Riboswitch-controlled IL-12 gene therapy reduces hepatocellular cancer in mice.

Hepatocellular carcinoma (HCC) and solid cancers with liver metastases are indications with high unmet medical need. Interleukin-12 (IL-12) is a proinflammatory cytokine with substantial anti-tumor properties, but its therapeutic potential has not been realized due to severe toxicity. Here, we show that orthotopic liver tumors in mice can be treated by targeting hepatocytes via systemic delivery of adeno-associated virus (AAV) vectors carrying the murine IL-12 gene. Controlled cytokine production was achieved in vivo by using the tetracycline-inducible K19 riboswitch. AAV-mediated expression of IL-12 led to STAT4 phosphorylation, interferon-γ (IFNγ) production, infiltration of T cells and, ultimately, tumor regression. By detailed analyses of efficacy and tolerability in healthy and tumor-bearing animals, we could define a safe and efficacious vector dose. As a potential clinical candidate, we characterized vectors carrying the human IL-12 (huIL-12) gene. In mice, bioactive human IL-12 was expressed in a vector dose-dependent manner and could be induced by tetracycline, suggesting tissue-specific AAV vectors with riboswitch-controlled expression of highly potent proinflammatory cytokines as an attractive approach for vector-based cancer immunotherapy.

Machine learning reveals the selection pressure exerted by nonantibiotic pharmaceuticals at environmentally relevant concentrations on antibiotic resistance genotypes.

The emergence and increasing prevalence of antibiotic resistance pose a global public risk for human health, and nonantimicrobial pharmaceuticals play an important role in this process. Herein, five nonantimicrobial pharmaceuticals, including acetaminophen (ACT), clofibric acid (CA), carbamazepine (CBZ), caffeine (CF) and nicotine (NCT), tetracycline-resistant strains, five ARGs (sul1, sul2, tetG, tetM and tetW) and one integrase gene (intI1), were detected in 101 wastewater samples during two typical sewage treatment processes including anaerobic-oxic (A/O) and biological aerated filter (BAF) in Harbin, China. The impact of nonantibiotic pharmaceuticals at environmentally relevant concentrations on both the resistance genotypes and resistance phenotypes were explored. The results showed that a significant impact of nonantibiotic pharmaceuticals at environmentally relevant concentrations on tetracycline resistance genes encoding ribosomal protection proteins (RPPs) was found, while no changes in antibiotic phenotypes, such as minimal inhibitory concentrations (MICs), were observed. Machine learning was applied to further sort out the contribution of nonantibiotic pharmaceuticals at environmentally relevant concentrations to different ARG subtypes. The highest contribution and correlation were found at concentrations of 1400-1800 ng/L for NCT, 900-1500 ng/L for ACT and 7000-10,000 ng/L for CF for tetracycline resistance genes encoding RPPs, while no significant correlation was found between the target compounds and ARGs when their concentrations were lower than 500 ng/L for NCT, 100 ng/L for ACT and 1000 ng/L for CF, which were higher than the concentrations detected in effluent samples. Therefore, the removal of nonantibiotic pharmaceuticals in WWTPs can reduce their selection pressure for resistance genes in wastewater.

Refractoriness to anti-Helicobacter pylori treatment attributed to phenotypic resistance patterns in patients with gastroduodenopathy in Guayaquil-Ecuador.

