Search Results (446)

γ-Aminobutyric acid (GABA), a major inhibitory neurotransmitter, is known for its physiological functions in alleviating anxiety and improving sleep. Currently, high-yielding GABA food products are mainly obtained through screening wild-type high-producing strains (e.g., Saccharomyces cerevisiae isolated from Sichuan pickles yielding 0.67 g/L) or employing co-culture systems (e.g., Enterococcus faecium and Lactiplantibacillus plantarum reaching 6.35 g/L). While effective, these methods often rely on natural screening strains or multi-microbial interactions. This study employed CRISPR-Cas9 technology to knockout the UGA1 gene in Saccharomyces cerevisiae, a key gene responsible for GABA degradation. Starting from the low higher alcohol Saccharomyces cerevisiae SY-LH, we successfully constructed the recombinant strain SY-LHU. Remarkably, this study discovered a significant upregulation of GAD1 gene expression following UGA1 knockout, which further enhanced GABA synthesis capacity. Under optimal fermentation conditions (inoculum size 4 × 10⁷ cells/mL, wort concentration 10 °P, sugar addition 60 g/L, 30 °C for 10 days, and mixing the malt broth every 48 h), the validation fermentation was performed and the GABA content in the wort beverage reached 280.36 mg/L, representing a 385.4% increase compared to the pre-optimization level. Furthermore, sensory evaluation by a trained panel yielded a mean score of 88, with no significant off-flavors detected, demonstrating the product’s high consumer acceptance. This pioneering work provides a novel and feasible technical pathway for developing functional alcoholic beverages with sleep-aiding properties. Full article

Streptococcus suis is a serious zoonotic pathogen responsible for rapid progression and deadly infections in both humans and pigs. With an increasing number of reported cases and considering the limitations of standard routine identification, a simple, rapid, and cost-effective approach is needed. In this study, a label-free colorimetric assay based on gold nanoparticles (AuNPs) was applied with a specific aptamer, R8-su12. This assay offered simplified detection through observable color change, enabling visual analysis by the naked eye or assessment via UV–Vis spectrophotometry. Under the optimal assay conditions, the detection procedure was carried out within 45 min. The reaction of the aptasensor and other bacterial species, including Staphylococcus aureus, S. pneumoniae, S. pyogenes, Pseudomonas aeruginosa, Escherichia coli, Enterococcus faecium, and E. faecalis, was not present, indicating the specificity of this assay. Moreover, the aptasensor exhibited high sensitivity with a limit of detection (LOD) at 1 CFU of S. suis and had broad reactivity with S. suis serotypes 1, 1/2, 9, and 14, as well as with S. suis isolated from clinical specimens. Thus, this aptasensor demonstrates proof-of-concept feasibility including clinical sample testing before practical implementation. It holds promise as a practical tool for the early screening and outbreak management of S. suis in a variety of settings, such as clinical laboratories, food safety, and the environment. Full article

Enterococci are widely used indicators of fecal contamination because they originate in the gastrointestinal tracts of warm-blooded animals, and species-level identification can support source attribution. This study evaluated the temporal abundance and species composition of enterococci in Quebrada Mondongo, southwestern Puerto Rico, a stream influenced by wastewater treatment plant (WWTP) effluent and nonpoint-source inputs. Five sampling campaigns for species distribution and fourteen for population quantification were conducted over approximately one year at the WWTP effluent discharge and at upstream and downstream stations. Enterococci concentrations exceeded the regulatory threshold for surface waters. Among the confirmed isolates, E. faecium dominated upstream and in the effluent, occurring approximately twofold more frequently than E. faecalis. Downstream, E. faecalis increased in relative abundance, shifting the species ratio of E. faecium/E. faecalis from 2.3–3.2 to 0.89. E. casseliflavus was detected at low frequency, and E. gallinarum was not observed. Virulence-associated genes (esp, gelE) were identified in ~75% of E. faecalis isolates, consistent with enhanced environmental persistence. Although upstream and effluent patterns reflected a strong human fecal signal, the downstream enrichment of E. faecalis suggests additional secondary inputs and/or naturalization. This study provides empirical evidence of species shifts in a tropical stream, with an increase in E. faecalis downstream of a WWTP despite E. faecium dominance in the effluent highlighting the likely influence of other nonpoint fecal sources within the watershed. Overall, these results suggest that the WWTP effluent did not contribute substantially to enterococci concentrations nor significantly influence the species composition of enterococci downstream in Quebrada Mondongo, highlighting the likely influence of other nonpoint fecal sources within the watershed. Full article

