The Development of Third-Generation Tetracycline Antibiotics and New Perspectives

A novel coumarin-incorporated lanthanide coordination nanoprobe for ratiometric sensing of tetracycline

Tetracycline (Tc), a broad-spectrum antibiotic for treating bacterial infections, poses significant risks to human health and the environment. This study presents a novel lanthanide coordination probe, AMP/Eu/CMP, for the ratiometric detection of Tc. The pyridine-appended coumarin derivative, CMP, acting as a stable internal reference, combines with AMP and Eu3+ to form the robust ratiometric probe AMP/Eu/CMP. Upon binding to Tc, Eu3+ fluorescence (emission at 616 nm) is sensitized while CMP fluorescence (emission at 505 nm) remains unchanged, resulting in a clear fluorescence shift from blue-green to red, enabling effective ratiometric detection of Tc. By integrating a smartphone color recognition app, rapid and visual detection of tetracycline concentrations is achieved. Additionally, paper-based test strips were developed for on-site Tc detection, exhibiting a linear response across a wide concentration range, making this method suitable for applications in food safety, pharmaceutical analysis, and environmental monitoring. The use of a fluorescent molecule with unique photophysical properties as an internal reference enables the construction of a high-performance, ratiometric lanthanide coordination polymer probe that is rapid, simple, and cost-effective, providing valuable insights for the development of future fluorescence sensors.

Acinetobacter baumannii: A comprehensive review of global epidemiology, clinical implications, host interactions, mechanisms of antimicrobial resistance and mitigation strategies

Since the discovery of Acinetobacter baumannii, it has emerged as a significant global health threat due to its increasing prevalence in healthcare settings and remarkable ability to develop resistance to various antibiotics. This detailed review addresses global epidemiology, emphasizing the worldwide distribution of carbapenem-resistant A. baumannii (CRAb), which is particularly prevalent in high-density healthcare settings and regions with intensive antibiotic usage, such as India. Clinically, A. baumannii infection poses serious health challenges, with mortality rates ranging from 30 % to 75 % for multidrug-resistant (MDR) strains. The review highlights the clinical impact and disease spectrum of A. baumannii, associated with pneumonia, wound infections, bloodstream infections, and, urinary tract infections with a strong association to invasive medical procedures and devices. Additionally, it discusses human-pathogen interactions by exploring various mechanisms, persistence in hospital environments, and survival under harsh conditions. The review further elaborates on different resistance mechanisms, focusing broadly on antibiotic degradation, altered drug targets, reduced drug permeability, and efflux systems, which facilitate the survival and persistence of A. baumannii. Finally, it evaluates strategies to combat AMR, emphasizing infection control measures, antimicrobial stewardship, and the urgent need for innovative therapeutic approaches such as phage therapy and new antibiotic development. The review calls for concerted, collaborative efforts among researchers, healthcare professionals, and public health authorities to mitigate the global threat posed by MDR A. baumannii strains.

Fostering kappa (κ)-carrageenan hydrogels with the power of a natural crosslinker: a comparison between tender coconut water and potassium chloride (KCl) for therapeutic applications

This study investigated the potential of tender coconut water as a natural alternative to potassium chloride (KCl) to crosslink κ-carrageenan hydrogels. κ-Carrageenan hydrogels crosslinked with tender coconut water, KCl, and their combination were formulated with diclofenac sodium as model drug, and their morphology, chemical bonding, compressive strength, water uptake capacity, degradation resistance, and cytotoxicity were assessed. The results showed that crosslinking κ-carrageenan hydrogels with both tender coconut water and KCl increased their compressive strength by up to 450%, provided excellent water retention capacity, and resulted in only 5% degradation after 20 days. Scanning electron microscopy revealed that crosslinking the hydrogel with both tender coconut water and KCl compacted its morphological structure, which remained biocompatible when tested with 3T3 cells. Infrared analysis confirmed that incorporated diclofenac sodium remained inert during preparation of the hydrogel matrices. Furthermore, the in vitro release behavior and antimicrobial properties of the hydrogels were assessed. The drug release profile from hydrogels crosslinked with both tender coconut water and KCl was sustained over 24 h. Such hydrogels also showed a unique antibacterial activity against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli)-with the activity against E. coli being more pronounced. In conclusion, these results confirm that crosslinking with tender coconut water and KCl is a superior alternative to just with KCl for κ-carrageenan hydrogels.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-025-04254-0.

Synthesis and antibacterial study of anhydrotetracycline derivatives

A novel and new type of tetracycline with a different mechanism of action was necessary, due to the drug resistance of existing tetracyclines. This study outlines the synthesis and antibacterial evaluation of anhydro-tetracycline derivatives, which are unconventional tetracyclines with unique mechanisms of action. These derivatives include C4-NH2, C4-OH, and C9-substituted variations, and our synthetic approach focuses on semi-synthesis using natural tetracyclines as the starting precursors. Several derivatives of C4-NH2, C4-OH, and C9-substituted compounds have demonstrated effective antibiotic activity against both Gram-positive and Gram-negative bacteria.

Enhanced tetracycline removal through "in situ" europium incorporation in poly (vinyl alcohol) (PVA) electrospun mats: Advantages of this strategy in adsorption and reuse over doping

Tetracycline (TC) is a widespread contaminant resulting from human, veterinary, and agricultural activities, necessitating urgent removal to protect aquatic ecosystems and the environment from persistent pollutants. We report a novel adsorbent with high efficiency for TC removal, developed by immobilizing europium ions (Eu³⁺) in PVA nanofiber mats through a single-step electrospinning process using an aqueous solution of the polymer containing europium salt ("in situ" process). This approach is three times more efficient than traditional doping methods. Additionally, when "in situ" Eu incorporation is combined with alkaline treatment, the removal capacity significantly increases from 235.8 mg/g to 322.6 mg/g (at pH 7) with only 0.36% Eu³⁺. This improvement results from the excellent dispersion of Eu ions in the mats and the alkaline treatment, which promotes the formation of Eu³⁺-TC diketone complexes and thus enhances the adsorption capacity. The adsorption mechanism follows the Langmuir isotherm model, indicating that TC is adsorbed in a monolayer at specific, homogeneous sites on the adsorbent. Notably, the "in situ" strategy combined with alkaline treatment allows for at least five reuse cycles while maintaining high efficiency. Furthermore, the adsorbent retains its high adsorption capacity even in the presence of coexisting pharmaceuticals such as ibuprofen, diclofenac, trimethoprim, and chlorpheniramine.

Rapid diagnosis and precision treatment of Helicobacter pylori infection in clinical settings

Helicobacter pylori is a gram-negative bacterium that colonizes the stomach of approximately half of the worldwide population, with higher prevalence in densely populated areas like Asia, the Caribbean, Latin America, and Africa. H. pylori infections range from asymptomatic cases to potentially fatal diseases, including peptic ulcers, chronic gastritis, and stomach adenocarcinoma. The management of these conditions has become more difficult due to the rising prevalence of drug-resistant H. pylori infections, which ultimately lead to gastric cancer and mucosa-associated lymphoid tissue (MALT) lymphoma. In 1994, the International Agency for Research on Cancer (IARC) categorized H. pylori as a Group I carcinogen, contributing to approximately 780,000 cancer cases annually. Antibiotic resistance against drugs used to treat H. pylori infections ranges between 15% and 50% worldwide, with Asian countries having exceptionally high rates. This review systematically examines the impacts of H. pylori infection, the increasing prevalence of antibiotic resistance, and the urgent need for accurate diagnosis and precision treatment. The present status of precision treatment strategies and prospective approaches for eradicating infections caused by antibiotic-resistant H. pylori will also be evaluated.

The efficacy and safety of omadacycline in treating acute bacterial infections: a meta-analysis of randomized controlled trials

INTRODUCTION

This study aimed to reevaluate the clinical efficacy and safety of omadacycline in treating acute bacterial infections.

METHODS

We searched PubMed, Embase, Cochrane Library, Web of Science, and Clinical Trials up to 1 January 2024, including only randomized controlled trials comparing OMC with other antibiotics in adults. Primary outcomes were clinical and microbiological responses; secondary outcomes included adverse events.

RESULTS

Seven RCTs with 2957 patients met the inclusion criteria. OMC showed a slightly better clinical response at the post-therapy evaluation phase in the clinically evaluable population (RR = 1.03, 95% CI = 1.01-1.05, I2 = 0%). Microbial eradication rates for Gram-positive and Gram-negative infections showed no significant differences between OMC and comparators. Safety analysis revealed no significant differences in overall AEs, treatment-related AEs, serious AEs, or drug discontinuation due to AEs. However, OMC had a lower risk of diarrhea (RR: 0.48, 95% CI = 0.23-1.00, I2 = 65%). All-cause mortality did not differ significantly between OMC and comparators.

