Search Results (559)

Background/Objectives: Antimicrobial resistance is a major public health concern requiring integrated surveillance across human, animal, and environmental sectors. Enterococcus spp. are widely distributed opportunistic bacteria with the capacity to acquire and disseminate resistance and virulence determinants. This study aimed to characterize species distribution, phenotypic antimicrobial resistance, resistance genes, and virulence-associated traits in Enterococcus spp. from One Health sources. Methods: Enterococci were recovered from 66 samples collected in Lisbon, Portugal, between late 2022 and early 2024, including healthy and sick humans, healthy and sick animals, canteen food, surface water, and public transport surfaces. RAPD-PCR was used to assess genetic diversity among 90 isolates and select 74 representative enterococci. Species identification, resistance gene screening, and virulence gene detection were performed by PCR. Antimicrobial susceptibility was assessed by disk diffusion against 12 antibiotics using CLSI criteria. Vancomycin resistance was further evaluated by agar dilution and Etest when applicable. Results: Enterococcus faecalis predominated, representing 63/74 isolates (85.1%), followed by Enterococcus faecium (5/74, 6.8%) and other Enterococcus spp. (6/74, 8.1%). Antibiotic resistance was detected across all One Health sectors. Sick Human isolates showed higher resistance than Healthy Human isolates. E. faecium showed higher resistance than E. faecalis, and all E. faecium isolates across sectors were multidrug-resistant. Rifampicin resistance was frequent, as was quinupristin-dalfopristin resistance (excluding intrinsically resistant E. faecalis), while linezolid resistance was not detected. Resistance and virulence determinants were distributed across sectors. Conclusions: Enterococci from human, animal, and environmental sources carried antimicrobial resistance and virulence-associated traits. These findings support integrated One Health surveillance to monitor resistant enterococci across interconnected reservoirs. Full article

Enterococci are environmentally persistent bacteria that are relevant to both water quality and the spread of antimicrobial resistance. This study aimed to phenotypically and genotypically characterize Enterococcus spp. isolated from freshwater (lakes and rivers) in north–central Poland, with a focus on antimicrobial susceptibility, virulence genes, and biofilm-forming capacity. Surface water samples were collected during the vegetation seasons of 2022 and 2023. Enterococci were isolated by culture-based methods and confirmed by MALDI-TOF MS. Antimicrobial susceptibility testing (AST) was performed using the disk diffusion method, virulence-associated genes were detected by multiplex PCR, and biofilm formation was evaluated using a crystal violet assay. In total, 96 Enterococcus spp. isolates representing 12 species were identified from 328 freshwater samples, with E. faecalis (24.0%) and E. hirae (21.9%) being the most frequently isolated. Thirty-one isolates (32.3%) were resistant to at least one antibiotic, and two isolates were classified as multidrug-resistant. The most prevalent virulence genes were gelE, srtA, and hyl. The ace gene was detected exclusively in E. faecalis. Most isolates were non-biofilm producers, while biofilm formation was confirmed in 8 strains (6 weak and 2 moderate producers), with no strong biofilm-forming strains detected. These findings suggest that freshwater ecosystems may constitute important reservoirs of antimicrobial-resistant and virulence-associated Enterococcus spp., underscoring the importance of continuous surveillance within the One Health framework. Full article

