Search Results (513)

Background/Objectives: Staphylococcus aureus is a major pathogen of concern in raw milk due to its potential to cause foodborne illness and its increasing antimicrobial resistance (AMR). In Romania, data on the occurrence and resistance patterns of S. aureus in raw sheep milk from traditional farming systems remain limited. This study investigated the presence and antimicrobial resistance of S. aureus in 106 raw sheep milk samples collected from traditional farms in the Banat region of western Romania. Methods: Coagulase-positive staphylococci (CPS) were enumerated using ISO 6888-1:2021 protocols. Isolates were identified at the species level using the Vitek 2 system and molecularly confirmed via PCR targeting the 16S rDNA and nuc genes. Methicillin resistance was assessed by detecting the mecA gene. Antimicrobial susceptibility was determined using the Vitek 2 AST-GP79 card. Results: CPS were detected in 69 samples, with S. aureus confirmed in 34.9%. The mecA gene was identified in 13.5% of S. aureus isolates, indicating the presence of methicillin-resistant S. aureus (MRSA). Resistance to at least two antimicrobials was observed in 97.3% of isolates, and 33 strains (89.2%) met the criteria for multidrug resistance (MDR). The most frequent MDR phenotype involved resistance to lincomycin, macrolides, β-lactams, tetracyclines, and aminoglycosides. Conclusions: The high prevalence of S. aureus, including MRSA and MDR strains, in raw sheep milk from traditional farms represents a potential public health risk, particularly in regions where unpasteurized dairy consumption persists. These findings underscore the need for enhanced hygiene practices, prudent antimicrobial use, and AMR monitoring in small-scale dairy systems. Full article

Secondary methicillin-resistant Staphylococcus aureus (MRSA) infection causes high mortality in patients with influenza A virus (IAV). Our previous study observed that the relative abundance of Lactobacillus murinus (L. murinus) was significantly reduced in both the respiratory tract and gut of IAV-infected mice and negatively correlated with the severity of IAV–MRSA coinfection pneumonia, but the role of L. murinus remains unclear. Here, we supplemented the respiratory tract and gut of IAV-infected mice with live L. murinus and performed a secondary MRSA infection challenge to investigate the effects and potential mechanisms further. Data showed that L. murinus supplementation significantly reduced mortality and pathogen loads in IAV–MRSA coinfected mice and upregulated the lung T cell-independent (TI) IgA response in IAV-infected mice. The 16S rRNA gene sequencing results showed that L. murinus supplementation ameliorated microbiota composition disorder and regulated metabolic dysfunction in the gut of IAV-infected mice. The correlation analysis and antibiotic cocktail treatment experiment showed that the TI IgA response in lungs is dependent on gut microbiota. These findings demonstrated that L. murinus supplementation reduces susceptibility to secondary MRSA infection in IAV-infected mice by promoting the TI IgA response, and provide a new perspective on the use of probiotics to prevent secondary bacterial infection following IAV infection. Full article

Staphylococcus aureus (S. aureus) is a major cause of opportunistic infections in humans and animals, leading to severe systemic diseases. The rise of MDR strains associated with animal carriage poses significant health challenges, underscoring the need to investigate animal-derived S. aureus. Objectives: This study examined the genotypic relatedness and phenotypic profiles of antimicrobial resistance in S. aureus, previously sampled from nostril swabs of healthy horses from two geographically distant Brazilian states (Northeast and South), separated by over 3700 km. The study also sought to confirm the presence of methicillin-resistant (MRSA) and borderline oxacillin-resistant (BORSA) strains and to characterize the isolates through molecular typing using PCR. Methods: Among 123 screened staphylococci, 21 isolates were confirmed as S. aureus via biochemical tests and PCR targeting species-specific genes (femA, nuc, coa). Results: REP-PCR analysis generated genotypic profiles, revealing four antimicrobial resistance patterns, with MDR observed in ten isolates. Six isolates exhibited cefoxitin resistance, suggesting methicillin resistance, despite the absence of the mecA gene. REP-PCR demonstrated high discriminatory power, grouping the isolates into five major clusters. Conclusions: The genotyping indicated no clustering by geographical origin, highlighting significant genetic diversity among S. aureus strains colonizing horses’ nostrils in Brazil. These findings highlight the widespread and varied nature of S. aureus among horses, contributing to a deeper understanding of its epidemiology and resistance profiles in animals across diverse regions. Ultimately, this genetic diversity can pose a public health risk that the epidemiological surveillance services must investigate. Full article

