Disrupting the ArcA Regulatory Network Amplifies the Fitness Cost of Tetracycline Resistance in Escherichia coli

There is an urgent need for strategies to discover secondary drugs to prevent or disrupt antimicrobial resistance (AMR), which is causing >700,000 deaths annually. Here, we demonstrate that tetracycline-resistant (Tet^R) Escherichia coli undergoes global transcriptional and metabolic remodeling, including downregulation of tricarboxylic acid cycle and disruption of redox homeostasis, to support consumption of the proton motive force for tetracycline efflux. Using a pooled genome-wide library of single-gene deletion strains, at least 308 genes, including four transcriptional regulators identified by our network analysis, were confirmed as essential for restoring the fitness of Tet^R E. coli during treatment with tetracycline. Targeted knockout of ArcA, identified by network analysis as a master regulator of this new compensatory physiological state, significantly compromised fitness of Tet^R E. coli during tetracycline treatment. A drug, sertraline, which generated a similar metabolome profile as the arcA knockout strain, also resensitized Tet^R E. coli to tetracycline. We discovered that the potentiating effect of sertraline was eliminated upon knocking out arcA, demonstrating that the mechanism of potential synergy was through action of sertraline on the tetracycline-induced ArcA network in the Tet^R strain. Our findings demonstrate that therapies that target mechanistic drivers of compensatory physiological states could resensitize AMR pathogens to lost antibiotics. IMPORTANCE Antimicrobial resistance (AMR) is projected to be the cause of >10 million deaths annually by 2050. While efforts to find new potent antibiotics are effective, they are expensive and outpaced by the rate at which new resistant strains emerge. There is desperate need for a rational approach to accelerate the discovery of drugs and drug combinations that effectively clear AMR pathogens and even prevent the emergence of new resistant strains. Using tetracycline-resistant (Tet^R) Escherichia coli, we demonstrate that gaining resistance is accompanied by loss of fitness, which is restored by compensatory physiological changes. We demonstrate that transcriptional regulators of the compensatory physiologic state are promising drug targets because their disruption increases the susceptibility of Tet^R E. coli to tetracycline. Thus, we describe a generalizable systems biology approach to identify new vulnerabilities within AMR strains to rationally accelerate the discovery of therapeutics that extend the life span of existing antibiotics.

Enhanced Activation of Peroxymonosulfate for Tetracycline Degradation Using CoNi-Based Electrodeposited Films

Synthesizing efficient heterogeneous catalysts with multiple active sites able to activate peroxymonosulfate (PMS) for the degradation of persistent organic pollutants continues to be a challenge for societies worldwide. In response, cost-effective, eco-friendly oxidized Ni-rich and Co-rich CoNi micro-nanostructured films were fabricated following a two-step process based on simple electrodeposition using green deep eutectic solvent as an electrochemical media and thermal annealing. The CoNi-based catalysts demonstrated exceptional efficiency in the heterogeneous catalyzed activation of PMS for tetracycline degradation and mineralization. The effects of the catalysts' chemical nature and morphology, the pH, the concentration of PMS, irradiation with visible light, and the duration of contact with the catalysts on the degradation and mineralization of tetracycline were also studied. In dark conditions, oxidized Co-rich CoNi degraded more than 99% of tetracyclines in only 30 min and mineralized more than 99% of them in only 60 min. Moreover, the degradation kinetics doubled from 0.173 min^-1 in dark conditions to 0.388 min^-1 under visible light irradiation. In addition, the material demonstrated excellent reusability and can be easily recovered with simple heat treatment. Given those findings, our work provides new strategies for constructing high-efficiency and cost-effective PMS catalysts and elucidating the effects of operational parameters and primary reactive species formed by the catalyst-PMS system on water treatment technologies.

Toxicity of Tetracycline and Metronidazole in Chlorella pyrenoidosa

Antibiotics have become a new kind of organic pollutant as they are widely used in the water environment of China. Tetracycline (TC) is a class of broad-spectrum antibiotics produced or semi-synthesized by actinomycetes. Metronidazole (MTZ) is the first generation of typical nitroimidazoles. The content of nitroimidazoles is relatively high in medical wastewater, and their ecotoxicity is worthy of attention because they are difficult to completely eliminate. In this paper, the effects of TC and MTZ on the growth, cell morphology, extracellular polymer and oxidative stress of Chlorella pyrenoidosa (C. pyrenoidosa) were studied, and the toxic interactions between TC and MTZ mixture components were analyzed. The results showed that the 96h-EC50 of TC and MTZ was 8.72 mg/L and 45.125 mg/L, respectively. The toxicity of TC to C. pyrenoidosa was higher than that of MTZ, and the combined toxicity effect of TC and MTZ was synergistic after the combined action of a 1:1 toxicity ratio. In addition, the algal cells of C. pyrenoidosa died to varying degrees, the membrane permeability of algal cells was increased, the membrane was damaged, the surface of algal cells exposed to higher concentration of pollutants was wrinkled, and their morphology was changed. The extracellular polymer of C. pyrenoidosa was affected by a change in concentration. The effect of pollutants on the reactive oxygen species (ROS) level and malondialdehyde (MDA) content of C. pyrenoidosa also had an obvious dose-effect relationship. This study contributes to the assessment of the possible ecological risks to green algae due to the presence of TC and MTZ in aquatic environments.

