Infections caused by Pseudomonas aeruginosa (P. aeruginosa) pose a severe threat to public health due to high antibiotic resistance and robust biofilm formation, which collectively hinder the penetration and efficacy of antibiotics and antibodies. To address this issue, we developed a chemo-bio-hybrid delivery system, termed EcN@TGG, by chemically engineering the probiotic strain Escherichia coli Nissle 1917 (EcN). Leveraging its intrinsic swimming capability, EcN was harnessed as an active penetration vehicle against established biofilms. Via a simple co-incubation process, EcN is functionalized with tannic acid (TA), gallium (Ga3+), and a bispecific monoclonal antibody Gremubamab (MEDI3902) targeting P. aeruginosa. EcN@TGG actively penetrates biofilm matrix, enabling deep delivery of therapeutic payloads (Ga3+ and MEDI3902) thereby achieving effective biofilm disruption and potent bactericidal activity. The robust antimicrobial efficacy and biocompatibility of EcN@TGG confer potent antibiofilm activity against P. aeruginosa, as demonstrated both in vitro and in vivo. This platform not only provides a promising strategy for treating refractory infections caused by P. aeruginosa, but also establishes a versatile chemo-bio-hybrid strategy for combating diverse biofilm-associated diseases.

Enterotoxigenic Escherichia coli (ETEC) is a leading cause of diarrhea in infants and travelers. However, antibiotic treatment is challenged by growing resistance. This study investigated the potential of Enterococcus faecalis, an early colonizer of the infant gut, as a probiotic to combat ETEC. From 125 healthy infant feces, 54 E. faecalis strains were isolated and evaluated for safety and function. E. faecalis LX25 and LX39 showed significant inhibition of ETEC growth, virulence gene (eltA and stA) expression (P < 0.05) and disrupted biofilm formation. Notably, LX39's cell-free supernatant (CFS) increased reactive oxygen species in ETEC, leading to cellular damage. HPLC revealed the three most concentrated organic acids, lactic (10.31 mg/mL), acetic (1.72 mg/mL) and citric acids (1.58 mg/mL) in LX39's CFS, which exceeding or approaching the MIC for ETEC. These findings indicate that E. faecalis LX39 could serve as effective probiotics candidates to inhibit ETEC, highlighting their potential in managing intestinal pathogen infection.

Ilaprazole, a proton pump inhibitor, has been approved and marketed in Korea and China for the treatment of gastric ulcer, duodenal ulcer, gastroesophageal reflux disease, and erosive esophagitis. This study evaluated the in vitro antibacterial activity of ilaprazole against Helicobacter pylori (H. pylori), both as a single agent and in combination with other components used in the standard quadruple therapy. The antibacterial activity of ilaprazole was tested on 25 H. pylori strains, including the clinical isolates resistant to clarithromycin (CLA), amoxicillin (AMX), levofloxacin, and/or metronidazole. Antibacterial activities and killing kinetics were evaluated by the minimal inhibitory concentration (MIC) and time-kill curve determination, respectively. Synergistic effects were assessed in checkerboard and time-kill assays. Resistance development was assessed through serial passage over 12 cycles. Ilaprazole exhibited potent in vitro antibacterial activity against H. pylori, with MIC50 and MIC90 values of 8 µg/mL, demonstrating activity against drug-resistant strains. When combined with CLA, ilaprazole showed synergistic effects against 36% of the tested strains. Notably, the quadruple combination of ilaprazole + AMX + CLA + bismuth potassium citrate exhibited an obvious synergistic effect. Importantly, repeated exposure to ilaprazole over 12 passages did not induce resistance. These findings highlight the promising in vitro antibacterial activity of ilaprazole against H. pylori, including drug-resistant strains, and its potential to enhance the efficacy of quadruple therapy. The study supports the inclusion of ilaprazole in treatment regimens for H. pylori infections, offering a compelling rationale for its clinical use. IMPORTANCE H. pylori infection remains a major global health issue, contributing to a wide range of gastric diseases. Despite current treatment regimens, rising antibiotic resistance limits their effectiveness, emphasizing the need for novel therapeutic approaches. This study highlights the promising in vitro antibacterial activity of ilaprazole against H. pylori, including drug-resistant strains. Ilaprazole not only exhibits direct antimicrobial effects but also enhances the efficacy of combination therapy, particularly in quadruple therapy regimens, which are recommended as first-line treatment. The findings demonstrate that ilaprazole, in combination with clarithromycin, shows synergistic effects, offering a potential solution to overcome antibiotic resistance challenges. Importantly, repeated exposure to ilaprazole did not induce resistance, a critical factor for its long-term use. These results provide compelling evidence for ilaprazole's inclusion in clinical treatment strategies, contributing to improved eradication rates and better patient outcomes in H. pylori management.