CONCLUSIONS

OMC is a safe and effective treatment for acute bacterial infections, comparable to other antibiotics.

REGISTRATION

This study has been registered in the online systematic review database (Prospective Register of Systematic Reviews [PROSPERO]), and the registration number is CRD42024575416.

(Bio)Electroanalysis of Tetracyclines: Recent Developments

Tetracyclines (TCs) are antibiotics used extensively in medicine, veterinary science, and animal husbandry. Their overuse and the widespread presence of their residues in the environment contribute to intensifying the phenomenon of antibiotic resistance (ABR). The efforts are being made to reduce the spread of antibiotics and control the phenomenon of ABR, and one of the key methods is monitoring the presence of antibiotic residues in the environment and food of animal origin. Herein, we provide the overview of the recent developments in electrochemical (bio)sensing of tetracyclines in different types of samples. The review presents a comprehensive view of such aspects of the practical (bio)sensor application as sample preparation, the reusability of (bio)sensors, and the possibility of determining antibiotics at levels required by regulations. Advances, existing challenges, and future trends in the development of novel (bio)electrochemical methods of tetracycline quantification were discussed.

Antimicrobial Blue Light Reduces Human-Wound Pathogens' Resistance to Tetracycline-Class Antibiotics in Biofilms

Biofilms contribute to chronic infections and the development of antimicrobial resistance (AMR). We are developing an antimicrobial blue light (aBL) device to reduce bacterial bioburden in wounds and decrease reliance on systemic antibiotics. aBL induces the generation of reactive oxygen species (ROS) through photoexcitation of endogenous chromophores, causing bacterial damage and death. This study explores the combination of tetracyclines (TCs) with aBL for the treatment of biofilm infections in vitro. Tetracyclines (TCs), including second-generation minocycline (MC), doxycycline (DOCT), and third-generation agents omadacycline (OM) and tigecycline (TG), were evaluated for their ability to enhance bactericidal effects and ROS production during aBL treatment of abiotic biofilm. TCs were tested under dark conditions and with varying aBL light parameters against biofilms of methicillin-resistant Staphylococcus aureus (MRSA), Pseudomonas aeruginosa (PA), and Escherichia coli (E. coli). Results showed that TCs alone were ineffective against these biofilm cultures. However, when combined with aBL either before or after TC treatment, significant enhancement of microbicidal activity was observed. When the aBL is added before the TCs, there was equivalent bactericidal effect, indicating that TCs primary action against biofilms were not as photosensitizers. These findings suggest that aBL can significantly enhance the antimicrobial activity of TCs, potentially offering a new effective approach to treating biofilm-associated infections and combating AMR when aBL is applicable.

A tale of two old drugs tetracycline and salicylic acid with new perspectives-Coordination chemistry of their Co(II) and Ni(II) complexes, redox activity of Cu(II) complex, and molecular interactions

Extensive use of the broad-spectrum tetracycline antibiotics (TCs) has resulted their wide spread in the environment and drive new microecological balances, including the infamous antibiotic resistance. TCs require metal ions for their antibiotic activity and resistance via interactions with ribosome and tetracycline repressor TetR, respectively, at specific metal-binding sites. Moreover, the Lewis-acidic metal center(s) in metallo-TCs can interact with Lewis-basic moieties of many bioactive secondary metabolites, which in turn may alter their associated chemical equilibria and biological activities. Thus, it is ultimately important to reveal detailed coordination chemistry of metallo-TC complexes. Herein, we report (a) conclusive specific Co2+, Ni2+, and Cu2+-binding of TC revealed by paramagnetic 1H NMR, showing different conformations of the coordination and different metal-binding sites in solution and solid state, (b) significant metal-mediated activity of Cu-TC toward catechol oxidation with different mechanisms by air and H2O2 (i.e., mono- and di-nuclear pathways, respectively), (c) interactions of metallo-TCs with bioactive salicylic acid and its precursor benzoic acid, and (d) noticeable change of TC antibiotic activity by metal and salicylic acid. The results imply that TCs may play broad and versatile roles in maintaining certain equilibria in microecological environments in addition to their well-established antibiotic activity. We hope the results may foster further exploration of previously unknown metal-mediated activities of metallo-TC complexes and other metalloantibiotics.

Effects of Antimicrobial Agents Used for Dental Treatments: Impacts on the Human Oral Ecosystem and the Resistome

Antimicrobial resistance (AMR) is a major public health concern, especially with regard to bacterial resistance to antibiotics. Dentists are responsible for approximately 10% of all antibiotic prescriptions. In addition, there seems to be a lack of awareness of potential resistance toward antiseptics and biocides such as chlorhexidine digluconate (CHX) or cetylpyridinium chloride (CPC), which are commonly used in dental practice but also included in over-the-counter products. In comparison to the gut microbiome, only a small number of studies have investigated the impact of antibiotics on the oral microbiome. Amoxicillin is a commonly prescribed antibiotic in dentistry, often used in combination with metronidazole. Several studies have addressed its impact on the oral microbiome. Similarly, the effects of ciprofloxacin, clindamycin, cephazolin, and benzylpenicillin have also been examined in various studies. However, due to variations in study designs, it is difficult to compare the effects of antibiotics on the oral microbiota, and conclusions can only be drawn at the phyla level. In contrast, studies on CPC and CHX have also focused on the genus level. The oral resistome mainly contains genes involved in resistance to macrolides, MLSB (macrolide, lincosamide, and streptogramin B), lincosamide and streptogramin A, fluoroquinolone, tetracycline, or penicillin. The oral cavity therefore serves as a reservoir for antibiotic resistance genes (ARGs), which are of crucial importance both for inflammations in the oral cavity and for the treatment of the entire human organism. Therefore, dentists must weigh up the benefits and risks of using antibiotics very carefully.

Toward Enhanced Antibiotic Efficacy: Exploring the Synergistic Potential of Marine-Derived Lectins Against Human Pathogenic Bacteria

This study aimed to assess the combined antibacterial effect of lectins and antibiotics on S. aureus ATCC 25923, multidrug-resistant E. coli ATCC 11303 and S. aureus ATCC 700698. Using the checkerboard assay, we evaluated the antibacterial effects of eight lectins isolated from marine organisms combined with two common antibiotics, oxacillin and tetracycline, on three virulent bacterial strains. Initially, none of the tested lectins exhibited antibacterial effects when used individually. However, when combined with antibiotics, the lectins exhibited synergistic, additive, antagonistic, or no interaction. Overall, the tested lectins alone had no effect on the efficacy of oxacillin. On the other hand, different lectins in combination with tetracycline potentiated its antimicrobial effect. Lectins from red algae of the Bryothamnium genus, for example, exhibited the most significant synergistic effects, reducing the minimum inhibitory concentration (MIC) of tetracycline by up to 16 times. Lectins from the Hypnea genus also reduced the MIC of tetracycline. Our findings suggest that some lectins binding to complex carbohydrates containing fucosylated cores (α1-6) are excellent candidates to boost the efficacy of some antibiotics.

High-generation tetracyclines shifted microbial community composition and induced the emergence of antibiotic resistant bacteria in soil

Tetracyclines (TCs) have been widely detected in agricultural soil due to their widespread use in animal husbandry. The impact of low-generation TCs, i.e., the first- and second- generations, on soil ecosystem has attracted widespread attention. However, the dynamic response of soil microbial community to high-generation TCs, i.e., the third- and fourth- generations, remains largely unknown. Herein, we characterized the variations in the composition, diversity and succession of microbial community and the proliferation of antibiotic resistance genes (ARGs) under the stress of four generations of TCs in brown soil and red soil. The results demonstrated that the exposure of low- and high- generation TCs consistently decreased the alpha diversity and stimulated the succession rate of microbial community in soil. High-generation TCs strongly shifted microbial community composition by reducing community resilience. The complexity of microbial networks and cross-module associations were strengthened to cope with the stress of high-generation TCs in soil. The abundance of ARGs was exacerbated by 1.75 times in response to the fourth-generation TCs compared to control in brown soil. The potential bacterial hosts of ARGs were more diverse in brown soil exposed to high-generation TCs, but the dominant hosts were not changed. These results highlight the potential ecological risk of the newly developed antibiotics, which is helpful for a comprehensive risk assessment of emerging contaminants.

First Trimester Tetracycline Exposure and Risk of Major Congenital Malformations

Importance

Safety data on tetracycline antibiotic use during pregnancy are limited.

Objective

To investigate the association between first trimester exposure to tetracyclines and the risk of major congenital malformations (MCMs).