Effects of Aging on Adsorption of Tetracycline Hydrochloride by Humin

To explore the effects of "aging", an environmental factor, on adsorption of tetracycline hydrochloride (TC) by humin (HM), this paper coats HM surface with ferric hydroxide precipitate to simulate the aging process. The research findings indicate that compared with fresh HM, aged HM (HM-Fe) displays an accelerated adsorption rate and higher adsorption capacity on TC. With an initial concentration of 20 mg·L-1, TC's equilibrium adsorption capacity on HM and HM-Fe is 4.6 and 5.3 mg·g-1, respectively, whereas the corresponding initial adsorption rate is 0.036 and 0.132 mg·g-1·min-1. The pseudo-second-order kinetic model and Freundlich adsorption isotherm model could adequately simulate the adsorption process of TC by HM and HM-Fe, suggesting the occurrence of chemical adsorption and multimolecular layer adsorption between TC and HM and HM-Fe. Based on ΔAbs deduced from Job's calculation, it can be assumed a complex reaction occurs between the iron element on the HM-Fe surface and TC, which acts as a sort of bridge in strengthening the adsorption of TC by HM-Fe. The aforesaid findings may provide subsequent further study on environmental behaviors of TC in the soil with both fundamental theories and a scientific basis.

Evolution of Helicobacter pylori Resistance to Antibiotics: A Topic of Increasing Concern

Antibiotic resistance among Helicobacter pylori strains is the major cause of eradication failure. Resistance prevalence is dynamic and can greatly vary among countries over the years. We revealed H. pylori resistance trends for five antibiotics in 14 countries through articles predominantly published in 2018-2022, since the latest data can best show the most recent trends in resistance evolution. Amoxicillin resistance generally exhibited no evolution, yet it increased in Bulgaria, Iran, China, and Vietnam. Metronidazole resistance exhibited different trends, including an increase, a decrease and no evolution in six, three, and five studies, respectively. Clarithromycin resistance increased in Australia, Belgium, Bulgaria, Italy, Iran, and Taiwan, but remained stable in France, Spain, Russia, China, Chile, and Colombia. Tetracycline resistance was low and stable except in Iran. Levofloxacin resistance increased in four European and six other countries/regions, without significant increases in France, Spain, and Chile. In Chile, triple resistance also increased. In countries such as France and Spain, resistance to most antibiotics was stabilized, while in Bulgaria, Belgium, Iran and Taiwan, resistance to three or more agents was reported. Use of non-recommended regimens, national antibiotic consumption, patient's compliance, host factors, strain virulence, migrations, and azithromycin overuse during the COVID-19 pandemic can influence resistance evolution. New drugs, eradication regimens and diagnostic methods, such as next-generation sequencing can improve H. pylori infection control.

Bismuth, esomeprazole, metronidazole and amoxicillin or tetracycline as a first-line regimen for Helicobacter pylori eradication: A randomized controlled trial

BACKGROUND

Due to general unavailability and common side effects of tetracycline, the clinical application of bismuth quadruple therapy (BQT) is greatly limited. Whether amoxicillin can replace tetracycline in BQT remains unknown. This study aimed to compare the eradication rate, safety and compliance between amoxicillin-containing and tetracycline-containing BQT as a first-line regimen for Helicobacter pylori eradication.

METHODS

This randomized trial was conducted on 404 naïve patients for H. pylori eradication. The participants were randomly assigned to 14-day amoxicillin-containing (bismuth potassium citrate 110 mg four times/day, esomeprazole 20 mg twice daily, metronidazole 400 mg four times/day and amoxicillin 500 mg four times/day) and tetracycline-containing (tetracycline 500 mg four times/day and the other three drugs used as above) BQT. Safety and compliance were assessed within 3 days after eradication. Urea breath test was performed 4-8 weeks after eradication to evaluate outcome.

RESULTS

As for the eradication rates of amoxicillin-containing and tetracycline-containing BQT, the results of both intention-to-treat and per-protocol analyses showed that the difference rate of the lower limit of 95% confidence interval was above -10.0% (intention-to-treat analysis: 81.7% vs. 83.2%, with a rate difference of -1.5% [-6.3% to 9.3%]; per-protocol analysis: 89.0% vs. 91.6%, -2.6% [-4.1% to 9.3%]). The incidence of adverse events in amoxicillin-containing BQT was significantly lower than tetracycline-containing BQT (29.5% vs. 39.7%). Both groups achieved relatively good compliance (92.0% vs. 89.9%).

CONCLUSION

The eradication efficacy of amoxicillin-containing BQT was non-inferior to tetracycline-containing BQT as a first-line regimen for H. pylori eradication with better safety and similar compliance.