The treatment of sepsis caused by multidrug-resistant (MDR) Gram-negative bacterial infections remains challenging. With these pathogens exhibiting resistance to carbapenems and new generation cephalosporins, the traditional antibiotic polymyxin B (PMB) has reemerged as a critical treatment option. However, its severe neurotoxicity and nephrotoxicity greatly limit the clinical application. Therefore, we designed negatively charged high-density lipoprotein (HDL) mimicking nanodiscs as a PMB delivery system, which can simultaneously reduce toxicity and enhance drug efficacy. The negative charge prevented the PMB release in physiological conditions and binding to cell membranes, significantly reducing toxicity in mammalian cells and mice. Notably, nanodisc-PMB exhibits superior efficacy than free PMB in sepsis induced by carbapenem-resistant Acinetobacter baumannii (CRAB) strains. Nanodisc-PMB shows promise as a treatment for carbapenem-resistant Gram-negative bacterial sepsis, especially caused by Acinetobacter baumannii, and the nanodiscs could be repurposed for other toxic antibiotics as an innovative delivery system. STATEMENT OF SIGNIFICANCE: Multidrug-resistant Gram-negative bacteria, notably carbapenem-resistant Acinetobacter baumannii, currently pose a substantial challenge due to the scarcity of effective treatments, rendering Polymyxins a last-resort antibiotic option. However, their therapeutic application is significantly limited by severe neurotoxic and nephrotoxic side effects. Prevailing polymyxin delivery systems focus on either reducing toxicity or enhancing bioavailability yet fail to simultaneously achieve both. In this scenario, we have developed a distinctive HDL-mimicking nanodisc for polymyxin B, which not only significantly reduces toxicity but also improves efficacy against Gram-negative bacteria, especially in sepsis caused by CRAB. This research offers an innovative drug delivery system for polymyxin B. Such advancement could notably improve the therapeutic landscape and make a significant contribution to the arsenal against these notorious pathogens.

Background: The emergence and spread of vancomycin-resistant enterococci (VRE) have posed a significant challenge to clinical treatment, underscoring the need to develop novel strategies. As therapeutic options for VRE are limited, discovering vancomycin enhancer is a feasible way of combating VRE. Gambogic acid (GA) is a natural product derived from the resin of Garcinia hanburyi Hook.f. (Clusiaceae), which possesses antibacterial activity. Purpose: This study aimed to investigate the potential of GA as an adjuvant to restore the susceptibility of VRE to vancomycin. Methods: In vitro antibacterial and synergistic activities were evaluated against vancomycin-susceptible and resistant strains by the broth microdilution method for the Minimal Inhibitory Concentrations (MICs) determi- nation, and checkerboard assay and time-kill curve analysis for synergy evaluation. In vivo study was conducted on a mouse multi-organ infection model. The underlying antibacterial mechanism of GA was also explored. Results: GA showed a potent in vitro activity against all tested strains, with MICs ranging from 2 to 4 mu g/ml. The combination of GA and vancomycin exhibited a synergistic effect against 18 out of 23 tested VRE strains, with a median fractional inhibitory concentration index (FICI) of 0.254, and demonstrated a synergistic effect in the time-kill assay. The combination therapy exhibited a significant reduction in tissue bacterial load compared with either compound used alone. GA strongly binds to the ParE subunit of topoisomerase IV, a bacterial type II DNA topoisomerase, and suppresses its activity. Conclusions: The study suggests that GA has a significant antibacterial activity against enterococci, and sub-MIC concentrations of GA can restore the activity of vancomycin against VRE in vitro and in vivo . These findings indicate that GA has the potential to be a new antibacterial adjuvant to vancomycin in the treatment of infections caused by VRE.