BACKGROUND: Treatment of Helicobacter pylori gastric infection is complex and associated with increased rates of therapeutic failure. This research aimed to characterize the H. pylori infection status, strain resistance to antimicrobial agents, and the predominant lesion pattern in the gastroduodenal mucosa of patients with clinical suspicion of refractoriness to first- and second-line treatment who were diagnosed and treated in a health center in Guayaquil, Ecuador. METHODS: A total of 374 patients with upper gastrointestinal symptoms and H. pylori infection were preselected and prescribed one of three triple therapy regimens for primary infection, as judged by the treating physician. Subsequently, 121 patients who returned to the follow-up visit with persistent symptoms after treatment were studied. RESULTS: All patients had H. pylori infection. Histopathological examination diagnosed chronic active gastritis in 91.7% of cases; premalignant lesions were observed in 15.8%. The three triple therapy schemes applied showed suboptimal efficacy (between 47.6% and 77.2%), with the best performance corresponding to the scheme consisting of a proton pump inhibitor + amoxicillin + levofloxacin. Bacterial strains showed very high phenotypic resistance to all five antimicrobials tested: clarithromycin, 82.9%; metronidazole, 69.7%; amoxicillin and levofloxacin, almost 50%; tetracycline, 38.2%. Concurrent resistance to clarithromycin-amoxicillin was 43.4%, to tetracycline-metronidazole 30.3%, to amoxicillin-levofloxacin 27.6%, and to clarithromycin-metronidazole 59.2%. CONCLUSIONS: In vitro testing revealed resistance to all five antibiotics, indicating that H. pylori exhibited resistance phenotypes to these antibiotics. Consequently, the effectiveness of triple treatments may be compromised, and further studies are needed to assess refractoriness in quadruple and concomitant therapies.

45 years of tetracycline post exposure prophylaxis for STIs and the risk of tetracycline resistance: a systematic review and meta-analysis.

There is considerable interest in the use of doxycycline post exposure prophylaxis (PEP) to reduce the incidence of bacterial sexually transmitted infections (STIs). An important concern is that this could select for tetracycline resistance in these STIs and other species. We searched PubMed and Google Scholar, (1948-2023) for randomized controlled trials comparing tetracycline PEP with non-tetracycline controls. The primary outcome was antimicrobial resistance (AMR) to tetracyclines in all bacterial species with available data. Our search yielded 140 studies, of which three met the inclusion criteria. Tetracycline PEP was associated with an increasedprevalence of tetracycline resistance in Neisseria gonorrhoeae, but this effect was not statistically significant (Pooled OR 2.3, 95% CI 0.9-3.4). PEP had a marked effect on the N. gonorrhoeae tetracycline MIC distribution in the one study where this was assessed. Prophylactic efficacy was 100% at low MICs and 0% at high MICs. In the one study where this was assessed, PEP resulted in a significant increase in tetracycline resistance in commensal Neisseria species compared to the control group (OR 2.9, 95% CI 1.5-5.5) but no significant effect on the prevalence of tetracycline resistance in Staphylococcus aureus. The available evidence suggests that PEP with tetracyclines could be associated with selecting tetracycline resistance in N. gonorrhoeae and commensal Neisseria species.

Antimicrobial Resistance Patterns in Patients with Vaginal Discharge: A 2019-2022 Analysis at the National Health Laboratory in Eritrea.

Background: Antimicrobial resistance poses a significant global threat to the treatment of bacterial infections, particularly in low- and middle-income regions such as Africa. This study is aimed at analyzing antimicrobial resistance patterns in vaginal swab samples from patients at the National Health Laboratory from 2019 to 2022. Methods: This retrospective study examined patient records from vaginal swab analyses performed at the National Health Laboratory between January 1, 2019, and December 31, 2022. Ethical approval was obtained from the Ministry of Health Research Ethical Approval and Clearance Committee on 15/02/2023. Results: Of the 622 samples, 83% underwent microbial isolation and identification. Citrobacter spp. exhibited high resistance (>43%) to antibiotics such as cephalexin, ceftazidime, nalidixic acid, ampicillin, gentamicin, and tetracycline. E. coli showed resistance rates of more than 50% to ampicillin, trimethoprim-sulfamethoxazole, and tetracycline. Klebsiella spp. and Proteus spp. exhibited resistance rates that exceeded 47% to specific antibiotics. Gram-positive bacteria have resistance rates of more than 49% with ampicillin, trimethoprim-sulfamethoxazole, tetracycline, oxacillin, vancomycin, and penicillin G. In particular, S. aureus demonstrated no resistance to rifampicin or clindamycin, while Streptococcus spp. showed 100% resistance to rifampicin and vancomycin. Several species, including Proteus species, Streptococcus spp., S. aureus, and Klebsiella spp. exhibited multidrug resistance. Conclusion: Most gram-negative bacteria displayed higher resistance of >45% to ampicillin, trimethoprim-sulfamethoxazole, and tetracycline. Among gram-positive bacteria, a higher resistance rate with ampicillin, trimethoprim-sulfamethoxazole, tetracycline, oxacillin, vancomycin, and penicillin G was recorded. S. aureus showed no resistance to rifampicin and clindamycin, and Strep. spp. indicated 100% resistance to rifampicin and vancomycin. This study highlights critical gaps and areas for further exploration. Expanding the spectrum of antibiotics tested and investigating underlying multidrug resistance mechanisms would provide a more comprehensive understanding of resistance patterns.