Emerging multidrug resistance contributes to treatment failure in Mycoplasma genitalium infected patients in China

The increased treatment failure in patients with sexually transmitted Mycoplasma genitalium infection is associated with antimicrobial resistance. We performed a retrospective survey of antimicrobial clinical outcomes in M. genitalium-infected patients. In addition, we detected macrolide, fluoroquinolone and tetracycline resistance-associated markers to determine their role in treatment failure. The overall incidence of treatment failure was 28.29%, regardless of the drug used. In the present study, the prevalence of macrolide resistance-associated mutations in the 23S rRNA gene was 64%; that of fluroquinolone resistance-associated S83/D87 substitutions in the parC gene was 67.5%; and that of the tetracycline resistance-associated C1192T mutation in the 16S rRNA gene was 22.5%. Furthermore, evidence of dual antimicrobial resistance was found in 46.4% of pretreatment samples, and triple antimicrobial resistance was identified in 9.9%. These findings regarding the emergence of multidrug-resistant strains of M. genitalium in China are concerning and emphasize the importance of guiding M. genitalium treatment with antimicrobial resistance assays.

Prevalence of Plasmid-Associated Tetracycline Resistance Genes in Multidrug-Resistant Escherichia coli Strains Isolated from Environmental, Animal and Human Samples in Panama

Antimicrobial resistance bacteria are nowadays ubiquitous. Its presence has been reported in almost every type of source, from water for agricultural and recreative use, water distribution pipes, and wastewater, to food, fomites, and clinical samples. Enterobacteriaceae, especially Escherichia coli, are not the exception, showing an increased resistance to several antibiotics, causing a global health and economic burden. Therefore, the monitoring of fecal microbiota is important because it is present in numerous reservoirs where gene transfer between commensal and virulent bacteria can take place, representing a potential source of resistant E. coli. In this work, antibiotic resistance profiles of 150 E. coli isolates from environmental, animal, and human samples, collected in three rural areas in Panama, were analyzed. A total of 116 isolates were resistant to at least one of the nine antibiotics tested. Remarkably, almost 100% of these exhibited resistance to tetracycline. Plasmid-associated tetA and tetB genes were detected in 42.86% of the isolates analyzed, tetA being the most prevalent. These results suggest that tetracycline resistance would be used as a convenient indicator of genetic horizontal transfer within a community.

Cross-Section Observational Study to Assess Antimicrobial Resistance Prevalence among Bovine Respiratory Disease Bacterial Isolates from Commercial US Feedlots

Antimicrobial resistance (AMR) is a global public health threat that jeopardizes efficacy of antibiotics in veterinary and human medicine. Antibiotics are commonly administered to target the bacterial component of bovine respiratory disease (BRD). The objectives of this study were to obtain a better understanding of antibiotic resistance in BRD-associated bacteria (Mannheimia haemolytica, Pasteurella multocida, and Histophilus somni), investigate the clinical significance of AMR by monitoring clinical outcomes, and determine if regional differences exist in AMR trends. Deep pharyngeal swabs were used to sample beef cattle at initial BRD diagnosis (n = 453) from US feedlots representing three geographic regions. Organisms were identified by bacterial culture and subjected to broth microdilution antimicrobial susceptibility testing. Bacterium prevalence include P. multocida (36.0%), M. haemolytica (32.7%), and H. somni (28.5%). Of the Histophilus isolates, 39.5% were resistant to at least one antimicrobial, compared to 11.7% and 8.8% Pasteurella and Mannheimia, respectively. Non-susceptibility across all organisms was 5.7 X more likely in animals that received metaphylaxis, than those that did not (p < 0.0001; OR 5.7; CI 2.6-12.5). During days on feed 21-40, non-susceptibility of Histophilus was 8.7 X more likely than Mannheimia (p = 0.0002; OR 8.7; CI 2.8 to 27.4) and 6 X more likely than Pasteurella (p = 0.0016; OR 6.0; CI 2.0-18.0).

A Zn(II)-Metal-Organic Framework Based on 4-(4-Carboxy phenoxy) Phthalate Acid as Luminescent Sensor for Detection of Acetone and Tetracycline

As hazardous environmental pollutants, residual tetracycline (TC) and acetone are harmful to the ecosystem. Therefore, it is necessary to detect the presence of these pollutants in the environment. In this work, using Zn (II) salt, 4-(4-carboxy phenoxy) phthalic acid (H₃L), and 3,5-bis(1-imidazolyl) pyridine (BMP), a new metal-organic framework (Zn-MOF) known as [Zn₃(BMP)₂L₂(H₂O)₄]·2H₂O was synthesized using a one-pot hydrothermal method. The Zn-MOF has a three-dimensional framework based on the [Zn1N₂O₂] and [Zn2N₂O₄] nodes linked by a tridentate bridge BMP ligand and an L ligand with the μ₁:η¹η⁰/μ₁:η¹η⁰/μ₀:η⁰η⁰ coordination mode. There were two kinds of left- and right-handed helix chains, Zn1-BMP and Zn1-BMP-Zn1-L. The complex was stable in aqueous solutions with pH values of 4-10. The Zn-MOF exhibited a strong emission band centered at 385 nm owing to the π*→π electron transition of the ligand. It showed high luminescence in some common organic solvents as well as in the aqueous solutions of pH 4-10. Interestingly, TC and acetone effectively quenched the luminescence of the Zn-MOF in aqueous solution and enabled the Zn-MOF to be used as a sensor to detect TC and acetone. The detection limits of TC and acetone were observed to be 3.34 µM and 0.1597%, respectively. Even in acidic (pH = 4) and alkaline (pH = 10) conditions, the Zn-MOF showed a stable luminescence sensing capability to detect TC. Luminescence sensing of the Zn-MOF for TC in urine and aquaculture wastewater systems was not affected by the interfering agent. Furthermore, the mechanism of sensing TC was investigated in this study. Fluorescence resonance energy transfer and photoinduced electron transfer were found to be the possible quenching mechanisms via UV-Vis absorption spectra/the excitation spectra measurements and DFT calculations.

