Efficacy Of Antibiotics Research Articles

Efficacy and safety of antibiotics for treatment of leptospirosis: a systematic review and network meta-analysis

BackgroundLeptospirosis, an important zoonotic bacterial disease, commonly affects resource-poor populations and results in significant morbidity and mortality worldwide. The value of antibiotics in leptospirosis remains unclear, as evidenced by the conflicting opinions published.MethodsWe conducted a search in the PubMed, Web of Science, and Cochrane Library databases for studies. These studies included clinical trials and retrospective studies that evaluated the efficacy or safety of antibiotics for leptospirosis treatment. The primary outcomes assessed were defervescence time, mortality rate, and hospital stays. Subgroup analyses were performed based on whether there were cases involving children and whether there were cases of severe jaundice. Safety was defined as the prevalence of adverse events associated with the use of antibiotics. p scores were utilized to rank the efficacy of the antibiotics.ResultsThere are included 9 randomized controlled trials (RCTs), 1 control trial (CT), and 3 retrospective studies (RS) involving 920 patients and 8 antibiotics. Six antibiotics resulted in significantly shorter defervescence times compared to the control, namely cefotaxime (MD, − 1.88; 95% CI = − 2.60 to − 1.15), azithromycin (MD, − 1.74; 95% CI = − 2.52 to − 0.95), doxycycline (MD, − 1.53; 95% CI = − 2.05 to − 1.00), ceftriaxone (MD, − 1.22; 95% CI = − 1.89 to − 0.55), penicillin (MD, − 1.22; 95% CI = − 1.80 to − 0.64), and penicillin or ampicillin (MD, − 0.08; 95% CI = − 1.01 to − 0.59). The antibiotics were not effective in reducing the mortality and hospital stays. Common adverse reactions to antibiotics included Jarisch–Herxheimer reaction, rash, headache, and digestive reactions (nausea, vomiting, diarrhea, abdominal pain, and others).ConclusionsFindings recommend that leptospirosis patients be treated with antibiotics, which significantly reduced the leptospirosis defervescence time. Cephalosporins, doxycycline, and penicillin are suggested, and azithromycin may be a suitable alternative for drug-resistant cases.Systematic review registrationPROSPERO CRD42022354938.

Inhibition Zones: A Window into Antibiotic Resistance

Antibiotic resistance poses a significant global health threat, necessitating innovative approaches to combat it effectively. This survey paper presents a comprehensive overview of the challenges associated with antibiotic resistance and the critical role of antibiotic susceptibility testing (AST) in guiding treatment decisions. We propose leveraging advancements in image processing and machine learning to develop an automated algorithm for measuring the Zone of Inhibition in AST, addressing the limitations of manual methods. Additionally, we discuss the potential of mobile applications and expert systems to simplify AST, particularly in resource-limited settings. Standardization efforts and future trends in AST are also explored to enhance testing strategies and preserve antibiotic efficacy. Through this research, we aim to contribute to the ongoing efforts to mitigate antibiotic resistance and improve patient care worldwide.

Antibiotics efficacy in clinical and microbiological cure of uncomplicated urinary tract infection: a systematic review and network meta-analysis.