Staphylococcus aureus (S. aureus) is a major pathogen responsible for mastitis in dairy cows and can contaminate raw milk, thereby posing significant health risks to consumers. The emergence of methicillin-resistant S. aureus (MRSA) has further heightened public health concerns due to its antibiotic resistance and infectious potential. In this study, we examined the prevalence, virulence genes, antimicrobial resistance, spa types, and biofilm formation of S. aureus isolates from dairy farms in Guangxi Province, China. Among 242 randomly selected samples, 37 S. aureus strains were identified (15.3% infection rate), including 67.5% MRSA. Antibiotic resistance was observed in 78.4% of isolates, with 35.1% exhibiting multidrug resistance (MDR). Enterotoxin gene analysis showed sea as the most common (67.6%), followed by ser (54.1%) and seh (51.4%), whereas seb and selj were absent. All isolates formed biofilms in vitro, with 64.8% showing strong biofilm-forming ability. Staphylococcal protein A (spa) typing classified the 37 S. aureus strains into 11 spa types, with t030 being the most prevalent (43.2%). These findings indicate that S. aureus is moderately prevalent in raw milk, often carrying multiple virulence genes, forming robust biofilms, and showing antimicrobial resistance. The MRSA that is “latent” in raw milk reminds us of the need for monitoring at the farm level. Full article

Background/Objectives: Methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant Staphylococcus pseudintermedius (MRSP) represent important antimicrobial resistance threats related to companion animals, which can directly or indirectly lead to adverse health effects in humans and animals living in close contact. Characterizing the phenotypic resistance of MRSA and MRSP to a panel of antimicrobials relevant to both veterinary and human medicine is crucial within a “One Health” framework. Methods: In this study, a total of 79 presumptive MRSA isolates (34 from cats, 45 from dogs) and 110 presumptive MRSP isolates (105 from dogs, 5 from cats) from clinical cases were analysed. Real-time PCR was used to detect the presence of mecA and mecC genes, and susceptibility testing was performed using the Sensititre EUST2 panel. Results: Most of the isolates (88.9%, 168/189) were positive for the mecA gene, while a minority (1.1%, 2/189) were mecC-positive (2 MRSA, 1 dog, 1 cat). MRSP isolates exhibited acquired resistance to a broader range of antibiotics compared to MRSA strains. Furthermore, several isolates demonstrated acquired resistance to antibiotics considered critically important for human medicine. Resistance to vancomycin was found in an MRSP isolate from a dog, and resistance to linezolid in an MRSP isolate from a cat. This study reveals that 83.3% (30/36) of MRSA isolates from dogs and 89.3% (25/28) from cats were multidrug-resistant organisms, while MRSP isolates exhibited multidrug resistance in 99% (101/102) of cases for dogs and 100% (4/4) for cats. Conclusions: The extremely high level of multidrug resistance, with some isolates resistant to critically important antibiotics used in human medicine, highlight the importance of monitoring antimicrobial susceptibility in MRSA and MRSP isolates collected from cats and dogs in a One Health perspective. Full article