What role do biocontrol agents with Mg2+ play in the fate of antibiotic resistome and pathogenic bacteria in the phyllosphere?

The contamination of the plant phyllosphere with antibiotics and antibiotic resistance genes (ARGs), caused by application of antibiotics, is a significant environmental issue in agricultural management. Alternatively, biocontrol agents are environmentally friendly and have attracted a lot of interest. However, the influence of biocontrol agents on the phyllosphere resistome remains unknown. In this study, we applied biocontrol agents to control the wildfire disease in the Solanaceae crops and investigated their effects on the resistome and the pathogen in the phyllosphere by using metagenomics. A total of 250 ARGs were detected from 15 samples, which showed a variation in distribution across treatments of biocontrol agents (BA), BA with Mg2+ (T1), BA with Mn2+ (T2), and kasugamycin (T3) and nontreated (CK). The results showed that the abundance of ARGs under the treatment of BA-Mg2+ was lower than that in the CK group. The abundance of cphA3 (carbapenem resistance), PME-1 (carbapenem resistance), tcr3 (tetracycline antibiotic resistance), and AAC (3)-VIIIa (aminoglycoside antibiotic resistance) in BA-Mg2+ was significantly higher than that in BA-Mn2+ (P < 0.05). The abundance of cphA3, PME_1, and tcr3 was significantly negatively related to the abundance of the phyllosphere pathogen Pseudomonas syringae (P < 0.05). We also found that the upstream and downstream regions of cphA3 were relatively conserved, in which rpl, rpm, and rps gene families were identified in most sequences (92%). The Ka/Ks of cphA3 was 0 in all observed sequences, indicating that under the action of purifying selection, nonsynonymous substitutions are often gradually eliminated in the population. Overall, this study clarifies the effect of biocontrol agents with Mg2+ on the distribution of the phyllosphere resistome and provides evolutionary insights into the biocontrol process. IMPORTANCE: Our study applied metagenomics analysis to examine the impact of biocontrol agents (BAs) on the phyllosphere resistome and the pathogen. Irregular use of antibiotics has led to the escalating dissemination of antibiotic resistance genes (ARGs) in the environment. The majority of BA research has focused on the effect of monospecies on the plant disease control process, the role of the compound BA with nutrition elements in the phyllosphere disease, and the resistome is still unknown. We believe BAs are eco-friendly alternatives for antibiotics to combat the transfer of ARGs. Our results revealed that BA-Mg2+ had a lower relative abundance of ARGs compared to the CK group, and the phyllosphere pathogen Pseudomonas syringae was negatively related to three specific ARGs, cphA3, PME-1, and tcr3. These three genes also present different Ka/Ks. We believe that the identification of the distribution and evolution modes of ARGs further elucidates the ecological role and facilitates the development of BAs, which will attract general interest in this field.

Sequence-structure-function characterization of the emerging tetracycline destructase family of antibiotic resistance enzymes.

Tetracycline destructases (TDases) are flavin monooxygenases which can confer resistance to all generations of tetracycline antibiotics. The recent increase in the number and diversity of reported TDase sequences enables a deep investigation of the TDase sequence-structure-function landscape. Here, we evaluate the sequence determinants of TDase function through two complementary approaches: (1) constructing profile hidden Markov models to predict new TDases, and (2) using multiple sequence alignments to identify conserved positions important to protein function. Using the HMM-based approach we screened 50 high-scoring candidate sequences in Escherichia coli, leading to the discovery of 13 new TDases. The X-ray crystal structures of two new enzymes from Legionella species were determined, and the ability of anhydrotetracycline to inhibit their tetracycline-inactivating activity was confirmed. Using the MSA-based approach we identified 31 amino acid positions 100% conserved across all known TDase sequences. The roles of these positions were analyzed by alanine-scanning mutagenesis in two TDases, to study the impact on cell and in vitro activity, structure, and stability. These results expand the diversity of TDase sequences and provide valuable insights into the roles of important residues in TDases, and flavin monooxygenases more broadly.

