Antibiotic-eluting scaffolds with responsive dual-release kinetics facilitate bone healing and eliminate S. aureus infection.

Osteomyelitis (OM) is a progressive, inflammatory infection of bone caused predominately by Staphylococcus aureus. Herein, we engineered an antibiotic-eluting collagen-hydroxyapatite scaffold capable of eliminating infection and facilitating bone healing. An iterative freeze-drying and chemical crosslinking approach was leveraged to modify antibiotic release kinetics, resulting in a layered dual-release system whereby an initial rapid release of antibiotic to clear infection was followed by a sustained controlled release to prevent reoccurrence of infection. We observed that the presence of microbial collagenase accelerated antibiotic release from the crosslinked layer of the scaffold, indicating that the material is responsive to microbial activity. As exemplar drugs, vancomycin and gentamicin-eluting scaffolds were demonstrated to be bactericidal, and supported osteogenesis in vitro. In a pilot murine model of OM, vancomycin-eluting scaffolds were observed to reduce S. aureus infection within the tibia. Finally, in a rabbit model of chronic OM, gentamicin-eluting scaffolds both facilitated radial bone defect healing and eliminated S. aureus infection. These results show that antibiotic-eluting collagen-hydroxyapatite scaffolds are a one-stage therapy for OM, which when implanted into infected bone defects simultaneously eradicate infection and facilitate bone tissue healing.

Methicillin resistant Staphylococcus aureus mazEF expression promotes infections by influencing cellular growth, antibiotic sensitivity, and formation of biofilms.

Staphylococcus aureus infections are hard to treat due to the emergence of antibiotic resistant strains, as well as their ability to form biofilms. The MazEF toxin-antitoxin system is thought play a role in bacterial biofilm phenotype as well as antibiotic resistance. In S. aureus, the physiologic function of the mazEF gene in the disease transition from acute to chronic infection is not well understood. In methicillin resistant S. aureus (MRSA), loss of mazF expression results in loss of resistance to first generation cephalosporins. mazF::tn displayed sensitivity while the isogenic wild type (WT) remained resistant. mazF::tn displayed significantly increased growth of biofilms on metal implants over 48 h compared to WT and the complemented transposon mutant. mazF::tn biofilms displayed significantly decreased antibiotic tolerance to vancomycin and cefazolin in comparison to WT and complement biofilms. Mice given mazF::tn in a sepsis model displayed less abscess burden and increased survival (100%) when treated with cefazolin compared to WT bacteremia treated with cefazolin (20%). mazF::tn periprosthetic joint infections displayed increased biofilm burden at acute time points and decreased biofilm burden at chronic time points. Our data suggests MazEF in MRSA is responsible for controlling growth of biofilms, antibiotic tolerance, and influence chronic infections in vivo.

Pheno- and Genotypic Epidemiological Characterization of Vancomycin-Resistant Enterococcus faecium Isolates from Intensive Care Unit Patients in Central Türkiye.

Vancomycin-resistant Enterococcus faecium (VRE) has been detected in Türkiye. Only limited information is available on its dissemination in the central regions of the country. This study describes the first epidemiological characterization of VRE clinical isolates detected in patients in a hospital in the province of Aksaray. In this one-year study conducted between 2021 and 2022, stool samples from intensive care unit patients were screened for VRE using the phenotypic E-test method, and the antibiotic sensitivity test was analyzed by using the VITEK® 2 system. A molecular assay for confirmation of species level was carried out by 16S rRNA gene-based sequencing and testing for antibiotic resistance (vanA or vanB) and virulence factor-encoding genes (esp, asa1, and hyl). Further, genotypic characterization was determined by macro-restriction fragment pattern analysis (MRFPA) of genomic DNA digested with SmaI restriction enzyme. Of the total 350 Enterococcus positive patients from different hospital intensive care units, 22 (6.3%) were positive for VRE using the phenotypic E-test method. All isolates showed resistance to ampicillin, ciprofloxacin, vancomycin, and teicoplanin and positive amplification for the vanA gene. However, none of the isolates was positive for the vanB gene. The most prevalent virulence gene was esp. The results indicate that the isolates are persistent in the hospital environment and subsequently transmitted to hospitalized patients, thus representing challenges to an outbreak and infection control. These study results would also help formulate more effective strategies to reduce the transmission and propagation of VRE contamination in various hospital settings.