Semi-Interpenetrating Polymer Networks Based on Hydroxy-Ethyl Methacrylate and Poly(4-vinylpyridine)/Polybetaines, as Supports for Sorption and Release of Tetracycline

Semi-interpenetrating polymer networks (semi-IPN) represent a type of polymeric material that has gained increasing amount of interest for their potential biomedical application. This study presents the synthesis, characterization and tetracycline loading/release capacities of semi-IPNs based on hydroxyethyl methacrylate (HEMA) and poly(4-vinylpyridine) (P4VP) or poly (1-vinyl-4-(1-carboxymethyl) pyridinium betaine) (P4VPB-1) and poly (1-vinyl-4-(2-carboxyethyl) pyridinium betaine) (P4VPB-2). The optimization of the semi-IPNs synthesis was achieved by studying the influence of reaction parameters (chemical structure of the cross-linking agent, HEMA:crosslinker ratio, HEMA:linear polymers ratio and the type of solvent of the linear polymers) on the yield of obtaining semi-IPNs and swelling capacity of these systems. Fourier-transform infrared analysis and scanning electron microscopy highlighted the chemical structures and morphologies of the semi-IPNs. The higher swelling capacity was observed in the case of the PHEMA/P4VPB-2 network due to the increased hydrophilicity of P4VPB-2 compared with P4VP and P4VPB-1 polymers. In vitro release studies of tetracycline reveal that the release mechanism is represented by non-Fickian diffusion being controlled by both diffusion and swelling processes. The antimicrobial activity of semi-IPN-tetracycline systems was tested against E. coli and S. aureus, demonstrating that tetracycline is released from the semi-IPN and retains its bactericidal activity. An increased value of the inhibition zone diameter compared with that of tetracycline indicates the possibility that the semi-IPN containing P4VPB-2 also exhibits intrinsic antimicrobial activity due to the presence of the polybetaine in the network structure.

A Novel Adsorbent of Attapulgite & Carbon Composites Derived from Spent Bleaching Earth for Synergistic Removal of Copper and Tetracycline in Water

Simultaneously eliminating tetracycline (TC) and copper (Cu-II) from wastewater was investigated by applying a novel adsorbent fabricated by transforming spent bleaching earth (SBE) into attapulgite & carbon composites (A&Cs). Pyrolysis temperature for A&Cs preparation exhibited a positive effect on Cu(II) adsorption, while the AC500 possessed the greatest performance for TC remediation. Interestingly, a synergistic effect instead of competitive adsorption occurred between Cu(II) and TC under the combined binary system, as both TC and Cu(II) adsorption amount on A&C500 increased more than that in the single system, which could be mainly attributed to the bridge actions between the TC and Cu(II). In addition, hydrogen bonding, ᴨ-ᴨ EDA interaction, pore-filling and complexation exerted significant roles in the adsorption process of TC and Cu(II). In general, this study offered a new perspective on the regeneration of livestock and poultry industry wastewater polluted with antibiotics and heavy metals.

Ixodes ricinus ticks have a functional association with Midichloria mitochondrii

In addition to being vectors of pathogenic bacteria, ticks also harbor intracellular bacteria that associate with ticks over generations, aka symbionts. The biological significance of such bacterial symbiosis has been described in several tick species but its function in Ixodes ricinus is not understood. We have previously shown that I. ricinus ticks are primarily inhabited by a single species of symbiont, Midichloria mitochondrii, an intracellular bacterium that resides and reproduces mainly in the mitochondria of ovaries of fully engorged I. ricinus females. To study the functional integration of M. mitochondrii into the biology of I. ricinus, an M. mitochondrii-depleted model of I. ricinus ticks was sought. Various techniques have been described in the literature to achieve dysbiosed or apo-symbiotic ticks with various degrees of success. To address the lack of a standardized experimental procedure for the production of apo-symbiotic ticks, we present here an approach utilizing the ex vivo membrane blood feeding system. In order to deplete M. mitochondrii from ovaries, we supplemented dietary blood with tetracycline. We noted, however, that the use of tetracycline caused immediate toxicity in ticks, caused by impairment of mitochondrial proteosynthesis. To overcome the tetracycline-mediated off-target effect, we established a protocol that leads to the production of an apo-symbiotic strain of I. ricinus, which can be sustained in subsequent generations. In two generations following tetracycline administration and tetracycline-mediated symbiont reduction, M. mitochondrii was gradually eliminated from the lineage. Larvae hatched from eggs laid by such M. mitochondrii-free females repeatedly performed poorly during blood-feeding, while the nymphs and adults performed similarly to controls. These data indicate that M. mitochondrii represents an integral component of tick ovarian tissue, and when absent, results in the formation of substandard larvae with reduced capacity to blood-feed.