The aim of this study was to isolate and molecularly identify lactic acid bacteria (LAB) associated with the epiphytic microflora and silage of wheatgrass (Agropyron spp.), as well as to evaluate their biotechnological potential as starter cultures for the ensiling of difficult-to-ensile forage crops under the climatic conditions of northern Kazakhstan. A total of 63 bacterial isolates were obtained and grown on MRS medium under different temperature conditions. Based on growth characteristics, pH values, and titratable acidity, 15 highly active strains were selected, demonstrating stable acidification (pH 3.99–4.75) and high metabolic activity. All isolates were catalase negative and capable of fermenting a wide range of carbohydrates and polyols, although pronounced strain-specific differences were observed. The selected strains exhibited proteolytic and antagonistic activity against test microorganisms and showed high tolerance to osmotic stress, maintaining growth at NaCl concentrations of up to 8–10%. Molecular identification based on 16S rRNA gene sequencing revealed that nine technologically significant strains belonged to the species Lactococcus garvieae, Pediococcus acidilactici, Lactiplantibacillus plantarum, Enterococcus faecalis and Enterococcus faecium. The results obtained in this study demonstrate the high environmental adaptability of the isolated strains and confirm their potential for the development of effective microbial inoculants aimed at improving fermentation processes and enhancing the preservation of difficult-to-ensile forage crops under cold-climate conditions. Full article

The rise in antimicrobial resistance and the resilience of microbial biofilms demand innovative strategies that combine, for instance, membrane-active agents with marketed drugs. Arginine-based surfactants are promising alternatives to conventional quaternary ammonium compounds, but comparative data on their antimicrobial, antibiofilm and modulatory activities remain limited. Five arginine-derived surfactants, the single-chain Nα-lauroyl-L-arginine methyl ester (LAM) and ethyl ester (LAE), together with their double-chain homologues LANHC₃, LANHC₅ and LANHC₈ were evaluated against Gram-positive and Gram-negative bacteria and four Candida spp. Minimum inhibitory (MIC) and lethal (MLC) concentrations were determined by broth microdilution method. Antibiofilm activity was assessed through minimum biofilm inhibitory (MBIC) and eradication (MBEC) concentrations. Checkerboard assays were used to evaluate the synergism between the surfactants and conventional therapeutic antibacterial and antifungal agents. LANHC₃ and LANHC₈ exhibited uniform antibacterial MICs of 19.53 µg/mL, while LAM and LANHC₅ showed MICs of 19.53 µg/mL for most strains, with Enterococcus faecalis requiring 39.06 µg/mL. LANHC₃ was the most potent surfactant over Candida spp. With MICs of 9.76 µg/mL for all species, and similarly to LAM, both were fungicidal at 39.06 µg/mL. LAM and LANHC₃ also showed the lowest MBIC and MBEC values, inhibiting the Candida biofilm formation at 39.06 µg/mL and eradicating mature biofilms at 78.12 µg/mL, while the other surfactants required higher concentrations to disrupt the microbial biofilms. Synergic or additive interactions were found between the surfactants and selected β-lactam and macrolide antibiotics, as well as azole antifungals, with no antagonism observed. LAM and particularly LANHC₃ combined broad-spectrum antimicrobial activity, relevant antibiofilm effects and the ability to potentiate the activity of conventional agents, supporting their choice as alternative or complementary antimicrobial adjuvants over resistant microorganisms and their biofilms. Full article

Attention-deficit/hyperactivity disorder (ADHD) is a complex neurodevelopmental disorder increasingly discussed within the microbiota-gut–brain axis. This narrative review synthesizes evidence on bacterial and fungal dysbiosis in ADHD, with emphasis on Candida spp., diet, probiotics, synbiotics, and health-related quality of life. A structured narrative search of PubMed/MEDLINE, Scopus, and KoBSON-accessible sources was performed for studies addressing ADHD, gut microbiota, mycobiome, Candida, nutrition, microbiome-targeted interventions, and quality of life. Evidence was synthesized thematically because of methodological heterogeneity. Available studies suggest that ADHD may be associated with altered gut microbial diversity, changes in taxa such as Faecalibacterium, Blautia, Odoribacter, and Enterococcus, and immune–metabolic alterations. However, findings are heterogeneous and do not support a single ADHD-specific microbial signature. The fungal component remains insufficiently investigated, although evidence indicates increased Candida, particularly Candida albicans, in children with ADHD and a possible link with intestinal permeability. Dietary quality, micronutrient status, probiotics, and synbiotics may modulate microbiota–gut–brain pathways, but should be considered complementary and individualized, particularly in patients with gastrointestinal, dietary, immune, or metabolic vulnerability. Bacterial and fungal dysbiosis may represent biologically plausible, primarily associative components of ADHD-related pathophysiology. Evidence remains preliminary, exploratory, non-causal, and requires cautious interpretation in future research and clinical settings. Full article