The effect of combinations of a glyphosate-based herbicide with various clinically used antibiotics on phenotypic traits of Gram-negative species from the ESKAPEE group.

The emission of glyphosate and antibiotic residues from human activities threatens the diversity and functioning of the microbial community. This study examines the impact of a glyphosate-based herbicide (GBH) and common antibiotics on Gram-negative bacteria within the ESKAPEE group (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacter spp. and Escherichia coli). Ten strains, including type and multidrug-resistant strains for each species were analysed and eight antibiotics (cefotaxime, meropenem, aztreonam, ciprofloxacin, gentamicin, tigecycline, sulfamethoxazole-trimethoprim, and colistin) were combined with the GBH. While most combinations yielded additive or indifferent effects in 70 associations, antagonistic effects were observed with ciprofloxacin and gentamicin in five strains. GBH notably decreased the minimum inhibitory concentration of colistin in eight strains and displayed synergistic activity with meropenem against metallo-ß-lactamase (MBL)-producing strains. Investigation into the effect of GBH properties on outer membrane permeability involved exposing strains to a combination of this GBH and vancomycin. Results indicated that GBH rendered strains sensitive to vancomycin, which is typically ineffective against Gram-negative bacteria. Furthermore, we examined the impact of GBH in combination with three carbapenem agents on 14 strains exhibiting varying carbapenem-resistance mechanisms to assess its effect on carbapenemase activity. The GBH efficiently inhibited MBL activity, demonstrating similar effects to EDTA (ethylenediaminetetraacetic acid). Chelating effect of GBH may have multifaceted impacts on bacterial cells, potentially by increasing outer membrane permeability and inactivating metalloenzyme activity.

Exploring naphthoquinone and anthraquinone derivatives as antibiotic adjuvants against Staphylococcus aureus biofilms: Synergistic effects of menadione.

Given the ability of Staphylococcus aureus to form biofilms and produce persister cells, making infections difficult to treat with antibiotics alone, there is a pressing need for an effective antibiotic adjuvant to address this public health threat. In this study, a series of quinone derivatives were evaluated for their antimicrobial and antibiofilm activities against methicillin-susceptible and methicillin-resistant S. aureus reference strains. Following analyses using broth microdilution, growth curve analysis, checkerboard assay, time-kill experiments, and confocal laser scanning microscopy, menadione was identified as a hit compound. Menadione exhibited a notable antibacterial profile (minimum inhibitory concentration, MIC = 4-16 µg/ml; minimum bactericidal concentration, MBC = 256 µg/ml) against planktonic S. aureus and its biofilms (minimum biofilm inhibitory concentration, MBIC50 = 0.0625-0.25 µg/ml). When combined with oxacillin, erythromycin, and vancomycin, menadione exhibited a synergistic or additive effect against planktonic cells and biofilms of two S. aureus reference strains and six clinical isolates, highlighting its potential as a suitable adjuvant for further development against S. aureus biofilm-associated infections.

6-Methoxyldihydrochelerythrine Chloride Inhibiting Intra and Extracellular Drug-Resistant Bacteria.

Vancomycin-resistant enterococcus (VRE) is a major nosocomial pathogen that exhibits enhanced infectivity due to its robust virulence and biofilm-forming capabilities. In this study, 6-methoxyldihydrochelerythrine chloride (6-MDC) inhibited the growth of exponential-phase VRE and restored VRE's sensitivity to vancomycin. 6-MDC predominantly suppressed the de novo biosynthetic pathway of pyrimidine and purine in VRE by the RNA-Seq analysis, resulting in obstructed DNA synthesis, which subsequently weakened bacterial virulence and impeded intracellular survival. Furthermore, 6-MDC inhibited biofilm formation, eradicated established biofilms, reduced virulence, and enhanced the host immune response to prevent intracellular survival and replication of VRE. Finally, 6-MDC reduced the VRE load in peritoneal fluid and cells significantly in a murine peritoneal infection model. This paper provides insight into the potential antimicrobial target of benzophenanthridine alkaloids for the first time.