Design, Setting, and Participants

This cohort study used data from nationwide registers for singleton infants live-born in Sweden from July 1, 2006, to December 31, 2018, with follow-up through December 2019. Tetracycline-exposed and unexposed infants were matched on propensity scores (ratio 1:10). Data analysis was performed from June 2023 to May 2024.

Exposure

First trimester exposure to tetracyclines determined from maternal prescription fills, compared with no exposure.

Main Outcomes and Measures

The primary outcome was any MCM diagnosed in the first year of life; secondary outcomes were 12 major malformation organ system subgroups and 16 individual malformations selected on the basis of prior safety signals and/or fulfillment of prespecified statistical power criteria. Malformations were identified by International Statistical Classification of Diseases and Related Health Problems, Tenth Revision (ICD-10) codes aligned to the European Surveillance of Congenital Anomalies (EUROCAT) classification. Log binomial regression was used to estimate relative risks (RRs) with 95% CIs.

Results

From a source cohort of 1 245 889 eligible infants (640 892 male [51.4%]), a propensity score-matched analytical cohort of 69 656 infants (35 903 male [51.5%]) was generated. Of 6340 infants exposed to tetracyclines during the first trimester (3325 male [52.4%]), 252 received a diagnosis of any MCM (39.75 cases per 1000 infants; 95% CI, 35.14-44.93 cases per 1000 infants) compared with 2454 of 63 316 unexposed infants (38.76 cases per 1000 infants; 95% CI, 37.27-40.30 cases per 1000 infants). Tetracycline exposure was not associated with any MCM (RR, 1.03; 95% CI, 0.90-1.16). The RRs for specific tetracycline substances were 1.07 (95% CI, 0.93-1.23) for doxycycline, 0.83 (95% CI, 0.60-1.15) for lymecycline, and 0.78 (95% CI, 0.32-1.92) for tetracycline-oxytetracycline. There was no increased risk for 10 of 12 malformation subgroups or for any of the 16 individual malformations analyzed. The higher RRs in the main analysis for nervous system anomalies (1.92; 95% CI, 0.98-3.78) and eye anomalies (1.76; 95% CI, 1.07-2.91) were attenuated in a sensitivity analysis with follow-up extended to age 3 years (nervous system anomalies, RR, 1.08; 95% CI, 0.52-2.24; eye anomalies, RR, 1.42; 95% CI, 0.88-2.29).

Conclusions and Relevance

In this cohort study, first trimester tetracycline exposure was not associated with increased risks of any MCMs. Additional studies are needed to rule out potential risks owing to power limitations for several MCM subgroups and individual malformations.

Tetracycline antibiotics in agricultural soil: Dissipation kinetics, transformation pathways, and structure-related toxicity

Tetracyclines (TCs) are the most common antibiotics in agricultural soil, due to their widespread usage and strong persistence. Biotic and abiotic degradation of TCs may generate toxic transformation products (TPs), further threatening soil ecological safety. Despite the increasing attention on the environmental behavior of TCs, a systematic review on the dissipation of TCs, evolution of TPs, and structure-toxicity relationship of TCs in agricultural soil remains lacking. This review aimed to provide a comprehensive overview of the environmental fate of TCs in agricultural soil. We first introduced the development history and structural features of different generations of TCs. Then, we comparatively evaluated the dissipation kinetics, transportation pathways, and ecological impacts of three representative TCs, namely tetracycline (TC), oxytetracycline (OTC), and chlortetracycline (CTC), in agricultural soil. The results showed that the dissipation kinetics of TCs generally followed the first-order kinetic model, with the median dissipation half-lives ranging from 20.0 to 38.8 days. Among the three TCs, OTC displayed the lowest dissipation rates due to its structural stability. The typical degradation pathways of TCs in soil included epimerization/isomerization, demethylation, and dehydration. Isomerization and dehydration reactions may lead to the formation of more toxic TPs, while demethylation was accompanied by the alteration of the minimal pharmacophore of TCs thus potentially reducing the toxicity. Toxicological experiments are urgently needed in future to comprehensively evaluate the ecological risks of TCs in agricultural soil.

Mechanism of staphylococcal resistance to clinically relevant antibiotics

Staphylococcus aureus, a notorious pathogen with versatile virulence, poses a significant challenge to current antibiotic treatments due to its ability to develop resistance mechanisms against a variety of clinically relevant antibiotics. In this comprehensive review, we carefully dissect the resistance mechanisms employed by S. aureus against various antibiotics commonly used in clinical settings. The article navigates through intricate molecular pathways, elucidating the mechanisms by which S. aureus evades the therapeutic efficacy of antibiotics, such as β-lactams, vancomycin, daptomycin, linezolid, etc. Each antibiotic is scrutinised for its mechanism of action, impact on bacterial physiology, and the corresponding resistance strategies adopted by S. aureus. By synthesising the knowledge surrounding these resistance mechanisms, this review aims to serve as a comprehensive resource that provides a foundation for the development of innovative therapeutic strategies and alternative treatments for S. aureus infections. Understanding the evolving landscape of antibiotic resistance is imperative for devising effective countermeasures in the battle against this formidable pathogen.

Mechanistic Insights into Clinically Relevant Ribosome-Targeting Antibiotics

Antibiotics targeting the bacterial ribosome are essential to combating bacterial infections. These antibiotics bind to various sites on the ribosome, inhibiting different stages of protein synthesis. This review provides a comprehensive overview of the mechanisms of action of clinically relevant antibiotics that target the bacterial ribosome, including macrolides, lincosamides, oxazolidinones, aminoglycosides, tetracyclines, and chloramphenicol. The structural and functional details of antibiotic interactions with ribosomal RNA, including specific binding sites, interactions with rRNA nucleotides, and their effects on translation processes, are discussed. Focus is placed on the diversity of these mechanisms and their clinical implications in treating bacterial infections, particularly in the context of emerging resistance. Understanding these mechanisms is crucial for developing novel therapeutic agents capable of overcoming bacterial resistance.

Machine learning-based prediction model for hypofibrinogenemia after tigecycline therapy

BACKGROUND

In clinical practice, the incidence of hypofibrinogenemia (HF) after tigecycline (TGC) treatment significantly exceeds the probability claimed by drug manufacturers.

OBJECTIVE

We aimed to identify the risk factors for TGC-associated HF and develop prediction and survival models for TGC-associated HF and the timing of TGC-associated HF.

METHODS

This single-center retrospective cohort study included 222 patients who were prescribed TGC. First, we used binary logistic regression to screen the independent factors influencing TGC-associated HF, which were used as predictors to train the extreme gradient boosting (XGBoost) model. Receiver operating characteristic curve (ROC), calibration curve, decision curve analysis (DCA), and clinical impact curve analysis (CICA) were used to evaluate the performance of the model in the verification cohort. Subsequently, we conducted survival analysis using the random survival forest (RSF) algorithm. A consistency index (C-index) was used to evaluate the accuracy of the RSF model in the verification cohort.

RESULTS

Binary logistic regression identified nine independent factors influencing TGC-associated HF, and the XGBoost model was constructed using these nine predictors. The ROC and calibration curves showed that the model had good discrimination (areas under the ROC curves (AUC) = 0.792 [95% confidence interval (CI), 0.668-0.915]) and calibration ability. In addition, DCA and CICA demonstrated good clinical practicability of this model. Notably, the RSF model showed good accuracy (C-index = 0.746 [95%CI, 0.652-0.820]) in the verification cohort. Stratifying patients treated with TGC based on the RSF model revealed a statistically significant difference in the mean survival time between the low- and high-risk groups.

CONCLUSIONS

The XGBoost model effectively predicts the risk of TGC-associated HF, whereas the RSF model has advantages in risk stratification. These two models have significant clinical practical value, with the potential to reduce the risk of TGC therapy.

Lattice Defects and Electronic Modulation of Flower-Like Zn3In2S6 Promote Photocatalytic Degradation of Multiple Antibiotics

Photocatalysis is an effective technique to remove antibiotic residues from aquatic environments. Typical metal sulfides like Zn3In2S6 have been applied to a wide range of photocatalytic applications. However, there are currently no readily accessible methods to increase its antibiotic-degrading activity. Here, a facile hydrothermal approach is developed for the preparation of flower-like Zn3In2S6 with tunable sulfur lattice defects. Photogenerated carriers can be separated and transferred more easily when there is an adequate amount of lattice defects. Moreover, lattice defect-induced electronic modulation enhances light utilization and adsorption properties. The modified Zn3In2S6 demonstrates outstanding photocatalytic degradation activity for levofloxacin, ofloxacin, and tetracycline. This work sheds light on exploring metal sulfides with sulfur lattice defects for enhancing photocatalytic activity.