Possibility of transfer and activation of 'silent' tetracycline resistance genes among Enterococcus faecalis under high-pressure processing.

In this study, the tetracycline resistance of Enterococcus faecalis strains isolated from food was determined and molecular analyses of the resistance background were performed by determining the frequency of selected tetracycline resistance genes. In addition, the effect of high-pressure stress (400 and 500 MPa) on the expression of selected genes encoding tetracycline resistance was determined, as well as changes in the frequency of transfer of these genes in isolates showing sensitivity to tetracyclines. In our study, we observed an increase in the expression of genes encoding tetracyclines, especially the tet(L) gene, mainly under 400 MPa pressure. The study confirmed the possibility of transferring genes encoding tetracyclines such as tet(M), tet(L), tet(K), tet(W) and tet(O) by horizontal gene transfer in both control strains and exposed to high-pressure. Exposure of the strains to 400 MPa pressure had a greater effect on the possibility of gene transfer and expression than the application of a higher-pressure. To our knowledge, this study for the first time determined the effect of high-pressure stress on the expression of selected genes encoding tetracycline resistance, as well as the possibility and changes in the frequency of transfer of these genes in Enterococcus faecalis isolates showing sensitivity to tetracyclines and possessing silent genes. Due to the observed possibility of increased expression of some of the genes encoding tetracycline resistance and the possibility of their spread by horizontal gene transfer to other microorganisms in the food environment, under the influence of high-pressure processing in strains phenotypically susceptible to this antibiotic, it becomes necessary to monitor this ability in isolates derived from foods.

Tetracycline hydrochloride loaded-alginate based nanoparticle-hydrogel beads for potential wound healing applications: In vitro drug delivery, release kinetics, and antibacterial activity.

Novel hydrogel beads based on nanocomposite with outstanding antibacterial and swelling capabilities have been successfully produced as an efficient drug carrier for potential drug delivery systems in wound healing applications. The beads were characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and EDX-Mapping analysis. Then, using tetracycline hydrochloride (TCH) as a model drug system, they were studied in vitro for their potential efficiency as pH and temperature dependent sustained drug delivery carriers. Moreover, they were assessed in terms of porosity, swelling degree, encapsulation efficiency, and in vitro release kinetics. Beads released drugs at their highest levels under alkaline circumstances (pH = 8) and at a temperature of 39 °C, with a cumulative TCH release of 96.2 % at 36 h and in accordance with the Weibull kinetics model (R2 = 0.98). Additionally, the disc diffusion experiment demonstrated the strong antibacterial activity of the synthesized beads and offered a feasible and cost-effective wound dressing material for treating infected wounds.

Doxycycline is a viable alternative to tetracycline for use in insect Tet-Off transgenic sexing systems, as assessed in the blowflies Cochliomyia hominivorax and Lucilia cuprina (Diptera: Calliphoridae).

Transgenic insect strains with tetracycline repressible (Tet-Off) female-lethal genes provide significant advantages over traditional sterile insect techniques for insect population control, such as reduced diet and labor costs and more efficient population suppression. Tet-Off systems are suppressed by tetracycline-class antibiotics, most commonly tetracycline (Tc) or doxycycline (Dox), allowing for equal sex ratio colonies of transgenic insects when reared with Tc or Dox and male-only generations in their absence. Dox is a more stable molecule and has increased uptake than Tc, which could be advantageous in some insect mass-rearing systems. Here, we evaluated the suitability of Dox for rearing Tet-Off female-lethal strains of Australian sheep blowfly, Lucilia cuprina (Wiedemann, 1830) (Diptera: Calliphoridae), and New World screwworm, Cochliomyia hominivorax (Coquerel, 1858) (Diptera: Calliphoridae), and the effects of dosage on strain performance. For both species, colonies were able to be maintained with mixed-sex ratios at much lower dosages of Dox than Tc. Biological yields of C. hominivorax on either antibiotic were not significantly different. Reduction of Dox dosages in C. hominivorax diet did not affect biological performance, though rearing with 10 or 25 µg/mL was more productive than 50 µg/mL. Additionally, C. hominivorax mating performance and longevity were equal on all Dox dosages. Overall, Dox was a suitable antibiotic for mass-rearing Tet-Off female-lethal L. cuprina and C. hominivorax and was functional at much lower dosages than Tc.