The development of resistance against most of the available antibiotics has made Acinetobacter baumannii (A. baumannii) a pathogen of high risk. In this study, thirty novel berberine derivatives are rationally designed, synthesized, and evaluated for their synergistic antibacterial activities against A. baumannii. Among them, compound 2d shows the most potent synergetic effect to aztreonam against A. baumannii, including carbapenem-resistant and extended-spectrum β-lactamases-producing strains. Moreover, synergistic effects were observed for the combinations of 2d and different antibacterial used in clinical practices, indicating its potent broad-spectrum antibiotic-sensitizing effects against A. baumannii. The combination of 2d and aztreonam significantly improves the survival rates of G. mellonella larvae compared with aztreonam treatment alone. Mechanism studies indicate that 2d inhibits the drug efflux and iron acquisition of the bacteria by targeting the AdeB transporter protein, thus achieving a synergistic antimicrobial efficacy with different antibacterials. Therefore, berberine derivatives represent a new family of antimicrobial adjuvants against A. baumannii, with the advantage of dual-function antibacterial effect, and are worthy of further investigation.

Helicobacter pylori (H. pylori) is currently recognized as the primary carcinogenic pathogen associated with gastric tumorigenesis, and its high prevalence and resistance make it difficult to tackle. A graph neural network-based deep learning model, employing different training sets of 13,638 molecules for pre-training and fine-tuning, was aided in predicting and exploring novel molecules against H. pylori. A positively predicted novel berberine derivative 8 with 3,13-disubstituted alkene exhibited a potency against all tested drug-susceptible and resistant H. pylori strains with minimum inhibitory concentrations (MICs) of 0.25–0.5 μg/mL. Pharmacokinetic studies demonstrated an ideal gastric retention of 8, with the stomach concentration significantly higher than its MIC at 24 h post dose. Oral administration of 8 and omeprazole (OPZ) showed a comparable gastric bacterial reduction (2.2-log reduction) to the triple-therapy, namely OPZ + amoxicillin (AMX) + clarithromycin (CLA) without obvious disturbance on the intestinal flora. A combination of OPZ, AMX, CLA, and 8 could further decrease the bacteria load (2.8-log reduction). More importantly, the mono-therapy of 8 exhibited comparable eradication to both triple-therapy (OPZ + AMX + CLA) and quadruple-therapy (OPZ + AMX + CLA + bismuth citrate) groups. SecA and BamD, playing a major role in outer membrane protein (OMP) transport and assembling, were identified and verified as the direct targets of 8 by employing the chemoproteomics technique. In summary, by targeting the relatively conserved OMPs transport and assembling system, 8 has the potential to be developed as a novel anti-H. pylori candidate, especially for the eradication of drug-resistant strains.

The β-1–6-linked poly-N-acetylglucosamine (PNAG) polymer is a conserved surface polysaccharide produced by many bacteria, fungi, and protozoan (and even filarial) parasites. This wide-ranging expression makes PNAG an attractive target for vaccine development, as it potentially encompasses a broad range of microorganisms. Significant progress has been made in discovering important properties of the biology of PNAG expression in recent years. The molecular characterization and regulation of operons for the production of PNAG biosynthetic proteins and enzymes have been studied in many bacteria. In addition, the physiological function of PNAG has been further elucidated. PNAG-based vaccines and PNAG-targeting antibodies have shown great efficacy in preclinical research. Furthermore, clinical tests for both vaccines and antibodies have been carried out in humans and economically important animals, and the results are promising. Although it is not destined to be a smooth road, we are optimistic about new vaccines and immunotherapeutics targeting PNAG becoming validated and eventually licensed for clinical use against multiple infectious agents.