Antibiotic delivery in the presence of green AgNPs using multifunctional bilayer carrageenan nanofiber/sodium alginate nanohydrogel for rapid control of wound infections

This study constructed bilayer nano-hydrogels using solvent casting and electrospinning techniques. The first layer consisted of a hydrogel containing sodium alginate and gellan gum, while the second layer was a carrageenan/polyvinyl alcohol nanofibrous membrane. The nanohydrogels were prepared with different doses of doxycycline antibiotic (0.12, 0.06, 0.03 g) and a fixed amount of silver nanoparticles (0.012 g), which were synthesized using the green method including Capparis spinosa leaf extract. The films were tested for their mechanical properties, swelling behavior, XRD, and FTIR, and their morphology was characterized using SEM. The biological properties of the nanohydrogels were also extensively assayed. X-ray diffraction analysis showed peak 111 for silver nanoparticles. Incorporating silver nanoparticles significantly enhanced nanohydrogels' mechanical and antibacterial properties and improved their ability to heal wounds. Nanohydrogels exhibited biodegradability, biocompatibility, anti-inflammatory properties (57.63 %), and high cell viability (>85 %) in laboratory conditions. The study confirmed that wound dressings containing doxycycline with controlled release are highly effective against pathogenic bacteria and prevent the formation of biofilms (92 %). The rats in-vivo study demonstrated that 100 % wound closure was achieved in nanohydrogels containing SA/GG/PVA/CAR/AgNPs/DOX0.12 after 14 days. The films could potentially lead to the development of new treatments against bacterial infections and inflammatory conditions of wounds.

Impact of untreated tannery wastewater in the evolution of multidrug-resistant bacteria in Bangladesh

The tannery industry produces one of the worst contaminants, and unsafe disposal in nearby waterbodies and landfills has become an imminent threat to public health, especially when the resulting multidrug-resistant bacteria and heavy metals enter community settings and animal food chains. In this study, we have collected 10 tannery wastewater (TWW) samples and 10 additional non-tannery wastewater (NTW) samples to compare the chemical oxygen demand (COD), pH, biological oxygen demand (BOD), dissolved oxygen (DO), total dissolved solids (TDS), chromium concentration, bacterial load, and antibiotic resistance profiles. While COD, pH, and chromium concentration data were previously published from our lab, this part of the study uncovers that TWW samples had a significantly higher bacterial load, compared to the non-tannery wastewater samples (5.89 × 104 and 9.38 × 103 cfu/mL, respectively), higher BOD and TDS values, and significantly lower DO values. The results showed that 53.4, 46.7, 40.0, and 40.0% of the TWW isolates were resistant to ceftriaxone, erythromycin, nalidixic acid, and azithromycin, respectively. On the other hand, 20.0, 30.0, 50.0, and 40.0% of the NTW isolates were resistant to the same antibiotics, respectively. These findings suggest that the TWW isolates were more resistant to antibiotics than the NTW isolates. Moreover, the TWW isolates exhibited higher multidrug resistance than the NTW isolates, 33.33, and 20.00%, respectively. Furthermore, spearman correlation analysis depicts that there is a negative correlation between BOD and bacterial load up to a certain level (r = - 0.7749, p = 0.0085). In addition, there is also a consistent negative correlation between COD and bacterial load (r = - 0.7112, p = 0.0252) and TDS and bacterial load (r = - 0.7621, p = 0.0104). These findings suggest that TWW could pose a significant risk to public health and the environment and highlight the importance of proper wastewater treatment in tannery industries.

Current challenges in pulmonary nontuberculous mycobacterial infection: a case series with literature review

BACKGROUND

The prevalence of nontuberculous mycobacteria pulmonary disease (NTM-PD), particularly caused by Mycobacterium avium complex (MAC), is rising due to improved diagnostics, increased awareness, and more susceptible populations. NTM-PD significantly affects quality of life and imposes substantial economic costs. Understanding its clinical features, risk factors, and treatment challenges is vital for enhancing patient outcomes.

PATIENTS AND METHODS

A convenience sample from the University of Connecticut Health Center and Wayne State University involving patients with NTM-PD from 2021 to 2024 was studied retrospectively. Cases were selected to demonstrate typical diagnostic and treatment challenges, followed by a multidisciplinary roundtable discussion to examine patient-centered care strategies.

RESULTS

Analysis of six cases pinpointed chronic lung conditions and immunomodulatory therapy as key risk factors. Standard treatment, involving extensive multi-drug regimens, frequently results in poor adherence due to side effects and complex management requirements. The discussions underlined the importance of a customized, interdisciplinary approach to improve treatment effectiveness and patient quality of life.

CONCLUSIONS

NTM-PD is an escalating public health issue with notable clinical and economic consequences. Managing this disease effectively demands a comprehensive, patient-centered strategy that includes precise diagnosis, flexible treatment plans, and collaborative care.

Respiratory diseases and gut microbiota: relevance, pathogenesis, and treatment

Preclinical evidence has firmly established a bidirectional interaction among the lung, gut, and gut microbiome. There are many complex communication pathways between the lung and intestine, which affect each other's balance. Some metabolites produced by intestinal microorganisms, intestinal immune cells, and immune factors enter lung tissue through blood circulation and participate in lung immune function. Altered gut-lung-microbiome interactions have been identified in rodent models and humans of several lung diseases such as pulmonary fibrosis, chronic obstructive pulmonary disease, lung cancer, asthma, etc. Emerging evidence suggests that microbial therapies can prevent and treat respiratory diseases, but it is unclear whether this association is a simple correlation with the pathological mechanisms of the disease or the result of causation. In this review, we summarize the complex and critical link between the gut microbiota and the lung, as well as the influence and mechanism of the gut microbiota on respiratory diseases, and discuss the role of interventions such as prebiotics and fecal bacteria transplantation on respiratory diseases. To provide a reference for the rational design of large-scale clinical studies, the direct application of microbial therapy to respiratory-related diseases can reduce the incidence and severity of diseases and accompanying complications.

Enhancing outer membrane permeability of tetracycline antibiotics in P. aeruginosa using TOB-CIP conjugates

Pseudomonas aeruginosa is an opportunistic critical 'priority 1' Gram-negative bacterium that poses a severe threat to public healthcare due to rising antibiotic resistance. Particularly, low membrane permeability and overexpression of efflux pumps in P. aeruginosa lead to intrinsic resistance that compromises the antibacterial activity of antibiotics. The broad-spectrum antibiotics class, tetracyclines, are rarely used to treat P. aeruginosa infections. In the present study, we describe a series of tobramycin-ciprofloxacin (TOB-CIP) conjugates in which the carboxylic acid of ciprofloxacin is linked to the aminoglycoside tobramycin using various tethers thereby generating a cationic amphiphile. The emerging amphiphilic conjugates potentiate tetracycline antibiotics including minocycline, doxycycline, tigecycline, and eravacycline against multidrug-resistant P. aeruginosa isolates. The structure-activity relationship investigation indicates that the flexible hydrophobic C12 carbon-chain linker in TOB-CIP conjugate 1a is an optimal potentiator of tetracyclines against tetracycline-resistant and -susceptible strains of P. aeruginosa. Furthermore, conjugate 1a consistently synergized with the 3rd generation tetracycline, eravacycline, in P. aeruginosa PAO1 in the presence of up to 25% fetal bovine serum (FBS).

Design of Thermosensitive Niosomes by Eutectic Mixture of Natural Fatty Acids

In the current study, a smart release system responsive to temperature was developed to improve the efficiency of tetracycline (TC) in antibacterial therapy. The nanovesicles designed consist of a non-ionic surfactant, SPAN60, cholesterol and a phase change material (PCM) as a thermoresponsive gating material. Niosomes were prepared using an increasing amount of PCM and characterized in terms of size, zeta potential, colloidal stability and thermoresponsive properties. The vesicles that developed were homogenous in size, had good biocompatibility and stability for up to 3 months and demonstrated thermoresponsive behavior. A low drug leakage was observed at 37 °C, while a rapid release occurred at 42 °C, due to the faster diffusion rate of the drug trough the melted PCM. This controllable drug release capacity allows us to avoid premature drug release, minimizing unwanted and toxic effects and ensuring a long retention time in the nanodevice so that it reaches the infected sites. In addition, TC-loaded niosomes were screened to investigate their antibacterial activity against various Gram-positive and Gram-negative bacteria by minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) assays. An interesting temperature-dependent antibacterial activity was observed against some bacterial strains: the niosomes activity against S. epidermis, for example, was improved by the temperature increase, as suggested by a reduction in MIC values from 112.81 to 14.10 μM observed at 37 and 42 °C, respectively. Taken together, the thermoresponsive platform developed allows us to use lower antibiotic amounts while ensuring therapeutic efficacy and, so, will advance the development of a novel antibacterial agent in clinical practice.