Fosfomycin has been used more frequently in managing uncomplicated urinary tract infections (UTIs) due to decreased compliance and increased multidrug-resistant bacteria. The aim of this network meta-analysis was to assess the efficacy of Fosfomycin compared to Nitrofurantoin, Trimethoprim-Sulfamethoxazole (TMP-SMX), and Ciprofloxacin in terms of clinical and microbiological cure alongside with other measurements. We searched MEDLINE, Embase, and Cochrane Central Register of Controlled Trials (CENTRAL). We included randomized control trials (RCTs) with uncomplicated UTI patients who received Fosfomycin, Nitrofurantoin, TMP-SMX, or Ciprofloxacin and reported the clinical or microbiological cure. We used Cochrane Risk of Bias Assessment Tool to assess the included studies' quality. R-software was used for all statistical analysis. We ranked all antibiotics using the netrank function which yielded P scores. Frequentist network meta-analysis was used to assess the efficacy of all outcomes. We included 13 RCTs with a total number of 3856 patients that showed Fosfomycin ranked the highest among the other antibiotics with respect to clinical cure (P-score = 0.99) and microbiological cure (P-score = 0.99) while Ciprofloxacin ranked the lowest (P-score = 0.11 and 0.02, respectively). Moreover, Ciprofloxacin yielded the highest relapse rate (P-score = 1), whereas TMP-SMX had the lowest relapse rate (P-score = 0.07). As for the adverse events, Ciprofloxacin demonstrated the highest adverse events as opposed to Fosfomycin (P-score = 0.98 and 0.05, respectively). The network meta-analysis demonstrated that Fosfomycin is the most effective antibiotic in treating uncomplicated UTIs with respect to clinical cure, microbiological cure, and adverse events profile.

Comprehensive assessment of dental implant procedures: a comparative study on different antibiotic prophylaxis regimens

Relevance. The administration of antibiotics in implantology is indicated to prevent suppurative inflammation conditions. Two regimens are commonly used: a single preoperative dose or prolonged postoperative antibiotic administration. Due to ethical constraints, certain parameters of antibiotic efficacy cannot be directly evaluated within clinical trials. These include the status of the implant-mandibular segment microbiome and the histological parameters of the tissue's inflammatory response at the implant site.Materials and methods. This study employed a miniature pig model comprising 10 males. The cohort was equally divided into two groups of five animals each. Group 1 received a single preoperative dose of amoxicillin/clavulanic acid 2 ml per 20 kg body weight. Group 2 received the same initial dose prior to implantation, followed by a daily postoperative dose of amoxicillin/clavulanic acid at 1 ml per 20 kg body weight for five days. Each animal received six dental implants. An implant site microbiological test was performed pre-surgery, on Day 1, 3, 7 and 14 post-surgery. Core needle biopsies for histological examination of the tissues were performed on the same postoperative days.Results. Microbiological testing revealed that Group 2 exhibited lower levels of Streptococcus spp. on Day 3 (p = 0.04) and Porphyromonas spp. on Day 7 (p = 0.04). Group 1 demonstrated reduced levels of Fusobacterium spp. on Day 1 (p = 0.02) and Porphyromonas spp. both pre-surgery (p = 0.04) and on Day 1 (p = 0.012). Comparative analysis of histological assays from the implant sites indicated identical tissue inflammatory responses, regardless of the antibiotic prophylaxis regimen.Conclusion. Both the single-dose and the prolonged antibiotic prophylaxis regimens, using amoxicillin/clavulanic acid for dental implantation, demonstrated similar histological patterns of tissue inflammation at the implant site, along with comparable microbiota profiles within the implant site. The oral mucosa exhibited an increased population of Staphylococcus spp. and Streptococcus spp., which might contribute to the development of resistant strains, as well as Candida spp., potentially increasing the risk of candidiasis infection onset.

A review of the mechanisms that confer antibiotic resistance in pathotypes of E. coli.

The dissemination of antibiotic resistance in Escherichia coli poses a significant threat to public health worldwide. This review provides a comprehensive update on the diverse mechanisms employed by E. coli in developing resistance to antibiotics. We primarily focus on pathotypes of E. coli (e.g., uropathogenic E. coli) and investigate the genetic determinants and molecular pathways that confer resistance, shedding light on both well-characterized and recently discovered mechanisms. The most prevalent mechanism continues to be the acquisition of resistance genes through horizontal gene transfer, facilitated by mobile genetic elements such as plasmids and transposons. We discuss the role of extended-spectrum β-lactamases (ESBLs) and carbapenemases in conferring resistance to β-lactam antibiotics, which remain vital in clinical practice. The review covers the key resistant mechanisms, including: 1) Efflux pumps and porin mutations that mediate resistance to a broad spectrum of antibiotics, including fluoroquinolones and aminoglycosides; 2) adaptive strategies employed by E. coli, including biofilm formation, persister cell formation, and the activation of stress response systems, to withstand antibiotic pressure; and 3) the role of regulatory systems in coordinating resistance mechanisms, providing insights into potential targets for therapeutic interventions. Understanding the intricate network of antibiotic resistance mechanisms in E. coli is crucial for the development of effective strategies to combat this growing public health crisis. By clarifying these mechanisms, we aim to pave the way for the design of innovative therapeutic approaches and the implementation of prudent antibiotic stewardship practices to preserve the efficacy of current antibiotics and ensure a sustainable future for healthcare.

