Search Results (579)

The rapid emergence of multi-drug resistant (MDR) bacteria has become a major health concern, driving the need to identify new antimicrobial resources. Recently, endophytes, inhabiting in internal tissues of medicinal plants, have drew important interest from the scientific community, as reservoirs of bioactive metabolites. Numerous studies highlight the symbiotic relationship between plants and their endophytes, in which these microorganisms produce antimicrobial compounds, helping the host plant’s defense against pathogens. Plantago major (commonly known as plantain) is widely recognized for its therapeutic properties, especially for its antimicrobial properties. In this study, endophytic fungi were isolated from Plantago major, morphologically characterized and identified using ITS sequencing. Their antibacterial activity was assessed using the agar diffusion assay. In total, 21 endophytic fungal isolates were obtained from different plant tissues, including leaves, stems, roots, and flowers. Antibacterial assays against methicillin-resistant Staphylococcus aureus (MRSA) were investigated on PDA, SDA, and CDA media. Amongst the isolates, nine strains (MD-H1, MD-L1, MD-L2, MD-L3, MD-L4, MD-L5, MD-R1, MD-T1, MD-T2, and MD-T10) showed medium to strong antibacterial effects, with inhibition zones exceeding 15 mm. The result suggests that endophytic fungi associated with Plantago is a valuable source of anti-MRSA compounds. Further work will focus on identifying the secondary metabolites responsible for this activity and elucidating their chemical structures, providing a basis for the development of new potent antibiotic agents. Full article

Methicillin-resistant Staphylococcus aureus (MRSA) is a major antimicrobial-resistant pathogen affecting both human and animal health. Although historically associated with healthcare settings, MRSA is now established in livestock production and throughout the production chain. Its detection in animals, food products, and processing environments reflects the complex ecology of antimicrobial resistance (AMR) in modern food systems. This narrative review synthesizes current evidence on the molecular basis of methicillin resistance and multidrug resistance determinants, as well as the epidemiology of MRSA in food-associated settings. Particular emphasis is placed on its occurrence in animal-derived foods and key reservoirs within farms, slaughterhouses, and processing environments. Livestock-associated populations are dominated by clonal complex CC398. In contrast, CC9 is prevalent in pig production systems in Asia, while CC5-related lineages occur at the human and animal interface. MRSA has been detected in retail meat and animal-derived foods at low but measurable prevalence, indicating contamination during slaughter and processing. Virulence determinants include staphylococcal enterotoxins linked to food poisoning and Panton–Valentine leukocidin associated with severe infections. Biofilm formation and adhesins further support persistence and colonization. Epidemiological and molecular evidence indicates that livestock, processing environments, and food-contact surfaces act as interconnected reservoirs sustaining MRSA circulation. Human exposure occurs primarily through occupational contact and environmental pathways, whereas foodborne transmission appears less common. Effective control requires integrated surveillance, responsible antimicrobial use in livestock production, and strict hygiene practices throughout the production chain within a One Health framework. Full article

Background/Objectives: Carbon dots (CDs) are promising antimicrobial nanomaterials owing to their biocompatibility, environmental friendliness, and tunable surface chemistry. This study aimed to synthesize nitrogen-doped CDs (AS-CDs) and develop a light-responsive antibacterial system through conjugation with chlorin e6 (Ce6). Methods: AS-CDs were synthesized by a microwave-assisted method using L-ascorbic acid and spermidine, followed by conjugation with Ce6. The materials were characterized by transmission electron microscopy, zeta potential analysis, and spectroscopic methods, and their antibacterial activity was evaluated against Escherichia coli, Staphylococcus aureus, and methicillin-resistant S. aureus (MRSA) under both dark and visible-light conditions. Cytotoxicity was assessed using HaCaT cells. Results: The AS-CDs exhibited a uniform nanoscale morphology with an average diameter of 6.3 nm and a positive surface charge of +15.6 mV, together with intrinsic broad-spectrum antibacterial activity. Ce6 conjugation further enhanced antibacterial efficacy under light irradiation, with the CDs-Ce6 conjugate achieving complete eradication of S. aureus and MRSA and marked inhibition of E. coli at 2.5 μg/mL. Cytotoxicity studies demonstrated low toxicity in HaCaT cells within the effective antibacterial concentration range. Conclusions: These findings highlight the potential of microwave-synthesized, photosensitizer-conjugated CDs as next-generation antimicrobial agents. This platform offers a cost-effective, sustainable, eco-friendly, and efficient platform for combating bacterial infections, with broader potential in pharmaceutical and biomedical applications. Full article