Background/Objectives: Enterococcus spp. are important indicators of AMR and potential opportunistic pathogens. Urban green spaces, frequented by dogs and humans, may serve as reservoirs for resistant bacteria. This study assessed the occurrence, AMR profiles, and virulence traits of Enterococcus spp. in dog feces from urban green spaces in Porto (Portugal). Methods: In December 2023 and May 2024, 240 dog fecal samples were collected from 12 urban green spaces across Porto. Enterococcus spp. were isolated using selective culture, identified to species level, and tested for antimicrobial susceptibility following CLSI guidelines. PCR screening was performed for resistance genes (vanA, vanB, erm(A/B/C), vatD/E, tet(M/O/L/K)) and virulence genes (gelE, ace). Environmental and socioeconomic features, including vegetation density (NDVI), presence of water features, and neighborhood deprivation (EDI), were recorded to explore associations with bacterial occurrence and traits. Results: Thirty-two isolates were recovered, mainly E. faecium (n = 9) and E. faecalis (n = 7). High resistance rates were observed to tetracycline (56.3%) and quinupristin/dalfopristin (37.5%), with lower rates for vancomycin, teicoplanin, and ciprofloxacin (3.1%), and imipenem (6.3%). Tet(M) was the most prevalent resistance gene (40.6%), and gelE and ace were frequently detected, often co-occurring with resistance determinants. Distribution of resistance and virulence genes varied across green spaces, with widely used parks showing more isolates. Vegetation density and water features were not directly associated with bacterial recovery. Conclusions: Dog feces in urban green spaces contribute to localized AMR hotspots, acting as potential reservoirs of resistant and potentially pathogenic Enterococcus spp. These findings highlight the importance of One Health strategies for urban sanitation and AMR surveillance. Full article

Antimicrobial resistance is an emerging challenge in veterinary medicine, particularly in dogs, where bacterial skin infections are highly prevalent. Honey and its bioactive extracts have emerged as potential natural alternatives to conventional antimicrobials. This study evaluated the antimicrobial activity of methanolic extracts from four honey types collected in Central Chile against multidrug-resistant (MDR) bacterial isolates from canine patients, including Enterococcus faecium, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Pasteurella multocida, and Enterobacter cloacae. Antimicrobial potency was assessed by minimum inhibitory concentration (MIC), and phenolics, flavonoids, and antioxidant capacity were quantified. All extracts inhibited bacterial growth, with E. coli, E. faecium and S. aureus being the most susceptible (MIC 3.13% w/v), while Gram-negative bacteria such a P. aeruginosa, P. multocida, and E. cloacae required higher concentrations (MIC 12.5% w/v). Secondary metabolite analysis revealed seasonal and apiary-related variations, with apiary 2 honey showing significantly higher phenolic (195.58 ± 4.28 mg GAE/100 g) and flavonoid (65.46 ± 4.35 mg QE/100 g) contents in summer. In contrast, antioxidant capacity (FRAP) did not differ significantly. These findings indicate that honey’s antimicrobial properties are closely related to its bioactive composition and influenced by season and floral origin, reinforcing its potential as a sustainable alternative to antibiotics in veterinary medicine under the One Health approach. Full article