Oxidized glutathione reverts carbapenem resistance in blaNDM-1-carrying Escherichia coli.

The emergence of drug-resistant Enterobacteriaceae carrying plasmid-mediated β-lactamase genes has become a significant threat to public health. Organisms in the Enterobacteriaceae family containing New Delhi metallo-β-lactamase‑1 (NDM-1) and its variants, which are capable of hydrolyzing nearly all β-lactam antibacterial agents, including carbapenems, are referred to as superbugs and distributed worldwide. Despite efforts over the past decade, the discovery of an NDM-1 inhibitor that can reach the clinic remains a challenge. Here, we identified oxidized glutathione (GSSG) as a metabolic biomarker for blaNDM-1 using a non-targeted metabolomics approach and demonstrated that GSSG supplementation could restore carbapenem susceptibility in Escherichia coli carrying blaNDM-1 in vitro and in vivo. We showed that exogenous GSSG promotes the bactericidal effects of carbapenems by interfering with intracellular redox homeostasis and inhibiting the expression of NDM-1 in drug-resistant E. coli. This study establishes a metabolomics-based strategy to potentiate metabolism-dependent antibiotic efficacy for the treatment of antibiotic-resistant bacteria.

Enhancing Antibiotic Efficacy in Regenerative Endodontics by Improving Biofilm Susceptibility

IntroductionVarious strategies have been researched to enhance the susceptibility of biofilms, given their tolerance to antibiotics. This study evaluated the effect of the anti-microbial peptide nisin in association with antibiotics used in regenerative endodontics, exploring different treatment times and biofilm growth conditions. MethodsA mixture of 10 bacterial species was cultivated on dentin specimens anaerobically for 21 days. Biofilms were treated with 1 mL of high-purity nisin Z (nisin ZP, 200 μg/mL) and a triple antibiotic mixture (TAP: ciprofloxacin + metronidazole + minocycline, 5 mg/mL), alone or in combination. The effectiveness of antimicrobial agents was assessed after 1 and 7 days. During the 7-day period, biofilms were treated under 2 conditions: a single dose in a nutrient-depleted setting (ie, no replenishment of growth medium) and multiple doses in a nutrient-rich environment (ie, renewal of medium and antimicrobial agents every 48 h). After treatments, biofilm cells were dispersed, and total colony-forming units were counted. ResultsAfter 1 d-treatment, nisin ZP + TAP resulted in 2-log cell reduction compared to TAP alone (P < .05). After 7 d-treatment with a single dose, nisin ZP + TAP and TAP reduced bacteria to nonculturable levels (P < .05), whereas repeated antimicrobial doses did not eliminate bacteria in a nutrient-rich environment. No bacterial reduction was observed with nisin ZP alone in any treatment time. ConclusionsThe additional use of nisin improved the TAP activity only after a short exposure time. Longer exposure to TAP or nisin + TAP in a nutrient-deprived environment effectively eliminated biofilms.

Effect of antibiotics efficacy in patients with sepsis and septic shock presenting in the emergency department: A literature review

Effect of antibiotics efficacy in patients with sepsis and septic shock presenting in the emergency department: A literature review

The functional small RNA interactome reveals targets for the vancomycin-responsive sRNA RsaOI in vancomycin-tolerant Staphylococcus aureus.