Background/Objectives: The rise in healthcare-associated infections caused by multidrug-resistant (MDR) bacteria in hospitals, particularly in intensive care units, has resulted in increased rates of morbidity and mortality, escalating costs, and has become a significant public health concern. In our Intensive Care Unit, we address healthcare-associated infections caused by multidrug-resistant bacteria, with a specific focus on those listed in the WHO 2024 List of Critically and Highly Prioritized Pathogens. Methods: Over the course of 1 year, from 1 January to 31 December 2024, we monitored the prevalence of healthcare-associated infections in the Intensive Care Unit of the Sibiu County Emergency Clinical Hospital, Romania, and the antibiotic susceptibility of the isolated bacteria. Results: The majority of infections were caused by pathogens in the ESKAPEE group. The most frequently isolated microorganism was Klebsiella pneumoniae (36.8%), followed by Acinetobacter baumannii (24.5%), classified as a critical priority by the WHO in 2024. Most positive samples for critical priority pathogens, including Klebsiella pneumoniae and Acinetobacter baumannii, as well as all MRSA strains (high priority), were obtained from tracheal aspirates collected from intubated and mechanically ventilated patients. A significant proportion of the isolated bacteria were multidrug-resistant, including extensively drug-resistant and pan-drug-resistant strains. Conclusions: The increase in antibiotic and antimicrobial resistance among hospital strains raises serious concerns about limited treatment options. Full article

Methicillin-resistant S. aureus (MRSA) is listed by the World Health Organization as a priority pathogen posing a major worldwide threat to public health. Two lineages of MRSA predominate as causes of human infections in the U.S.: USA300 and USA100. Although they are most often grouped together as MRSA, these two lineages differ in pathogenetic mechanisms in important ways. The epidemic spread of these two dominant lineages has been problematic because of the multidrug-resistant profile of USA100 and the virulence of USA300, as well as their ability to adapt to both community and hospital environments. In this perspective, we examine what is currently known about their distinctive biology and the consequent differences in infections caused by these two main MRSA epidemic clones. The purpose of this perspective is to provide critical insights to the clinical microbiology community to stimulate further research to inform the design of new prevention and management strategies for MRSA. Full article

Background: Staphylococcus aureus bloodstream infections cause substantial hospital mortality (20–50%). Surveillance programs primarily focus on methicillin-resistant S. aureus (MRSA) as a quality indicator, while comprehensive data comparing MRSA and methicillin-susceptible S. aureus (MSSA) hospital-onset bacteremia remain limited outside the UK, the USA, and Canada. This study aims to evaluate incidence trends of all hospital-onset S. aureus bloodstream infections (HO-SABSIs, defined as positive blood cultures ≥ 48 h post-admission) from 2013 onwards, comparing MRSA and MSSA incidence patterns and their associated mortality rates in an Italian tertiary-care hospital through surveillance data. Methods: Retrospective cohort study of all HO-SABSIs from January 2013 to December 2023 at a 458-bed Italian tertiary hospital. Primary outcome was incidence density (cases per 1000 patient-days) stratified by methicillin resistance. Standardized Infection Ratios (SIRs) were calculated using 2013–2015 and 2013–2019 as baseline periods. Temporal trends were analyzed using negative binomial regression. Results: Among 414 HO-SABSI cases, 183 (44.2%) were MRSA and 231 (55.8%) MSSA. MRSA incidence decreased significantly (−6.5% annually; IRR 0.935, 95%CI 0.883–0.991; p = 0.023) from 0.198 to 0.111 per 1000 patient-days. MSSA increased non-significantly (+4.9% annually; IRR 1.049, 95%CI 0.999–1.103; p = 0.056) from 0.103 to 0.239, surpassing MRSA after 2016 and peaking during COVID-19 (2021: SIR 2.41, 95%CI 1.33–4.37). MRSA cases had higher mortality than MSSA (40.6% vs. 27.5%; p = 0.005). Conclusions: MSSA has replaced MRSA as the predominant hospital-onset S. aureus bacteremia pathogen since 2016, with sustained elevation during and after the COVID-19 pandemic. Current MRSA-focused surveillance misses the majority of preventable staphylococcal bacteremias. Comprehensive hospital-onset S. aureus surveillance encompassing both phenotypes is essential for accurate epidemiological assessment and infection prevention. Full article