[Co-occurrence of Tetracycline Antibiotic Resistance Genes and Microbial Communities in Plateau Wetlands Under the Influence of Human Activities]

The widespread use of antibiotics has led to a large number of antibiotics entering the environment, to which microorganisms have become resistant. In recent years, with the intensification of human activities in the plateau region, the occurrence and migration of antibiotic resistance genes (ARGs) in plateau wetlands have attracted considerable attention. Here, we selected the Caohai National Wetland Park, located in the Yunnan-Guizhou Plateau, as our study area. The contents of tetracyclines, sulfonamides, quinolones, and macrolides in sediments from the upstream (the pristine habitat near the spring eye) and downstream (the sewage discharge outlet of residents) areas of the river in the park were analyzed. Among them, the detection content of tetracycline antibiotics was 103.65-2185 μg·kg^-1, which was the highest antibiotic detection content. To further investigate the occurrence characteristics and influencing factors of tetracycline resistance genes, the influence of environmental factors, bacterial community structure, and pathogenic bacteria on tetracycline ARGs under the influence of human activities were revealed via correlation analysis and network analysis. The results showed that a total of 15 tetracycline resistance genes were detected in the upstream and downstream sediments. Among them, seven resistance genes including tetPA, tetD, and tetPB were detected in the upstream, and 13 resistance genes such as tetPA, tetE, tetM, and tetX were detected in the downstream. The abundance of eight new resistance genes in the downstream accounted for 43.44% of the downstream genes. The tetracycline-like antibiotics and soil physicochemical indicators (i.e., available phosphorus, total organic carbon, nitrate nitrogen, and total phosphorus) were the main environmental factors affecting the distribution of tetracycline ARGs. Additionally, the bacteria detected in the upstream and downstream sediments belonged to 64 bacterial phyla, among which Proteobacteria, Firmicutes, and Bacteroidota were the main phyla affecting the abundance of tetracycline ARGs; meanwhile, 27 pathogenic bacteria were detected in the upstream and downstream sediments. Network analysis showed that the correlation between the eight new resistance genes and pathogens in the downstream area accounted for 70% of the network connectivity, and Listeria monocytogenes, Enterococcus faecalis, and Bacteroides vulgatus were identified as potential hosts for the transmission of tetracycline ARGs. Compared to the pristine habitat, the discharge of domestic sewage introduced large amounts of antibiotics and also changed the microenvironment and microbial community structure of the river wetland. Additionally, it increased the species of ARGs in sediments, which promoted the spread and transmission of ARGs among microorganisms and even pathogens.

Cryo-Induced Cellulose-Based Nanogel from Elaeis guineensis for Antibiotic Delivery Platform

Cryo-induced hydrogel from cellulose is a new class of biomaterials for drug delivery, cell delivery, bone and skin tissue engineering for cell proliferation and regeneration applications. This research aimed to synthesize cryo-induced hydrogel from cellulose and carboxymethyl cellulose (CMC) produced from empty bunch's cell wall of Elaeis guineensis. First, the experiment was to produce cellulose-rich material using hot-compressed water extraction followed by alkaline delignification and bleaching with H₂O₂. The obtained bleached EFB cellulose was used as the substrate for CMC, and the optimal condition with the highest degree of carboxyl substitution (DS) of 0.75 was achieved when varying NaOH and monochloroacetic acid concentration as well as etherification temperature using fractional factorial design. For cryogelation study, hydrogels were synthesized from cellulose, CMC and beta-cyclodextrin (β-CD) by dissolving cellulose-based matrix in a NaOH/urea system, and the cellulose (CEL) solution was frozen spontaneously at -40 °C followed by high speed mixing to loosen cellulose fibrils. Epichlorohydrin (ECH) and Polyethylene glycol diglycidyl ether (PEGDE) were used as a cross-linker. First, the ratio of cellulose and CMC with different amounts of ECH was investigated, and subsequently the proper ratio was further studied by adding different crosslinkers and matrices, i.e., CMC and β-CD. From the result, the ECH crosslinked CMC-CEL (E-CMC-CEL) gel had the highest swelling properties of 5105% with the average pore size of lyophilized hydrogel of 300 µm. In addition, E-CMC-CEL gel had the highest loading and release capability of tetracycline in buffer solution at pH 7.4 and 3.2. At pH 7.4, tetracycline loading and release properties of E-CMC-CEL gel were 65.85 mg g^-1 dry hydrogel and 46.48 mg g^-1 dry hydrogel (70.6% cumulative release), respectively. However, at pH 3.2, the loading and release capabilities of Tetracycline were moderately lower at 16.25 mg g^-1 dry hydrogel and 5.06 mg g^-1 dry hydrogel, respectively. The findings presented that E-CMC-CEL hydrogel was a suitable material for antibiotic tetracycline drug carrying platform providing successful inhibitory effect on Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa, respectively.