The emergence of multidrug-resistant Staphylococcus aureus (MRSA) is a major public health concern. Current treatment is dependent on the efficacy of last-line antibiotics like vancomycin. The most common cause of vancomycin treatment failure is strains with intermediate resistance or tolerance that arise through the acqusition of a diverse repertoire of point mutations. These strains have been shown to altered small RNA (sRNA) expression in response to antibiotic treatment. Here, we have used a technique termed RNase III-CLASH to capture sRNA interactions with their target mRNAs. To understand the function of these interactions, we have looked at RNA and protein abundance for mRNAs targeted by sRNAs. Messenger RNA and protein levels are generally well correlated and we use deviations from this correlation to infer post-transcriptional regulation and the function of individual sRNA-mRNA interactions. Using this approach we identify mRNA targets of the vancomycin-induced sRNA, RsaOI, that are repressed at the translational level. We find that RsaOI represses the cell wall autolysis Atl and carbon transporter HPr suggestion a link between vancomycin treatment and suppression of cell wall turnover and carbon metabolism.

Structural and kinetic analysis of the monofunctional Staphylococcus aureus PBP1

Staphylococcus aureus, an ESKAPE pathogen, is a major clinical concern due to its pathogenicity and manifold antimicrobial resistance mechanisms. The commonly used β-lactam antibiotics target bacterial penicillin-binding proteins (PBPs) and inhibit crosslinking of peptidoglycan strands that comprise the bacterial cell wall mesh, initiating a cascade of effects leading to bacterial cell death. S. aureus PBP1 is involved in synthesis of the bacterial cell wall during division and its presence is essential for survival of both antibiotic susceptible and resistant S. aureus strains. Here, we present X-ray crystallographic data for S. aureus PBP1 in its apo form as well as acyl-enzyme structures with distinct classes of β-lactam antibiotics representing the penicillins, carbapenems, and cephalosporins, respectively: oxacillin, ertapenem and cephalexin. Our structural data suggest that the PBP1 active site is readily accessible for substrate, with little conformational change in key structural elements required for its covalent acylation of β-lactam inhibitors. Stopped-flow kinetic analysis and gel-based competition assays support the structural observations, with even the weakest performing β-lactams still having comparatively high acylation rates and affinities for PBP1. Our structural and kinetic analysis sheds insight into the ligand–PBP interactions that drive antibiotic efficacy against these historically useful antimicrobial targets and expands on current knowledge for future drug design and treatment of S. aureus infections.

Synthesis, Stereochemical Resolution, and Analogue Synthesis of Variabiline, an Aporphine Alkaloid That Sensitizes Acinetobacter baumannii and Klebsiella pneumoniae to Colistin.

Increasing antimicrobial resistance, coupled with the absence of new antibiotics, has led physicians to rely on colistin, a polymyxin with known nephrotoxicity, as the antibiotic of last resort for the treatment of infections caused by Gram-negative bacteria. One approach to increasing antibiotic efficacy and thereby reducing dosage is the use of small-molecule potentiators that augment antibiotic activity. We recently identified the aporphine alkaloid (±)-variabiline, which lowers the minimum inhibitory concentration of colistin in Acinetobacter baumannii and Klebsiella pneumoniae. Herein, we report the first total synthesis of (±)-variabiline to confirm structure and activity, the resolution, and evaluation of both enantiomers as colistin potentiators, and a structure-activity relationship study that identifies more potent variabiline derivatives. Preliminary mechanistic studies indicate that (±)-variabiline and its derivatives potentiate colistin by targeting the Gram-negative outer membrane.

Murepavadin promotes the killing efficacies of aminoglycoside antibiotics against Pseudomonas aeruginosa by enhancing membrane potential.

Murepavadin is a peptidomimetic that specifically targets the lipopolysaccharide transport protein LptD of Pseudomonas aeruginosa. Here, we found that murepavadin enhances the bactericidal efficacies of tobramycin and amikacin. We further demonstrated that murepavadin enhances bacterial respiration activity and subsequent membrane potential, which promotes intracellular uptake of aminoglycoside antibiotics. In addition, the murepavadin-amikacin combination displayed a synergistic bactericidal effect in a murine pneumonia model.