Background: The opportunistic pathogen Staphylococcus aureus causes skin and soft tissue infections that are associated with biofilm formation, and in immunocompromised patients can progress to surgical site infections, pneumonia, bacteremia, sepsis, and even death. Most antibiotics actively damage living, dividing cells on the surface of the biofilm, where there is a high concentration of nutrients and oxygen, while in the depths, where these factors are scarce, slowly growing cells remain. Objectives: The aim of our study was to evaluate the antibiofilm potential of ethyl acetate roots (EtOAcR) and aerial parts (EtOAcAP) extracts from the perennial Bulgarian plant Geum urbanum L. against methicillin-resistant S. aureus (MRSA) NBIMCC 8327. Methods: The effects of both extracts on the expression of biofilm-related genes, icaA and icaD, were investigated. The cytotoxicity of EtOAcR and EtOAcAP on A-375 (human melanoma), A-431 (epidermoid skin cancer) and HaCaT (normal keratinocytes) cell lines, and the induction of apoptosis were determined. Finally, the in vivo skin irritation potential of the most active extract was studied. Results: Both tested extracts inhibited biofilm formation at concentrations that did not affect bacterial growth. Interestingly, the expression of icaA and icaD was upregulated, although the biofilm development was inhibited 72.4–90.5% by EtOAcAP and 18.9–20.4% by EtOAcR at sub-MICs. EtOAcAP extract showed a more favorable cytotoxic profile on non-tumorigenic cells and stronger antineoplastic activity (IC₅₀ = 6.7–14.68 µg/mL) as compared to EtOAcR extract (IC₅₀ = 8.73–23.67 µg/mL). Therefore, a skin irritation test was performed with the EtOAcAP extract at ten-times higher concentrations than the minimum inhibitory one, and, resultantly, the primary irritation index was equal to zero (no skin irritation observed). Conclusions: The EtOAcAP extract was proven to be an effective antistaphylococcal agent with favorable skin tolerance. The extract showed strong antineoplastic activity and antibiofilm effect at sub-MICs, which outlines new prospects for its development as a natural product for specific skin applications in medical practice. Full article

Given the limited genetic characterization of methicillin-resistant Staphylococcus aureus (MRSA) in South Korea, we performed whole-genome sequencing (WGS) on eight MRSA strains isolated from raw fish products, including 327 sliced raw flatfish, 111 flatfish stew products, 85 sliced raw rockfish, and 11 rockfish stew products. Phylogenetic analysis revealed two distinct clusters—comprising five ST72-t324-SCCmecIVc strains and two novel sequence types—as well as a singleton strain (ST630-t4549-SCCmecV). A total of five antimicrobial resistance genes (ARGs), four plasmid replicon genes, three mobile genetic element genes, and seventy-three virulence factor genes were identified, with distinct genetic profiles observed between the clusters. Notably, several MRSA strains were isolated from samples obtained at the same retail market, indicating potential local clustering. Four ST72-t324-SCCmecIVc strains, collected from the same market, shared identical profiles in terms of four ARGs, two plasmid replicons, two mobile genetic elements, and several virulence factor genes. These findings provide valuable insights into the genomic characteristics of MRSA in raw fish products and highlight the need for ongoing surveillance and monitoring efforts in South Korea. Full article

Staphylococcus aureus is a significant bacterial pathogen responsible for a wide range of diseases in both humans and animals. This study aimed to investigate nucleotide sequence variations, gene expression patterns, and serum biomarkers, including acute phase proteins (APPs), hormonal fluctuations, and iron profile parameters in sheep affected by pneumonia. Additionally, the study focused on the isolation and characterization of S. aureus from pneumonic sheep, with particular emphasis on the prevalence of methicillin-resistant S. aureus (MRSA) strains. Blood samples were collected from both healthy and pneumonic sheep for gene expression and biochemical analyses, while nasal swabs from pneumonic sheep were used for bacterial isolation and identification. Out of 100 nasal swabs analyzed, 44% tested positive for Staphylococcus spp., and 61.4% of these were confirmed as S. aureus by PCR. The mecA gene, a key marker of methicillin resistance, was identified in 17 isolates (38.6% of the S. aureus-positive samples). MRSA isolates showed complete resistance to amoxicillin, cloxacillin, and erythromycin, and high resistance to penicillin, amoxicillin, and tetracycline; however, all MRSA strains remained fully susceptible to vancomycin. Gene expression analysis revealed that TLR2, CLEC4E, PTX3, CXCL8, and IL15RA were significantly upregulated (p < 0.05) in pneumonic ewes, while SOCS3 expression was markedly downregulated. Sequence analysis of immune-related genes revealed notable nucleotide differences between healthy and affected animals. Furthermore, the pneumonic group exhibited significantly elevated levels of APPs, cortisol, and growth hormone, along with reduced levels of insulin, T3, and T4. These findings underscore the zoonotic risk posed by MRSA and emphasize the need for robust surveillance and antibiotic stewardship to control its spread. The study also highlights the importance of molecular diagnostics in accurately identifying MRSA and elucidating resistance mechanisms, thereby facilitating targeted treatment and informed management strategies. Full article