Antibacterial efficacy of antimicrobial peptide-functionalized hydrogel particles combined with vancomycin and oxacillin antibiotics.

The rise of antibiotic resistant bacteria, such as methicillin-resistant Staphylococcus aureus (MRSA), requires novel approaches to combat infections. Medical devices like implants and wound dressings are frequently used in conjunction with antibiotics, motivating the development of antibacterial biomaterials capable of exhibiting combined antibacterial effects with conventional antibiotics. This study explores the synergistic antibacterial effects of combining antimicrobial peptide (AMP) functionalized hydrogel particles with conventional antibiotics, vancomycin (VCM) and oxacillin (OXA), against Staphylococcus aureus and MRSA. The AMP employed, RRPRPRPRPWWWW-NH2, has previously demonstrated broad-spectrum activity and enhanced stability when attached to hydrogel substrates. Here, checkerboard assays revealed additive and synergistic interactions between the free AMP and both VCM and OXA against Staphylococcus aureus and MRSA. Notably, the AMP-OXA combination displayed a significant synergistic effect against MRSA, with a 512-fold reduction in OXA's minimum inhibitory concentration (MIC) when combined with free AMP. The observed synergism against MRSA was retained upon covalent AMP immobilization onto the hydrogel particles; however, at a lower rate with a 64-fold reduction in OXA MIC. Despite this, the OXA-AMP hydrogel particle combinations retained considerable synergistic potential against MRSA, a strain resistant to OXA, highlighting the potential of AMP-functionalized materials for enhancing antibiotic efficacy. These findings underscore the importance of developing antimicrobial biomaterials for future medical devices to fight biomaterial-associated infections and reverse antimicrobial resistance.

Genetic characterization of vancomycin-resistant Enterococcus faecium isolates from neutropenic patients in Tunisia: spread of the pandemic CC17 clone associated with high genetic diversity in Tn1546-like structures.

AIMS: In Tunisia, limited research has focused on characterizing clinical vancomycin-resistant Enterococcus faecium (VREfm). This study aimed to bridge this knowledge gap by molecular characterization of antimicrobial resistance, determining the genetic elements mediating vancomycin-resistance, and whole-genome sequencing of one representative VREfm isolate. METHODS AND RESULTS: Over 6 years (2011-2016), a total of eighty VREfm isolates responsible for infection or colonization were identified from hospitalized patients, with the incidence rate increasing from 2% in 2011 to 27% in 2016. All of these strains harbored the vanA gene. The screening for antimicrobial resistance genes revealed the predominance of ermB, tetM, and aac(6')-Ie-aph(2'')-Ia genes and 81.2% of strains harbored the Tn1545. Pulsed-field gel electrophoresis identified seven clusters, with two major clusters (belonging to ST117 and ST80) persisting throughout the study period. Seven Tn1546 types were detected, with type VI (truncated transposon) being the most prevalent (57.5%). Whole-genome sequencing revealed a 3 028 373 bp chromosome and five plasmids. Mobile genetic elements and a type I CRISPR-cas locus were identified. Notably, the vanA gene was carried by the classic Tn1546 transposon with ISL3 insertion on a rep17pRUM plasmid. CONCLUSION: A concerning trend in the prevalence of VREfm essentially attributed to CC17 persistence and to horizontal transfer of multiple genetic variants of truncated vanA-Tn1546.

Restriction of arginine induces antibiotic tolerance in Staphylococcus aureus.