Antimicrobial resistance (AMR) represents a critical global health challenge, with methicillin-resistant Staphylococcus aureus (MRSA) posing a significant threat in both hospital-acquired and community-associated infections. Research has demonstrated that biofilm formation is a key factor contributing to drug resistance in MRSA. In this study, we investigated an fungus, Fusarium oxysporum BPF55, isolated from Blaps rynchopetera, which inhibits MRSA biofilm formation. The aim of this research was to identify the fungal strain and comprehensively characterize its genomic features, as well as to evaluate its anti-MRSA biofilm potential. Whole-genome sequencing revealed a genome size of 50,097,681 base pairs, a GC content of 47.36%, and 16,507 predicted coding genes. AntiSMASH analysis identified 56 secondary metabolite biosynthetic gene clusters, including those involved in the synthesis of various natural products such as terpenes, non-ribosomal peptides, and polyketides. Using UPLC-MS/MS, 15 compounds were annotated from the ethyl acetate extract. Molecular docking studies demonstrated that four compounds exhibit varying affinities for SarA and AgrA, two key proteins involved in MRSA biofilm formation. Overall, these findings suggest that the fungus F. oxysporum BPA55 produces a variety of secondary metabolites and contains bioactive compounds with potential anti-MRSA biofilm activity. Full article

Background: The increasing antimicrobial resistance has led to a greater demand for alternative treatment options, which in turn has increased interest in naturally occurring biomolecules such as pyocyanin. Methods: In this study, a three-factor Box–Behnken Design (BBD)-based response surface methodology (RSM) was employed to optimize the effects of glycerol, peptone, and pH on pyocyanin production by Pseudomonas aeruginosa OG1. The antimicrobial efficacy of the optimized pyocyanin was subsequently evaluated in vitro against three Candida species and four clinically important bacterial pathogens using the disk diffusion method, with gentamicin and fluconazole used as positive controls. Results: The second-order polynomial model demonstrated excellent fit (F = 176.3, p < 0.0001) with a non-significant lack of fit, indicating adequate representation of the experimental data. The optimal conditions were determined to be glycerol at 1.11% (w/v), peptone at 17.86 g/L, and a pH of 7.27, yielding a predicted pyocyanin concentration of 25.92 mg/L. Antimicrobial testing revealed broad-spectrum, dose-dependent activity against all tested microorganisms. The highest efficacy was observed against Bacillus cereus (26.4 ± 1.3 mm at 40 µg/mL), followed by Candida glabrata (21.5 ± 1.6 mm), Klebsiella pneumoniae (17.6 ± 1.4 mm), Candida albicans (15.4 ± 1.8 mm), Candida parapsilosis (13.2 ± 1.9 mm), Proteus mirabilis (12.5 ± 1.3 mm), and MRSA Staphylococcus aureus (9.2 ± 1.1 mm). Conclusions: These findings demonstrate that BBD-based RSM is a robust approach for optimizing pyocyanin production and that pyocyanin represents a promising dose-dependent antimicrobial agent against susceptible pathogens. Full article