Monitoring antimicrobial resistance in Campylobacter isolates of chickens and turkeys at the slaughter establishment level across the United States, 2013-2021.

Foodborne infections with antimicrobial-resistant Campylobacter spp. remain an important public health concern. Publicly available data collected by the National Antimicrobial Resistance Monitoring System for Enteric Bacteria related to antimicrobial resistance (AMR) in Campylobacter spp. isolated from broiler chickens and turkeys at the slaughterhouse level across the United States between 2013 and 2021 were analysed. A total of 1,899 chicken-origin (1,031 Campylobacter coli (C. coli) and 868 Campylobacter jejuni (C. jejuni)) and 798 turkey-origin (673 C. coli and 123 C. jejuni) isolates were assessed. Chicken isolates exhibited high resistance to tetracycline (43.65%), moderate resistance to ciprofloxacin (19.5%), and low resistance to clindamycin (4.32%) and azithromycin (3.84%). Turkey isolates exhibited very high resistance to tetracycline (69%) and high resistance to ciprofloxacin (39%). The probability of resistance to all tested antimicrobials, except for tetracycline, significantly decreased during the latter part of the study period. Turkey-origin Campylobacter isolates had higher odds of resistance to all antimicrobials than isolates from chickens. Compared to C. jejuni isolates, C. coli isolates had higher odds of resistance to all antimicrobials, except for ciprofloxacin. The study findings emphasize the need for poultry-type-specific strategies to address differences in AMR among Campylobacter isolates.

Detection of antimicrobial resistance in <5 h in Neisseria gonorrhoeae isolates using flow cytometry-proof of concept for seven clinically relevant antimicrobials.

INTRODUCTION: Antimicrobial resistance in Neisseria gonorrhoeae compromises gonorrhoea treatment and rapid antimicrobial susceptibility testing (AST) would be valuable. We have developed a rapid and accurate flow cytometry method (FCM) for AST of gonococci. METHODS: The 2016 WHO gonococcal reference strains, and WHO Q, R and S (n = 17) were tested against seven clinically relevant antibiotics (ceftriaxone, cefixime, azithromycin, spectinomycin, ciprofloxacin, tetracycline and gentamicin). After 4.5 h incubation of inoculated broth, the fluorescent dye Syto™ 9 was added, followed by FCM analysis. After gating, the relative remaining population of gonococci, compared with unexposed growth control samples, was plotted against antimicrobial concentration, followed by non-linear curve regression analysis. Furthermore, the response at one single concentration/tested antibiotic was evaluated with the intention to use as a screening test for detection of resistant gonococci. RESULTS: A dose-dependent response was seen in susceptible isolates for all tested antimicrobials. There was a clear separation between susceptible/WT and resistant/non-WT isolates for ceftriaxone, cefixime, spectinomycin, ciprofloxacin and tetracycline. In contrast, for azithromycin, only high-level-resistant isolates were distinguished, while resistant isolates with MICs of 4 mg/L were indistinguishable from WT (MIC ≤ 1 mg/L) isolates. For gentamicin, all tested 17 isolates were WT and FCM analysis resulted in uniform dose-response curves. Using a single antibiotic concentration and a 50% remaining cell population cut-off, the overall sensitivity and specificity for resistance detection were 93% and 99%, respectively. CONCLUSIONS: By providing results in <5 h for gonococcal isolates, FCM-based AST can become a rapid screening method for antimicrobial resistance or antimicrobial susceptibility in gonococci.

Synergistic Antibacterial Activity of Gallic Acid Based Chalcone Indl 2 by Inhibiting Efflux Pump Transporters.