Third-Generation Tetracyclines: Current Knowledge and Therapeutic Potential

Tetracyclines constitute a unique class of antibiotic agents, widely prescribed for both community and hospital infections due to their broad spectrum of activity. Acting by disrupting protein synthesis through tight binding to the 30S ribosomal subunit, their interference is typically reversible, rendering them bacteriostatic in action. Resistance to tetracyclines has primarily been associated with changes in pump efflux or ribosomal protection mechanisms. To address this challenge, tetracycline molecules have been chemically modified, resulting in the development of third-generation tetracyclines. These novel tetracyclines offer significant advantages in treating infections, whether used alone or in combination therapies, especially in hospital settings. Beyond their conventional antimicrobial properties, research has highlighted their potential non-antibiotic properties, including their impact on immunomodulation and malignancy. This review will focus on third-generation tetracyclines, namely tigecycline, eravacycline, and omadacycline. We will delve into their mechanisms of action and resistance, while also evaluating their pros and cons over time. Additionally, we will explore their therapeutic potential, analyzing their primary indications of prescription, potential future uses, and non-antibiotic features. This review aims to provide valuable insights into the clinical applications of third-generation tetracyclines, thereby enhancing understanding and guiding optimal clinical use.

Structural basis for differential inhibition of eukaryotic ribosomes by tigecycline

Tigecycline is widely used for treating complicated bacterial infections for which there are no effective drugs. It inhibits bacterial protein translation by blocking the ribosomal A-site. However, even though it is also cytotoxic for human cells, the molecular mechanism of its inhibition remains unclear. Here, we present cryo-EM structures of tigecycline-bound human mitochondrial 55S, 39S, cytoplasmic 80S and yeast cytoplasmic 80S ribosomes. We find that at clinically relevant concentrations, tigecycline effectively targets human 55S mitoribosomes, potentially, by hindering A-site tRNA accommodation and by blocking the peptidyl transfer center. In contrast, tigecycline does not bind to human 80S ribosomes under physiological concentrations. However, at high tigecycline concentrations, in addition to blocking the A-site, both human and yeast 80S ribosomes bind tigecycline at another conserved binding site restricting the movement of the L1 stalk. In conclusion, the observed distinct binding properties of tigecycline may guide new pathways for drug design and therapy.

Metabolomics analysis of the lactobacillus plantarum ATCC 14917 response to antibiotic stress

BACKGROUND

Lactobacillus plantarum has been found to play a significant role in maintaining the balance of intestinal flora in the human gut. However, it is sensitive to commonly used antibiotics and is often incidentally killed during treatment. We attempted to identify a means to protect L. plantarum ATCC14917 from the metabolic changes caused by two commonly used antibiotics, ampicillin, and doxycycline. We examined the metabolic changes under ampicillin and doxycycline treatment and assessed the protective effects of adding key exogenous metabolites.

RESULTS

Using metabolomics, we found that under the stress of ampicillin or doxycycline, L. plantarum ATCC14917 exhibited reduced metabolic activity, with purine metabolism a key metabolic pathway involved in this change. We then screened the key biomarkers in this metabolic pathway, guanine and adenosine diphosphate (ADP). The exogenous addition of each of these two metabolites significantly reduced the lethality of ampicillin and doxycycline on L. plantarum ATCC14917. Because purine metabolism is closely related to the production of reactive oxygen species (ROS), the results showed that the addition of guanine or ADP reduced intracellular ROS levels in L. plantarum ATCC14917. Moreover, the killing effects of ampicillin and doxycycline on L. plantarum ATCC14917 were restored by the addition of a ROS accelerator in the presence of guanine or ADP.

CONCLUSIONS

The metabolic changes of L. plantarum ATCC14917 under antibiotic treatments were determined. Moreover, the metabolome information that was elucidated can be used to help L. plantarum cope with adverse stress, which will help probiotics become less vulnerable to antibiotics during clinical treatment.

Rapid Determination of Tetracyclines in Drinking and Environmental Waters Using Fully Automatic Solid-Phase Extraction with Ultra-Performance Liquid Chromatography-Tandem Mass Spectrometry

The abuse and irrational use of tetracyclines (TCs) in human medicine and animal husbandry has become a serious concern, affecting the ecological environment and human health. The aim of this study was to develop a sensitive and selective method using fully automatic solid-phase extraction coupled with ultra-performance liquid chromatography-tandem mass spectrometry for the determination of twelve TCs in water. Four isotope-labeled internal standards for TCs were used to correct matrix effects. Several parameters affecting extraction efficiency were systematically optimized, and the optimum experimental conditions found were 1.0 L water sample with 0.5 g/L Na2EDTA (pH 3.0) extracted and enriched by CNW HLB cartridge and eluted by 4 mL of acetone:methanol (v/v, 1:1). The enrichment factors were up to 798-1059 but only requiring about 60 min per six samples. Under the optimized conditions, the linearity of the method ranged from 0.2 to 100 μg/L for 12 TCs, the detection limits were as low as 0.01-0.15 ng/L, and the recoveries were in the range of 70%-118%, with relative standard deviations less than 15%. The developed method can be successfully utilized for the determination of 12 TCs in pure water, tap water, river water, and mariculture seawater. In summary, three and six TCs were detected in river water and mariculture seawater, respectively, with total concentrations of 0.074-0.520 ng/L (mean 0.248 ng/L) and 0.792-58.369 ng/L (12.629 ng/L), respectively. Tetracycline (TC) and oxytetracycline (OTC) were the dominant TCs in river water, while doxytetracycline (DXC) and OTC were dominant in mariculture seawater.

Sensing the Bactericidal and Bacteriostatic Antimicrobial Mode of Action Using Raman Deuterium Stable Isotope Probing (DSIP) in Escherichia coli

The mode of action of antibiotics can be broadly classified as bacteriostatic and bactericidal. The bacteriostatic mode leads to the arrested growth of the cells, while the bacteriocidal mode causes cell death. In this work, we report the applicability of deuterium stable isotope probing (DSIP) in combination with Raman spectroscopy (Raman DSIP) for discriminating the mode of action of antibiotics at the community level. Escherichia coli, a well-known model microbe, was used as an organism for the study. We optimized the concentration of deuterium oxide required for metabolic activity monitoring without compromising the microbial growth. Our findings suggest that changes in the intensity of the C-D band in the high-wavenumber region could serve as a quantifiable marker for determining the antibiotic mode of action. This can be used for early identification of the antibiotic's mode of action. Our results explore the new perspective that supports the utility of deuterium-based vibrational tags in the field of clinical spectroscopy. Understanding the antibiotic's mode of action on bacterial cells in a short and objective manner can significantly enhance the clinical management abilities of infectious diseases and may also help in personalized antimicrobial therapy.

Synergistic adsorption and photocatalytic degradation of tetracycline using a Z-scheme kaolin/g-C3N4/MoO3 nanocomposite: A sustainable approach for water treatment

This research focuses on the synthesis and application of a novel kaolin-supported g-C3N4/MoO3 nanocomposite for the degradation of tetracycline, an important antibiotic contaminant in water systems. The nanocomposite was prepared through a facile and environmentally friendly approach, leveraging the adsorption and photocatalytic properties of kaolin, g-C3N4 and MoO3 nanoparticles, respectively. Comprehensive characterization of the nanocomposite was conducted using techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR) and optical spectra. The surface parameters were studied using N2 adsorption-desorption isotherm. The elemental composition was studied using X-ray photoelectron spectroscopy. The efficiency of the developed nanocomposite in tetracycline degradation was evaluated and the results revealed an efficient tetracycline degradation exhibiting the synergistic effects of adsorption and photocatalytic degradation in the removal process. The tetracycline degradation was achieved in 60 min. Kinetic studies and thermodynamic analyses provided insights into the degradation mechanism, suggesting potential applications for the nanocomposite in wastewater treatment. Additionally, the recyclability and stability of the nanocomposite were investigated, demonstrating its potential for sustainable and long-term application in water treatment.

A Retrospective Review of a Cohort of Patients with Periorificial Dermatitis Treated with Sarecycline

Introduction

Periorificial dermatitis (POD) is a common, chronic, inflammatory facial skin rash that presents as tiny papules and papulopustules with underlying eczematous-like patches, typically confined to the perioral, perinasal, and periorbital areas. There is currently no Food and Drug Administration (FDA)-indicated treatment for POD; however, broad-spectrum antibiotics are efficacious as a treatment option. Broad-spectrum antibiotics negatively impact gut flora and lead to antibiotic resistance. Narrow-spectrum tetracyclines, such as sarecycline, have a low potential for promoting bacterial resistance and gastrointestinal issues.