Staphylococcus aureus is an important cause of food intoxication, which has the potential to induce diverse infections, toxinoses and life-threatening diseases among humans and animals. This study investigated the prevalence, antimicrobial resistance, and genetic diversity of S. aureus and methicillin-resistant S. aureus (MRSA) in retail raw meat from Shandong (March 2021–October 2022). The distribution of virulence genes, antimicrobial susceptibility, and genetic diversity of these isolates were analyzed. From a total of 442 samples, 87 (19.7%) S. aureus and 11 (2.5%) MRSA were isolated. According to the antimicrobial susceptibility testing, it was found that all the S. aureus isolates were resistant to at least one antimicrobial. Most isolates (95.9%) were resistant to penicillin, with high resistance to ampicillin (82.7%) and multidrug resistance in 76.5% of cases. One isolate could simultaneously resist eleven antimicrobials (ERY-CLI-GEN-SMZ-FFC-PEN-PRL-AMC-CIP-TET-AMP). In contrast, all the isolates showed sensitivity to vancomycin. The most prevalent virulence gene was sed, accounting for 10.2%, followed by sec (8.2%). Regarding genetic polymorphism, these isolates were divided into 21 different sequence types (STs) using multilocus sequence typing (MLST) and 33 staphylococcal protein A (spa) types using spaTyper 1.0 tool. The most prevalent sequence types were ST398 (22.4%), followed by ST7 (20.4%), while ST59, ST1, ST188, ST9, ST398, and ST7 were observed in MRSA isolates. The most prevalent spa types were t034 (15.3%), followed by t899 (10.2%), while t441, t127, t184, t899, t034, and t091 were observed in MRSA isolates. In conclusion, our study highlights the high prevalence of S. aureus and MRSA in different retail raw meats in Shandong. This poses a potential threat to food safety and underscores the need for enhanced surveillance and stricter antibiotic control measures. Full article

The emergence of methicillin-resistant Staphylococcus aureus (MRSA) and its biofilm-forming ability underscore the limitations of current antibiotics. In this study, a new compound named tripterhyponoid A was found to effectively combat MRSA, with an MIC of 2.0 μg/mL. It inhibited biofilm formation by downregulating genes related to the quorum sensing (QS) pathway (sarA, agrA, agrB, agrC, agrD, and hld) and eradicated mature biofilms. Furthermore, it induced DNA damage by binding to bacterial DNA, enhancing its efficiency against MRSA. Therefore, its anti-MRSA properties with multiple mechanisms of action make it less prone to developing resistance over 20 days. In addition, it reduced the bacterial load and regulated the levels of inflammatory cytokines IL-6 and IL-10 at the wound site in a mouse skin infection model. This paper provides the first in-depth investigation of the mechanisms of triterpenoids against MRSA by inhibiting the expression of QS system genes and binding to DNA. Full article