Background: The global rise in antimicrobial resistance (AMR) has created an urgent need for innovative antibacterial strategies and localized delivery systems. This study aimed to develop and characterize electrospun poly (vinyl alcohol) (PVA) nanofibers co-loaded with atorvastatin (ATR) and zinc oxide (ZnO) nanoparticles for use as a multifunctional topical platform for wound healing and infection control. Methods: ZnO nanoparticles were prepared via ball milling and characterized for size and zeta potential. Four PVA-based nanofiber formulations were fabricated using electrospinning: blank (F1), ZnO-loaded (F2), ATR-loaded (F3), and ATR/ZnO co-loaded (F4). The nanofibers were evaluated for morphology, thermal properties, crystallinity, and drug release. Antibacterial efficacy was tested against S. aureus, S. epidermidis, MRSA, and P. aeruginosa using broth microdilution and checkerboard assays. Biocompatibility and wound healing potential were assessed via MTT and fibroblast scratch assays on human foreskin fibroblasts (hFFs). Results: SEM imaging confirmed the production of uniform, bead-free nanofibers. ATR and ZnO nanoparticles were successfully incorporated in the nanofiber. The co-loaded formulation (F4) demonstrated a sustained release profile, releasing approximately 78.7% of ATR over 24 h. While all treatments showed limited activity against P. aeruginosa, the ATR/ZnO co-loaded nanofibers exhibited significantly enhanced antibacterial activity against Gram-positive strains, achieving the lowest MIC values (1.5–2.0 mg/mL). Synergy analysis confirmed an enhanced effect with ATR and ZnO against MRSA. Furthermore, F4 achieved the highest wound closure rate of 92.41% in 24 h while maintaining acceptable cytocompatibility. Conclusions: The integration of ATR and ZnO into PVA nanofibers provides an enhanced antibacterial effect consistent with the synergistic potential observed between free agents targeting Gram-positive wound pathogens. The platform’s ability to simultaneously inhibit bacterial growth and promote rapid fibroblast migration positions it as a promising localized therapeutic for managing infected wounds. Full article

Nanotechnology combined with photodynamic therapy (PDT) has been explored to enhance antitumor and antimicrobial photobiological activity. Aluminum phthalocyanine chloride (Al-Pc-Cl), with or without magnetic nanoparticles (MagNPs), was incorporated into polymeric nanoparticles (PNPs) to improve the PDT for treating tumors and infectious diseases. Three batches of the nanoparticles (MagNPs, PNPs-PS and PNPs-PS-MagNPs) were developed and characterized in terms of size, PdI, morphology by TEM, release study, and antitumor (against A549 cells) and antimicrobial (against MRSA and C. albicans) photobiological activity. The developed nanoparticles were nanometric in size, with MagNPs, PNPs-PS, and PNPs-PS-MagNPs showing 33.6, 186.9, and 333.5 nm, respectively, maintained the magnetic properties (for MagNPs and PNPs-PS-MagNPs), and provided slow and sustained release of the photosensitizer. PNPs-PS and PNPs-PS-MagNPs showed excellent antitumor photobiological activity with cell viabilities of 42 and 34%, respectively, and were not cytotoxic in the dark, with cell viabilities above 70%. PNPs-PS showed strong antibacterial activity against MRSA with an IC₅₀ of 8.26 μg/mL, which was lower to free Al-Pc-Cl with an IC₅₀ of 14.22 μg/mL after I radiation. The results of the antifungal photobiological activity against C. albicans were excellent, with IC₅₀ values of 3.75 and 3.5 μg/mL for PNPs-PS and PNPs-PS-MagNPs, respectively, values which were significantly lower with p < 0.05 than free PS (IC₅₀ > 30 μg/mL) after irradiation with light and fluconazole (IC₅₀ > 30 μg/mL), the reference antifungal agent. PNPs-PS showed promising results regarding antitumor, antibacterial, and antifungal photobiological activity. However, PNPs-PS-MagNPs showed weak results for antibacterial photobiological activity against MRSA but with promising results for tumor cells and C. albicans. Full article

Background/Objectives: The widespread use of mupirocin and fusidic acid for the treatment and decolonization of Staphylococcus aureus (SA) skin infections has led to a rapid emergence of resistant strains, limiting the effectiveness of the few topical agents currently available for clinical use. Methods: In this study, we evaluate Fe(tropo)₃, a neutral and lipophilic iron(III)–tropolone complex, as a non-antibiotic topical antimicrobial candidate for the management of drug-resistant SA skin and soft tissue infections. Results: Fe(tropo)₃ exhibits potent in vitro activity against methicillin-susceptible SA, methicillin-resistant SA (MRSA), vancomycin-intermediate SA, and strains with high-level resistance to mupirocin and fusidate, with minimum inhibitory concentrations of 2 µg/mL across all tested isolates. The compound effectively penetrates bacterial cells, induces intracellular iron accumulation, and triggers dose-dependent reactive oxygen species generation, resulting in rapid bacterial killing and significant antibiofilm activity. Importantly, Fe(tropo)₃ shows a slower development of resistance compared with ciprofloxacin and displays synergistic activity with oxacillin against MRSA. When formulated as a 1% topical ointment, Fe(tropo)₃ significantly reduces bacterial burden in a murine excisional wound infection model, achieving a 98% ± 1% reduction in SA load without detectable hemolysis or skin irritation. Conclusions: These pilot study results support Fe(tropo)₃ as a clinically relevant, mechanism-distinct topical antimicrobial with potential utility in settings where resistance to existing topical antibiotics compromises standard care. Full article