Objective

We conducted a retrospective chart review in order to evaluate the efficacy of sarecycline in a cohort of patients diagnosed with POD that were treated with sarecycline.

Methods

A review of medical records was completed using an electronic medical record. Inclusion criteria included males and females aged 18 to 95 with a diagnosis of POD, treated with sarecycline with a documented follow-up.

Results

Six patients met inclusion criteria, all of which had shown improvement with no reported side effects. Of the six patients, four were female and two were male and the patient ages ranged from 26 to 58 years old (mean=41 years). The course of therapy ranged from 30 to180 days (median=90 days).

Conclusion

Based on the outcomes, there are many potential benefits to treatment of POD with sarecycline over the alternative tetracycline-class antibiotics. There is a need for more large-scale clinical studies evaluating treatment options for POD. Based on the efficacy and tolerability of sarecycline in large- scale acne studies, sarecycline may be an appropriate novel treatment option for POD and should be explored further.

Investigation of doxycycline residues in bones after oral administration to broiler chickens

Introduction

Chicken bones, a by-product of the poultry industry, can directly or indirectly enter the food chain. Bone meal and bone products could be sources of many contaminants. Considering the wide range of uses made of bones in the culinary and food industries, this material needs to be safe and antibiotic residue-free. To determine if such is the case, the concentration of doxycycline in chicken bones was investigated, this antimicrobial being one of the most commonly used in poultry production.

Material and Methods

Ross 308 broilers were grouped into three experimental and one control group. Doxycycline was administered in drinking water at therapeutic and sub-therapeutic doses, as well as via spray treatment. The concentration of doxycycline in bones was determined post slaughter by ultra-high performance liquid chromatography-tandem mass spectrometry.

Results

Doxycycline was quantified at 135 μg/kg 22 days after the last day of antibiotic administration at therapeutic doses; 2,285 μg/kg after sub-therapeutic treatment for 27 days and 9.62 μg/kg 22 days after the end of spray application.

Conclusion

High concentrations and long persistence of doxycycline in bones were found in this study. Doxycycline can contaminate all bone-derived products in the food and fertiliser industries.

CATH-2-derived antimicrobial peptide inhibits multidrug-resistant Escherichia coli infection in chickens

Avian colibacillosis (AC), caused by infection with Escherichia coli (E. coli), is a major threat to poultry health, food safety and public health, and results in high mortality and significant economic losses. Currently, new drugs are urgently needed to replace antibiotics due to the continuous emergence and increasing resistance of multidrug-resistant (MDR) strains of E. coli caused by the irrational use of antibiotics in agriculture and animal husbandry. In recent years, antimicrobial peptides (AMPs), which uniquely evolved to protect the host, have emerged as a leading alternative to antibiotics in clinical settings. CATH-2, a member of the antimicrobial cathelicidin peptide family, has been reported to have antibacterial activity. To enhance the antimicrobial potency and reduce the adverse effects on animals, we designed five novel AMPs, named C2-1, C2-2, C2-3, C2-4 and C2-5, based on chicken CATH-2, the secondary structures of these AMPs were consistently α-helical and had an altered net charge and hydrophobicity compared to those of the CATH-2 (1-15) sequences. Subsequently, the antimicrobial activities of CATH-2 (1-15) and five designed peptides against MDR E. coli were evaluated in vitro. Specifically, C2-2 showed excellent antimicrobial activity against either the ATCC standard strain or veterinary clinical isolates of MDR E. coli, with concentrations ranging from 2-8 μg/mL. Furthermore, C2-2 maintained its strong antibacterial efficacy under high temperature and saline conditions, demonstrating significant stability. Similarly, C2-2 retained a high level of safety with no significant hemolytic activity on chicken mature red blood cells or cytotoxicity on chicken kidney cells over the concentration range of 0-64 μg/mL. Moreover, the administration of C2-2 improved the survival rate and reduced the bacterial load in the heart, liver and spleen during MDR E. coli infection in chickens. Additionally, pathological damage to the heart, liver and intestine was prevented when MDR E. coli infected chickens were treated with C2-2. Together, our study showed that C2-2 may be a promising novel therapeutic agent for the treatment of MDR E. coli infections and AC.

Development strategy of novel drug formulations for the delivery of doxycycline in the treatment of wounds of various etiologies

Doxycycline hyclate (DOXH) is a broad-spectrum antibiotic derived synthetically from tetracycline. Despite its use in clinical practice for more than 40 years, DOXH remains an effective antibiotic with retained activity. The potential advantages of DOXH for wound healing therapy include its mechanisms of action, such as anti-inflammatory effects, antioxidant properties, modulation of cellular processes, stimulation of collagen synthesis, and antimicrobial activity. As current standards of care aim to improve wound healing by promoting rapid closure, a relevant direction is the development of novel DOXH formulations for parenteral delivery that enhance both skin regeneration and control of infectious conditions. Oral delivery is the most common and commercially available route for administering DOXH therapeutic agents. However, parenteral delivery of DOXH, where the antibiotic substance is not in a solid state (as in powdered or compressed solid form) but rather dissolved in any carrier, presents challenges regarding DOX solubility and the stability of DOXH solutions, which are major factors complicating the development of new formulations for parenteral administration. This review discusses the achievements in research strategies and the development of new pharmaceutical formulations for the delivery of doxycycline in the treatment of wounds of various etiologies.

Efficacy of new generation biosorbents for the sustainable treatment of antibiotic residues and antibiotic resistance genes from polluted waste effluent

Antimicrobials are frequently used in both humans and animals for the treatment of bacterially-generated illnesses. Antibiotic usage has increased for more than 40% from last 15 years globally per day in both human populations and farm animals leading to the large-scale discharge of antibiotic residues into wastewater. Most antibiotics end up in sewer systems, either directly from industry or healthcare systems, or indirectly from humans and animals after being partially metabolized or broken down following consumption. To prevent additional antibiotic compound pollution, which eventually impacts on the spread of antibiotic resistance, it is crucial to remove antibiotic residues from wastewater. Antibiotic accumulation and antibiotic resistance genes cannot be effectively and efficiently eliminated by conventional sewage treatment plants. Because of their high energy requirements and operating costs, many of the available technologies are not feasible. However, the biosorption method, which uses low-cost biomass as the biosorbent, is an alternative technique to potentially address these problems. An extensive literature survey focusing on developments in the field was conducted using English language electronic databases, such as PubMed, Google Scholar, Pubag, Google books, and ResearchGate, to understand the relative value of the available antibiotic removal methods. The predominant techniques for eliminating antibiotic residues from wastewater were categorized and defined by example. The approaches were contrasted, and the benefits and drawbacks were highlighted. Additionally, we included a few antibiotics whose removal from aquatic environments has been the subject of extensive research. Lastly, a few representative publications were identified that provide specific information on the removal rates attained by each technique. This review provides evidence that biosorption of antibiotic residues from biological waste using natural biosorbent materials is an affordable and effective technique for eliminating antibiotic residues from wastewater.

Efficacy and safety of omadacycline for treating complicated skin and soft tissue infections: a meta-analysis of randomized controlled trials

OBJECTIVE

In the present study, we aimed to compare the clinical efficacy and safety of omadacycline (OMC) with its comparators for the treatment of complicated skin and soft tissue infections (cSSTIs) in adult patients.

METHODS

Randomized controlled trials (RCTs) evaluating OMC for cSSTIs were searched in databases of PubMed, Embase, Cochrane, Web of Science, and Clinical Trial, up to July 2022. The primary outcomes were clinical efficacy and microbiological response, with secondary outcome was safety.

RESULTS

Four RCTs consisting of 1,757 patients were included, with linezolid (LZD) as a comparator drug. For clinical efficacy, OMC was not inferior to LZD in the modified intent-to-treat (MITT) (OR: 1.24, 95% Cl: [0.93, 1.66], P = 0.15) and clinically evaluable (CE) populations (OR: 1.92, 95% Cl: [0.94, 3.92], P = 0.07). For microbiological response, OMC was numerically higher than LZD in the microbiologically evaluable (ME) (OR: 1.74, 95% Cl: [0.81, 3.74], P = 0.16) and microbiological MITT (micro-MITT) populations (OR: 1.27, 95% Cl: [0.92, 1.76], P = 0.14). No significant difference was found in subpopulations of monomicrobial or polymicrobial mixed infection populations. The mortality and adverse event rates were similar between OMC and LZD.