Introduction: Bacterial multidrug resistance (MDR) drives treatment with expensive, toxic, or pharmacokinetically suboptimal antibiotics. Objectives: To assess the prevalence of MDR Gram-positive cocci among isolates from cardiac implantable electronic device (CIED) infections at a Polish reference center. Methods: Data come from the “EXTRACT” registry (ClinicalTrials.gov ID NCT05775783), which covers 702 transvenous lead extraction procedures. Blood samples and intraoperative swabs were collected from participants with CIED infection. Results: From 209 cases with isolated pocket infection (PI) (107, 51.2%) or systemic infections (102, 48.8%), 263 Gram-positive cocci were cultured. They were: coagulase-negative staphylococci (CoNS) (177, 67.3%), Staphylococcus aureus (62, 23.6%), enterococci (15, 5.7%), streptococci (8, 3.0%), and others (1, 0.4%). The highest MDR rate was among CoNS (46.9%). CoNS exhibited methicillin resistance (MR-CoNS) in 55.9% with co-resistance to macrolides (73.2%), lincosamides (51.0%), fluoroquinolones (56.1%), aminoglycosides (41.4%), tetracyclines (29.6%), and co-trimoxazole (29.3%). Resistance to daptomycin (5.3%) and linezolid (2.0%) in MR-CoNS was rare. The frequency of MDR S. aureus was 8.1%. Methicillin resistance in S. aureus (MRSA, 6.5%) co-occurred with resistance to macrolides/lincosamides and fluoroquinolones (100% for both) or linezolid (25.0%). All MDR staphylococci were vancomycin-susceptible. High-level aminoglycoside resistance (HLAR) in Enterococcus faecalis (53.8%) was accompanied by levofloxacin co-resistance (66.7%). Conversely, E. faecium HLAR (50.0%) strains showed 100.0% β-lactam resistance. Vancomycin-resistant enterococci (VRE) accounted for 6.7%; the VRE E. faecium strain was tigecycline- and linezolid-susceptible. Among viridans group streptococci, β-lactam and lincosamides resistance was common (40.0% for both), with 50.0% of co-resistance. Conclusions: Epidemiological data may improve the effectiveness of empirical antibiotic therapy for CIED-related infections. Full article

Tebipenem is a new carbapenem antibiotic that binds to penicillin-binding proteins (PBPs). Given the need for effective antibiotics against multidrug-resistant (MDR) bacteria, this review evaluated the in vitro antimicrobial activity of tebipenem against Gram-negative and Gram-positive bacteria, focusing on uropathogens. Five resources (Google Scholar, Web of Science, Embase, Scopus, and PubMed) were used to identify relevant articles. Of the 1322 articles identified, 9 relevant studies were included, which evaluated 12,501 Gram-negative and 122 Gram-positive pathogens. All nine studies (100%) assessed the activity of tebipenem against Escherichia coli, with an MIC₉₀ value range of 0.015–>4 mg/L. Seven studies (77.8%) included Klebsiella pneumoniae, with an MIC₉₀ value range of 0.015–0.5 mg/L. Six studies (66.7%) reported data on Proteus mirabilis, with an MIC₉₀ value range of ≤0.125–0.5 mg/L. Two studies (22.2%) evaluated the activity of tebipenem against Enterococcus faecalis, with MIC₉₀ of 1 mg/L among vancomycin-susceptible isolates and 32 mg/L in isolates with not-reported mechanisms of resistance. Two studies (22.2%) evaluated the activity of tebipenem against Enterococcus faecium, with MIC₉₀ of >4 mg/L among both vancomycin-susceptible and vancomycin-resistant isolates and MIC₉₀ of 128 mg/L among isolates with no resistance mechanism reported. Tebipenem demonstrated good activity against Enterobacterales, such as E. coli and K. pneumoniae. The antimicrobial agent exhibited higher MICs and a higher proportion of resistance among P. mirabilis isolates. Tebipenem could be effective for outpatient treatment of infections caused by MDR Gram-negative pathogens. However, given its potential to exert selective pressure for the development of antimicrobial resistance, it should be considered for patients with cUTIs when none of the first-line treatment options demonstrate in vitro antimicrobial activity. Full article