Quebrachitol, an optically active cyclitol derived from plants, has recently gained attention as a potential natural product with therapeutic properties, though its antimicrobial effects remain unclear. This systematic review aims to determine, appraise, and consolidate evidence of the antimicrobial potential of quebrachitol. PRISMA-guided searches of PubMed, Scopus, and Google Scholar (2000–2024) identified English-language experimental in vitro, in vivo, and in ovo studies. Data on antimicrobial activity, dosage or treatment duration, and mechanisms were extracted, with study quality assessed using QUIN and SYRCLE tools. Of 866 studies screened, 11 met inclusion criteria: seven in vitro, one in vivo, one in ovo, and two combining both approaches. Quebrachitol demonstrated inhibitory effects against Salmonella sp., Candida albicans, infectious bursal disease virus (Avibirnavirus gumboroense), Newcastle disease virus, Plasmodium sp., and notably, biofilm formation by Staphylococcus epidermidis and methicillin-resistant Staphylococcus aureus (MRSA). Overall, quebrachitol exhibits promising antimicrobial potential, but rigorous in vivo studies are required to confirm its efficacy and safety in addressing antimicrobial resistance. Full article

Methicillin-resistant Staphylococcus aureus (MRSA) is a significant pathogen in both healthcare-associated (HA-MRSA) and community-associated (CA-MRSA) infections, posing major challenges due to its evolving antimicrobial resistance (AMR) and genetic diversity. This study investigates the prevalence, antimicrobial resistance patterns, and molecular characteristics of HA-MRSA and CA-MRSA isolates in Saudi Arabia. A retrospective analysis was conducted on 178 MRSA isolates obtained from clinical samples. MRSA identification was performed using cefoxitin disk diffusion, and antimicrobial susceptibility testing for vancomycin, linezolid, and ciprofloxacin was conducted using the BD Phoenix M50 system. Molecular characterization included SCCmec typing, spa typing, and PCR-based detection of virulence genes (pvl, tst, eta, etb, lukS, lukF). Statistical analysis was carried out using SPSS, with a significance threshold of p < 0.05. Among 1496 S. aureus isolates, 178 (11.9%) were confirmed as MRSA, with HA-MRSA (61.8%) being more prevalent than CA-MRSA (38.2%). Notably, 7.8% of HA-MRSA isolates exhibited heteroresistant vancomycin-intermediate S. aureus (hVISA). Ciprofloxacin resistance was significantly higher in HA-MRSA (85.0%) compared to CA-MRSA (38.9%). SCCmec type V was the predominant genotype (87.1%), suggesting increased infiltration of CA-MRSA strains into hospital settings. Spa typing revealed high genetic diversity, with t037 being the most common (27%). Virulence genes were detected in 6% of isolates, indicating limited dissemination of these factors. The findings highlight the increasing prevalence of MRSA, the emergence of hVISA, and shifts in clonal distribution, underscoring the need for ongoing molecular surveillance and stringent antimicrobial stewardship programs to control MRSA spread in both healthcare and community environments. Full article