CONCLUSIONS

OMC was as good as LZD in terms of clinical efficacy and microbiological response, and has similar safety issues in treating cSSTIs. OMC might be a promising option for treating cSSTIs in adult patients.

Toxicity of tigecycline on the freshwater microalga Scenedesmus obliquus: Photosynthetic and transcriptional responses

Tigecycline (TGC) is a new tetracycline antibiotic medication against multidrug-resistant bacteria. However, the toxicity of TGC to microalgae remains largely unknown. In this study, the toxicity of TGC on Scenedesmus obliquus was examined, focusing on changes in algal growth, photosynthetic activity, and transcriptome. According to an acute toxicity test, the IC10 and IC50 values were 0.72 mg/L and 4.15 mg/L, respectively. Analyses of photosynthetic efficiency and related parameters, such as light absorption, energy capture, and electron transport, identified a 35% perturbation in the IC50 group, while the IC10 group remained largely unaffected. Transcriptomic analysis showed that in the IC10 and IC50 treatment groups, there were 874 differentially expressed genes (DEGs) (220 upregulated and 654 downregulated) and 4289 DEGs (2660 upregulated and 1629 downregulated), respectively. Gene Ontology enrichment analysis showed that TGC treatment markedly affected photosynthesis, electron transport, and chloroplast functions. In the IC50 group, a clear upregulation of genes related to photosynthesis and chloroplast functions was observed, which could be an adaptive stress response. In the IC10 group, significant downregulation of DEGs involved in ribosomal pathways and peptide biosynthesis processes was observed. Kyoto Encyclopedia of Gene and Genomes enrichment analysis showed that treatment with TGC also disrupted energy production, protein synthesis, and metabolic processes in S. obliquus. Significant downregulation of key proteins related to Photosystem II was observed under the IC10 TGC treatment. Conversely, IC50 TGC treatment resulted in substantial upregulation across a broad array of photosystem-related proteins from both Photosystems II and I. IC10 and IC50 TGC treatments differentially influenced proteins involved in the photosynthetic electron transport process. This study emphasizes the potential risks of TGC pollution to microalgae, which contributes to a better understanding of the effects of antibiotic contamination in aquatic ecosystems.

Pharmacokinetic and pharmacodynamic evaluation of the atypical tetracyclines chelocardin and amidochelocardin in murine infection models

IMPORTANCE

There is a strong need to find novel treatment options against urinary tract infections associated with antimicrobial resistance. This study evaluates two atypical tetracyclines, namely chelocardin (CHD) and amidochelocardin (CDCHD), with respect to their pharmacokinetics and pharmacodynamics. We show CHD and CDCHD are cleared at high concentrations in mouse urine. Especially, CDCHD is highly effective in an ascending urinary tract infection model, suggesting further preclinical evaluation.

New Antibiotics for the Treatment of Nosocomial Central Nervous System Infections

Nosocomial central nervous system (CNS) infections with carbapenem- and colistin-resistant Gram-negative and vancomycin-resistant Gram-positive bacteria are an increasing therapeutic challenge. Here, we review pharmacokinetic and pharmacodynamic data and clinical experiences with new antibiotics administered intravenously for the treatment of CNS infections by multi-resistant bacteria. Cefiderocol, a new siderophore extended-spectrum cephalosporin, pharmacokinetically behaves similar to established cephalosporins and at high doses will probably be a valuable addition in our therapeutic armamentarium for CNS infections. The new glycopeptides dalbavancin, telavancin, and oritavancin are highly bound to plasma proteins. Although effective in animal models of meningitis, it is unlikely that they reach effective cerebrospinal fluid (CSF) concentrations after intravenous administration alone. The β-lactam/β-lactamase inhibitor combinations have the principal problem that both compounds must achieve adequate CSF concentrations. In the commercially available combinations, the dose of the β-lactamase inhibitor tends to be too low to achieve adequate CSF concentrations. The oxazolidinone tedizolid has a broader spectrum but a less suitable pharmacokinetic profile than linezolid. The halogenated tetracycline eravacycline does not reach CSF concentrations sufficient to treat colistin-resistant Gram-negative bacteria with usual intravenous dosing. Generally, treatment of CNS infections should be intravenous, whenever possible, to avoid adverse effects of intraventricular therapy (IVT). An additional IVT can overcome the limited penetration of many new antibiotics into CSF. It should be considered for patients in which the CNS infection responds poorly to systemic antimicrobial therapy alone.

Reviewing particulate delivery systems loaded with repurposed tetracyclines - From micro to nanoparticles

Tetracyclines (TCs) are a class of broad-spectrum antibacterial agents recognized for their multifaceted properties, including anti-inflammatory, angiogenic and osteogenic effects. This versatility positions them as suitable candidates for drug repurposing, benefitting from well-characterized safety and pharmacological profiles. In the attempt to explore both their antibacterial and pleiotropic effects locally, innovative therapeutic strategies were set on engineering tetracycline-loaded micro and nanoparticles to tackle a vast number of clinical applications. Moreover, the conjoined drug carrier can function as an active component of the therapeutic approach, reducing off-target effects and accumulation, synergizing to an improvement of the therapeutic efficacy. In this comprehensive review we will critically evaluate recent advances involving the use of tetracyclines loaded onto micro- or nanoparticles, intended for biomedical applications, and discuss emerging approaches and current limitations associated with these drug carriers. Owing to their distinctive physical, chemical, and biological properties, these novel carriers have the potential to become a platform technology in personalized regenerative medicine and other therapeutic applications.

The combination of tetracyclines effectively ameliorates liver fibrosis via inhibition of EphB1/2

Eph receptor tyrosine kinase EphB1/2 contributes to the development of liver fibrosis, suggesting the rationale that EphB1/2 inhibitors may be effective in liver fibrosis therapy. Since tetracycline antibiotics were recently demonstrated as EphB kinase inhibitors, in present study we investigated their therapeutic potential against liver fibrosis. Our results showed that the tetracycline combination of demeclocycline (D), chlortetracycline (C), and minocycline (M) inhibited the activation of hepatic stellate cells (HSCs) in vitro and alleviated CCl4-induced animal model of liver fibrosis in vivo. Mechanistically, DCM combination inhibited EphB1/2 phosphorylation and subsequent activation of the MAPK signaling. Moreover, we found that short-term and low-dose DCM combination treatment decreased tissue inflammation and improved liver fibrosis in mice. Thus, our study indicates that tetracyclines may be repurposed for the treatment of liver fibrosis.

Efficacy of Oxytetracycline Hydrocortisone-Soaked Gauze Pack on Postoperative Sequelae in Lower Third Molar Surgery: A Prospective Study

Background Though various advancements came into the field of surgery to do the atraumatic procedure, post-operative pain, and swelling are unavoidable complications. Hence, various medicaments are packed in the extracted third molar sockets to prevent these post-operative complications. Aim The study aimed to evaluate the efficacy of oxytetracycline hydrocortisone-soaked gauze in reducing post-operative pain and swelling compared to conventional surgical procedures without any packing in patients undergoing surgical extraction of the impacted mandibular third molars. Materials and methods The study was conducted in the Department of Oral and Maxillofacial Surgery at Saveetha Dental College and Hospitals, Chennai. In this study, 50 patients were randomly included in two groups of 25 participants each. In group A, oxytetracycline hydrocortisone-soaked gauze was placed, and in group B, conventional closure was done without any pack after surgical removal of impacted mandibular third molars. Post-operative pain was assessed on days one, three, and five using a 10-point visual analog scale. Post-operative swelling was assessed on the third and seventh days using a four-point swelling measurement. Data analysis was done using SPSS (IBM Corp. Armonk, NY). A p-value less than 0.05 was considered statistically significant. Independent sample t-test was done to compare the outcomes between the two groups. Results The results demonstrated that group A (Oxytetracycline Hydrocortisone-soaked gauze) showed superior pain reduction compared to group B (conventional closure) at all post-operative intervals (P=0.001). Moreover, group A exhibited reduced swelling, resulting in higher patient satisfaction levels compared to group B on the third post-operative day (P=0.001). Conclusion It can be concluded from the study that there was a significant reduction in post-operative pain and swelling with the use of oxytetracycline hydrocortisone-soaked gauze, as it acts like a local drug delivery system in patients undergoing impacted mandibular third molar surgeries.

Emerging infections in vulnerable hosts: Stenotrophomonas maltophilia and Elizabethkingia anophelis

PURPOSE OF REVIEW

This systematic review aimed to explore the recent trends in the epidemiology, risk factors, and antimicrobial susceptibility of two emerging opportunistic pathogens, Stenotrophomonas maltophilia and Elizabethkingia anophelis .