A series of new monobactam sulfonates is continuously synthesized and evaluated for their antimicrobial efficacies against Gram-negative bacteria. Compound 33a（IMBZ18G） is highly effective in vitro and in vivo against clinically intractable multi-drug-resistant（MDR） Gram-negative strains, with a highly druglike nature. The checkerboard assay reveals its significant synergistic effect with β-lactamase inhibitor avibactam, and the MIC values against MDR enterobacteria were reduced up to 4—512folds. X-ray co-crystal and chemoproteomic assays indicate that the anti-MDR bacteria effect of 33a results from the dual inhibition of the common PBP3 and some class A and C β-lactamases. Accordingly,preclinical studies of 33a alone and 33a-avibactam combination as potential innovative candidates are actively going on, in the treatment of β-lactamase-producing MDR Gram-negative bacterial infections.

Pseudomonas aeruginosa is one of the multipledrug-resistant (MDR) Gram-negative pathogens with few drugs available for treatment. Antibiotic adjuvant approach provides an alternative and complementary strategy. In this study, the stereo-structure-activity relationship of monobactams against MDR Gram-negative organisms was extended. Meanwhile, a series of novel peptidemimetic derivatives as antibiotic adjuvants was synthesized and evaluated for their synergistic effects with aztreonam (AZT) against P. aeruginosa, using dipeptide PAβN as the lead. Among the analogues, compound 22j showed a significant synergistic effect against MDR P. aeruginosa in vitro and in vivo, presumably through the mechanism of affecting the permeability of outer membrane. Thus, we identified 22j as a novel peptidemimetic lead compound to potentiate the activity of AZT against MDR P. aeruginosa, which is worthy of further development as antibiotic adjuvant candidates.

The emergence and transmission of VRE pose a significant medical and public health challenge. CEL, well-known for a wide range of biological activities, has not previously been investigated for its synergistic effect with vancomycin against VRE. ABSTRACT Enterococci can cause various infectious diseases, including urinary tract infection, wound infection, and life-threatening endocarditis and meningitis. The emergence and transmission of vancomycin-resistant enterococci (VRE) have presented a challenge to clinical treatment. There is an urgent need to develop new strategies to fight against this pathogen. This study investigated the antibacterial and anti-biofilm activity of celastrol (CEL), a natural product originating from Tripterygium wilfordii Hook F, against enterococci, and its adjuvant capacity of restoring the susceptibility of VRE to vancomycin in vitro and in vivo. CEL inhibited all enterococcus strains tested, with MICs ranging from 0.5 to 4 μg/mL. More than 50% of biofilm was eliminated by CEL at 16 μg/mL after 24 h of exposure. The combination of CEL and vancomycin showed a synergistic effect against all 23 strains tested in checkerboard assays. The combination of sub-MIC levels of CEL and vancomycin showed a synergistic effect in a time-kill assay and exhibited significant protective efficacy in Galleria mellonella larval infection model compared with either drug used alone. The underlying mechanisms of CEL were explored by conducting biomolecular binding interactions and an enzyme inhibition assay of CEL on bacterial cell-division protein FtsZ. CEL presented strong binding and suppression ability to FtsZ, with Kd and IC50 values of 2.454 μM and 1.04 ± 0.17 μg/mL, respectively. CEL exhibits a significant antibacterial and synergic activity against VRE in vitro and in vivo and has the potential to be a new antibacterial agent or adjuvant to vancomycin as a therapeutic option in combating VRE. IMPORTANCE The emergence and transmission of VRE pose a significant medical and public health challenge. CEL, well-known for a wide range of biological activities, has not previously been investigated for its synergistic effect with vancomycin against VRE. In the present study, CEL exhibited antibacterial activity against enterococci, including VRE strains, and restored the activity of vancomycin against VRE in vitro and in vivo. Hence, CEL has the potential to be a new antibacterial adjuvant to vancomycin and could provide a promising therapeutic option in combating VRE.