Staphylococcus aureus is responsible for a substantial number of invasive infections globally each year. These infections are problematic because they are frequently recalcitrant to antibiotic treatment. Antibiotic tolerance, the ability of bacteria to persist despite normally lethal doses of antibiotics, contributes to antibiotic treatment failure in S. aureus infections. To understand how antibiotic tolerance is induced, S. aureus biofilms exposed to multiple anti-staphylococcal antibiotics are examined using both quantitative proteomics and transposon sequencing. These screens indicate that arginine metabolism is involved in antibiotic tolerance within a biofilm and support the hypothesis that depletion of arginine within S. aureus communities can induce antibiotic tolerance. Consistent with this hypothesis, inactivation of argH, the final gene in the arginine synthesis pathway, induces antibiotic tolerance. Arginine restriction induces antibiotic tolerance via inhibition of protein synthesis. In murine skin and bone infection models, an argH mutant has enhanced ability to survive antibiotic treatment with vancomycin, highlighting the relationship between arginine metabolism and antibiotic tolerance during S. aureus infection. Uncovering this link between arginine metabolism and antibiotic tolerance has the potential to open new therapeutic avenues targeting previously recalcitrant S. aureus infections.

Metabolomic analysis in Amycolatopsis keratiniphila disrupted the competing ECO0501 pathway for enhancing the accumulation of vancomycin.

Vancomycin is a clinically important glycopeptide antibiotic against Gram-positive pathogenic bacteria, especially methicillin-resistant Staphylococcus aureus. In the mutant strain of Amycolatopsis keratiniphila HCCB10007 Δeco-cds4-27, the production of ECO-0501 was disrupted, but enhanced vancomycin yield by 55% was observed compared with the original strain of A. keratiniphila HCCB10007. To gain insights into the mechanism of the enhanced production of vancomycin in the mutant strain, comparative metabolomics analyses were performed between the mutant strain and the original strain, A. keratiniphila HCCB10007 via GC-TOF-MS and UPLC-HRMS. The results of PCA and OPLS-DA revealed a significant distinction of the intracellular metabolites between the two strains during the fermentation process. 64 intracellular metabolites, which involved in amino acids, fatty acids and central carbon metabolism, were identified as differential metabolites. The high-yield mutant strain maintained high levels of glucose-1-phosphate and glucose-6-phosphate and they declined with the increases of vancomycin production. Particularly, a strong association of fatty acids accumulation as well as 3,5-dihydroxyphenylacetic acid and non-proteinogenic amino acid 3,5-dihydroxyphenylglycine (Dpg) with enhancement of vancomycin production was observed in the high-yield mutant strain, indicating that the consumption of fatty acid pools might be beneficial for giving rise to 3,5-dihydroxyphenylacetic acid and Dpg which further lead to improve vancomycin production. In addition, the lower levels of glyoxylic acid and lactic acid and the higher levels of sulfur amino acids might be beneficial for improving vancomycin production. These findings proposed more advanced elucidation of metabolomic characteristics in the high-yield strain for vancomycin production and could provide potential strategies to enhance the vancomycin production.

Symbiotic biofilms formed by Clostridioides difficile and bacteroides thetaiotaomicron in the presence of vancomycin.

Vancomycin (VAN) treatment in Clostridioides difficile infection (CDI) suffers from a relatively high rate of recurrence, with a variety of reasons behind this, including biofilm-induced recurrent infections. C. difficile can form monophyletic or symbiotic biofilms with other microbes in the gut, and these biofilms protect C. difficile from being killed by antibiotics. In this study, we analyzed the ecological relationship between Bacteroides thetaiotaomicron and C. difficile and their formation of symbiotic biofilm in the VAN environment. The production of symbiotic biofilm formed by C. difficile and B. thetaiotaomicron was higher than that of C. difficile and B. thetaiotaomicron alone in the VAN environment. In symbiotic biofilms, C. difficile was characterized by increased production of the toxin protein TcdA and TcdB, up-regulation of the expression levels of the virulence genes tcdA and tcdB, enhanced bacterial cell swimming motility and c-di-GMP content, and increased adhesion to Caco-2 cells. The scanning electron microscope (SEM) combined with confocal laser scanning microscopy (CLSM) results indicated that the symbiotic biofilm was elevated in thickness, dense, and had an increased amount of mixed bacteria, while the fluorescence in situ hybridization (FISH) probe and plate colony counting results further indicated that the symbiotic biofilm had a significant increase in the amount of C. difficile cells, and was able to better tolerate the killing of the simulated intestinal fluid. Taken together, C. difficile and B. thetaiotaomicron become collaborative in the VAN environment, and targeted deletion or attenuation of host gut B. thetaiotaomicron content may improve the actual efficacy of VAN in CDI treatment.

