteria for virulence, resistance to grazing, and competition with other bacteria. We previously demonstrated that the role of the T6SS in interbacterial competition and in resistance to grazing is enhanced in Vibrio cholerae in the presence of subinhibitory concentrations of polymyxin B. Here, we performed a global quantitative proteomic analysis and a targeted transcriptomic analysis of the T6SS-known regulators in V. cholerae grown with and without polymyxin B. The proteome of V. cholerae is greatly modified by polymyxin B with more than 39% of the identified cellular proteins displaying a difference in their abundance, including T6SS-related proteins. We identified a regulator whose abundance and expression are increased in the presence of polymyxin B, vxrB, the response regulator of the two-component system VxrAB (VCA0565-66). In vxrAB, vxrA and vxrB deficient mutants, the expression of both hcp copies (VC1415 and VCA0017), although globally reduced, was not modified by polymyxin B. These hcp genes encode an identical protein Hcp, which is the major component of the T6SS syringe. Thus, the upregulation of the T6SS in the presence of polymyxin B appears to be, at least in part, due to the two-component system VxrAB.

Application of Iron Nanoparticles Synthesized from a Bioflocculant Produced by Yeast Strain Pichia kudriavzevii Obtained from Kombucha Tea SCOBY in the Treatment of Wastewater

Studying the production of Iron (Fe) nanoparticles using natural substances is an intriguing area of research in nanotechnology, as these nanoparticles possess biocompatibility and natural stability, which make them useful for a variety of industrial applications. The study utilized Fe nanoparticles that were synthesized using a bioflocculant and applied to eliminate different kinds of pollutants and dyes found in wastewater and solutions. The study involved the generation of Fe nanoparticles through a bioflocculant obtained from Pichia kudriavzevii, which were evaluated for their flocculation and antimicrobial capabilities. The impact of the Fe nanoparticles on human embryonic kidney (HEK 293) cell lines was studied to assess their potential cytotoxicity effects. An array of spectroscopic and microscopic methods was employed to characterize the biosynthesized Fe nanoparticles, including SEM-EDX, FT-IR, TEM, XRD, UV-vis, and TGA. A highly efficient flocculating activity of 85% was achieved with 0.6 mg/mL dosage of Fe nanoparticles. The biosynthesized Fe nanoparticles demonstrated a noteworthy concentration-dependent cytotoxicity effect on HEK 293 cell lines with the highest concentration used resulting in 34% cell survival. The Fe nanoparticles exhibited strong antimicrobial properties against a variety of evaluated Gram-positive and Gram-negative microorganisms. The efficiency of removing dyes by the nanoparticles was found to be higher than 65% for the tested dyes, with the highest being 93% for safranine. The Fe nanoparticles demonstrated remarkable efficiency in removing various pollutants from wastewater. In comparison to traditional flocculants and the bioflocculant, biosynthesized Fe nanoparticles possess significant potential for eliminating both biological oxygen demand (BOD) and chemical oxygen demand (COD) from wastewater samples treated. Hence, the Fe nanoparticles synthesized in this way have the potential to substitute chemical flocculants in the treatment of wastewater.

Leading reasons for antibiotic prescriptions in pediatric respiratory infections: influence of fever in a primary care setting

BACKGROUND

Antibiotic overuse in children is a significant public health concern, as it can lead to the emergence and spread of antibiotic-resistant bacteria. Although respiratory infections account for most antibiotic prescriptions in children, many of these infections are viral and do not require antibiotics. In this study, we aimed to investigate the use of antibiotics in children with respiratory infections in a primary care setting and to explore the possible role of fever on antibiotic prescription.

METHODS

We conducted a prospective observational study that evaluated preschool children aged 0-5 years who were assessed by their primary care pediatricians for respiratory infectious diseases between October 2019 and March 2021. The study involved 69 public primary care pediatricians and a total of 678 pediatric episodes for respiratory infections.

RESULTS

Amoxicillin/clavulanate was the most frequently prescribed drug. Bronchitis accounted for most of inappropriate antibiotic prescriptions (73%). Furthermore, the presence of fever was associated with a ~ 300% increase in the likelihood of prescribing antibiotics for respiratory infections that do not typically require antibiotics.

CONCLUSION

Our findings emphasize the need for adherence to international guidelines and recommendations in the primary care of children to reduce unnecessary antibiotic use and prevent the development of antibiotic resistance. This study also underscores the potential relevance of new studies to evaluate antibiotic prescription attitudes in other clinical settings and geographical areas.

Rapid Isolation of Low-Level Carbapenem-Resistant E. coli from Water and Foods Using Glycan-Coated Magnetic Nanoparticles

Carbapenem-resistant Enterobacterales (CRE) are one of the major global issues needing attention. Among them, carbapenemase-producing (CP) E. coli strains are commonly found in clinical and biological samples. Rapid and cost-effective detection of such strains is critical in minimizing their deleterious impact. While promising progress is being made in rapid detection platforms, separation and enrichment of bacteria are required to ensure the detection of low bacterial counts. The current separation methods, such as centrifugation, filtration, electrophoresis, and immunomagnetic separation, are often tedious, expensive, or ineffective for clinical and biological samples. Further, the extraction and concentration of antimicrobial-resistant bacteria (ARB) are not well documented. Thus, this study assessed the applicability of cost-effective glycan-coated magnetic nanoparticles (gMNPs) for simple and rapid extraction of CP E. coli. The study included two resistant (R)strains: Klebsiella pneumoniae carbapenemase (KPC)-producing E. coli (R: KPC) and New Delhi metallo-β-lactamase (NDM)-producing E. coli (R: NDM). A susceptible E. coli (S) strain was used as a control, a reference bacterium. The gMNPs successfully extracted and concentrated E. coli (R) and E. coli (S) at low concentrations from large volumes of buffer solution, water, and food samples. The gMNPs concentrated up to two and five times their initial concentration for E. coli (R) and E. coli (S) in the buffer solution, respectively. In water and food samples, the concentration of E. coli (S) and E. coli (R) were similar and ranged 1-3 times their initial inoculation. A variation in the concentration from different food samples was seen, displaying the impact of food microstructure and natural microflora. The cost-effective and rapid bacterial cell capture by gMNPs was achieved in 15 min, and its successful binding to the bacterial cells in the buffer solution and food matrices was also confirmed using Transmission Electron Microscopy (TEM). These results show promising applications of gMNPs to extract pathogens and ARB from biological samples.

Overview of Direct and Indirect Effects of Antibiotics on Terrestrial Organisms

Antibiotics (ABs) have made it possible to treat bacterial infections, which were in the past untreatable and consequently fatal. Regrettably, their use and abuse among humans and livestock led to antibiotic resistance, which has made them ineffective in many cases. The spread of antibiotic resistance genes (ARGs) and bacteria is not limited to nosocomial environments, but also involves water and soil ecosystems. The environmental presence of ABs and ARGs is a hot topic, and their direct and indirect effects, are still not well known or clarified. A particular concern is the presence of antibiotics in agroecosystems due to the application of agro-zootechnical waste (e.g., manure and biosolids), which can introduce antibiotic residues and ARGs to soils. This review provides an insight of recent findings of AB direct and indirect effects on terrestrial organisms, focusing on plant and invertebrates. Possible changing in viability and organism growth, AB bioaccumulation, and shifts in associated microbiome composition are reported. Oxidative stress responses of plants (such as reactive oxygen species production) to antibiotics are also described.

In Situ Polymerization of Methylene Blue on Bacterial Cellulose for Photodynamic/Photoelectricity Synergistic Inhibition of Bacterial Biofilm Formation

In the context of long-term antimicrobial treatment, the emergence of bacterial resistance poses a significant challenge. Therefore, there is a pressing need to develop novel antimicrobial materials and methods that can effectively and safely combat microbial infections. This study focuses on the synthesis of bacterial cellulose-polymethylene blue (BC-PMB) with integrated photodynamic and photoelectric antimicrobial properties. The polymerization of methyl blue (MB) onto bacterial celluloses (BC) was achieved, and through comprehensive computational analyses using density functional theory (DFT) and molecular dynamics simulations, it was confirmed that this polymerization greatly enhanced the binding efficiency between methylene blue and BC. Additionally, polymethylene blue (PMB) exhibited superior photoexcitation efficiency and conductivity compared to its precursor. When BC-PMB was exposed to a 30 mW 660 nm light source for 30 min, the material demonstrated a remarkable antimicrobial efficacy of 93.99% against Escherichia coli and 98.58% against Staphylococcus aureus. Furthermore, the synergistic effect of photodynamic and photoelectric antimicrobial mechanisms exhibited long-term inhibitory capabilities against bacterial biofilms.