As a part of novel discovery of drugs from natural resources, present study was undertaken to explore the antibacterial potential of chalcone Indl-2 in combination with different group of antibiotics. MIC of antibiotics was reduced up to eight folds against the different cultures of E. coli by both chalcones. Among the two compounds, the i. e. 1-(3', 4,'5'-trimethoxyphenyl)-3-(3-Indyl)-prop-2-enone (6, Indl-2), a chalcone derivative of gallic acid (Indl-2) was better along with tetracycline (TET) worked synergistically and was found to inhibit efflux transporters as obvious by ethidium bromide efflux confirmed by ATPase assays and docking studies. In combination, Indl-2 kills the MDREC-KG4 cells, post-antibiotic effect (PAE) of TET was prolonged and mutant prevention concentration (MPC) of TET was also decreased. In-vivo studies revealed that Indl-2 reduces the concentration of TNF-α. In acute oral toxicity study, Indl-2 was non-toxic and well tolerated up-to dose of 2000 mg/kg. Perhaps, the study is going to report gallic acid derived chalcone as synergistic agent acting via inhibiting the primary efflux pumps.

Earliest observation of the tetracycline destructase tet(X3).

Tigecycline is an antibiotic of last resort for infections with carbapenem-resistant Acinetobacter baumannii. Plasmids harboring variants of the tetracycline destructase gene tetX promote rising tigecycline resistance rates. We report the earliest observation of tet(X3) in a clinical strain predating tigecycline's commercialization, suggesting selective pressures other than tigecycline contributed to its emergence. IMPORTANCE: We present the earliest observation of a tet(X3)-positive bacterial strain, predating by many years the earliest reports of this gene so far. This finding is significant as tigecycline is an antibiotic of last resort for carbapenem-resistant Acinetobacter baumannii (CRAB), which the World Health Organization ranks as one of its top three critical priority pathogens, and tet(X3) variants have become the most prevalent genes responsible for enabling CRAB to become tigecycline resistant. Moreover, the tet(X3)-positive strain we report is the first and only to be found that predates the commercialization of tigecycline, an antibiotic that was thought to have contributed to the emergence of this resistance gene. Understanding the factors contributing to the origin and spread of novel antibiotic resistance genes is crucial to addressing the major global public health issue, which is antimicrobial resistance.

Enhanced Biofilm Formation by Tetracycline in a Staphylococcus aureus Naturally Lacking ica Operon and atl.

Staphylococcus aureus is a major, widespread pathogen, and its biofilm-forming characteristics make it even more difficult to eliminate by biocides. Tetracycline (TCY) is a major broad-spectrum antibiotic, the residues of which can cause deleterious health impacts, and subinhibitory concentrations of TCY have the potential to increase biofilm formation in S. aureus. In this study, we showed how the biofilm formation of S. aureus 123786 is enhanced in the presence of TCY at specific subinhibitory concentrations. S. aureus 123786 used in this study was identified as Staphylococcal Cassette Chromosome mec III, sequence type239 and naturally lacking ica operon and atl gene. Two assays were performed to quantify the formation of S. aureus biofilm. In the crystal violet (CV) assay, the absorbance values of biofilm stained with CV at optical density (OD)540 nm increased after 8 and 16 hr of incubation when the concentration of TCY was 1/2 minimum inhibitory concentration (MIC), whereas at the concentration of 1/16 MIC, the absorbance values increased after 16 and 24 hr of incubation. In tetrazolium salt reduction assay, the absorbance value at OD490 nm of S. aureus 123786 biofilms mixed with 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium solution increased after 8 hr when the concentration of TCY was 1/4 MIC, which may be correlated with the higher proliferation and maturation of biofilm. In conclusion, the biofilm formation of S. aureus 123786 could be enhanced in the presence of TCY at specific subinhibitory concentrations.

Pentachlorophenol affects doxycycline and tetracycline resistance genes in soil by altering microbial structure.