National Surveillance of Tetracycline, Erythromycin, and Clindamycin Resistance in Invasive Streptococcus pyogenes: A Retrospective Study of the Situation in Spain, 2007-2020

BACKGROUND

This work reports on antimicrobial resistance data for invasive Streptococcus pyogenes in Spain, collected by the 'Surveillance Program for Invasive Group A Streptococcus', in 2007-2020.

METHODS

emm typing was determined by sequencing. Susceptibility to penicillin, tetracycline, erythromycin, and clindamycin was determined via the E-test. tetM, tetO, msrD, mefA, ermB, ermTR, and ermT were sought by PCR. Macrolide-resistant phenotypes (M, cMLSB, and iMLSB) were detected using the erythromycin-clindamycin double-disk test. Resistant clones were identified via their emm type, multilocus sequence type (ST), resistance genotype, and macrolide resistance phenotype.

RESULTS

Penicillin susceptibility was universal. Tetracycline resistance was recorded for 237/1983 isolates (12.0%) (152 carried only tetM, 48 carried only tetO, and 33 carried both). Erythromycin resistance was detected in 172/1983 isolates (8.7%); ermB was present in 83, mefA in 58, msrD in 51, ermTR in 46, and ermT in 36. Clindamycin resistance (methylase-mediated) was present in 78/1983 isolates (3.9%). Eight main resistant clones were identified: two that were tetracycline-resistant only (emm22/ST46/tetM and emm77/ST63/tetO), three that were erythromycin-resistant only (emm4/ST39/mefA-msrD/M, emm12/ST36/mefA-msrD/M, and emm28/ST52/ermB/cMLSB), and three that were tetracycline-erythromycin co-resistant (emm11/ST403/tetM-ermB/cMLSB, emm77/ST63/tetO-ermTR/iMLSB, and emm77/ST63/tetM-tetO-ermTR/iMLSB).

CONCLUSIONS

Tetracycline, erythromycin, and clindamycin resistance rates declined between 2007 and 2020. Temporal variations in the proportion of resistant clones determined the change in resistance rates.

Effect of Sarecycline on the Acne Symptom and Impact Scale and Concerns in Moderate-to-Severe Truncal Acne in Open-Label Pilot Study

Truncal acne is common, and the psychosocial burden may be underestimated as patients most often complain of facial acne. The Acne Symptom and Impact Scale (ASIS) is a 17-item patient-reported outcome (PRO) measure designed to assess the signs and impacts of acne vulgaris. ASIS has previously been validated in a prospective, non-interventional study as a reliable PRO instrument for facial acne. In a pilot study, ASIS, and an additional 10 new questions that focused on the concerns of patients (ASIS-C), were given to 10 patients with moderate-to-severe truncal acne vulgaris who received 3 months of monotherapy with oral sarecycline, a narrow-spectrum tetracycline-class antibiotic. ASIS-C questionnaires were also given to 10 acne-free control subjects. Average ASIS-C answers decreased by 4% for Signs, 15% for Impact, and 16% for Concerns in the 10 patients, with greater decreases of 5% for Signs, 20% for Impact, and 19% for Concerns in the 60% of patients whose truncal acne was clear or almost clear after 12 weeks of sarecycline treatment. In this study, sarecycline was effective in reducing the psychosocial burden associated with truncal acne based on the ASIS-C PRO measures.

A Post Hoc Analysis of Efficacy Data on Sarecycline in Hispanics with Acne from Two Phase 3, Multicenter, Randomized, Double-Blind, Placebo-Controlled Clinical Trials

Sarecycline is a novel, narrow-spectrum, third generation tetracycline class antibiotic approved by the Food and Drug Administration (FDA) for the treatment of moderate-to-severe acne in patients ages nine and older. Recently, focus has increased on whether treatment responses differ in acne in skin of color. Here, we aimed to analyze the efficacy of using sarecycline in Hispanics. We report pooled post hoc analysis of efficacy data on sarecycline in Hispanics with acne from two phase 3, multicenter, randomized, double-blind, placebo-controlled clinical trials, SC1401 and SC1402. Of 2002 patients in the pooled trials with moderate-to-severe acne, 26.9% were Hispanic. Facial inflammatory lesion counts decreased as early as week 3 by 26% (p = 0.0279), with continued reduction by 41% by week 6 (p = 0.0003), by 51% by week 9 (p < 0.0001), and by 55% by week 12 (p < 0.0001). Acne is the most common skin condition diagnosed in Hispanics, and this study illustrates a statistically significant reduction in acne in Hispanic patients with moderate-to-severe acne treated with oral sarecycline. Therefore, oral sarecycline shows promising results as a safe and effective treatment for acne in Hispanics.