The ability to maintain redox homeostasis is critical for Mycobacterium tuberculosis (Mtb) to survive the redox stress of the host. There are many antioxidant systems in Mtb to ensure its normal replication and survival in the host, and cysteine thiols are one of them. S-sulfenylation is one of the reversible modifications of cysteine thiols to resist oxidative stress. In the study, we investigated the total cysteine thiols modification and S-sulfenylation modification of Mtb proteome under the oxidative stress provided by hydrogen peroxide. To determine and quantify the S-sulfenylation modified proteins, high specific IodoTMT6plex reagents and high resolution mass spectrometry were used to label and quantify the peptides and proteins modified. There are significant differences for the total cysteine modification levels of 279 proteins and S-sulfenylation modification levels of 297 proteins under hydrogen peroxide stress. Functional enrichment analysis indicated that these cysteine-modified proteins were involved in the oxidation-reduction process, fatty acid biosynthetic process, stress response, protein repair, cell wall, etc. In conclusion, our study provides a view of cysteine modifications of the Mtb proteome under oxidative stress, revealing a series of proteins that may play a role in maintaining redox homeostasis. IMPORTANCE With the continuous spread of drug-resistant tuberculosis, there is an urgent need for new antituberculosis drugs with new mechanisms. The ability of Mtb to resist oxidative stress is extremely important for maintaining redox homeostasis and survival in the host. The reversible modifications of cysteine residues have a dual role of protection from irreversible damage to protein functions and regulation, which plays an important role in the redox homeostasis system. Thus, to discover cysteine modification changes in the proteome level under oxidative stress is quintessential to elucidate its antioxidant mechanism. Our results provided a list of proteins involved in the antioxidant process that potentially could be considered targets for drug discovery and vaccine development. Furthermore, it is the first study to determine and quantify the S-sulfenylation-modified proteins in Mtb, which provided better insight into the Mtb response to the host oxidative defense and enable a deeper understanding of Mtb survival strategies.

Aim To investigate the effect of p-hydroxybenzaldehyde （HD） on intestinal fibrosis in mice based on mouse intestinal fibrosis model and in vitro EMT model,and to explore the underlying mechanism.Methods HE staining,Masson staining,immunohistochemistry,q PCR,Western blot and other experimental methods were used to verify the effect of HD on intestinal fibrosis in mice and the potential mechanism.Results In vivo experiments showed that compared with the normal group,the DSS-induced intestinal fibrosis model group had shortened colon,increased colon histopathological score,increased collagen volume fraction,and significantly increased collagenⅠexpression.After treatment with 4,10,and 25 mg·kg -1 HD,compared with the model group,the colon shortening of mice was alleviated,and the histopathological score,collagen volume fraction and the expression of collagenⅠdecreased in a dose-dependent manner.Compared with the model group,in colon tissue and IEC-6 cells,HD could dose-dependently inhibit the protein and mRNA level expression of EMT-related factors such as α-SMA,Vimentin,N-cadherin,and increase the expression of E-cadherin.Conclusion HD can improve experimental intestinal fibrosis by inhibiting EMT.

溃疡性结肠炎(Ulcerative colitis,UC)是一种长期、非特异性的炎症性疾病,其病因、发病机理尚未完全阐明,病变范围主要涉及到结直肠,已被世界卫生组织列入现代疑难病症之一.萜类是一种广泛存在于各种植物中的化合物,具有抗菌、抗氧化、抗肿瘤、调节免疫等多种生理功能.本文通过对常见萜类化合物抗溃疡性结肠炎的机制进行综述,以期为萜类治疗溃疡性结肠炎的应用及探讨其作用机理提供理论依据.

Antivirulence strategy has been developed as a nontraditional therapy which would engender a lower evolutionary pressure toward the development of antimicrobial resistance. However, the majority of the antivirulence agents currently in development could not meet clinical needs due to their narrow antibacterial spectrum and limited indications. Therefore, our main purpose is to develop broad-spectrum antivirulence agents that could target on both Gram-positive and Gram-negative pathogens. We discovered ML364, a novel scaffold compound, could inhibit the productions of both pyocyanin of Pseudomonas aeruginosa and staphyloxanthin of Staphylococcus aureus. Further transcriptome sequencing and enrichment analysis showed that the quorum sensing (QS) system of pathogens was mainly disrupted by ML364 treatment. To date, autoinducer-2 (AI-2) of the QS system is the only non-species-specific signaling molecule that responsible for the cross-talk between Gram-negative and Gram-positive species. And further investigation showed that ML364 treatment could significantly inhibit the sensing of AI-2 or its nonborated form DPD signaling in Vibrio campbellii MM32 and attenuate the biofilm formation across multi-species pathogens including Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae and Staphylococcus aureus. The results of molecular docking and MM/GBSA free energy prediction showed that ML364 might have higher affinity with the receptors of DPD/AI-2, when compared with DPD molecule. Finally, the in vivo study showed that ML364 could significantly improve the survival rates of systemically infected mice and attenuate bacterial loads in the organs of mice. Overall, ML364 might interfere with AI-2 quorum sensing system to exert broad-spectrum antivirulence effect both in vitro and in vivo.