Predicting Extended-Spectrum Beta-Lactamase and Carbapenem Resistance in Enterobacteriaceae Bacteremia: A Diagnostic Model Systematic Review and Meta-Analysis

Enterobacteriaceae bacteremia, particularly when associated with antimicrobial resistance, can result in increased mortality, emphasizing the need for timely effective therapy. Clinical risk prediction models are promising tools, stratifying patients based on their risk of resistance due to ESBL and carbapenemase-producing Enterobacteriaceae in bloodstream infections (BSIs) and, thereby, improving therapeutic decisions. This systematic review and meta-analysis synthesized the literature on the performance of these models. Searches of PubMed and EMBASE led to the identification of 10 relevant studies with 6106 unique patient encounters. Nine studies concerned ESBL prediction, and one focused on the prediction of carbapenemases. For the two ESBL model derivation studies, the discrimination performance showed sensitivities of 53-85% and specificities of 93-95%. Among the four ESBL model derivation and validation studies, the sensitivities were 43-88%, and the specificities were 77-99%. The sensitivity and specificity for the subsequent external validation studies were 7-37% and 88-96%, respectively. For the three external validation studies, only two models were evaluated across multiple studies, with a pooled AUROC of 65-71%, with one study omitting the sensitivity/specificity. Only two studies measured clinical utility through hypothetical therapy assessments. Given the limited evidence on their interventional application, it would be beneficial to further assess these or future models, to better understand their clinical utility and ensure their safe and impactful implementation.

Analyses of Extended-Spectrum-β-Lactamase, Metallo-β-Lactamase, and AmpC-β-Lactamase Producing Enterobacteriaceae from the Dairy Value Chain in India

The consumption of milk contaminated with antibiotic-resistant bacteria poses a significant health threat to humans. This study aimed to investigate the prevalence of Enterobacteriaceae producing β-lactamases (ESBL, MBL, and AmpC) in cow and buffalo milk samples from two Indian states, Haryana and Assam. A total of 401 milk samples were collected from dairy farmers and vendors in the specified districts. Microbiological assays, antibiotic susceptibility testing, and PCR-based genotyping were employed to analyze 421 Gram-negative bacterial isolates. The overall prevalence of β-lactamase genes was 10% (confidence interval (CI) (7-13)), with higher rates in Haryana (13%, CI (9-19)) compared to Assam (7%, CI (4-11)). The identified β-lactamase genes in isolates were blaCMY, blaMOX, blaFOX, blaEBC, and blaDHA, associated with AmpC production. Additionally, blaCTX-M1, blaSHV, and blaTEM were detected as ESBL producers, while blaVIM, blaIMP, blaSPM, blaSIM, and blaGIM were identified as MBL producers. Notably, Shigella spp. were the dominant β-lactamase producers among identified Enterobacteriaceae. This study highlights the presence of various prevalent β-lactamase genes in milk isolates, indicating the potential risk of antimicrobial-resistant bacteria in dairy products. The presence of β-lactam resistance raises concern as this could restrict antibiotic options for treatment. The discordance between genotypic and phenotypic methods emphasizes the necessity for comprehensive approaches that integrate both techniques to accurately assess antibiotic resistance. Urgent collaborative action incorporating rational and regulated use of antibiotics across the dairy value chain is required to address the global challenge of β-lactam resistance.

The Biotechnological Application of Bacteriophages: What to Do and Where to Go in the Middle of the Post-Antibiotic Era

Amid the escalating challenges of antibiotic resistance, bacterial infections have emerged as a global threat. Bacteriophages (phages), viral entities capable of selectively infecting bacteria, are gaining momentum as promising alternatives to traditional antibiotics. Their distinctive attributes, including host specificity, inherent self-amplification, and potential synergy with antibiotics, render them compelling candidates. Phage engineering, a burgeoning discipline, involves the strategic modification of bacteriophages to enhance their therapeutic potential and broaden their applications. The integration of CRISPR-Cas systems facilitates precise genetic modifications, enabling phages to serve as carriers of functional genes/proteins, thereby enhancing diagnostics, drug delivery, and therapy. Phage engineering holds promise in transforming precision medicine, addressing antibiotic resistance, and advancing diverse applications. Emphasizing the profound therapeutic potential of phages, this review underscores their pivotal role in combatting bacterial diseases and highlights their significance in the post-antibiotic era.

Real-Time Deduction of Mechanisms and Kinetics Underlying Photocatalytic Water Disinfection: Cell Motility and Particle Tracking

The current methods used to study photocatalysis-assisted water disinfection at a laboratory scale may not lead to process scale-up for large-scale implementation. These methods do not capture the process complexity and address all the factors underlying disinfection kinetics, including the physical characteristics (e.g., shape and size) of the photocatalyst, the light intensity, the form of the catalyst (e.g., free-floating and immobilized), and the photocatalyst-microorganism interaction mode (e.g., collision mode and constant contact mode). This drawback can be overcome using in situ methods to track the interaction between the photocatalysts and the microorganisms (e.g., Escherichia coli) and thereby engineering the resulting disinfection kinetics. Contextually, this study employed microscopy and particle-tracking algorithms to quantify in situ cell motility of E. coli undergoing titanium dioxide (TiO2) nanowire-assisted photocatalysis, which was observed to correlate with cell viability closely. This experimentation also informed that the E. coli bacterium interacted with the photocatalysts through collisions (without sustained contact), which allowed for phenomenological modeling of the observed first-order kinetics of E. coli inactivation. Addition of fluorescent-tagging assays to microscopy revealed that cell membrane integrity loss is the primary mode of bacterial inactivation. This methodology is independent of the microorganism or the photocatalyst type and hence is expected to be beneficial for engineering disinfection kinetics.

Celecoxib-Loaded Cubosomal Nanoparticles as a Therapeutic Approach for Staphylococcus aureus In Vivo Infection

There is a great need for novel approaches to treating bacterial infections, due to the vast dissemination of resistance among pathogenic bacteria. Staphylococcus aureus are ubiquitous Gram-positive pathogenic bacteria and are rapidly acquiring antibiotic resistance. Here, celecoxib was encapsulated into cubosomal nanoparticles, and the particle morphology, size distribution, zeta potential, entrapment efficiency, and celecoxib release were evaluated in vitro. Also, a systemic infection model in mice elucidated the in vivo antibacterial action of the celecoxib cubosomes. Cubosomes are a nanotechnology-based delivery system which can adhere to the external peptidoglycan layers of Gram-positive bacteria and penetrate them. The size distribution investigation revealed that the prepared celecoxib-loaded cubosomes had a mean particle size of 128.15 ± 3.04 nm with a low polydispersity index of 0.235 ± 0.023. The zeta potential measurement showed that the prepared cubosomes had a negative surface charge of -17.50 ± 0.45, indicating a highly stable nanodispersion formation with little susceptibility to particle aggregation. The cubosomal dispersion exhibited an entrapment efficiency of 88.57 ± 2.36%. The transmission electron micrograph for the prepared celecoxib-loaded cubosomes showed a narrow size distribution for the cubosomal nanoparticles, which had a spherical shape and were non-aggregated. The tested cubosomes diminished the inflammation in the treated mice's liver and spleen tissues, as revealed by hematoxylin and eosin stain and Masson's trichrome stain. The immunostained tissues with nuclear factor kappa B and caspase-3 monoclonal antibodies revealed a marked decrease in these markers in the celecoxib-treated group, as it resulted in negative or weak immunostaining in liver and spleen that ranged from 4.54% to 17.43%. This indicates their inhibitory effect on the inflammatory pathway and apoptosis, respectively. Furthermore, they reduced the bacterial burden in the studied tissues. This is alongside a decrease in the inflammatory markers (interleukin-1 beta, interleukin-6, cyclooxygenase-2, and tumor necrosis factor-alpha) determined by ELISA and qRT-PCR. The IL-1β levels were 16.66 ± 0.5 pg/mg and 17 ± 0.9 pg/mg in liver and spleen, respectively. Also, IL-6 levels were 85 ± 3.2 pg/mg and 84 ± 2.4 pg/mg in liver and spleen, respectively. In conclusion, the current study introduced cubosomes as an approach for the formulation of celecoxib to enhance its in vivo antibacterial action by improving its oral bioavailability.

Parametric study and process modeling for metronidazole removal by rhombic dodecahedron ZIF-67 crystals

Metronidazole (MNZ) is an extensively used antibiotic against bacterial infections for humans and farm animals. Prevention of antibiotics discharge is essential to prevent adverse environmental and health impacts. A member of metal-organic frameworks, zeolite imidazole framework-67 with cobalt sulfate precursor (ZIF-67-SO4) and exceptional physio-chemical properties was prepared via room temperature precipitation to adsorb MNZ. The study framework was designed by Box-Behnken Design to evaluate the effect of pH, ZIF-67-SO4 dose, and contact time on adsorption efficiency. The polynomial model fitted the adsorption system indicated the optimal condition for 97% MNZ removal occurs at pH = 7, adsorbent dosage = 1 g/L, and mixing time = 60 min. The model also revealed that the removal increased with contact time and decreased at strong pH. Equilibrium and kinetic study also indicated the adsorption of MNZ followed the intra-particle diffusion model and the Langmuir isotherm model with a qmax = 63.03 mg/g. The insignificant loss in removal efficacy in use-reuse adsorption cycles reflected the practical viability of ZIF-67-SO4.