Effects of dual therapy with betamethasone and tetracycline in a NC/Nga mouse model of atopic dermatitis

Purpose: Our previous study has demonstrated that tetracycline exerts excellent bactericidal activity against Staphylococcus aureus strains isolated from patients with atopic dermatitis (AD) while simultaneously inhibiting the development of T helper (Th) type 2 (Th2) cells. The present study was designed to evaluate the effectiveness of dual therapy with betamethasone and tetracycline for AD. Methods: Betametasone (0.1%) and tetracycline (3%) were topically administered to NC/Nga mice with AD-like skin lesions. Skin severity scores, histological changes to the lesioned skin, and serum IgE levels were assessed as indicators of therapeutic effectiveness. Results: Topical treatment with both drugs reduced the skin severity score more significantly than was the case with betamethasone alone or tetracycline alone. This was associated with a reduction in the degree of epidermal thickening, the density of cellular infiltration into the dermis, the mast cell count in the dermis and the serum IgE concentration. Furthermore, the degree of Th1/Th2 cell development in auricular lymph nodes and the S. aureus count on the lesioned skin were synergistically suppressed by simultaneous application of both drugs. Conclusion: The present results show that simultaneous topical application of betamethasone and tetracycline synergistically ameliorates AD-like skin lesions in NC/Nga mice. This suggests that dual therapy with betamethasone and tetracycline for AD lesions colonized by S. aureus might be one of the best options for inhibiting the development of both Th1 and Th2 cells and acting on superficially located S. aureus .

Prevalence of antimicrobial resistance in fecal Escherichia coli and Enterococcus spp. isolates from beef cow-calf operations in northern California and associations with farm practices

Antimicrobials are necessary for the treatment of bacterial infections in animals, but increased antimicrobial resistance (AMR) is becoming a concern for veterinarians and livestock producers. This cross-sectional study was conducted on cow-calf operations in northern California to assess prevalence of AMR in Escherichia coli and Enterococcus spp. shed in feces of beef cattle of different life stages, breeds, and past antimicrobial exposures and to evaluate if any significant factors could be identified that are associated with AMR status of the isolates. A total of 244 E. coli and 238 Enterococcus isolates were obtained from cow and calf fecal samples, tested for susceptibility to 19 antimicrobials, and classified as resistant or non-susceptible to the antimicrobials for which breakpoints were available. For E. coli, percent of resistant isolates by antimicrobial were as follows: ampicillin 100% (244/244), sulfadimethoxine 25.4% (62/244), trimethoprim-sulfamethoxazole 4.9% (12/244), and ceftiofur 0.4% (1/244) while percent of non-susceptible isolates by antimicrobial were: tetracycline 13.1% (32/244), and florfenicol 19.3% (47/244). For Enterococcus spp., percent of resistant isolates by antimicrobial were as follows: ampicillin 0.4% (1/238) while percent of non-susceptible isolates by antimicrobial were tetracycline 12.6% (30/238) and penicillin 1.7% (4/238). No animal level or farm level management practices, including antimicrobial exposures, were significantly associated with differences in isolate resistant or non-susceptible status for either E. coli or Enterococcus isolates. This is contrary to the suggestion that administration of antibiotics is solely responsible for development of AMR in exposed bacteria and demonstrates that there are other factors involved, either not captured in this study or not currently well understood. In addition, the overall use of antimicrobials in this cow-calf study was lower than other sectors of the livestock industry. Limited information is available on cow-calf AMR from fecal bacteria, and the results of this study serve as a reference for future studies to support a better understanding and estimation of drivers and trends for AMR in cow-calf operations.

Tapping the potential of synthetic riboswitches: reviewing the versatility of the tetracycline aptamer

Synthetic riboswitches are a versatile class of regulatory elements that are becoming increasingly established in synthetic biology applications. They are characterized by their compact size and independence from auxiliary protein factors. While naturally occurring riboswitches were mostly discovered in bacteria, synthetic riboswitches have been designed for all domains of life. Published design strategies far exceed the number of riboswitches found in nature. A core element of any riboswitch is a binding domain, called an aptamer, which is characterized by high specificity and affinity for its ligand. Aptamers can be selected de novo, allowing the design of synthetic riboswitches against a broad spectrum of targets. The tetracycline aptamer has proven to be well suited for riboswitch engineering. Since its selection, it has been used in a variety of applications and is considered to be well established and characterized. Using the tetracycline aptamer as an example, we aim to discuss a large variety of design approaches for synthetic riboswitch engineering and their application. We aim to demonstrate the versatility of riboswitches in general and the high potential of synthetic RNA devices for creating new solutions in both the scientific and medical fields.