An accurate and reliable susceptibility testing method for polymyxins is urgently needed not only for the clinical laboratory but also for new polymyxin-like lipopeptide development. Reference broth microdilution (rBMD), which was the recommended method by CLSI-EUCAST in clinics, has been proven not to be ideal, while the agar dilution (AD) method that was widely used in new antibiotics discovery has been neglected. In the present study, the AD method was compared with rBMD and broth macrodilution (BMAD) in susceptibility testing of polymyxin B and colistin against >200 Gram-negative isolates. AD showed strong agreement with BMAD for colistin (except for Klebsiella aerogenes and Pseudomonas aeruginosa); however, its performance was poor for polymyxin B or compared to rBMD. MICs of AD method were not affected when different types of Petri dishes were used, while glass-bottom microtiter plates could lower the MIC of polymyxins 2–8 times compared to tissue-culture-treated polystyrene plates when using rBMD, which demonstrated that tissue-culture-treated plates were not suitable. It was then validated with non-tissue-culture-treated plates. The culture volume was another influencing factor of accuracy for rBMD, and 200 μL seemed to be the most suitable volume for MIC detection of polymyxins. Additionally, no lack of growth phenomenon (skipped well) was observed for AD when it frequently occurred for both BMAD and rBMD. As for strains carrying mcr-1 gene, 100% of AD results were in essential agreement (EA) and categorical agreement (CA) with both rBMD and BMAD. Overall, rBMD is convenient and widely accepted for susceptibility testing of polymyxins. Although it may be too early to say that AD is superior compared to rBMD and BMAD, it did show some advantages in repeatability and anti-interference ability.

The shortage of new antibiotics makes infections caused by gram-negative (G(-)) bacteria a significant clinical problem. The key enzymes involved in folate biosynthesis represent important targets for drug discovery, and new antifolates with novel mechanisms are urgently needed. By targeting to dihydrofolate reductase (DHFR), a series of 1,3-diamino-7H-pyrrol[3,2-f]quinazoline (PQZ) compounds were designed, and exhibited potent antibacterial activities in vitro, especially against multi-drug resistant G(-) strains. Multiple experiments indicated that PQZ compounds contain a different molecular mechanism against the typical DHFR inhibitor, trimethoprim (TMP), and the thymidylate synthase (TS) was identified as another potential but a relatively weak target. A significant synergism between the representative compound, OYYF-175, and sulfamethoxazole (SMZ) was observed with a strong cumulative and significantly bactericidal effect at extremely low concentrations (2 mu g/mL for SMZ and 0.03 pg/mL for OYYF-175), which could be resulted from the simultaneous inhibition of dihydropteroate synthase (DHPS), DHFR and TS. PQZ compounds exhibited therapeutic effects in a mouse model of intraperitoneal infections caused by Escherichia coli (E. coli). The co-crystal structure of OYYF-175-DHFR was solved and the detailed interactions were provided. The inhibitors reported represent innovative chemical structures with novel molecular mechanism of action, which will benefit the generation of new, efficacious bactericidal compounds. (C) 2021 Elsevier Masson SAS. All rights reserved.