Combination of bacteriophages and vancomycin in a co-delivery hydrogel for localized treatment of fracture-related infections.

Fracture-related infections (FRIs), particularly those caused by methicillin-resistant Staphylococcus aureus (MRSA), are challenging to treat. This study designed and evaluated a hydrogel loaded with a cocktail of bacteriophages and vancomycin (1.2 mg/mL). The co-delivery hydrogel showed 99.72% reduction in MRSA biofilm in vitro. The hydrogel released 54% of phages and 82% of vancomycin within 72 h and maintained activity for eight days, in vivo the co-delivery hydrogel with systemic antibiotic significantly reduced bacterial load by 0.99 log10 CFU compared to controls, with active phages detected in tissues at euthanasia (2 × 103 PFU/mL). No phage resistance was detected in the phage treatment groups, and serum neutralization resulted in only a 20% reduction in phage count. In this work, we show that a phage-antibiotic co-delivery system via CMC hydrogel is a promising adjunct to systemic antibiotic therapy for MRSA-induced FRI, highlighting its potential for localized, sustained delivery and improved treatment outcomes.

Nanoarchitectonics of in Situ Antibiotic-Releasing Acicular Nanozymes for Targeting and Inducing Cuproptosis-like Death to Eliminate Drug-Resistant Bacteria.

A series of progress has been made in the field of antimicrobial use of nanozymes due to their superior stability and decreased susceptibility to drug resistance. However, catalytically generated reactive oxygen species (ROS) are insufficient for coping with multidrug-resistant organisms (MDROs) in complex wound environments due to their low targeting ability and insufficient catalytic activity. To address this problem, chemically stable copper-gallic acid-vancomycin (CuGA-VAN) nanoneedles were successfully constructed by a simple approach for targeting bacteria; these nanoneedles exhibit OXD-like and GSH-px-like dual enzyme activities to produce ROS and induce bacterial cuproptosis-like death, thereby eliminating MDRO infections. The results of in vitro experiments showed that the free carboxylic acid of GA could react with the free ammonia of teichoic acid in the methicillin-resistant Staphylococcus aureus (MRSA) cell wall skeleton. Thus, CuGA-VAN nanoneedles can rapidly "capture" MRSA in liquid environments, releasing ROS, VAN and Cu2+ on bacterial surfaces to break down the MRSA barrier, destroying the biofilm. In addition, CuGA-VAN effectively promoted wound repair cell proliferation and angiogenesis to facilitate wound healing while ensuring biosafety. According to transcriptome sequencing, highly internalized Cu2+ causes copper overload toxicity; downregulates genes related to the bacterial glyoxylate cycle, tricarboxylic acid cycle, and oxidative respiratory chain; and induces lipid peroxidation in the cytoplasm, leading to bacterial cuproptosis-like death. In this study, CuGA-VAN was cleverly designed to trigger a cascade reaction of targeting, drug release, ROS-catalyzed antibacterial activity and cuproptosis-like death. This provides an innovative idea for multidrug-resistant infections.

Antibiotic-induced gut microbiota disruption promotes vascular calcification by reducing short-chain fatty acid acetate.