Free Radical Scavenging, Anti-inflammatory and Antibacterial Activity of Acorus calamus Leaves Extract Against Pseudomonas aeruginosa and Staphylococcus aureus.

Background Herbal medicine, or phytotherapy, has been used for centuries in traditional healing practices to harness the therapeutic properties of different plant-derived elements. Acorus calamus, a perennial herbaceous plant, has significant historical importance in traditional medicine, specifically in Ayurveda, where it is referred to as "Vacha."This study investigates the antioxidant, anti-inflammatory, and antimicrobial characteristics of the A. calamus dimethyl sulfoxide (DMSO) extract. The objectives of the research are to provide valuable knowledge about the preparation of A. calamus DMSO extract and to explore its potential anti-inflammatory, antioxidant, and antimicrobial effects. Materials and methods The A. calamus DMSO extract was derived from leaves, and its antioxidant activity was evaluated through the use of the 2,2-diphenyl-1-picryl hydrazyl (DPPH) assay, hydroxyl radical scavenging assay (H2O2 assay), and ferric reducing antioxidant power (FRAP) assay. The anti-inflammatory activity was assessed using the Bovine serum albumin (BSA) denaturation assay, egg albumin (EA) denaturation assay, and membrane stabilization assays. The antimicrobial activity was analyzed using the agar well diffusion technique and the time-kill curve assay. Results In DPPH and H2O2 tests, the DMSO extract of A. calamus showed significant antioxidant activity, near that ofstandard ascorbic acid. The FRAP assay demonstrated a correlation between the dose and the activity of reducing ferric ions. The A. calamusDMSO extract exhibited significant anti-inflammatory properties in BSA and EA denaturation assays, similar to the standard diclofenac sodium. The anti-inflammatory potential of the A. calamus DMSO extract was further confirmed through the membrane stabilization assay. The DMSO extract of A. calamus exhibited a significant inhibition zone against the pathogens Streptococcus mutans and Pseudomonas aeruginosa during the antimicrobial evaluation, surpassing the efficacy of the standard antibiotic. The time-kill curve assay validated the antibacterial efficacy, which was dependent on the concentration. Conclusion The A. calamus DMSO extract exhibited promising antioxidant, anti-inflammatory, and antimicrobial properties, supporting its traditional use in alternative medicine. The findings suggest its potential as a natural resource of compounds with bioactive properties for use in pharmaceutical and nutraceutical applications.

Investigating the synergic effects of the extracts of Camellia sinensis, Rosmarinus officinalis and Thymus with ampicillin against resistant Pseudomonas aeruginosa species

Introduction: The most common bacterium linked to the hospital and pneumonia-related infections is Pseudomonas aeroginosa, a known opportunistic pathogen. High mortality rates are brought on by this bacterium in hospitalized patients, immunocompromised individuals, and cystic fibrosis patients. The formation of biofilm structures has also made it more challenging to treat patients. Due to the severe side effects of the antibiotics, the lack of efficacy due to resistance, and the well-documented antibacterial effects of traditional plants, this study investigated the antibacterial properties of the combination of thyme, rosemary, and green tea. Therefore, the main purpose of the current study was to examine the antibacterial and anti-biofilm effects of the extracts of these three plants. Method: Pseudomonas arginosa strains were obtained from patients at Ghaem Hospital, Mashhad, Iran. The efficacy of various antibiotics on different strains was studied, and bacterial strains were classified into sensitive, semi-sensitive, and resistant. The minimum inhibitory concentration (MIC) of the combination of the three extracts, as well as the antibiotic of choice, was determined. The effect of the extract on the biofilm formation was also investigated. Results: The results indicated that the ternary composition has significant antibacterial and anti-biofilm effects; also, the combination of these three extracts has shown significant synergistic properties with each other. Further, the extracts inhibited the formation and growth of the biofilm. Conclusion: Results of this study indicated that the optimum combination of the three extracts possessed a remarkable antibacterial and anti-biofilm activity. Further, we have shown the synergistic antibacterial activity of the three extracts improved in the presence of the antibiotic of choice, resulting in a decrease in the MIC value of the antibiotic.