Background: Aerobic vaginitis (AV) is characterized by dysbiotic vaginal microflora with overgrowth of aerobic pathogens of enteric origin, presence of vaginal inflammation and immature epithelial cells. This study aimed to evaluate, over a period of 10 years, women of reproductive age (non-pregnant and pregnant) as well as menopausal women affected by AV. Methods: We included non-pregnant, pregnant and menopausal women diagnosed with AV over a period of 10 years. Diagnosis of AV was determined according to the criteria proposed by Donders in 2002. The isolated pathogens were identified with the rapid identification system I-dOne (Alifax S.r.l, Polverara, Italy) and the automated system VITEK2 (Biomerieux, Marcy l’Etoile, France), which was used for antimicrobial susceptibility testing. Results: The overall aerobic vaginitis prevalence rate during the studied period was 9.5%. The most common isolated pathogens were Escherichia coli 27.3%, Enterococcus faecalis 25.0%, Streptococcus agalactiae 22.2%, Klebsiella pneumoniae 8.9%, Proteus spp 4.7%, and Staphylococcus aureus 3.5%. E. coli infection significantly increased the odds of mild AV by 1.65 times (p = 0.002) and Proteus species infection was over 6 times more likely to progress to severe disease (p < 0.001). Furthermore, pregnant women were more likely to be infected with E. faecalis (p < 0.001) while menopausal women were diagnosed significantly more with severe AV (p < 0.001) compared to the other groups. Conclusions: The prevalence of aerobic vaginitis in the population studied was in concordance with global rates. Menopausal women displayed increased severe AV cases while, in contrast, mild cases were recorded during pregnancy. The most commonly isolated pathogens were of enteric origin. Full article

Background/Objectives: The role of the endometrial microbiome in reproductive failure remains incompletely understood. This study aimed to describe the composition of the endometrial microbiome in women evaluated for infertility or recurrent miscarriage. Methods: In this single-center descriptive study, endometrial samples were collected from women evaluated for infertility or recurrent miscarriage. Microbiome profiling was performed using 16S rRNA gene next-generation sequencing. Samples were classified as Lactobacillus-dominant when Lactobacillus spp. accounted for ≥90% of the total bacterial community. Alpha diversity was assessed using the Shannon and Simpson indices, while beta diversity was evaluated using Bray–Curtis dissimilarity, principal coordinates analysis (PCoA), PERMANOVA, and PERMDISP. Results: Of the 60 samples, 20 (33.3%) were Lactobacillus-dominant and 40 (66.7%) were non-Lactobacillus-dominant. Across all samples, Firmicutes was the predominant phylum (76.6%). Non-Lactobacillus-dominant samples showed significantly higher alpha diversity than Lactobacillus-dominant samples for both the Shannon and Simpson indices (p = 1.19 × 10⁻⁶ and p = 1.51 × 10⁻⁶, respectively), as well as higher observed taxa richness (p = 0.000017). PCoA based on Bray–Curtis dissimilarity demonstrated clear separation between microbiome profiles, supported by PERMANOVA (pseudo-F = 13.87, R² = 0.193, p = 0.001). PERMDISP showed significantly greater dispersion among non-Lactobacillus-dominant samples (F = 566.94, p < 0.001). Non-Lactobacillus-dominant samples showed greater representation of Enterococcus and Prevotella. Conclusions: In this cohort non-Lactobacillus-dominant communities were more frequent with greater diversity, richness, and compositional heterogeneity than Lactobacillus-dominant communities. These findings highlight the need for larger, standardized studies with appropriate control populations to clarify their clinical significance. Full article