BACKGROUND: Vascular calcification is a common vascular lesion associated with high morbidity and mortality from cardiovascular events. Antibiotics can disrupt the gut microbiota (GM) and have been shown to exacerbate or attenuate several human diseases. However, whether antibiotic-induced GM disruption affects vascular calcification remains unclear. METHODS: Antibiotic cocktail (ABX) treatment was utilized to test the potential effects of antibiotics on vascular calcification. The effects of antibiotics on GM and serum short-chain fatty acids (SCFAs) in vascular calcification mice were analyzed using 16 S rRNA gene sequencing and targeted metabolomics, respectively. Further, the effects of acetate, propionate and butyrate on vascular calcification were evaluated. Finally, the potential mechanism by which acetate inhibits osteogenic transformation of VSMCs was explored by proteomics. RESULTS: ABX and vancomycin exacerbated vascular calcification. 16 S rRNA gene sequencing and targeted metabolomics analyses showed that ABX and vancomycin treatments resulted in decreased abundance of Bacteroidetes in the fecal microbiota of the mice and decreased serum levels of SCFAs. In addition, supplementation with acetate was found to reduce calcium salt deposition in the aorta of mice and inhibit osteogenic transformation in VSMCs. Finally, using proteomics, we found that the inhibition of osteogenic transformation of VSMCs by acetate may be related to glutathione metabolism and ubiquitin-mediated proteolysis. After adding the glutathione inhibitor Buthionine sulfoximine (BSO) and the ubiquitination inhibitor MG132, we found that the inhibitory effect of acetate on VSMC osteogenic differentiation was weakened by the intervention of BSO, but MG132 had no effect. CONCLUSION: ABX exacerbates vascular calcification, possibly by depleting the abundance of Bacteroidetes and SCFAs in the intestine. Supplementation with acetate has the potential to alleviate vascular calcification, which may be an important target for future treatment of vascular calcification.

Identification of pathways to high-level vancomycin resistance in Clostridioides difficile that incur high fitness costs in key pathogenicity traits.

Clostridioides difficile is an important human pathogen, for which there are very limited treatment options, primarily the glycopeptide antibiotic vancomycin. In recent years, vancomycin resistance has emerged as a serious problem in several gram-positive pathogens, but high-level resistance has yet to be reported for C. difficile, although it is not known if this is due to constraints upon resistance evolution in this species. Here, we show that resistance to vancomycin can evolve rapidly under ramping selection but is accompanied by fitness costs and pleiotropic trade-offs, including sporulation defects that would be expected to severely impact transmission. We identified 2 distinct pathways to resistance, both of which are predicted to result in changes to the muropeptide terminal D-Ala-D-Ala that is the primary target of vancomycin. One of these pathways involves a previously uncharacterised D,D-carboxypeptidase, expression of which is controlled by a dedicated two-component signal transduction system. Our findings suggest that while C. difficile is capable of evolving high-level vancomycin resistance, this outcome may be limited clinically due to pleiotropic effects on key pathogenicity traits. Moreover, our data identify potential mutational routes to resistance that should be considered in genomic surveillance.

Biguanide-Vancomycin Conjugates are Effective Broad-Spectrum Antibiotics against Actively Growing and Biofilm-Associated Gram-Positive and Gram-Negative ESKAPE Pathogens and Mycobacteria.

Strategies to increase the efficacy and/or expand the spectrum of activity of existing antibiotics provide a potentially fast path to clinically address the growing crisis of antibiotic-resistant infections. Here, we report the synthesis, antibacterial efficacy, and mechanistic activity of an unprecedented class of biguanide-antibiotic conjugates. Our lead biguanide-vancomycin conjugate, V-C6-Bg-PhCl (5e), induces highly effective cell killing with up to a 2 orders-of-magnitude improvement over its parent compound, vancomycin (V), against vancomycin-resistant enterococcus. V-C6-Bg-PhCl (5e) also exhibits improved activity against mycobacteria and each of the ESKAPE pathogens, including the Gram-negative organisms. Furthermore, we uncover broad-spectrum killing activity against biofilm-associated Gram-positive and Gram-negative bacteria as well as mycobacteria not observed for clinically used antibiotics such as oritavancin. Mode-of-action studies reveal that vancomycin-like cell wall synthesis inhibition with improved efficacy attributed to enhanced engagement at vancomycin binding sites through biguanide association with relevant cell-surface anions for Gram-positive and Gram-negative bacteria. Due to its potency, remarkably broad activity, and lack of acute mammalian cell toxicity, V-C6-Bg-PhCl (5e) is a promising candidate for treating antibiotic-resistant infections and notoriously difficult-to-treat slowly growing and antibiotic-tolerant bacteria associated with chronic and often incurable infections. More generally, this study offers a new strategy (biguanidinylation) to enhance antibiotic activity and facilitate clinical entry.