Polytrichadelphus purpureus is a bryophyte distributed in tropical and subtropical regions. It represents an underexploited source of bioactive metabolites. In this study, the volatile fraction (VF) obtained by steam distillation was analyzed by gas chromatography (GC-MS and GC-FID) on a DB-5ms capillary column, identifying 86 volatile compounds, representing the 97% of the volatile profile. Sesquiterpene hydrocarbons (23.6%), alcohols (15.6%), and alkanes (14.1%) were the major group compounds. Major components include (Z)-falcarinol (14%), hexacosane (4%), β-Curcumene (3%), and oleic acid (3%), among others. In addition, the volatile fraction exhibited moderate in vitro inhibitory activity against Gram-positive bacteria (E. faecium, S. aureus), fungus A. niger at concentrations of 250 µg/mL and 500 µg/mL, respectively, and E. faecalis and L. monocytogenes (250–500 µg/mL) and a weak inhibition of acetylcholinesterase (IC₅₀: 392 µg/mL). These effects were evaluated for the first time in this species. While they are within the range reported for other plant-derived volatile fraction, they do not, on their own, justify claims of therapeutic efficacy. This study primarily advances our understanding of the genus Polytrichadelphus, suggesting potential as a source of bioactive sesquiterpenes for future phytochemical screening. Full article

Background: Raw-meat-based diets (RMBDs) for companion animals have gained popularity but may serve as vehicles for antimicrobial-resistant (AMR) bacteria, posing risks to animal and public health. This study investigated the occurrence and risk factors of AMR in indicator bacteria (Escherichia coli, Enterococcus faecalis, Enterococcus faecium) and Campylobacter spp. from commercial RMBD products. Methods: In 2023, 50 RMBD samples were collected in Belgium, representing 21 brands from five countries. After both selective and non-selective isolation and MALDI-TOF identification, antimicrobial susceptibility testing of the isolates was performed using broth microdilution. Results: From non-selective media, E. coli was found in 45 samples (90.0%), E. faecalis in 31 samples (62.0%), E. faecium in 23 samples (46.0%), and Campylobacter spp. in 3 samples (6.0%). Among these, one E. faecalis strain with acquired resistance to vancomycin and daptomycin was isolated. Multidrug resistance (MDR) was identified in 17 isolates from 15 samples (30.0%), including 14 MDR E. coli, 1 MDR E. faecalis, and 2 MDR E. faecium. From selective media, presumptive ESBL/AmpC-producing E. coli were detected in 17 samples (34.0%), and 5 E. faecium from linezolid-supplemented media were confirmed by the broth microdilution method. Samples from Belgian origin showed significantly higher E. faecium prevalence (76.5%) compared to Dutch samples (21.4%) (OR = 11.9, p < 0.001). Minor livestock sources were associated with increased MDR risk (OR = 5.52, p = 0.016). Conclusions: Commercial RMBDs in Belgium exhibit widespread bacterial contamination with concerning AMR patterns. These findings highlight the need for improved production standards in the RMBD industry and the need to raise awareness in pet owners. Full article

Background: Enterococcus species are involved in urinary tract infections (UTIs), and they are known to be intrinsically resistant to certain antibiotics. We aimed to investigate the clinical characteristics and treatment outcomes of enterococcal UTIs in three hospitals in Saudi Arabia and Oman. Methods: A retrospective cohort study was conducted on adults with clinically and microbiologically confirmed enterococcal UTI based on urinary symptoms and a urine culture of ≥100,000 CFU/mL, who received an antibiotic active against the pathogen. The primary endpoint was clinical cure. Secondary endpoints included microbiological cure, length of stay (LOS), in-hospital mortality, and recurrence. Results: E. faecalis and E. faecium were isolated from 188 (67.1%) and 92 (32.9%), respectively, of 280 included patients. Ampicillin/amoxicillin (25%) and vancomycin (22.1%) were the most-used antibiotics. Compared with E. faecium, E. faecalis was associated with higher clinical cure rates (75% vs. 57.6%; p = 0.003), lower in-hospital mortality (15.7% vs. 38.5%; p < 0.0001), and shorter LOS (12.5 vs. 25 days; p < 0.0001). No difference in recurrence was observed. Ciprofloxacin was associated with high odds of clinical cure (OR, 4.28; 95% CI, 1.18–15.56). Conversely, the recent cancer chemotherapy and growth of Enterococcus at another site were associated with lower odds of clinical cure. Urinary catheter removal was associated with lower recurrence odds (OR, 0.48; 95% CI, 0.24–0.98). Conclusions: This study highlights the clinical challenges posed by enterococcal UTIs, particularly by E. faecium. Ciprofloxacin remains an effective option, particularly against E. faecalis. Patients with advanced age, critical illness, complicated infections, and liver disease, as well as patients on hemodialysis, require close monitoring to improve outcomes. Full article