Integrons in the development of antimicrobial resistance: critical review and perspectives

Antibiotic resistance development and pathogen cross-dissemination are both considered essential risks to human health on a worldwide scale. Antimicrobial resistance genes (AMRs) are acquired, expressed, disseminated, and traded mainly through integrons, the key players capable of transferring genes from bacterial chromosomes to plasmids and their integration by integrase to the target pathogenic host. Moreover, integrons play a central role in disseminating and assembling genes connected with antibiotic resistance in pathogenic and commensal bacterial species. They exhibit a large and concealed diversity in the natural environment, raising concerns about their potential for comprehensive application in bacterial adaptation. They should be viewed as a dangerous pool of resistance determinants from the "One Health approach." Among the three documented classes of integrons reported viz., class-1, 2, and 3, class 1 has been found frequently associated with AMRs in humans and is a critical genetic element to serve as a target for therapeutics to AMRs through gene silencing or combinatorial therapies. The direct method of screening gene cassettes linked to pathogenesis and resistance harbored by integrons is a novel way to assess human health. In the last decade, they have witnessed surveying the integron-associated gene cassettes associated with increased drug tolerance and rising pathogenicity of human pathogenic microbes. Consequently, we aimed to unravel the structure and functions of integrons and their integration mechanism by understanding horizontal gene transfer from one trophic group to another. Many updates for the gene cassettes harbored by integrons related to resistance and pathogenicity are extensively explored. Additionally, an updated account of the assessment of AMRs and prevailing antibiotic resistance by integrons in humans is grossly detailed-lastly, the estimation of AMR dissemination by employing integrons as potential biomarkers are also highlighted. The current review on integrons will pave the way to clinical understanding for devising a roadmap solution to AMR and pathogenicity. Graphical AbstractThe graphical abstract displays how integron-aided AMRs to humans: Transposons capture integron gene cassettes to yield high mobility integrons that target res sites of plasmids. These plasmids, in turn, promote the mobility of acquired integrons into diverse bacterial species. The acquisitions of resistant genes are transferred to humans through horizontal gene transfer.

Synergistic Effect, Improved Cell Selectivity, and Elucidating the Action Mechanism of Antimicrobial Peptide YS12

Antimicrobial peptides (AMPs) have attracted considerable attention as potential substitutes for traditional antibiotics. In our previous research, a novel antimicrobial peptide YS12 derived from the Bacillus velezensis strain showed broad-spectrum antimicrobial activity against Gram-positive and Gram-negative bacteria. In this study, the fractional inhibitory concentration index (FICI) indicated that combining YS12 with commercial antibiotics produced a synergistic effect. Following these findings, the combination of YS12 with an antibiotic resulted in a faster killing effect against bacterial strains compared to the treatment with the peptide YS12 or antibiotic alone. The peptide YS12 maintained its antimicrobial activity under different physiological salts (Na+, Mg2+, and Fe3+). Most importantly, YS12 exhibited no cytotoxicity towards Raw 264.7 cells and showed low hemolytic activity, whereas positive control melittin indicated extremely high toxicity. In terms of mode of action, we found that peptide YS12 was able to bind with LPS through electrostatic interaction. The results from fluorescent measurement revealed that peptide YS12 damaged the integrity of the bacterial membrane. Confocal laser microscopy further confirmed that the localization of peptide YS12 was almost in the cytoplasm of the cells. Peptide YS12 also exhibited anti-inflammatory activity by reducing the release of LPS-induced pro-inflammatory mediators such as TNF-α, IL-1β, and NO. Collectively, these properties strongly suggest that the antimicrobial peptide YS12 may be a promising candidate for treating microbial infections and inflammation.

Assessing Changes in Bacterial Load and Antibiotic Resistance in the Legon Sewage Treatment Plant between 2018 and 2023 in Accra, Ghana

Wastewater treatment plants are efficient in reducing bacterial loads but are also considered potential drivers of environmental antimicrobial resistance (AMR). In this study, we determined the effect of increased influent wastewater volume (from 40% to 66%) in the Legon sewage treatment plant (STP) on the removal of E. coli from sewage, along with changes in AMR profiles. This before and after study compared E. coli loads and AMR patterns in influent and effluent samples from a published baseline study (January-June 2018) with a follow-up study (March-May 2023). Extended-spectrum beta-lactamase (ESBL) E. coli were measured pre- and post-sewage treatment during the follow-up study. The follow-up study showed 7.4% and 24% ESBL E. coli proportions in influent and effluent, respectively. In both studies, the STP was 99% efficient in reducing E. coli loads in effluents, with no significant difference (p = 0.42) between the two periods. More E. coli resistance to antimicrobials was seen in effluents in the follow-up study versus the baseline study. The increased influent capacity did not reduce the efficiency of the STP in removing E. coli from influent wastewater but was associated with increased AMR patterns in effluent water. Further studies are required to determine whether these changes have significant effects on human health.

Evaluation of a Tetracycline-Resistant E. coli Enumeration Method for Correctly Classifying E. coli in Environmental Waters in Kentucky, USA

The global concern over antimicrobial resistance (AMR) and its impact on human health is evident, with approximately 4.95 million annual deaths attributed to antibiotic resistance. Regions with inadequate water, sanitation, and hygiene face challenges in responding to AMR threats. Enteric bacteria, particularly E. coli, are common agents linked to AMR-related deaths (23% of cases). Culture-based methods for detecting tetracycline-resistant E. coli may be of practical value for AMR monitoring in limited resource environments. This study evaluated the ColiGlow™ method with tetracycline for classifying tetracycline-resistant E. coli. A total of 61 surface water samples from Kentucky, USA (2020-2022), provided 61 presumed E. coli isolates, of which 28 isolates were obtained from tetracycline-treated media. Species identification and tetracycline resistance evaluation were performed. It was found that 82% of isolates were E. coli, and 18% were other species; 97% were identified as E. coli when using the API20E identification system. The MicroScan system yielded Enterobacter cloacae false positives in 20% of isolates. Adding tetracycline to ColiGlow increased the odds of isolating tetracycline-resistant E. coli 18-fold. Tetracycline-treated samples yielded 100% tetracycline-resistant E. coli when the total E. coli densities were within the enumeration range of the method. ColiGlow with tetracycline shows promise for monitoring tetracycline-resistant E. coli in natural waters and potentially aiding AMR surveillance in resource-limited settings among other environments.

Recent Advances in Optical Sensing for the Detection of Microbial Contaminants

Microbial contaminants are responsible for several infectious diseases, and they have been introduced as important potential food- and water-borne risk factors. They become a global burden due to their health and safety threats. In addition, their tendency to undergo mutations that result in antimicrobial resistance makes them difficult to treat. In this respect, rapid and reliable detection of microbial contaminants carries great significance, and this research area is explored as a rich subject within a dynamic state. Optical sensing serving as analytical devices enables simple usage, low-cost, rapid, and sensitive detection with the advantage of their miniaturization. From the point of view of microbial contaminants, on-site detection plays a crucial role, and portable, easy-applicable, and effective point-of-care (POC) devices offer high specificity and sensitivity. They serve as advanced on-site detection tools and are pioneers in next-generation sensing platforms. In this review, recent trends and advances in optical sensing to detect microbial contaminants were mainly discussed. The most innovative and popular optical sensing approaches were highlighted, and different optical sensing methodologies were explained by emphasizing their advantages and limitations. Consequently, the challenges and future perspectives were considered.

Light-absorption-driven photocatalysis and antimicrobial potential of PVP-capped zinc oxide nanoparticles

Toxic dyes in water bodies and bacterial pathogens pose serious global challenges to human health and the environment. Zinc oxide nanoparticles (ZnO NPs) demonstrate remarkable photocatalytic and antibacterial potency against reactive dyes and bacterial strains. In this work, PVP-ZnO NPs have been prepared via the co-precipitation method using polyvinylpyrrolidone (PVP) as a surfactant. The NPs' microstructure and morphology were studied using X-ray diffraction (XRD), having a size of 22.13 nm. High-resolution transmission electron microscope (HR-TEM) and field emission scanning electron microscopy (FESEM) analysis showed spherical-shaped PVP-ZnO NPs with sizer ranging from 20 to 30 nm. Fourier Transform Infrared Spectroscopy (FT-IR) confirmed the hybrid nature of the NPs, and UV-Vis spectroscopy showed an absorption peak at 367 nm. The PVP-ZnO NPs exhibited high photocatalytic activity, achieving 88% and nearly 95% degradation of reactive red-141 azo dye with 10 mg and 20 mg catalyst dosages, respectively. The antibacterial properties of the NPs were demonstrated against Escherichia coli and Bacillus subtilis, with inhibition zones of 24 mm and 20 mm, respectively. These findings suggest that PVP-ZnO NPs can be effectively used for water treatment, targeting both dye and pathogenic contaminants.