Vancomycin-resistant Staphylococcus aureus (VRSA) can overcome the cost of antibiotic resistance and may threaten vancomycin's clinical durability.

Vancomycin has proven remarkably durable to resistance evolution by Staphylococcus aureus despite widespread treatment with vancomycin in the clinic. Only 16 cases of vancomycin-resistant S. aureus (VRSA) have been documented in the United States. It is thought that the failure of VRSA to spread is partly due to the fitness cost imposed by the vanA operon, which is the only known means of high-level resistance. Here, we show that the fitness cost of vanA-mediated resistance can be overcome through laboratory evolution of VRSA in the presence of vancomycin. Adaptation to vancomycin imposed a tradeoff such that fitness in the presence of vancomycin increased, while fitness in its absence decreased in evolved lineages. Comparing the genomes of vancomycin-exposed and vancomycin-unexposed lineages pinpointed the D-alanine:D-alanine ligase gene (ddl) as the target of loss-of-function mutations, which were associated with the observed fitness tradeoff. Vancomycin-exposed lineages exhibited vancomycin dependence and abnormal colony morphology in the absence of drug, which were associated with mutations in ddl. However, further evolution of vancomycin-exposed lineages in the absence of vancomycin enabled some evolved lineages to escape this fitness tradeoff. Many vancomycin-exposed lineages maintained resistance in the absence of vancomycin, unlike their ancestral VRSA strains. These results indicate that VRSA might be able to compensate for the fitness deficit associated with vanA-mediated resistance, which may pose a threat to the prolonged durability of vancomycin in the clinic. Our results also suggest vancomycin treatment should be immediately discontinued in patients after VRSA is identified to mitigate potential adaptations.

The clinical significance of inflammatory biomarkers, IL6 cytokine, and systemic immune inflammatory index in rabbit model of acute and chronic Methicillin-resistant Staphylococcus epidermidis-induced osteomyelitis.

Infections are a major complication of open fractures and fracture fixation. In this study, an innovative bioactive medical device was used to experimentally treat MRSE-induced osteomyelitis in rabbit tibia. This paper investigates the clinical significance of inflammatory biomarkers (NLR, PLR, MLR and PMR), SII and IL-6 and assesses their role in the development of osteomyelitis. The main objective is to identify the utility of hematological reports derived from neutrophils, leukocytes, monocytes and platelets in the evolution of implant-related osteomyelitis and the estimation of treatment efficiency. In particular, this study compares the response of these inflammatory markers to different treatments in the presence or absence of bioactive materials and/or topical antibiotics over time. The analysis of the threads showed that NLR, PLR and SII had high values in the acute phase of the disease, so that after chronicization, they decrease. The animals treated with vancomycin nano-functionalized peptide-enriched silk fibroin-coated implants showed lower levels of inflammatory biomarkers compared to the other groups (empty implants and peptide-enriched silk fibroin-coated implants). NLR, PLR and SII, complemented by IL-6 can be used as fairly accurate biomarkers for the diagnosis of osteomyelitis.

Antibiotic dip and irrigation solutions confer increased antimicrobial efficacy of inflatable penile prosthesis hydrophilic surfaces compared with 0.05% chlorhexidine gluconate.