Nosocomial pathogens persist on hospital surfaces contributing to healthcare-associated infections (HAIs), especially among vulnerable patients and in the presence of multidrug-resistant strains. Environmental surveillance is essential to prevent cross-contamination and support timely infection control interventions. However, conventional culture-based methods, although considered the gold standard, are labor-intensive and time-consuming, often delaying critical responses. This study evaluated loop-mediated isothermal amplification (LAMP) as a rapid screening tool for hospital environmental monitoring. A total of 100 surface samples were collected from different hospital wards and analyzed using both culture and LAMP assays targeting six major HAI-related pathogens: Pseudomonas aeruginosa, Staphylococcus aureus, Enterococcus spp., Escherichia coli, Klebsiella pneumoniae, and Acinetobacter baumannii. LAMP showed excellent performance, with sensitivity of 1.00 for all targets and specificity ranging from 0.94 to 1.00. No statistically significant differences were observed between LAMP and culture results (p > 0.05). LAMP may represent a valuable complementary method for routine environmental surveillance. Full article

Background/Objectives: Vancomycin-resistant (VRE) and vancomycin-variable (VVE) Enterococcus spp. represent an increasing clinical challenge due to limited treatment options and the potential for undetected dissemination of such resistance genes. Data on Enterococci genomic epidemiology in healthcare settings remain rather limited. Our study aimed to investigate vancomycin resistance determinants in Enterococcus spp., clonal structure, and occurrence of VVE using whole-genome sequencing (WGS) in Latvia. Methods: Clinical isolates collected from hospitalised patients in two tertiary-level hospitals in Latvia (2021–2024) were analysed using WGS following routine laboratory identification. Vancomycin resistance determinants were identified in silico, along with MLST and cgMLST genotyping. Results: Of 532 sequenced isolates, 482 met the quality and inclusion criteria. E. faecalis (56.64%) and E. faecium (40.25%) predominated. Among 125 isolates carrying vancomycin resistance genes, vanB (54.40%) was the most frequent, followed by vanA (38.20%) and vanC (6.40%); vanC was restricted to E. gallinarum and E. casseliflavus. Vancomycin resistance was more prevalent in E. faecium (51.03%) than in E. faecalis (6.59%). cgMLST identified outbreak clusters among E. faecium ST80 and ST78 with complex type-specific resistance patterns and hospital specificity. E. faecalis showed polyclonal endemicity with the vanB gene present in different clades. Three (0.62%) vancomycin-variable E. faecium (VVE) isolates were identified in one hospital, harbouring vanA-type gene clusters comprising vanHAX but lacking the sensory gene vanS and the regulatory gene vanR. Conclusions: The VanB gene predominated in both hospitals, driven by clonal expansion of hospital-adapted E. faecium ST80/ST78, contrasting with earlier vanA predominance in Europe but aligning with recent regional vanB trends. The detection of VVE highlights clinically relevant genotype–phenotype discordance, underscoring the importance of integrating genomic surveillance with routine phenotypic testing to detect cryptic resistance and guide effective antimicrobial therapy. Full article

Background: Infections remain a major complication in patients with left ventricular assist devices (LVADs). Enterococcal infections are increasingly recognized and are therapeutically challenging because of antimicrobial tolerance, biofilm formation on prosthetic material, and the frequent impossibility of device removal. Objective and method: We report two clinical cases of Enterococcus faecalis LVAD infection and a PRISMA-based systematic review of cases published between 1996 and 2025 that were identified through PubMed/MEDLINE. Primary outcomes were clinical cure, relapse or recurrence, mortality, and device removal. Results were synthesized descriptively. Results: Seventeen cases were analyzed, including 15 previously reported cases and two new cases. E. faecalis accounted for 47% of infections, Enterococcus faecium for 29%, and Enterococcus spp. without species identification for 24%. Bacteremia was the most common presentation, occurring in 76%, whereas LVAD-associated endocarditis occurred in 18%. Driveline or pocket involvement was reported in 41%. Suppressive antimicrobial therapy (SAT) was used in 29%, often as a bridge to heart transplantation. Cultures from explanted LVAD components were positive in 47% of cases despite prolonged antimicrobial therapy. Recurrence or relapse and overall mortality each occurred in 18% of patients. Conclusions: Enterococcal LVAD infections may be associated with microbiological persistence despite prolonged therapy. SAT may help control infection in selected patients and bridge to heart transplantation when device removal is not feasible. Full article