RECENT FINDINGS

Since 2020, numerous outbreaks of S. maltophilia and E. anophelis have been reported worldwide. Most of these outbreaks have been associated with healthcare facilities, although one outbreak caused by E. anophelis in France was considered a community-associated infection. In terms of antimicrobial susceptibility, trimethoprim/sulfamethoxazole (TMP-SMZ), levofloxacin, and minocycline have exhibited good efficacy against S. maltophilia . Additionally, cefiderocol and a combination of aztreonam and avibactam have shown promising results in in vitro susceptibility testing. For E. anophelis , there is currently no consensus on the optimal treatment. Although some studies have reported good efficacy with rifampin, TMP-SMZ, piperacillin/tazobactam, and cefoperazone/sulbactam, minocycline had the most favourable in vitro susceptibility rates. Cefiderocol may serve as an alternative due to its low minimum inhibitory concentration (MIC) against E. anophelis . The role of vancomycin in treatment is still uncertain, although several successful cases with vancomycin treatment, even with high MIC values, have been reported.

SUMMARY

Immunocompromised patients are particularly vulnerable to infections caused by S. maltophilia and E. anophelis , but the optimal treatment strategy remains inconclusive. Further research is necessary to determine the most effective use of conventional and novel antimicrobial agents in combatting these multidrug-resistant pathogens.

Pd/C-Catalyzed Carbonylative Amidation for the Synthesis of 2-Carboxamidocyclohexane-1,3-diones

Herein, a first-ever heterogeneous Pd/C-catalyzed single-step tandem approach for the synthesis of 2-carboxamidocyclohexane-1,3-diones via direct carbonylative C-H amidation of cyclohexane-1,3-diones is reported. The reaction progressed under base-, oxidant-, and ligand-free conditions employing oxalic acid as a CO surrogate and sodium azide as a nitrogen precursor in a double-layer vial system.

The Role of Five-Membered Heterocycles in the Molecular Structure of Antibacterial Drugs Used in Therapy

Five-membered heterocycles are essential structural components in various antibacterial drugs; the physicochemical properties of a five-membered heterocycle can play a crucial role in determining the biological activity of an antibacterial drug. These properties can affect the drug's activity spectrum, potency, and pharmacokinetic and toxicological properties. Using scientific databases, we identified and discussed the antibacterials used in therapy, containing five-membered heterocycles in their molecular structure. The identified five-membered heterocycles used in antibacterial design contain one to four heteroatoms (nitrogen, oxygen, and sulfur). Antibacterials containing five-membered heterocycles were discussed, highlighting the biological properties imprinted by the targeted heterocycle. In some antibacterials, heterocycles with five atoms are pharmacophores responsible for their specific antibacterial activity. As pharmacophores, these heterocycles help design new medicinal molecules, improving their potency and selectivity and comprehending the structure-activity relationship of antibiotics. Unfortunately, particular heterocycles can also affect the drug's potential toxicity. The review extensively presents the most successful five-atom heterocycles used to design antibacterial essential medicines. Understanding and optimizing the intrinsic characteristics of a five-membered heterocycle can help the development of antibacterial drugs with improved activity, pharmacokinetic profile, and safety.

Tetracycline antibiotics: Potential anticancer drugs

In recent years, research on tetracycline antibiotics has gradually shifted from their antibacterial effects to anticancer effects. Doxycycline, minocycline, and tigecycline as the US Food and Drug Administration (FDA) approved tetracycline antibiotics have been the main subjects of studies. Evidence indicated that they have anticancer properties and are able to control cancer progression through different mechanisms, such as anti-proliferation, anti-metastasis, and promotion of autophagy or apoptosis. In addition, studies have shown that these three tetracycline antibiotics can be utilized in conjunction with chemotherapeutic and targeted drugs to inhibit cancer progression and improve the quality of patient survival. Therefore, doxycycline, minocycline, and tigecycline are taken as examples in this work. Their mechanisms of action in different cancers and related combination therapies are introduced. Their current roles in alleviating the suffering of patients undergoing chemotherapy when used as adjuvant drugs in clinical treatment are also described. Finally, the research gaps and potential research directions at this stage are briefly summarized.

Unveiling the Osteogenic Potential of Tetracyclines: A Comparative Study in Human Mesenchymal Stem Cells

Tetracyclines (TCs) are a class of broad-spectrum antibiotics with diverse pharmacotherapeutic properties due to their various functional groups being attached to a common core structure. Beyond their antibacterial activity, TCs trigger pleiotropic effects on eukaryotic cells, including anti-inflammatory and potentially osteogenic capabilities. Consequently, TCs hold promise for repurposing in various clinical applications, including bone-related conditions. This study presents the first comprehensive comparison of the in vitro osteogenic potential of four TCs-tetracycline, doxycycline, minocycline, and sarecycline, within human mesenchymal stem cells. Cultures were characterized for metabolic activity, cell morphology and cytoskeleton organization, osteogenic gene expression, alkaline phosphatase (ALP) activity, and the activation of relevant signaling pathways. TCs stimulated actin remodeling processes, inducing morphological shifts consistent with osteogenic differentiation. Osteogenic gene expression and ALP activity supported the osteoinduction by TCs, demonstrating significant increases in ALP levels and the upregulation of RUNX2, SP7, and SPARC genes. Minocycline and sarecycline exhibited the most potent osteogenic induction, comparable to conventional osteogenic inducers. Signaling pathway analysis revealed that tetracycline and doxycycline activate the Wnt pathway, while minocycline and sarecycline upregulated Hedgehog signaling. Overall, the present findings suggest that TCs promote osteogenic differentiation through distinct pathways, making them promising candidates for targeted therapy in specific bone-related disorders.

The role of matrix metalloproteinases in infectious corneal ulcers

During infectious keratitis, the production of collagenolytic and inflammatory substances, along with increased corneal matrix metalloproteinase (MMP) activity, induces the degradation of corneal collagen and may cause postkeratitis complications, such as opacity, thinning, and corneal perforation. MMPs, especially MMP-2 and MMP-9, are overexpressed in infectious keratitis and sustained over time by inflammatory and nonmicrobial mechanisms. The high MMP levels are correlated with excessive corneal destruction in bacterial, herpetic, fungal, and acanthamoeba infections. Nonspecific treatments, such as tetracyclines, particularly doxycycline, or corticosteroids, are used as adjuvants to antimicrobials to alleviate the disproportionate degradation and inflammation of the corneal layers caused by corneal MMPs and decrease the recruitment and infiltration of inflammatory cells. Treatments showing inhibition of specific MMPs (Galardin, ZHAWOC7726), interfering with pro-MMP activation (EDTA, ascorbic acid), or showing anticytokine effect (epigallocatechin-2-gallate, TRAM-34) have been reported. Other treatments show a direct action over corneal collagen structure such as corneal cross-linking or have been associated with reduction of MMP levels such as amniotic membrane grafting. Although the use of these drugs has been shown in studies to be effective in controlling inflammation, especially in experimental ones, robust studies are still needed based on randomized and randomized clinical trials to demonstrate their potential effect as adjuvants in the management of infectious keratitis.

Exploring Antibiotic-Potentiating Effects of Tobramycin-Deferiprone Conjugates in Pseudomonas aeruginosa

Metal ions, including Fe3+, affect the target site binding of some antibiotics and control the porin- and siderophore-mediated uptake of antibiotics. Amphiphilic tobramycins are an emerging class of antibiotic potentiators capable of synergizing with multiple classes of antibiotics against Gram-negative bacteria, including Pseudomonas aeruginosa. To study how the antibiotic-potentiating effect of amphiphilic tobramycins is affected by the presence of intermolecular iron chelators, we conjugated the FDA-approved iron chelator deferiprone (DEF) to tobramycin (TOB). Three TOB-DEF conjugates differing in the length of the carbon tether were prepared and tested for antibacterial activity and synergistic relationships with a panel of antibiotics against clinical isolates of P. aeruginosa. While all TOB-DEF conjugates were inactive against P. aeruginosa, the TOB-DEF conjugates strongly synergized with outer-membrane-impermeable antibiotics, such as novobiocin and rifampicin. Among the three TOB-DEF conjugates, 1c containing a C12 tether showed a remarkable and selective potentiating effect to improve the susceptibility of multidrug-resistant P. aeruginosa isolates to tetracyclines when compared with other antibiotics. However, the antibacterial activity and antibiotic-potentiating effect of the optimized conjugate was not enhanced under iron-depleted conditions, indicating that the function of the antibiotic potentiator is not affected by the Fe3+ concentration.