Advances on sonophotocatalysis as a water and wastewater treatment technique: efficiency, challenges and process optimisation

Due to water shortage and increased water pollution, various methods are being explored to improve water quality by treating contaminants. Sonophotocatalysis is a combination of two individual water treatment processes i.e., photocatalysis and sonocatalysis. With advantages including shorter reaction times and enhanced activity, this technique shows possible futuristic applications as an efficient water treatment technology. Herein, background insight on sonophotocalysis as a water and wastewater treatment technique as well as the general mechanism of activity is explained. The commonly used catalysts for sonophotocatalytic applications as well as their synthesis pathways are also briefly discussed. Additionally, the utilisation of sonophotocatalysis for the disinfection of various microbial species as well as treatment of wastewater pollutants including organic (dyes, pharmaceuticals and pesticides) and inorganic species (heavy metals) is deliberated. This review also gives a critical analysis of the efficiency, enhancement strategies as well as challenges and outlooks in this field. It is thus intended to give insight to researchers in the context of facilitating future developments in the field of water treatment, and advancing sonophotocatalysis towards large-scale implementation and commercialization.

On the way to potential antifungal compounds: synthesis and in vitro activity of 2-benzofuranylacetic acid amides

Crop losses caused by microbial infections are a significant global issue, especially in tropical regions. The development of novel antimicrobial agents, particularly antifungal agents, has been explored from various perspectives, including chemical synthesis. However, conventional approaches typically involve synthesizing new and potent compounds on a small scale (a few milligrams), making the scale-up of the reaction a major challenge. In this manuscript, we present a method for the synthesis of new and active (against Fusarium oxysporum) benzofuranyl acetic acid amides. Our strategy allows us to synthesize the key precursor on the gram scale, enabling the production of sufficient quantities of other active compounds within short timeframes for conducting biological studies. All the reactions used in this manuscript are recognized by their industrial application.

Protective Role of Betulinic Acid against Cisplatin-Induced Nephrotoxicity and Its Antibacterial Potential toward Uropathogenic Bacteria

Acute kidney injury (AKI) is one of the major side effects of cisplatin, a remarkable anticancer agent. Therefore, there is a growing need to find an agent that could mitigate cisplatin-induced nephrotoxicity. Betulinic acid (BA) is a natural compound isolated from Silene succulenta Forssk for the first time, with miraculous biological activities and no reports of its effect on the nephrotoxicity induced by cisplatin. Mice received BA orally with doses of 30 and 50 mg/kg before the intraperitoneal injection of cisplatin. Betulinic acid was found to decrease serum levels of creatinine and tissue levels of NGAL and kidney injury molecule (KIM-1) and improve the histological changes in the kidney. In addition, BA decreased the oxidative stress marker malondialdehyde (MDA), increased superoxide dismutase (SOD) antioxidative activity and suppressed the intensity of IL-1B and NFкB immuno-staining. Interestingly, betulinic acid enhanced autophagy by increasing beclin 1, ATG5, and LC3II and decreasing p62 expressions. Thus, our findings suggest betulinic acid as a potential agent that may protect from acute kidney injury by targeting inflammation, oxidative stress, and autophagy processes. Novel drugs are needed to combat the spreading of multidrug resistance between pathogenic bacteria, especially uropathogenic isolates. So, we elucidated the antibacterial properties of BA on Pseudomonas aeruginosa, Escherichia coli, Proteus mirabilis, and Klebsiella pneumoniae. Betulinic acid had minimum inhibitory concentration values (128 to 512 µg/mL). In addition, it adversely affected the membrane integrity of the tested isolates. Accordingly, betulinic acid should be clinically investigated in the future for urinary tract diseases.

Antimicrobial Resistance Patterns and Risk Factors Associated with ESBL-Producing and MDR Escherichia coli in Hospital and Environmental Settings in Lusaka, Zambia: Implications for One Health, Antimicrobial Stewardship and Surveillance Systems

Antimicrobial resistance (AMR) is a public health problem threatening human, animal, and environmental safety. This study assessed the AMR profiles and risk factors associated with Escherichia coli in hospital and environmental settings in Lusaka, Zambia. This cross-sectional study was conducted from April 2022 to August 2022 using 980 samples collected from clinical and environmental settings. Antimicrobial susceptibility testing was conducted using BD PhoenixTM 100. The data were analysed using SPSS version 26.0. Of the 980 samples, 51% were from environmental sources. Overall, 64.5% of the samples tested positive for E. coli, of which 52.5% were from clinical sources. Additionally, 31.8% were ESBL, of which 70.1% were clinical isolates. Of the 632 isolates, 48.3% were MDR. Most clinical isolates were resistant to ampicillin (83.4%), sulfamethoxazole/trimethoprim (73.8%), and ciprofloxacin (65.7%) while all environmental isolates were resistant to sulfamethoxazole/trimethoprim (100%) and some were resistant to levofloxacin (30.6%). The drivers of MDR in the tested isolates included pus (AOR = 4.6, CI: 1.9-11.3), male sex (AOR = 2.1, CI: 1.2-3.9), and water (AOR = 2.6, CI: 1.2-5.8). This study found that E. coli isolates were resistant to common antibiotics used in humans. The presence of MDR isolates is a public health concern and calls for vigorous infection prevention measures and surveillance to reduce AMR and its burdens.

Beyond Penicillin: The Potential of Filamentous Fungi for Drug Discovery in the Age of Antibiotic Resistance

Antibiotics are a staple in current medicine for the therapy of infectious diseases. However, their extensive use and misuse, combined with the high adaptability of bacteria, has dangerously increased the incidence of multi-drug-resistant (MDR) bacteria. This makes the treatment of infections challenging, especially when MDR bacteria form biofilms. The most recent antibiotics entering the market have very similar modes of action to the existing ones, so bacteria rapidly catch up to those as well. As such, it is very important to adopt effective measures to avoid the development of antibiotic resistance by pathogenic bacteria, but also to perform bioprospecting of new molecules from diverse sources to expand the arsenal of drugs that are available to fight these infectious bacteria. Filamentous fungi have a large and vastly unexplored secondary metabolome and are rich in bioactive molecules that can be potential novel antimicrobial drugs. Their production can be challenging, as the associated biosynthetic pathways may not be active under standard culture conditions. New techniques involving metabolic and genetic engineering can help boost antibiotic production. This study aims to review the bioprospection of fungi to produce new drugs to face the growing problem of MDR bacteria and biofilm-associated infections.

Assessment of the magnitude and contributing factors of expired medicines in the public pharmaceutical supply chains of Western Ethiopia

BACKGROUND

The magnitude of expired medicines in supply chains are increasing globally due to lack of strict control of the supply chain, poor storage management and oversupply of medicines. This situation is very serious in resource-poor countries, including Ethiopia, where the supply of medicines is limited. Therefore, this study aimed to assess the magnitude and the contributing factors of expired medicines in the Public Pharmaceutical Supply Chains of Western Ethiopia.

METHODS

Explanatory sequential study design involving mixed quantitative and qualitative approach were employed among 62 public pharmaceutical supply chains of Western Ethiopia from July1 to August 30, 2021. An observational checklist and the self-administered questionnaire were used to review all records of the expired medicine file and to abstract secondary data on the extent, types of expired medicines and its contributing factors. The collected data was cleared, filtered, and coded using Microsoft Excel® 2010, and exported to SPSS version-23 (Amsterdam, Netherland) for statistical analysis. Bivariate logistic regression was used to check association between the outcome and independent variables. Multivariate logistic regression was analyzed when p-value is less than or equal to 0.25 in bivariate binary logistic regression, considering the statistical at p-value < 0.05. Moreover, audio recordings were transcribed and coded for emergent themes using thematic analysis.

RESULTS

The study revealed 5% expire rate over past two financial (2012 up to 2013) years and the total amount of expired drugs is estimated at 20 million Ethiopian Birr (ETB). Tetanus antitoxin (TAT), in terms of single drug value, had the highest drug expiry (4,110,426.43ETB: 20%), followed by liquid dosage forms (11,614,266.11 ETB: 57%). The Binary logistic regression result indicated that, poor store management were more likely associated with the magnitude of expired medicine than those with good store management (COR: 10.706, 95% CI: 2.148, 53.348). Multivariate logistic regression revealed that poor store management (AOR: 9.718, 95% CI: 1.474, 64.082) was a significant contributor to the expire rate at 5% (P < 0.05). Most facilities did not have a procedure, and programme for disposing of expired medicines. According to key informants, inadequate inventory management, lack of policy and implementation of standards are the main contributing factors of the medicine's expiration.