Tetracycline antibiotics play a vital role in animal husbandry, primarily employed to uphold the health of livestock and poultry. Consequently, when manure is reintegrated into farmland, tetracycline antibiotics can persist in the soil. Simultaneously, to ensure optimal crop production, organochlorine pesticides (OCPs) are frequently applied to farmland. The coexistence of tetracycline antibiotics and OCPs in soil may lead to an increased risk of transmission of tetracycline resistance genes (TRGs). Nevertheless, the precise mechanism underlying the effects of OCPs on tetracycline antibiotics and TRGs remains elusive. In this study, we aimed to investigate the effects of OCPs on soil tetracycline antibiotics and TRGs using different concentrations of doxycycline (DOX) and pentachlorophenol (PCP). The findings indicate that PCP and DOX mutually impede their degradation in soil. Furthermore, our investigation identifies Sphingomonas and Bacillus as potential pivotal microorganisms influencing the reciprocal inhibition of PCP and DOX. Additionally, it is observed that the concurrent presence of PCP and DOX could impede each other's degradation by elevating soil conductivity. Furthermore, we observed that a high concentration of PCP (10.7 mg/kg) reduced the content of efflux pump tetA, ribosome protective protein tetM, tetQ, and passivating enzyme tetX. In contrast, a low PCP concentration (6.4 mg/kg) only reduced the content of ribosome protective protein tetQ. This suggests that PCP may reduce the relative abundance of TRGs by altering the soil microbial community structure and inhibiting the potential host bacteria of TRGs. These findings have significant implications in understanding the combined pollution of veterinary antibiotics and OCPs. By shedding light on the interactions between these compounds and their impact on microbial communities, this study provides a theoretical basis for developing strategies to manage and mitigate their environmental impact, and may give some information regarding the sustainable use of antibiotics and pesticides to ensure the long-term health and productivity of agricultural systems.

Doxycycline for transgene control disrupts gut microbiome diversity without compromising acute neuroinflammatory response.

The tetracycline transactivator (tTA) system provides controllable transgene expression through oral administration of the broad-spectrum antibiotic doxycycline. Antibiotic treatment for transgene control in mouse models of disease might have undesirable systemic effects resulting from changes in the gut microbiome. Here we assessed the impact of doxycycline on gut microbiome diversity in a tTA-controlled model of Alzheimer's disease and then examined neuroimmune effects of these microbiome alterations following acute LPS challenge. We show that doxycycline decreased microbiome diversity in both transgenic and wild-type mice and that these changes persisted long after drug withdrawal. Despite the change in microbiome composition, doxycycline treatment had minimal effect on basal transcriptional signatures of inflammation the brain or on the neuroimmune response to LPS challenge. Our findings suggest that central neuroimmune responses may be less affected by doxycycline at doses needed for transgene control than by antibiotic cocktails at doses used for experimental microbiome disruption.

A novel conjugative transposon carrying an autonomously amplified plasmid.

Tetracyclines serve as broad-spectrum antibiotics to treat bacterial infections. The discovery of new tetracycline resistance genes has led to new questions about the underlying mechanisms of resistance, gene transfer, and their relevance to human health. We tracked changes in the abundance of a 55-kbp conjugative transposon (CTn214) carrying tetQ, a tetracycline resistance gene, within a Bacteroides fragilis metagenome-assembled genome derived from shotgun sequencing of microbial DNA extracted from the ileal pouch of a patient with ulcerative colitis. The mapping of metagenomic reads to CTn214 revealed the multi-copy nature of a 17,044-nt region containing tetQ in samples collected during inflammation and uninflamed visits. B. fragilis cultivars isolated from the same patient during periods of inflammation harbored CTn214 integrated into the chromosome or both a circular, multi-copy, extrachromosomal region of the CTn214 containing tetQ and the corresponding integrated form. The tetracycline-dependent mechanism for the transmission of CTn214 is nearly identical to a common conjugative transposon found in the genome of B. fragilis (CTnDOT), but the autonomously amplified nature of a circular 17,044-nt region of CTn214 that codes for tetQ and the integration of the same sequence in the linear chromosome within the same cell is a novel observation. Genome and transcriptome sequencing of B. fragilis cultivars grown under different concentrations of tetracycline and ciprofloxacin indicates that tetQ in strains containing the circular form remains actively expressed regardless of treatment, while the expression of tetQ in strains containing the linear form increases only in the presence of tetracycline.IMPORTANCEThe exchange of antibiotic production and resistance genes between microorganisms can lead to the emergence of new pathogens. In this study, short-read mapping of metagenomic samples taken over time from the illeal pouch of a patient with ulcerative colitis to a Bacteroides fragilis metagenome-assembled genome revealed two distinct genomic arrangements of a novel conjugative transposon, CTn214, that encodes tetracycline resistance. The autonomous amplification of a plasmid-like circular form from CTn214 that includes tetQ potentially provides consistent ribosome protection against tetracycline. This mode of antibiotic resistance offers a novel mechanism for understanding the emergence of pathobionts like B. fragilis and their persistence for extended periods of time in patients with inflammatory bowel disease.