Enterococci are among the most frequently isolated environmental bacteria that cause mastitis in cows. This study aimed to determine the prevalence of virulence genes, as well as phenotypic and genotypic antibiotic resistance, among eighty enterococcal isolates from cases of bovine mastitis in Polish herds. The presence of virulence and antibiotic resistance genes was determined by PCR. E. faecalis isolates were found to carry more virulence genes than E. faecium isolates, including the efaA_fs (100%), ace (98.1%), gelE (86.5%), asa1 (63.5%), esp (57.7%) and cylA (17.3%) genes. The efaA_fm gene was the only virulence gene detected in E. faecium isolates. This study revealed that E. faecalis showed a higher virulence gene burden. The ermB gene was present in 90.9% of the Enterococcus spp. that were phenotypically resistant to erythromycin. Almost all tetracycline-resistant Enterococcus isolates carried the tet(M) gene (94.3%), either alone or in combination with the tet(L) and tet(O) genes. Three isolates harboured vanC genes and were susceptible to vancomycin (MIC = 4 μg/mL). The results confirm the high level of antimicrobial resistance of enterococci isolated from cows with mastitis and indicate the genes that may be responsible for this resistance. Full article

Background: Urinary tract infections (UTIs) are among the most common bacterial infections worldwide and represent a significant public health concern due to their high prevalence and increasing antimicrobial resistance. This study aimed to systematically review the epidemiology, uropathogens, and resistance patterns of UTIs in Portugal over the last decade. Methods: A systematic review was conducted in accordance with PRISMA 2020 guidelines. A literature search was performed in April 2026. A total of 425 records were identified. After removal of duplicates and preliminary exclusions, 121 records were screened by title and abstract. Following application of eligibility criteria, 41 full-text articles were assessed, of which 13 met the criteria for detailed eligibility assessment. Six studies met the inclusion criteria and were included in the final qualitative synthesis. Results: The included studies consistently reported a higher prevalence of UTIs in females and, in some cases, in older populations. Escherichia coli was identified as the predominant uropathogen across all studies, followed by Klebsiella pneumoniae, Proteus spp., and Enterococcus spp. A consistently high prevalence of antimicrobial resistance was observed, particularly against commonly used antibiotics such as ampicillin and trimethoprim–sulfamethoxazole. The presence of extended-spectrum β-lactamase (ESBL)-producing strains was also reported, especially in healthcare-associated infections, which exhibited higher resistance profiles compared to community-acquired infections. Conclusions: The available evidence suggests that UTIs in Portugal are predominantly caused by enterobacteria, particularly Escherichia coli. However, the limited number and heterogeneity of studies highlight the need for cautious interpretation. Further multicenter and methodologically robust studies are required to better characterize national epidemiological patterns and antimicrobial resistance trends. Full article