Antimicrobial resistance: Impacts, challenges, and future prospects

Antimicrobial resistance (AMR) is a critical global health issue driven by antibiotic misuse and overuse in various sectors, leading to the emergence of resistant microorganisms. The history of AMR dates back to the discovery of penicillin, with the rise of multidrug-resistant pathogens posing significant challenges to healthcare systems worldwide. The misuse of antibiotics in human and animal health, as well as in agriculture, contributes to the spread of resistance genes, creating a "Silent Pandemic" that could surpass other causes of mortality by 2050. AMR affects both humans and animals, with resistant pathogens posing challenges in treating infections. Various mechanisms, such as enzymatic modification and biofilm formation, enable microbes to withstand the effects of antibiotics. The lack of effective antibiotics threatens routine medical procedures and could lead to millions of deaths annually if left unchecked. The economic impact of AMR is substantial, with projected losses in the trillions of dollars and significant financial burdens on healthcare systems and agriculture. Artificial intelligence is being explored as a tool to combat AMR by improving diagnostics and treatment strategies, although challenges such as data quality and algorithmic biases exist. To address AMR effectively, a One Health approach that considers human, animal, and environmental factors is crucial. This includes enhancing surveillance systems, promoting stewardship programs, and investing in research and development for new antimicrobial options. Public awareness, education, and international collaboration are essential for combating AMR and preserving the efficacy of antibiotics for future generations.

Antibiotic resistance in livestock, environment and humans: One Health perspective.

Antibiotic resistance (AR) is a complex, multifaceted global health issue that poses a serious threat to livestock, humans, and the surrounding environment. It entails several elements and numerous potential transmission routes and vehicles that contribute to its development and spread, making it a challenging issue to address. AR is regarded as an One Health issue, as it has been found that livestock, human, and environmental components, all three domains are interconnected, opening up channels for transmission of antibiotic resistant bacteria (ARB). AR has turned out to be a critical problem mainly because of the overuse and misuse of antibiotics, with the anticipation of 10 million annual AR-associated deaths by 2050. The fact that infectious diseases induced by ARB are no longer treatable with antibiotics foreshadows an uncertain future in the context of health care. Hence, the One Health approach should be emphasized to reduce the impact of AR on livestock, humans, and the environment, ensuring the longevity of the efficacy of both current and prospective antibiotics.

Thermodynamic Modeling of Solubility of Some Antibiotics in Supercritical Carbon Dioxide Using Simplified Equation of State Approach

Antibiotics are playing crucial role in the treatment of humans since the last few centuries. Their usage has several benefits along with side effects. The efficacy of antibiotics for the treatment of ailments may be retained by controlling the drug dosage. This may be achieved with supercritical fluid technology (SFT). The antibiotic drug solubility in supercritical carbon dioxide (scCO2) is available only at specific temperature and pressure conditions, for effective utilization of SFT, solubility at various conditions are required. Equation of state (EoS) method is used for solubility data modeling and it requires critical properties of the solute, molar volume of the solute and sublimation pressure of the solute along with fugacity coefficient, pressure and temperature. These properties are estimated using group contribution methods. For antibiotics solute critical properties, molar volume and sublimation pressure are unavailable and existing group contribution methods are also not applicable due to the lack of functional group contributions in their techniques. Thus, there is a need to address EoS methodology without using solute properties. Hence, a new EoS methodology for solubility modeling is, proposed without using critical properties of the solute, molar volume of the solute and vapour pressure of the solute. Thus, this study focuses on the development of new solubility model that correlates antibiotics using equation of state (EoS). Importantly, the proposed solubility model does not use the critical properties of the antibiotics. Correlating ability of the proposed model is indicated in terms of regression coefficient and arithmetic average relative deviation percentage (AARD %).