Staphylococcus aureus has been recognized as an important foodborne pathogen and methicillin-resistant S. aureus (MRSA) can cause fatal infections worldwide. Of great concern is that MRSA have been found in animals and non-healthcare settings; however, knowledge about the prevalence and genetic characteristics of S. aureus, especially MRSA from animals, retail meats and market shared shopping vehicles in the same district, is limited. In this study, we collected 423 samples including handrail swabs (n = 226) of shopping trolleys and baskets from 18 supermarkets, retail meats (n = 137) and swine nasal swabs (n = 60) between 2018 and 2020 in China. S. aureus isolates were isolated and identified by PCR, and then the mecA was used to confirm the MRSA. The antibiotic resistance and virulence genes among S. aureus were also analyzed, followed by whole genome sequencing (WGS). S. aureus isolates were widely distributed in shared shopping vehicles (8.0%, 18/226), retail meats (14.6%, 20/137) and swine (18.3%, 11/60). In total, 49 S. aureus were obtained and 20 of the 49 isolates were MRSA. We firstly reported a high prevalence of MRSA in shared shopping vehicles (7.5%, 17/226), followed by raw meats (2.2%, 3/137), and 44.4% (8/18) of the 18 supermarkets possessed MRSA-positive shopping vehicles. All 20 MRSA isolates were SCCmec IVa MRSA clones. Enterotoxin genes (sea/seb) associated with S. aureus food poisoning were present in 45.0% of the 20 S. aureus isolates from retail meats and 25.0% of the 20 MRSA isolates carried enterotoxin genes. Retail meats in this study carried ST6-MRSA, a common ST type of S. aureus from food-poisoning outbreaks in China. WGS showed that the MRSA from meats harbored enterotoxin gene sea and immune evasion genes (sak and scn) associated with human infections, and were clustered with previously reported MRSA isolates from animals and humans. The MRSA isolates carrying multiple virulence genes from shopping vehicles were also clustered with previously reported MRSA isolates from humans and animals, suggesting that the exchange of MRSA isolates might occur among different niches. Our results highlighted the risk of retail meats and shared shopping vehicles in spreading antimicrobial-resistant pathogens including MRSA. To our knowledge, this is the first report of the wide spread of MRSA in shared shopping vehicles in China. Full article

Background/Objectives: Antimicrobial resistance (AMR) in ocular infections has become a serious concern with major implications for vision preservation. Bacterial AMR contributed to 4.71 million deaths worldwide in 2021, and ophthalmology mirrors these trends with multidrug resistance rates as high as 66% documented in some regions and persistently high methicillin resistance among common ocular pathogens. Across regions and care settings, traditional empiric therapies are losing effectiveness against an expanding range of pathogens, resulting in slower recovery, more complications, and, in many cases, permanent vision loss. This review aims to synthesize recent clinical, microbiologic, and pharmacologic evidence on ocular AMR, focusing on recent studies to capture current resistance patterns, therapeutic challenges, and evolving management strategies. Methods: Most included papers were published between 2020 and 2025, with additional foundational studies referenced where appropriate. Reports and systematic reviews addressing bacterial, viral, fungal, and parasitic ocular pathogens were evaluated to characterize current resistance mechanisms and management strategies across ocular pathogens. Results: The eye’s anatomic and physiologic barriers limit drug penetration, often promoting resistance and reducing therapeutic efficacy. Resistance mechanisms vary by pathogens; Pseudomonas keratitis is driven mainly by efflux pumps and biofilm formation, while CMV retinitis’ mutations in UL97 and UL54 are linked with clinical failure, and in MRSA associated Staphylococcus keratitis, the presence of mecA necessitates vancomycin-based therapy across bacterial, viral, fungal, and parasitic infections, with mechanisms such as β-lactamase production, efflux pump overexpression, target-site mutation, and biofilm formation contributing to poor response to standard therapy. MDR Pseudomonas keratitis remains the leading cause of rapidly progressive corneal infection with high risk of perforation and vision loss, while resistant CMV retinitis continues to threaten sight in immunocompromised patients despite antiviral advances. MDR organisms are recalcitrant to treatment and may lead to longer treatment courses and potentially worse outcomes and are discussed in detail within the manuscript. Conclusions: Ocular AMR represents an urgent and expanding clinical challenge. This review centers on the two most encountered multidrug-resistant organisms and their corresponding ocular sites, Pseudomonas aeruginosa (anterior segment) and CMV (posterior segment), while contextualizing them within the broader spectrum of resistant bacterial, viral, fungal, and parasitic pathogens. Despite growing awareness of AMR in ophthalmology, comprehensive surveillance data and longitudinal epidemiologic studies remain limited, making it difficult to track evolving resistance trends or guide region-specific therapy. Preserving vision in the AMR era will require faster diagnostics, improved ocular drug-delivery systems, and pathogen-specific therapies. Full article