CONCLUSION AND RECOMMENDATIONS

The current study found that the overall rate of medication expiration is high, at a significant cost to the budget. Inadequate inventory management, lack of policy, and implementation of standards are the main contributing factors to the medicine's expiration, as cited by key informants. Further research is necessary to determine the quality and efficacy of these expired drugs to extend their shelf life to ensure adequate access to drugs in resource-limited settings.

Meta-Analysis on the Global Prevalence of Tetracycline Resistance in Escherichia coli Isolated from Beef Cattle

Antimicrobial resistance (AMR) is an emerging global concern, with the widespread use of antimicrobials in One Health contributing significantly to this phenomenon. Among various antimicrobials, tetracyclines are extensively used in the beef cattle industry, potentially contributing to the development of resistance in bacterial populations. This meta-analysis aimed to examine the association between tetracycline use in beef cattle and the development of tetracycline resistance in Escherichia coli isolates. A comprehensive search was conducted using multiple databases to gather relevant observational studies evaluating tetracycline use and tetracycline resistance in Escherichia coli isolates from beef cattle. The rate of tetracycline resistance from each study served as the effect measure and was pooled using a random-effects model, considering possible disparities among studies. The meta-analysis of 14 prospective longitudinal studies resulted in a 0.31 prevalence of tetracycline resistance in Escherichia coli in non-intervention (no exposure), contrasting numerically elevated resistance rates in the intervention (exposed) groups of 0.53 and 0.39 in those receiving tetracyclines via feed or systemically, respectively. Despite the observed numerical differences, no statistically significant differences existed between intervention and non-intervention groups, challenging the conventional belief that antimicrobial use in livestock inherently leads to increased AMR. The findings of this study underscore the need for additional research to fully understand the complex relationship between antimicrobial use and AMR development. A considerable degree of heterogeneity across studies, potentially driven by variations in study design and diverse presentation of results, indicates the intricate and complex nature of AMR development. Further research with standardized methodologies might help elucidate the relationship between tetracycline use and resistance in Escherichia coli isolated from beef cattle.

Selected bacteria in sheep stool depending on breed and physiology state

One of the important factors influencing the microbial community of ruminants, besides environment or diet, are breed and physiology. Therefore, the purpose of this study was to assess these changes in the levels of basic microbial phyla and families. For this study, qPCR analysis was performed to determine the level of bacteria (Firmicutes, Bacteroidetes, Actinobacteria, Proteobacteria clusters and Clostridiaceae, Lactobacillaceae families) in the feces of ewes of three native Polish sheep breeds (Polish Lowland Sheep (PON), Świniarka Sheep (SW), and synthetic line BCP) at different physiological periods (conception, early pregnancy, lambing, end of lactation). The animals were kept in the same environment and were at the same age (2-years). The results showed a significant effect of both breed (p = 0.038) and physiological period (p < 0.05, p < 0.01) on the levels of bacteria analyzed. The breed showed differences across physiological periods. The influence of the race factor was noted primarily between the BCP synthetic line and the other two breeds (differences in terms of all analyzed clusters and families except Actinobacteria phyla). In the case of SW and PON, however, the observed differences were only at the level of Proteobacteria cluster and Clostridiaceae family. On the other hand, the early pregnant and lambing periods were the most microbiologically diverse in terms of the analyzed clusters and families of bacteria.

Surveys on Pet-Reptile-Associated Multi-Drug-Resistant Salmonella spp. in the Timișoara Metropolitan Region-Western Romania

The number of reptiles owned as pets has risen worldwide. Additionally, urban expansion has resulted in more significant human encroachment and interactions with the habitats of captive reptiles. Between May and October 2022, 48 reptiles from pet shops and 69 from households were sampled in the Timișoara metropolitan area (western Romania). Three different sample types were collected from each reptile: oral cavity, skin, and cloacal swabs. Salmonella identification was based on ISO 6579-1:2017 (Annex D), a molecular testing method (invA gene target), and strains were serotyped in accordance with the Kauffman-White-Le-Minor technique; the antibiotic susceptibility was assessed according to Decision 2013/652. This study showed that 43.28% of the pet reptiles examined from households and pet shops carried Salmonella spp. All of the strains isolated presented resistance to at least one antibiotic, and 79.32% (23/29) were multi-drug-resistant strains, with the most frequently observed resistances being to gentamicin, nitrofurantion, tobramycin, and trimethoprim-sulfamethoxazole. The findings of the study undertaken by our team reveal that reptile multi-drug-resistant Salmonella is present. Considering this aspect, the most effective way of preventing multi-drug-resistant Salmonella infections requires stringent hygiene control in reptile pet shops as well as ensuring proper animal handling once the animals leave the pet shop and are introduced into households.

Immunomodulation, Bioavailability and Safety of Bacteriocins

The rise of antibiotic-resistant bacteria and the emergence of new pathogens have created a need for new strategies to fight against infectious diseases. One promising approach is the use of antimicrobial peptides produced by a certain species of bacteria, known as bacteriocins, which are active against other strains of the same or related species. Bacteriocins can help in the treatment and prevention of infectious diseases. Moreover, bacteriocins can be obtained in prokaryotic organisms, and contribute s to their widespread use. While the use of bacteriocins is currently limited to the food industry (for example, nisin is used as a preservative, E234), a large number of studies on their microbicidal properties suggest that their use in medicine may increase in the foreseeable future. However, for the successful use of bacteriocins in medicine, it is necessary to understand their effect on the immune system, especially in cases where immunity is weakened due to infectious processes, oncological, allergic, or autoimmune diseases. Studies on the immuno-modulatory activity of bacteriocins in animal models and human cells have revealed their ability to induce both pro-inflammatory and anti-inflammatory factors involved in the implementation of innate immunity. The influence of bacteriocins on acquired immunity is revealed by an increase in the number of T-lymphocytes with a simultaneous decrease in B-lymphocyte levels, which makes them attractive substances for reducing inflammation. The widespread use of bacteriocins in the food industry, their low toxicity, and their broad and narrow specificity are reasons for researchers to pay attention to their immunomodulatory properties and explore their medical applications. Inflammation regulation by bacteriocins can be used in the treatment of various pathologies. The aim of the review was to analyze scientific publications on the immunomodulatory activity, bioavailability, and safety of bacteriocins in order to use the data obtained to organize preclinical and clinical studies.

Genome insight and probiotic potential of three novel species of the genus Corynebacterium

Three bacterial strains, B5-R-101^T, TA-R-1^T, and BL-R-1^T, were isolated from the feces of a healthy Korean individual. Cells of these strains were Gram-stain-positive, facultatively anaerobic, oxidase-negative, catalase-positive, rod-shaped, and non-motile. They were able to grow within a temperature range of 10-42°C (optimum, 32-37°C), at a pH range of 2.0-10.0 (optimum, pH 5.5-8.0), and at NaCl concentration of 0.5-10.5% (w/v). All the three strains exhibited 2,2-Diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activities ranging from 58 ± 1.62 to 79 ± 1.46% (% inhibition). These strains survived in lower pH (2.0) and in 0.3% bile salt concentration for 4 h. They did not show hemolytic activity and exhibited antimicrobial activity against pathogenic bacteria, such as Escherichia coli, Acinetobacter baumannii, Staphylococcus aureus, and Salmonella enterica. The genomic analysis presented no significant concerns regarding antibiotic resistance or virulence gene content, indicating these strains could be potential probiotic candidates. Phylogenetic analysis showed that they belonged to the genus Corynebacterium, with 98.5-99.0% 16S rRNA gene sequence similarities to other members of the genus. Their major polar lipids were diphosphatidylglycerol and phosphatidylglycerol. The abundant cellular fatty acids were C_16:0, C_18:1ω9c, and anteiso-C_19:0. Genomic analysis of these isolates revealed the presence of genes necessary for their survival and growth in the gut environment, such as multi-subunit ATPases, stress response genes, extracellular polymeric substance biosynthesis genes, and antibacterial genes. Furthermore, the genome of each strain possessed biosynthetic gene clusters with antioxidant and antimicrobial potentials, including terpenes, saccharides, polyketides, post-translationally modified peptides (RIPPs), and non-ribosomal peptides (NRPs). In silico DNA-DNA hybridization (dDDH) and average nucleotide identity (ANI) values were lower than the thresholds to distinguish novel species. Based on phenotypic, genomic, phylogenomic, and phylogenetic analysis, these potential probiotic strains represent novel species within the genus Corynebacterium, for which the names Corynebacterium intestinale sp. nov. (type strain B5-R-101^T = CGMCC 1.19408^T = KCTC 49761^T), Corynebacterium stercoris sp. nov. (type strain TA-R-1^T = CGMCC 1.60014^T = KCTC 49742^T), and Corynebacterium faecium sp. nov. (type strain BL-R-1^T = KCTC 49735^T = TBRC 17331^T) are proposed.