Urinary tract infections (UTIs) are among the most common bacterial infections worldwide and are traditionally considered acute and self-limited conditions. However, growing evidence suggests that recurrent or persistent UTIs may contribute to chronic kidney disease (CKD) progression through complex interactions between uropathogens and host responses. This review examines the pathophysiological links of UTIs caused by uropathogenic Escherichia coli, Klebsiella spp., and Enterococcus spp. and the development of chronic renal injury. Pathogen-specific persistence mechanisms, including intracellular survival, biofilm formation, and chronic colonization, may promote sustained inflammation, oxidative stress, and maladaptive repair responses. These processes are associated with tubular injury and progressive fibrotic remodeling. In addition, host-related factors such as diabetes, immune dysfunction, and antimicrobial resistance may further influence disease progression. Emerging biomarkers of inflammation, tubular injury, and fibrosis may improve early detection and risk stratification in patients with recurrent or complicated UTIs. Collectively, these findings support the concept that recurrent UTIs may represent potential contributors to CKD progression in susceptible individuals and highlight the importance of early recognition, pathogen-oriented management, and improved diagnostic strategies. Full article

Antimicrobial peptides such as Melittin exhibit potent broad-spectrum activity but are limited by high cytotoxicity. The rational design of bioinspired Melittin-derived analogues represents a promising strategy to reduce toxicity while maintaining antimicrobial efficacy. In this study, Melittin and analogues (TT-1, FKW, and WKW) were synthesized using solid-phase peptide synthesis (SPPS) and characterized for biological and biophysical essays. Antimicrobial and hemolytic activity, serum stability, secondary structure, and membrane interaction were analysed. FKW and WKW exhibited broad-spectrum antimicrobial activity, with minimum inhibitory concentration (MIC) as low as 8 and 16 µg/mL against Staphylococcus aureus and Enterococcus faecium. Both analogues also showed improved activity against Klebsiella pneumoniae (32 µg/mL) and Pseudomonas aeruginosa (128 and 256 µg/mL for FKW and WKW, respectively) compared to Melittin (64 and 512 µg/mL). In terms of cytotoxicity, FKW and WKW showed significantly reduced hemolytic activity, with HC₅₀ values of 264.8 µg/mL and 237.2 µg/mL, respectively, resulting in improved selectivity indexes relative to Melittin (HC₅₀ of 7.9 µg/mL). In liposomes, both adopt α-helical structures and cause disruption via pore formation or detergent-like mechanisms. TT-1 showed minimal toxicity but weak antimicrobial activity (MIC > 256 µg/mL). Although FKW and WKW exhibited limited serum stability (half-lives of 2.2 and 1.5 h), their degradation may reduce systemic toxicity. Overall, these analogues demonstrate an improved balance between antimicrobial activity and safety. Full article

Background/Objectives: Pet birds are increasingly recognized as potential reservoirs of zoonotic and antimicrobial-resistant bacteria, raising concerns within the One Health framework. However, data on bacterial diversity and resistance profiles in clinically affected ornamental birds remain limited. Methods: This study, conducted over three years (November 2022–March 2026), included 198 pet birds presenting with digestive and respiratory disorders. From these birds, clinical samples were analyzed bacteriologically; resulting isolates were identified by MALDI-TOF mass spectrometry, and antimicrobial susceptibility assessed using the Kirby-Bauer disk diffusion method according to EUCAST and CLSI guidelines. Results: Bacterial growth was detected in 87.9% of cases, yielding 249 distinct isolates. Gram-positive cocci predominated (62.3%), led by Staphylococcus spp. (33.3%) and Enterococcus spp. (9.6%), while Escherichia coli (9.2%) was the primary Gram-negative species. At the genus level, Staphylococcus spp. demonstrated high susceptibility to amikacin (88.5%) but significant resistance to gentamicin (75.6%) and oxytetracycline (63.6%). In contrast, Escherichia spp. isolates were largely resistant, showing only 50% susceptibility to enrofloxacin and 40% to doxycycline, with resistance to tylosin reaching 90%. Overall, 57% of isolates were multidrug-resistant, with Staphylococcus spp. contributing most to this burden. Conclusions: These findings characterize clinically ill pet birds as significant carriers of multidrug-resistant bacteria, highlighting the need for routine diagnostics and improved antimicrobial stewardship in avian medicine. Full article