Scallop shell coated Fe2O3 nanocomposite as an eco-friendly adsorbent for tetracycline removal

ABSTRACTThe present study focused on the usability of scallop shell coated Fe₂O₃ nanoparticles as an eco-friendly new absorbent in the treatment of tetracycline (TC). The process performance in terms of TC removal was investigated at different operating conditions, i.e. at solution pH of 3-11, Fe₂O₃-scallop dosage of 0.4-2.4 g L^-1, initial TC content of 20-120 mg L^-1 and temperature of 25-55°C. Solution pH of 7 yielded the highest TC removal efficiency (99%). At this pH value, almost complete TC removal was achieved at a Fe₂O₃-scallop shell nanocomposite dose of 1.6 g L^-1 and 25°C. The responsible TC removal mechanism is suggested as the non-electrical π-π dispersion interaction between the bulk π system on the absorbent surface and TC molecules bearing both benzene rings and double bonds at this solution pH. TC removal efficiency appreciably enhanced up to the Fe₂O₃-scallop dosage of 1.6 g L^-1 being an optimum. Adsorption rate was found to be fast at lower initial TC concentrations than 40 mg L^-1. The effect of temperature on TC removal efficiency was insignificant. Adsorption followed the pseudo-second-order kinetic model. Experimental data perfectly fitted by the Langmuir equation. The maximum adsorption capacity was calculated as 49.26 mg g^-1. Thermodynamic analysis demonstrated that adsorption process was spontaneous process and endothermic. The results obtained from the present study proved the excellent performance of scallop shell coated Fe₂O₃ nanoparticles as an eco-friendly adsorbent in TC treatment.

E. hirae Causing Biliary Tract Infection in a Patient with Cholangiocarcinoma: A Case Report

INTRODUCTION

E. faecium and E. faecalis are the common species of Enterococcus responsible for the majority of infections. Earlier, species other than the common ones were usually unidentified and reported as Enterococcus species. However, modern equipment, like MALDI-TOF and VITEK2, have been utilitarian, helping us to identify the previously unidentified species. E. hirae is an organism seldom reported to cause human infections. Here, we report a case of a biliary tract infection in a female patient with cholangiocarcinoma caused by E. hirae.

CASE

A 56-year-old female presented with fever and abdominal pain. Bile aspirated during the ERCP was received in our laboratory. The gram stain of the bile sample revealed abundant polymorphonuclear leucocytes along with gram-positive diplococci. The organism failed to grow on MacConkey agar. On blood agar, non-hemolytic colonies grew. The organism was identified as E. hirae by MALDI-TOF MS. The antibiotic susceptibility performed using VITEK2 revealed it to be resistant to high-level gentamicin and susceptible to all remaining drugs. She was successfully treated with oral ciprofloxacin for the infection.

DISCUSSION

Bile is colonized with bacteria due to obstruction in the biliary tree, leading to cholangitis. This causes bacterial proliferation and translocation of bacteria into the systemic circulation. Our case was resistant to high-level gentamicin, while all previously reported cases were susceptible. The resistant isolates of E. hirae being isolated from cattle and their surroundings amidst the rampant use of antibiotics in livestock can pose a difficult situation for humans. Thus, there should be regulations on antibiotic usage in livestock. Cases like these should be reported and recognized for their potential to cause outbreaks if they remain unreported.

CONCLUSION

Thus, E. hirae, when encountered, should not be ignored but considered a pathogen and reported. The presence of drug-resistant organisms in cattle and their surroundings, their zoonotic potential to cause infections in humans, and the uncontrolled usage of antibiotics in livestock are causes for concern. Thus, we need to be more vigilant regarding it in the future.

Corrigendum: Optimized riboswitch-regulated AAV vector for VEGF-B gene therapy

[This corrects the article DOI: 10.3389/fmed.2022.1052318.].

Enhanced Photo-Assisted Fenton Degradation of Antibiotics over Iron-Doped Bi-Rich Bismuth Oxybromide Photocatalyst

Herein, combining photocatalysis and Fenton oxidation, a photo-assisted Fenton system was conducted using Fe-doped Bi₄O₅Br₂ as a highly efficient photocatalyst to realize the complete degradation of Tetracycline antibiotics under visible light. It has been observed that the optimized photocatalyst 5%Fe-doped Bi₄O₅Br₂ exhibits a degradation efficiency of 100% for Tetracycline with H₂O₂ after 3 h visible-light irradiation, while a degradation percentage of 59.8% over the same photocatalyst and 46.6% over pure Bi₄O₅Br₂ were obtained without the addition of H₂O₂ (non-Fenton process). It is unambiguous that a boost photo-assisted Fenton system for the degradation of Tetracycline has been established. Based on structural analysis, it demonstrated that the Fe atoms in place of the Bi sites may result in the distortion of the local structure, which induced the occurrence of the spontaneous polarization and thus enhanced the built-in electric field. The charge separation efficiency is enhanced, and the recombination of electrons and holes is inhabited so that more charges are generated to reach the surface of the photocatalyst and therefore improve the photocatalytic degradation efficiency. Moreover, more Fe (II) sites formed on the 5%Fe-Bi₄O₅Br₂ photocatalyst and facilitated the activation of H₂O₂ to form oxidative species, which greatly enhanced the degradation efficiency of Tetracycline.