Optimization of ultrasound contrast agent and treatment duration for drug delivery to methicillin-resistant Staphylococcus aureus diabetic wound biofilms in mice

Chronic wounds are frequently infected with bacterial biofilms which pose a barrier to drug diffusion, drug uptake, and facilitate drug tolerance, thereby prolonging the healing process in chronic wounds and increasing the likelihood of relapse. A major contributor to relapse is persister cells, a subset resilient to high antibiotic doses. Previous work by our group showcased significantly improved gentamicin efficacy in a diabetic murine wound model using ultrasound, nanodroplets, and an anti-persister drug. Here, we aim to optimize nanodroplet formulation for persister cell targeting and treatment duration for clinical translation. In a methicillin-resistant Staphylococcus aureus (MRSA) diabetic wound model in SKH-1 hairless mice (n = 5), wounds were treated twice daily with gentamicin, ultrasound, and nanodroplets containing oxygen or palmitoleic acid (PA). These components aim to increase oxygenation and enhance persister uptake, respectively. Additionally, treatments with gentamicin, PA nanodroplets, and ultrasound for 2, 5, and 10 minutes were investigated (n = 3). Preliminary findings indicate PA most effectively potentiates antibiotic activity, 10- minute treatments improve efficacy by 1-log compared to 5-minutes, and 2-minute treatments achieve comparable efficacy to 5-minutes. These initial findings suggest a promising strategy for enhancing antibiotic efficacy and targeting persister cells in biofilms, with consideration for resource-efficient treatment times for clinical application.

Intoxication of antibiotic persisters by host RNS inactivates their efflux machinery during infection.

The host environment is of critical importance for antibiotic efficacy. By impacting bacterial machineries, stresses encountered by pathogens during infection promote the formation of phenotypic variants that are transiently insensitive to the action of antibiotics. It is assumed that these recalcitrant bacteria-termed persisters-contribute to antibiotic treatment failure and relapsing infections. Recently, we demonstrated that host reactive nitrogen species (RNS) transiently protect persisters against the action of β-lactam antibiotics by delaying their regrowth within host cells. Here, we discovered that RNS intoxication of persisters also collaterally sensitizing them to fluoroquinolones during infection, explaining the higher efficiency of fluoroquinolones against intramacrophage Salmonella. By reducing bacterial respiration and the proton-motive force, RNS inactivate the AcrAB efflux machinery of persisters, facilitating the accumulation of fluoroquinolones intracellularly. Our work shows that target inactivity is not the sole reason for Salmonella persisters to withstand antibiotics during infection, with active efflux being a major contributor to survival. Thus, understanding how the host environment impacts persister physiology is critical to optimize antibiotics efficacy during infection.

Construction of a versatile in vitro cultivation screening platform using human oral microbiota.

We developed a simulation model of human oral microbiota using Bio Palette oral medium (BPOM) containing 0.02% glucose and lower bacterial nitrogen sources, derived from saliva and dental plaque. By decreasing the concentration of Gifu anaerobic medium (GAM) from 30 to 10 g L-1 , we observed increased ratios of target pathogenic genera, Porphyromonas and Fusobacterium from 0.5% and 1.7% to 1.2% and 3.5%, respectively, in the biofilm on hydroxyapatite (HA) discs. BPOM exhibited the higher ratios of Porphyromonas and Fusobacterium, and amplicon sequence variant number on HA, compared with GAM, modified GAM and basal medium mucin. Mixing glycerol stocks of BPOM culture solutions from four human subjects resulted in comparable ratios of these bacteria to the original saliva. In this simulation model, sitafloxacin showed higher inhibitory effects on P. gingivalis than minocycline hydrochloride at a low dosage of 0.1 μg mL-1 . Probiotics such as Streptococcus salivarius and Limosilactobacillus fermentum also showed significant decreases in Porphyromonas and Fusobacterium ratios on HA, respectively. Overall, the study suggests that BPOM with low carbon and nutrients could be a versatile platform for assessing the efficacy of antibiotics and live biotherapeutics in treating oral diseases caused by Porphyromonas and Fusobacterium.