Boletus edulis Extract-A New Modulator of Dysbiotic Microbiota

The regular administration of antibiotics is a public concern due to the prejudices of large population groups and the high frequency with which antimicrobial products are prescribed. The current study aimed to evaluate the in vitro effect of a new extract from Boletus edulis (BEE) on the human microbiota. One of the disadvantages of this extensive use is the disruption of the human microbiota, leading to potential negative health consequences. The in vitro evaluation of BEE consisted in determining its cytotoxicity, influence on the concentration of four types of cytokines (IL-6, IL-10, IL-1β, TNFα), and capacity to modulate the human microbiota after administering antibiotics. The latter was assessed by microbiome analysis and the evaluation of short-chain fatty acid synthesis (SCFAs). Simultaneously, the content of total polyphenols, the antioxidant capacity, and the compositional analysis of the extract (individual polyphenols composition) were determined. The results showed that BEE modulates the microbial pattern and reduces inflammatory progression. The data demonstrated antioxidant properties correlated with the increase in synthesizing some biomarkers, such as SCFAs, which mitigated antibiotic-induced dysbiosis without using probiotic products.

Evaluation of Antimicrobial Activities against Various E. coli Strains of a Novel Hybrid Peptide-LENART01

Finding the ideal antimicrobial drug with improved efficacy and a safety profile that eliminates antibiotic resistance caused by pathogens remains a difficult task. Indeed, there is an urgent need for innovation in the design and development of a microbial inhibitor. Given that many promising antimicrobial peptides with excellent broad-spectrum antibacterial properties are secreted by some frog species (e.g., bombesins, opioids, temporins, etc.), our goal was to identify the antimicrobial properties of amphibian-derived dermorphin and ranatensin peptides, which were combined to produce a hybrid compound. This new chimera (named LENART01) was tested for its antimicrobial activity against E. coli strains K12 and R1-R4, which are characterized by differences in lipopolysaccharide (LPS) core oligosaccharide structure. The results showed that LENART01 had superior activity against the R2 and R4 strains compared with the effects of the clinically available antibiotics ciprofloxacin or bleomycin (MIC values). Importantly, the inhibitory effect was not concentration dependent; however, LENART01 showed a time- and dose-dependent hemolytic effect in hemolytic assays.

Symptoms, Treatment, and Outcomes of COVID-19 Patients Coinfected with Clostridioides difficile: Single-Center Study from NE Romania during the COVID-19 Pandemic

The Coronavirus disease 2019 (COVID-19) pandemic has brought new challenges across medical disciplines, particularly in infectious disease medicine. In Romania, the incidence of SARS-CoV-2 (Severe acute respiratory syndrome coronavirus 2) infection increased dramatically since March 2020 until March 2022. Antibiotic administration for pulmonary superinfections in COVID-19 intensified and, consequently, increased rates of Clostridioides difficile infection (CDI) were hypothesized. We conducted a single-center, retrospective, observational study on patients from North-Eastern Romania to assess clinical characteristics and outcomes of COVID-19 and Clostridioides difficile (CD) coinfection, and to identify risk factors for CDI in COVID-19 patients. The study enrolled eighty-six CDI and COVID-19 coinfected patients admitted during March 2020-February 2021 (mean age 59.14 years, 53.49% men, 67.44% urban residents) and a group of eighty-six COVID-19 patients. On admission, symptoms were more severe in mono-infected patients, while coinfected patients associated a more intense acute inflammatory syndrome. The main risk factors for severe COVID-19 were smoking, diabetes mellitus, and antibiotic administration. Third generation cephalosporins (55%) and carbapenems (24%) were the main antibiotics used, and carbapenems were significantly associated with severe COVID-19 in patients coinfected with CD during hospitalization. Coinfection resulted in longer hospitalization and poorer outcomes. The extensive use of antibiotics in COVID-19, particularly carbapenems, contributed substantially to CD coinfection.

A Review of Carbapenem Resistance in Enterobacterales and Its Detection Techniques

Infectious disease outbreaks have caused thousands of deaths and hospitalizations, along with severe negative global economic impacts. Among these, infections caused by antimicrobial-resistant microorganisms are a major growing concern. The misuse and overuse of antimicrobials have resulted in the emergence of antimicrobial resistance (AMR) worldwide. Carbapenem-resistant Enterobacterales (CRE) are among the bacteria that need urgent attention globally. The emergence and spread of carbapenem-resistant bacteria are mainly due to the rapid dissemination of genes that encode carbapenemases through horizontal gene transfer (HGT). The rapid dissemination enables the development of host colonization and infection cases in humans who do not use the antibiotic (carbapenem) or those who are hospitalized but interacting with environments and hosts colonized with carbapenemase-producing (CP) bacteria. There are continuing efforts to characterize and differentiate carbapenem-resistant bacteria from susceptible bacteria to allow for the appropriate diagnosis, treatment, prevention, and control of infections. This review presents an overview of the factors that cause the emergence of AMR, particularly CRE, where they have been reported, and then, it outlines carbapenemases and how they are disseminated through humans, the environment, and food systems. Then, current and emerging techniques for the detection and surveillance of AMR, primarily CRE, and gaps in detection technologies are presented. This review can assist in developing prevention and control measures to minimize the spread of carbapenem resistance in the human ecosystem, including hospitals, food supply chains, and water treatment facilities. Furthermore, the development of rapid and affordable detection techniques is helpful in controlling the negative impact of infections caused by AMR/CRE. Since delays in diagnostics and appropriate antibiotic treatment for such infections lead to increased mortality rates and hospital costs, it is, therefore, imperative that rapid tests be a priority.

Domestic Pets in the United Arab Emirates as Reservoirs for Antibiotic-Resistant Bacteria: A Comprehensive Analysis of Extended-Spectrum Beta-Lactamase Producing Escherichia coli Prevalence and Risk Factors

Extended-spectrum β-lactamases resistant (ESBL-R) Escherichia coli (E. coli) has been reported from healthy and sick pets. However, data from Middle Eastern countries, including the United Arab Emirates (UAE), are minimal. This study provides the first evidence of ESBL-R E. coli carriage among pets in the UAE. A total of 148 rectal swabs were collected from domestic cats (n = 122) and dogs (n = 26) attending five animal clinics in the UAE. Samples were cultured directly onto selective agar, and suspected colonies were confirmed as ESBL-producing using phenotypic and molecular methods. Confirmed isolates were screened for their phenotypic resistance to twelve antimicrobial agents using the Kirby Bauer method. The owners of the pets completed a questionnaire at the time of sampling, and the data were used to identify risk factors. ESBL-R E. coli was detected in rectal swabs of 35 out of 148 animals (23.65%) (95% confidence interval [CI]: 17.06-31.32). Multivariable logistic regression analysis identified cats and dogs with access to water in ditches and puddles as 3.71 (p-value = 0.020) times more likely to be positive to ESBL-R E. coli than those without access to open water sources. Ciprofloxacin resistance was evident in 57.14% (44/77) of the ESBL-R E. coli isolates. The percentage of resistance to azithromycin and cefepime was 12.99% (10/77) and 48.05% (37/77), respectively. The bla_CTX-M gene was detected in 82% of the PCR-screened isolates (n = 50). Multidrug resistance (MDR) phenotypes were evident in 91% (70/77) of the isolates. In conclusion, ESBL-R E. coli was detected at a noticeable rate among healthy pet cats and dogs in the UAE, and the majority are MDR to clinically important antimicrobials such as fluoroquinolones and 3rd and 4th generation cephalosporins. Our results call for strengthening antimicrobial stewardship among companion animal veterinarians in the UAE to reduce the potential transmission of ESBL-R E. coli between pets, humans, and urban environments.

The global profile of antibiotic resistance in bacteria isolated from goats and sheep: A systematic review

Background and Aim

Antibiotic resistance has become an issue of global importance due to increasing levels of bacterial infections worldwide. Farm management and usage of antibiotics in livestock are known risk factors associated with the increase in global levels of antibiotic resistance. Goats and sheep are examples of livestock with large populations. Although antibiotic resistance in bacteria from livestock negatively affects both human health and the economy, the global data regarding this issue in goats and sheep are limited. Therefore, this study aimed to provide information on the antibiotic-resistance profile of bacteria isolated from goats and sheep worldwide (Asia, Europe, and Africa).

Materials and Methods

We performed a systematic review of articles published on this topic without any restriction on the year of publication. We searched the Directory of Open Access Journals, PubMed, Google Scholar, and Scopus using Boolean logic through various keywords. The search generated a total of 1325 articles, and after screening for duplicates and implementing inclusion and exclusion criteria, qualitative synthesis (i.e., qualitative systematic review) was performed on 37 articles.