Daptomycin-resistant Enterococcus faecium (DRE) poses an increasing therapeutic challenge, particularly in immunocompromised patients and solid organ transplant recipients. Surveillance data from the Centers for Disease Control and Prevention indicate that approximately 6.5% of E. faecium isolates are daptomycin-resistant, underscoring the need for heightened clinical vigilance, particularly for prompt identification and treatment. In this case series, three patients with advanced liver disease, including two status post orthotopic liver transplantation, are described who developed DRE during treatment for bloodstream infection. These cases illustrate the dynamic nature of antimicrobial susceptibility under daptomycin exposure and highlight the contributions of persistent source control issues, intravascular infection, and altered host factors to treatment failure. All patients were successfully managed by escalating to combination therapy with high-dose daptomycin and ceftaroline, alongside appropriate source control. This series emphasizes the importance of periodic susceptibility reassessment during daptomycin therapy and cautions clinicians against assuming sustained susceptibility in patients with prolonged bacteremia or complex infections. Early recognition of evolving resistance and timely therapeutic adjustment may improve outcomes in this high-risk population. Full article

The global rise in antimicrobial resistance among the ESKAPE pathogens represents a major challenge to public health. Here, we report the broad-spectrum antibacterial activity of the synthetic antimicrobial and pore-forming peptide C14R against all six ESKAPE species. Using a radial diffusion assay and resazurin-based viability testing, C14R exhibited a potent bactericidal effect with minimum inhibitory concentrations (MICs), defined as the lowest concentration of an antimicrobial agent that completely inhibits visible growth of planktonic microorganisms, ranging from 3.4 µg/mL (Enterococcus faecium, vancomycin-resistant) to 45.2 µg/mL (Klebsiella quasipneumoniae, ESBL). C14R also inhibited biofilm formation by Gram-positive pathogens, with minimum biofilm inhibitory concentrations (MBICs), referring to the minimal concentration required to prevent the development of biofilms, of 15.0 µg/mL (Staphylococcus aureus, MRSA) and 22.0 µg/mL (E. faecium, VRE), whereas Gram-negative biofilms showed higher tolerance. Together, these findings demonstrate that C14R retains high activity against multidrug-resistant ESKAPE strains, highlighting its potential as a lead compound for the development of next-generation antimicrobial drugs to expand the portfolio of available antibiotics and brace health systems against emerging severe infections. Full article

Background: Poultry-associated Enterococcus spp. are widespread commensals but may serve as One Health indicators when virulence-associated determinants and antimicrobial resistance co-occur. We characterized paired phenotypic and genomic profiles to delineate species-stratified virulome and resistome patterns. Methods: Isolates originated from a previously established poultry collection with MIC testing. Genotype–phenotype analyses were restricted to the whole-genome sequenced subset (n = 31). The acquired antimicrobial resistance genes were identified using the Comprehensive Antibiotic Resistance Database (CARD), and virulence-associated determinants were screened using the Virulence Factors Database (VFDB). Results were summarized as isolate-level presence/absence matrices and integrated with MIC-derived susceptible/intermediate/resistant categories. Results: The WGS subset comprised E. faecalis (n = 23) and E. faecium (n = 8) with diverse sequence types. Virulome architecture was strongly species-dependent: E. faecalis carried a broad repertoire of adhesion/biofilm-associated determinants, whereas E. faecium showed a limited set of high-confidence virulence-associated hits. Acquired resistance determinants were common across isolates, and resistome profiles displayed structured co-occurrence. Integrated analyses suggested only a modest overall association between virulence-gene burden and acquired resistome size, largely driven by species-level differences. Genotype–phenotype concordance was class-dependent, with incomplete alignment in several antimicrobial classes, consistent with mechanisms beyond the screened acquired gene set. The acquired resistance determinants detected in the WGS subset predominantly mapped to antimicrobial classes commonly used in food-producing animals (e.g., tetracyclines, macrolides, lincosamides, aminoglycosides, and phenicols), supporting interpretation in the context of production-associated antimicrobial selection rather than implying last-line clinical resistance by default. Conclusions: Poultry-derived enterococci may combine genetic features compatible with persistence/colonization and acquired antimicrobial resistance, with co-occurrence patterns shaped primarily by species/lineage background. These findings support risk-stratified One Health surveillance and targeted functional and mechanism-focused follow-up. This integrated virulome–resistome view highlights species-specific risk signatures in poultry-associated Enterococcus and identifies discordant high-level phenotypes that merit targeted mechanistic follow-up. Full article