Biochar and zero-valent iron alleviated sulfamethoxazole and tetracycline co-stress on the long-term system performance of bioretention cells: Insights into microbial community, antibiotic resistance genes and functional genes.

Antibiotics and antibiotic resistance genes (ARGs), known as emerging contaminants, have raised widespread concern due to their potential environmental and human health risks. In this study, a conventional bioretention cell (C-BRC) and three modified bioretention cells with biochar (BC-BRC), microbial fuel cell coupled/biochar (EBC-BRC) and zero-valent iron/biochar (Fe/BC-BRC) were established and two antibiotics, namely sulfamethoxazole (SMX) and tetracycline (TC), were introduced into the systems in order to thoroughly investigate the co-stress associated with the long-term removal of pollutants, dynamics of microbial community, ARGs and functional genes in wastewater treatment. The results demonstrated that the SMX and TC co-stress significantly inhibited the removal of total nitrogen (TN) (C-BRC: 37.46%; BC-BRC: 41.64%; EBC-BRC: 55.60%) and total phosphorous (TP) (C-BRC: 53.11%; BC-BRC: 55.36%; EBC-BRC: 62.87%) in C-BRC, BC-BRC and EBC-BRC, respectively, while Fe/BC-BRC exhibited profoundly stable and high removal efficiencies (TN: 89.33%; TP: 98.36%). Remarkably, greater than 99% removals of SMX and TC were achieved in three modified BRCs compared with C-BRC (SMX: 30.86 %; TC: 59.29%). The decreasing absolute abundances of denitrifying bacteria and the low denitrification functional genes (nirK: 2.80 × 105-5.97 × 105 copies/g; nirS: 7.22 × 105-1.69 × 106 copies/g) were responsible for the lower TN removals in C-BRC, BC-BRC and EBC-BRC. The amendment of Fe/BC successfully detoxified SMX and TC to functional bacteria. Furthermore, the co-stress of antibiotics stimulated the propagation of ARGs (sulI, sulII, tetA and tetC) in substrates of all BRCs and only Fe/BC-BRC effectively reduced all the ARGs in effluent by an order of magnitude. The findings contribute to developing robust ecological wastewater treatment technologies to simultaneously remove nutrients and multiple antibiotics.

Novel Injectable, Self-Healing, Long-Effective Bacteriostatic, and Healed-Promoting Hydrogel Wound Dressing and Controlled Drug Delivery Mechanisms.

Multivalent ion cross-linking has been used to form hydrogels between sodium alginate (SA) and hyaluronic acid (HA) in previous studies. However, more stable and robust covalent cross-linking is rarely reported. Herein, we present a facile approach to fabricate a SA and HA hydrogel for wound dressings with injectable, good biocompatibility, and high ductility. HA was first reacted with ethylenediamine to graft an amino group. Then, it was cross-linked with oxidized SA with dialdehyde to form hydrogel networks. The dressing can effectively promote cell migration and wound healing. To increase the antibacterial property of the dressing, we successfully loaded tetracycline hydrochloride into the hydrogel as a model drug. The drug can be released slowly in the alkaline environment of chronic wounds, and the hydrogel releases drugs again in the more acidic environment with wound healing, achieving a long-term antibacterial effect. In addition, one-dimensional partial differential equations based on Fickian diffusion with time-varying diffusion coefficients and hydrogel thicknesses were used to model the entire complex drug release process and to predict drug release.