Aims:mcr-1 and blaNDM-1 co-harboring isolates have been reported, usually reside on different plasmids, suggesting co-transfer possibility of the two genes from separate donors to the same recipient strain. This study aims at screening and characterization of mcr-1 carrying Enterobacteriaceae in Northern China, and studying the transfer ability of mcr-1 alone and in company with blaNDM-1 from a second donor. Results: Three Escherichia coli strains and one Klebsiella pneumoniae strain carrying mcr-1 gene were screened out from 1992 isolates in our study. Co-existence of multiple resistance genes was found in the mcr-1-carrying strains, but none of them carried blaNDM-1. One E. coli demonstrated an single nucleotide polymorphism (SNP) (A-G) at -10 region of mcr-1, and one E. coli showed 2 SNPs (G-T and G-A) in the Shine-Dalgarno sequence-like region of mcr-1. The mcr-1 gene was located on plasmids of about 33-276 kb, and capable of transferring alone in three out of four mcr-1-positive isolates by conjugation. Co-transfer ability analysis demonstrated that mcr-1 from E. coli 13-68, which could not be transferred alone to E. coli C600, was successfully transferred in company with blaNDM-1 from K. pneumoniae ATCC BAA-2146. Conclusions:mcr-1 showed low incidence in our Enterobacteriaceae isolates. Co-transfer ability of mcr-1 and blaNDM-1 from separate donors provides direct evidence for the emergence of the mcr-1 and blaNDM-1 co-harboring isolates.

Background: Infections caused by drug-resistant Staphylococcus aureus , especially vancomycin-intermediate Staphylococcus aureus (VISA), leave clinicians with limited therapeutic options for treatment. Persister cells is a leading cause of recalcitrant infection and antibiotic treatment failure, and there is no drug in clinical use that specifically targets persister cells currently. Here, we report a promising combination therapy of sodium new houttuyfonate (SNH) and berberine chloride (BBR) which is able to eradicate both growing and persistent drug-resistant Staphylococcus aureus. Results: The susceptibility test showed SNH exhibited anti-MRSA activity with MIC 90 at 64 μg/mL, while BBR showed weak anti-MRSA activity with MIC 90 at 512 μg/mL. MICs of BBR in combination with 1/2 MIC SNH decreased by 4 to 64 folds compared with MICs of BBR alone. The results of time-killing assays revealed that the combined use of sub-MIC SNH and BBR offered an in vitro synergistic action against growing MRSA (including pathogenic MRSA) and VISA strains. More importantly, the combination of SNH and BBR was able to eradicate VISA Mu50 and pathogenic MRSA persister cells. The synergistic effect is likely related to the interruption of the cell membrane caused by SNH, which is confirmed by scanning electron microscope and membrane potential and permeability analysis. Conclusions: Our study provide a promising clinical curative strategy for combating drug-resistant S. aureus infections, especially for recalcitrant infections caused by persister cells.

(E)-N,N-dimethyl-4-oxo-4-(4-(pyridin-4-yl)phenyl)but-2-enamide hydrochloride (IMB-YH-4py5-2H) is a novel Protein Kinase B (PknB) inhibitor with potent activity against Mycobacterium tuberculosis strains. In the present study, a sensitive and specific liquid chromatography/tandem mass spectrometry (LC-MS/MS) method was developed and validated to determine IMB-YH-4py5-2H in rat plasma. Sample pretreatment was achieved by liquid-liquid extraction with ethyl acetate, and separation was performed on an XTerra MS C18 column (2.1×50 mm, 3.5 μm) with gradient elution (methanol and 0.1% formic acid) at a flow rate of 0.3 mL/min. Detection was performed in multiple reaction monitoring (MRM) mode. Linear calibration curves were obtained over a concentration range of 1-100 ng/mL. The intra-day and inter-day precisions were lower than 8.46%, and the accuracies ranged from -8.71% to 12.36% at all quality control levels. The extraction recoveries were approximately 70%, and the matrix effects were negligible. All quality control samples were stable under different storage conditions. The validated method was successfully applied to a preclinical pharmacokinetic study in Sprague-Dawley rats. IMB-YH-4py5-2H demonstrated improved pharmacokinetic properties (higher exposure level) compared with its leading compound. IMB-YH-4py5-2H was also distributed throughout the lung pronouncedly, especially inside alveolar macrophages, indicating its effectiveness against lower respiratory infections.