BACKGROUND: Chlorhexidine gluconate (CHG) (0.05%) has recently been suggested as both a dip for the hydrophilic surface and an irrigation solution in the setting of penile prosthesis (PP) surgery. AIM: The study sought to compare the antimicrobial efficacy of 0.05% CHG with vancomycin and gentamicin (VG) antibiotics as dip and/or irrigation solutions in the setting of a hydrophilic PP surface in vitro. METHODS: Sterile PPs with a hydrophilic coating were obtained. A series of experiments were performed to evaluate the efficacy of normal saline (NS), 0.05% CHG, or VG as dip and/or irrigation solutions to reduce methicillin-sensitive Staphylococcus aureus adhesion to PP surfaces. The 8-mm discs from PPs were incubated in 105 colony-forming units/mL of methicillin-sensitive S aureus for 48 hours, plated, and counted. Disc-diffusion tests were conducted by suspending 6-mm discs for 2 minutes in NS, 0.05% CHG, or VG, then placing them coated side down onto plates streaked with the following organisms: methicillin-sensitive S aureus, S epidermidis, Enterococcus, and Escherichia coli. After 24 hours of growth, zones of inhibition were measured. OUTCOMES: We found average bacterial counts (colony-forming units/mL) and zones of inhibition (mm) following a series of treatment protocols of PP discs. RESULTS: PP discs dipped in VG reduced bacterial adhesion to the implant surface >0.05% CHG (~5.5 log vs ~1.5 log; P < .01). Discs irrigated with either 0.05% CHG or NS removed all dip solution adsorbed to the hydrophilic surface, allowing bacterial growth. VG irrigation adsorbed to the hydrophilic surface even after 0.05% CHG or NS dips, reducing bacterial adherence (~3 log). Dipping and irrigating discs with VG was most effective in reducing adherent bacteria (~5.5 log) and was the only irrigation that showed antimicrobial activity. CLINICAL TRANSLATION: VG, when used both as a prophylactic dip and as an intraoperative irrigation solution for hydrophilic penile implant surfaces, has improved efficacy to 0.05% CHG and NS. STRENGTHS AND LIMITATIONS: This is the first study to compare the use of VG, 0.05% CHG, and NS as prophylactic dips and intraoperative irrigations for hydrophilic penile implant surfaces. Limitations include the use of in vitro studies, which serve as a proxy for in vivo practices and may not be entirely accurate nor translatable clinically. CONCLUSION: We demonstrated the superior efficacy of VG as a combined dip and irrigation solution for hydrophilic penile implant surfaces compared with 0.05% CHG.

Antimicrobial susceptibilities, resistance mechanisms and molecular characteristics of toxigenic Clostridioides difficile isolates in a large teaching hospital in Chongqing, China.

OBJECTIVES: Clostridioides difficile ranks among the primary sources of healthcare-related infections and diarrhoea in numerous nations. We evaluated the drug susceptibility and resistance mechanisms of C. difficile isolates from a hospital in Chongqing, China, and identified resistance rates and resistance mechanisms that differed from previous findings. METHODS: The toxin genes and drug resistance genes of clinical strains were detected using Polymerase Chain Reaction (PCR), and these strains were subjected to Multilocus Sequence Typing (MLST). The agar dilution technique was employed for assessing susceptibility of antibiotics. Clinical data collection was completed through a review of electronic medical records. RESULTS: A total of 67 strains of toxin-producing C. difficile were detected. All C. difficile isolates demonstrated susceptibility to both metronidazole and vancomycin. However, resistance was observed in 8.95%, 16.42%, 56.72%, 56.72%, 31.34% and 5.97% of the isolates for tigecycline, tetracycline, clindamycin, erythromycin, moxifloxacin and rifampin, respectively. Among the strains with toxin genotypes A + B + CDT - and belonging to the ST3, six strains exhibited reduced susceptibility to tigecycline (MIC=0.5mg/L) and tetracycline (MIC=8mg/L). The tetA(P) and tetB(P) genes were present in these six strains, but were absent in tetracycline-resistant strains. Resistance genes (ermB, tetM, tetA(P) and tetB(P)) and mutations (in gyrA, gyrB, and rpoB) were identified in resistant strains. CONCLUSIONS: In contrast to prior studies, we found higher proportions of ST3 isolates with decreased tigecycline sensitivity, sharing similar resistance patterns and resistance genes. In the resistance process of tigecycline and tetracycline, the tetA(P) and tetB(P) genes may play a weak role.