Vancomycin-resistant Enterococcus faecium (VREfm) is an emerging pathogen responsible for healthcare-associated infections. For this reason, 44 VREfm isolates collected during 2021–2023 were characterized using phenotypic and genomic approaches. VREfm isolates were identified by MALDI-TOF and antimicrobial susceptibility tests were performed with Vitek 2, Sensititre, or E-test. Sequence type (ST), antibiotic resistance genes, virulence factors and genetic relatedness were determined using Next Generation Sequencing. Forty-three isolates had a VanA phenotype and vanHAX genotype and one had a VanB phenotype and vanHBX genotype. Isolates showed high antibiotic resistance to various antibiotics, but generally remained susceptible to quinupristin/dalfopristin, tigecycline and eravacycline. Two isolates were resistant to linezolid, showing the chromosomal mutation G2576T in domain V of the 23S rRNA gene in one isolate, and the transferable linezolid resistance genes cfr(D) and optrA in the other. Thirty-eight isolates belonged to ST80, one to ST17 (ST80 and ST17 are included in CC17) and one to ST697. Genomic analysis of the ST80 isolates showed that nearly all of them belonged to a single cluster. To prevent further spread of VREfm in the nosocomial environment, in addition to the application of up-to-date infection control strategies and antibiotic stewardship programs, the implementation of genomic surveillance is recommended. Full article

The rise of multidrug-resistant enteric pathogens and increased demand for antibiotic alternatives have intensified efforts to find reliable, safe, and effective probiotics. This study reports the isolation, characterization, and assessment of the probiotic potential of five Enterococcus strains isolated from the feces of healthy goats aged 7–9 months raised under conventional management. Following an initial screening of 57 lactic acid bacteria, 5 isolates (Enterococcus faecium, E. hirae, E. faecalis, Enterococcus sp., and Streptococcus lutetiensis) were chosen based on their catalase-negative, non-motile, and non-hemolytic characteristics, in addition to their high tolerance to gastric (pH 2.0) and intestinal (pH 8.0, 0.3–1.5% bile salt) stress. In simulated gastric juice, survival rates reached 89.05% (E5) and 85.03% (E3), while in intestinal juice, survival peaked at 78.01% (E4). All strains thrived in 4% NaCl and maintained at least 8 Log₁₀ CFU/mL after 12 h of exposure to 1.5% porcine bile salt. Cell surface hydrophobicity (0.78–93.85%) and auto-aggregation (23–91%) properties were strain-dependent, but exceeded the thresholds required for efficient gut colonization. Co-aggregation assays demonstrated over 45% binding with E. coli and S. typhimurium, suggesting a strong potential to displace pathogens. Cell-free supernatants created inhibition zones measuring 15.02 mm against E. coli and 11.04 mm against S. flexneri, while maintaining activity against methicillin-resistant S. aureus (MRSA). Antibiotic testing indicated that all strains were sensitive to ciprofloxacin and florfenicol. No β-hemolysis or mobile resistance genes were found, supporting the initial safety findings. This study reveals that Enterococcus isolates from goats display a unique combination of gastrointestinal survivability and broad-spectrum antipathogenic activity and, therefore, are promising candidates for the development of next-generation probiotic strains for use in livestock (and, potentially, humans). Further in vivo validation and genome-based safety assessments are warranted. Full article