Results

The synthesized information indicated that 18 Gram-positive and 13 Gram-negative bacterial species from goats and sheep were resistant to ten antibiotics, namely penicillin, ampicillin, amoxicillin, chloramphenicol, streptomycin, tetracycline, cephalothin, gentamicin, ciprofloxacin (CIP), and sulfamethoxazole. The prevalence of antibiotic resistance ranged from 0.4% to 100%. However, up to 100% of some bacteria, namely, Salmonella Dublin, Aeromonas caviae, and Aeromonas sobria, were susceptible to CIP. Staphylococcus aureus and Escherichia coli were highly resistant to all antibiotics tested. Moreover, eight of the ten antibiotics tested were critically important antibiotics for humans.

Conclusion

Antibiotic-resistant bacteria in goats and sheep are a potential risk to animal and human health. Collaboration between all stakeholders and further research is needed to prevent the negative impacts of antibiotic resistance.

Antibiotic resistance profiling and valorization of food waste streams to starter culture biomass and exopolysaccharides through fed-batch fermentations

The present study evaluated antibiotic resistance (ABR) in bacteria isolated from different food wastes viz., meat slaughterhouses, dairy and restaurants. About 120 strains isolated from the food waste were subjected to ABR screening. More than 50% of all the strains were resistant to Vancomycin, Neomycin and Methicilin, which belong to third-generation antibiotics. Two lactic acid bacteria (LAB) free of ABR were chosen to be used as starter cultures in media formulated from food waste. Food waste combination (FWC-4) was found to be on par with the nutrient broth in biomass production. The non-ABR LAB strains showed excellent probiotic properties, and in the fed-batch fermentation process, adding a nitrogen source (soya protein) enhanced the microbial biomass (3.7 g/l). Additionally, exopolysaccharide production was found to be 2.3 g/l. This study highlights the ABR incidence in food waste medium and its economic advantage for starter culture biomass production.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-022-01222-9.

Hospital sanitary facilities on wards with high antibiotic exposure play an important role in maintaining a reservoir of resistant pathogens, even over many years

BACKGROUND

Hospitals with their high antimicrobial selection pressure represent the presumably most important reservoir of multidrug-resistant human pathogens. Antibiotics administered in the course of treatment are excreted and discharged into the wastewater system. Not only in patients, but also in the sewers, antimicrobial substances exert selection pressure on existing bacteria and promote the emergence and dissemination of multidrug-resistant clones. In previous studies, two main clusters were identified in all sections of the hospital wastewater network that was investigated, one K. pneumoniae ST147 cluster encoding NDM- and OXA-48 carbapenemases and one VIM-encoding P. aeruginosa ST823 cluster. In the current study, we investigated if NDM- and OXA-48-encoding K. pneumoniae and VIM-encoding P. aeruginosa isolates recovered between 2014 and 2021 from oncological patients belonged to those same clusters.

METHODS

The 32 isolates were re-cultured, whole-genome sequenced, phenotypically tested for their antimicrobial susceptibility, and analyzed for clonality and resistance genes in silico.

RESULTS

Among these strains, 25 belonged to the two clusters that had been predominant in the wastewater, while two others belonged to a sequence-type less prominently detected in the drains of the patient rooms.

CONCLUSION

Patients constantly exposed to antibiotics can, in interaction with their persistently antibiotic-exposed sanitary facilities, form a niche that might be supportive for the emergence, the development, the dissemination, and the maintenance of certain nosocomial pathogen populations in the hospital, due to antibiotic-induced selection pressure. Technical and infection control solutions might help preventing transmission of microorganisms from the wastewater system to the patient and vice versa, particularly concerning the shower and toilet drainage. However, a major driving force might also be antibiotic induced selection pressure and parallel antimicrobial stewardship efforts could be essential.

Molecular Characterization of Some Bacillus Species from Vegetables and Evaluation of Their Antimicrobial and Antibiotic Potency

Numerous natural habitats, such as soil, air, fermented foods, and human stomachs, are home to different Bacillus strains. Some Bacillus strains have a distinctive predominance and are widely recognized among other microbial communities, as a result of their varied habitation and physiologically active metabolites. The present study collected vegetable products (potato, carrot, and tomato) from local markets in Almaty, Kazakhstan. The bacterial isolates were identified using biochemical and phylogenetic analyses after culturing. Our phylogenetic analysis revealed three Gram-positive bacterial isolates BSS11, BSS17, and BSS19 showing 99% nucleotide sequence similarities with Bacillus subtilis O-3, Bacillus subtilis Md1-42, and Bacillus subtilis Khozestan2. The crude extract was prepared from bacterial isolates to assess the antibiotic resistance potency and the antimicrobial potential against various targeted multidrug-resistant strains, including Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus group B, Streptococcus mutans, Candida albicans, Candida krusei, Pseudomonas aeruginosa, Shigella sonnei, Klebsiella pneumoniae, Salmonella enteritidis, Klebsiella aerogenes, Enterococcus hirae, Escherichia coli, Serratia marcescens, and Proteus vulgaris. This study found that the species that were identified have the ability to produce antibiotic chemicals. Additionally, the GC-MS analysis of three bacterial extracts revealed the presence of many antibiotic substances including phenol, benzoic acid, 1,2-benzenedicarboxylic acid and bis(2-methylpropyl), methoxyphenyl-oxime, and benzaldehyde. This work sheds light on the potential of Bacillus to be employed as an antimicrobial agent to target different multidrug-resistant bacterial strains. The results indicate that market vegetables may be a useful source of strains displaying a range of advantageous characteristics that can be used in the creation of biological antibiotics.

A novel antimicrobial peptide YS12 isolated from Bacillus velezensis CBSYS12 exerts anti-biofilm properties against drug-resistant bacteria

Nowadays, the abuse of antibiotics has led to the rise of multi-drug-resistant bacteria. Antimicrobial peptides (AMPs), with broad-spectrum antimicrobial activity have attracted considerable attention as possible alternatives to traditional antibiotics. In this work, we aimed to evaluate the antimicrobial and anti-biofilm activity of an antimicrobial peptide designed as YS12 derived from Bacillus velezensis CBSYS12. The strain CBSYS12 was isolated from Korean food kimchi and purified followed by ultrafiltration and sequential chromatographic methodology. Hereafter, Tricine SDS-PAGE revealed a single protein band of around 3.3 kDa that was further confirmed in situ inhibitory activity of the gel. A similar molecular weight (~ 3348.4 Da) protein also appeared in MALDI-TOF confirming the purity and homogeneity of peptide YS12. Intriguingly, YS12 revealed a strong antimicrobial activity with a minimum inhibitory concentration (MIC) value ranging from 6 to 12 μg/ml for both Gram-positive and Gram-negative bacteria, such as E. coli, P. aeruginosa, MRSA 4-5, VRE 82, and M. smegmatis. We also determined the mode of action of the peptide against pathogenic microorganisms using different fluorescent dyes. In addition, the anti-biofilm assay demonstrated that peptide YS12 was able to inhibit biofilm formation  around 80% for both bacterial strains E. coli and P. aeruginosa at 80 µg/ml. Notably, YS12 exhibited a greater biofilm eradication activity than commercial antibiotics. In summary, our study proposed that peptide YS12 may be used as a promising therapeutic agent to overcome drug and biofilm-related infections.

Use of fermented Chinese medicine residues as a feed additive and effects on growth performance, meat quality, and intestinal health of broilers

Introduction

The purpose of this research was to investigate how dietary supplementation with fermented herbal residues (FCMR) affected birds' development capacity, quality of meat, gut barrier, and cecum microbiota.

Methods

540 cyan-shank partridge birds aged 47 days were chosen and divided into two groups of six replicates each and 45 birds for each replicate. The control group (CON) received a basal diet, while the trial group decreased a basic diet containing 5% FCMR.

Results and discussion

The findings revealed that the addition of FCMR decreased FCR and increased ADG in broilers (P < 0.05). Adding FCMR increased steaming loss in broiler chicken breasts (p < 0.05). Supplementation with FCMR significantly enhanced VH/CD and VH in the bird's intestine (jejunum, duodenum, and ileum) (p < 0.05). In addition, the addition of FCMR significantly down-regulated mRNA expression of INF-γ, IL-6, IL-1β, and TNF-α and up-regulated mRNA expression of ZO-1, Occludin, and Claudin (P < 0.05). Microbial 16S rDNA high-throughput sequencing study revealed that supplements with FCMR modified the cecum microbiota, and α-diversity analysis showed that supplementation with FCMR reduced the cecum bacterial abundance in broilers (P < 0.05). At the phylum level, the relative abundance of Spirochaetota increased considerably following FCMR supplementation (P < 0.05). The broiler cecum's close lot of Prevotellaceae_UCG-001 (P < 0.05), Desulfovibrio, Muribaculaceae, and Fusobacterium (p < 0.05) reduced when FCMR was supplemented. Supplementation with FCMR can promote growth capacity and maintain intestinal health in birds by enhancing gut barrier function and modulating the inflammatory response and microbial composition.

High prevalence of Escherichia coli co-harboring conjugative plasmids with colistin- and carbapenem resistance genes in a wastewater treatment plant in China

Emergence and dissemination of resistance to last-resort antibiotics such as carbapenem and colistin is a growing, global health concern. Wastewater treatment plants (WWTPs) link human activities and the environment, can act as reservoirs and sources for emerging antibiotic resistance, and likely play a large role in antibiotic resistance transmission. The aim of this study was to investigate occurrence and characteristics of colistin- and carbapenem-resistant Escherichia coli (CCREC) in wastewater and sludge samples collected over a one-year period from different functional areas of an urban WWTP in Jinan city, Shandong, China. A total of 8 CCREC were isolated from 168 samples with selective agar and PCR, corresponding to high prevalence of 4.8%, co-harboring carbapenem resistance genes (bla_NDM) and colistin resistance gene (mcr-1) and subsequently whole-genome sequenced. Additionally, all isolates were multidrug-resistant by antimicrobial susceptibility testing and carried a variety of antibiotic resistance genes. Two isolates carrying virulence genes associated with avian pathogenic E. coli were identified, one belonging to the high-risk clone O101:H9-ST167. Southern blotting was used to characterize CCREC isolates and plasmids carrying bla_NDM-genes or mcr-1 could be transferred to a recipient strain E. coli J53 by in vitro conjugation assays. Resistance to other antibiotic classes were sporadically co-transferred to the transconjugant. Transposition of and mcr-1-carrying element from a transferable IncHI2-plasmid was observed among two CCREC clones isolated within 4 days of each other. The occurrence of multidrug-resistant CCREC capable of transferring their antibiotic resistance genotypes via conjugative plasmids is alarming. WWTPs bring bacteria from different sources together, providing opportunities for horizontal exchange of DNA among compatible hosts. Further dissemination of the colistin-, carbapenem-, or both colistin- and carbapenem resistant E. coli could lead to a serious threat to public health.

Trends in Antibiotic Resistance of Nosocomial and Community-Acquired Infections in Italy

The World Health Organization has recently identified three categories of pathogens, namely: critical, high, and medium priority, according to the need for new antibiotics. Critical priority pathogens include carbapenem-resistant microorganism (CPO) such as A. baumannii and P. aeruginosa, K. pneumoniae, and Enterobacter spp., whereas vancomycin-resistant E. faecium (VRE), methicillin and vancomycin-resistant S. aureus (MRSA) are in the high priority list. We compared the trend of antimicrobial resistants (AMRs) in clinical isolates, divided by year and bacteria spp., of samples obtained from nosocomial and community patients. Patient records were collected, including age, sex, site of infection, isolated organisms, and drug susceptibility patterns. From 2019 to 2022, a total of 113,635 bacterial isolates were tested, of which 11,901 resulted in antimicrobial resistants. An increase in the prevalence of several antibiotics resistant bacteria was observed. Specifically, the percentage of CPO cases increased from 2.62% to 4.56%, the percentage of MRSA increased from 1.84% to 2.81%, and the percentage of VRE increased from 0.58% to 2.21%. AMRs trend resulted in increases in CPO and MRSA for both community and nosocomial. Our work aims to highlight the necessity of preventive and control measures to be adopted in order to reduce the spread of multidrug-resistant pathogens.

β-Lactamase Genes (blaCTX-M, blaSHV, blaTEM, blaOXA1 and blaOXA2) and Phylogenetic Groups in ESBL Producing Commensal Escherichia coli Isolated from Faecal Samples from Dairy Farm in the Municipality of Debar

β-lactamases are a diverse class of enzymes produced by bacteria that present a major cause for resistance to β-lactams. In this study we analysed 159 fecal samples from dairy cows, for the presence of presumptive ESBL, AmpC, and carbapenemase-producing E. coli. Phylotyping was done using Clermont phylo-typing method, targeting arpA, ChuA, and YjaA genes, along with the DNA fragment TspE4.C2. Convetional PCR method was used to confirm the presence of bla genes among 39 phenotypically confirmed ESBL producing E. coli. The results showed presence of CTX-M, SHV, TEM and OXA1 bla genes in 28 (71.79%), 1 (2.56%), 29 (74.35%), 2 (5.12%) of isolates, respectively Twenty (51.28%) isolates showed presence of both blaCTX-M and TEM genes. The strain that carried the blaSHV gene was found to carry blaTEM gene as well, while one of the strains that carried blaOXA1 gene was also carrying blaCTX-M and TEM gene. The ration between isolates and phylo-groups was as follows: 9 (23.07%) strains were assigned to phyllo-group D; 14 (35.89%) to phyllo-group B; 16 (41.02%) to phyllo-group A. Out of the 39 strains where bla genes were identified, 29 (74.35%) were categorized as multi drug resistant.

Photodegradation of Ciprofloxacin and Levofloxacin by Au@ZnONPs-MoS2-rGO Nanocomposites

This study aimed to investigate the photocatalytic performance of diverse zinc oxide catalysts containing gold nanoparticles (AuNPs), molybdenum disulfide (MoS2), and reduced graphene oxide (rGO) toward the degradation of the antibiotics levofloxacin (LFX) and ciprofloxacin (CFX) in aqueous solutions. The obtained results demonstrate that LFX is more resistant to degradation when compared with CFX and that the principal route of degradation under visible light is the formation of hydroxyl radicals. Photoluminescence (PL) measurements were employed to verify the inhibitory effect of electron–hole recombination when AuNPs, MoS2, and rGO are integrated into a semiconductor. The catalyst that achieved the highest percentage of CFX degradation was 1%Au@ZnONPs-3%MoS2-1%rGO, exhibiting a degradation efficiency of 96%, while the catalyst that exhibited the highest percentage of LFX degradation was 5%Au@ZnONPs-3%MoS2-1%rGO, displaying a degradation efficiency of 99.8%. A gas chromatography–mass spectrometry (GC-MS) analysis enabled the identification of reaction intermediates, facilitating the determination of a potential degradation pathway for both antibiotics. Additionally, recyclability assessments showed that the synthesized catalysts maintained stable photocatalytic efficiencies after 15 cycles, indicating that the heterostructures have the potential for further usage and may be tested with other organic contaminants as well.

Effects of co-selection of antibiotic-resistance and metal-resistance genes on antibiotic-resistance potency of environmental bacteria and related ecological risk factors

The inadequate elimination of micropollutants in wastewater treatment plants (WWTP), cause to increase in the incidence of antibiotic resistant bacterial strains. Growth of microbial pathogens in WWTP is one of the serious public health problems. The widespread and simultaneous emergence of antibiotic resistance genes (ARGs) and heavy metal resistance genes (HMRGs) in the environment with heavy metals create persistent and selective pressure for co-selection of both genes on environmental microorganisms. Co-localization of ARGs and HMRGs on the same horizontal mobile genetic elements (MGEs) allows the spreading of numerous antibiotic-resistant strains of bacteria in aquatic and terrestrial environment. The biofilm formation and colonization potential of environmental bacteria leads to the co-selection of multi-antibiotic resistance and multi-metal tolerance. Horizontal gene transfer (HGT), co-localization of both ARGs and HMRGs on the same MGEs, and the shared resistomes are important bacteria-associated ecological risks factors, which reduce the effectiveness of antibiotics against bacterial infections.

A sludge bulking wastewater treatment plant with an oxidation ditch-denitrification filter in a cold region: bacterial community composition and antibiotic resistance genes

Bacterial community structure of activated sludge directly affects the stable operation of WWTPS, and these bacterial communities may carry a variety of antibiotic resistance genes (ARGs), which is a threat to the public health. This study employed 16S rRNA gene sequencing and metagenomic sequencing to investigate the bacterial community composition and the ARGs in a sludge bulking oxidation ditch-denitrification filter WWTP in a cold region. The results showed that Trichococcus (20.34%), Blautia (7.72%), and Faecalibacterium (3.64%) were the main bacterial genera in the influent. The relative abundances of norank_f_Saprospiraceae and Candidatus_Microthrix reached 10.24% and 8.40%, respectively, in bulking sludge, and those of norank_f_Saprospiraceae and Candidatus_Microthrix decreased to 6.56 and 7.10% after the anaerobic tank, indicating that the anaerobic tank had an inhibitory effect on filamentous bacteria. After 20 mJ/cm² UV disinfection, about 540 bacterial genera, such as Romboutsia (7.99%), Rhodoferax (7.98%), and Thermomonas (4.13%), could still be detected in the effluent. The ARGs were 345.11 ppm in the influent and 11.20 ppm in the effluent; 17 subtypes, such as sul1, msrE, aadA5, ErmF, and tet(A), could be detected throughout the entire process. These ARG subtypes were persistent ARGs with a high health risk. Network analysis indicated that the changes in filamentous bacteria norank_f_Saprospiraceae abundance mainly contributed to the abundance shift of MexB, and Acinetobacter mainly increased the abundance of drfA1. These results above will provide theoretical support for the sludge bulking and ARGs controls of WWTPs in cold regions.