In this study, a global response analysis was performed to explore the mechanism of action of Usnic acid and its synergy with Norfloxacin, a well-known quinolone antibiotic to which MRSA clinical isolates showed resistance (MIC, 500 µg/mL). A microdilution assay, a growth kinetics analysis, a microscopic analysis, and cell-based assays consistently showed that Usnic acid possesses strong anti-staphylococcal activity (MIC, 7.8 µg/mL), causes cell leakage, modulates efflux pump activity, and synergizes with Norfloxacin against the multi-drug-resistant clinical isolate MRSA 2071. Whole-cell proteome profiling using gel-free proteomics-based nano-LC-ESI-QTOF-MS/MS revealed several proteins whose expression was significantly modulated by Usnic acid and Norfloxacin alone or in combination. Usnic acid downregulated the abundance of RNA polymerase subunits (RpoB and RpoC), carbamoyl phosphate synthase large subunit (PyrAB), chaperone (GroEL), and adenylosuccinate synthetase (PurA). Interestingly, proteins found to be upregulated in the presence of Usnic acid and Norfloxacin included oxidative-stress-related proteins such as peroxidase (Tpx), alkyl hydroperoxide reductase (AphC), and general stress protein (UspA). This study clearly shows that Usnic acid affects numerous cellular targets and can potentiate the action of Norfloxacin. Furthermore, an in vivo study showed that UA at low concentrations prevents body weight gain, but changes in other tested toxicological parameters were found to be within normal limits. Thus, UA at low doses appears to be a promising candidate for repurposing old antibiotics through combination therapy against MRSA infections. Full article

Background/Objectives: Dry eye disease (DED), also known as “keratoconjunctivitis sicca”, is a common chronic ocular surface disease accompanied by inflammation and diminished tear production. Bovine Lactoferrin (BLF), a multi-functional iron-binding glycoprotein found in tears, decreased significantly in patients with DED, used for the treatment of dry eye, conjunctivitis, and ocular inflammation. BLF has limited therapeutic efficacy due to poor ocular bioavailability. Methods: This study developed and optimized a BLF-loaded nanosuspension (BLF-NS) using the Box–Behnken Design (BBD). Optimized BLF-NS was then incorporated with polyvinyl pyrrolidone (PVP) and hydroxypropyl methyl cellulose (HPMC) dissolving microneedles (MNs). The formulations were characterized by Scanning and transmission microscopy, DSC, FTIR, ex vivo studies in corneal tissue from sheep and tested for its antibacterial and antifungal efficacy against Methicillin-Resistant Staphylococcus aureus (MRSA), Staphylococcus aureus, and Aspergillus niger, respectively. Moreover, they were tested for their Benzalkonium chloride (BCL) dry eye in a rabbit model. Results: The optimized nanosuspension showed a vesicle size of (215 ± 0.45) nm, a Z.P (zeta potential) of (−28 ± 0.34) mV, and an Entrapment Efficiency (EE%) of (90 ± 0.66) %. The MNs were fabricated using a ratio of biodegradable polymers, PVP/HPMC. The resulting BLF-NS-MNs exhibited sharp pyramidal geometry with high mechanical strength, ensuring ocular insertion. In vitro release showed 95% lactoferrin release over 24 h, while ex vivo permeation achieved 93% trans-corneal delivery. In vivo, BLF-NS-MNs significantly reduced pro-inflammatory cytokines (TNF-α, IL-6, MMP-9, IL-1β, MCP-1) and upregulated antioxidant and anti-inflammatory genes (PPARA, SOD 1), restoring their levels to near-normal (p < 0.001). Conclusions: The nanosuspension combined with MNs has shown higher ocular tolerance against DED ensured by the Draize and Schirmer Tear Test. Full article

Introduction/Objectives: Antibiotic resistance makes the treatment of pneumonia challenging. Effective management depends on accurate diagnostic techniques to identify resistance genes and customize drugs. This study primarily aimed to identify antibiotic resistance genes in respiratory samples from patients with pneumonia using polymerase chain reaction (PCR) to determine the prevalence of specific resistance genes and analyze clinical factors contributing to antibiotic resistance, as well as to provide actionable insights into resistance patterns in Jordan and support efforts to improve pneumonia management. Methods: This retrospective observational study included 114 patients who were diagnosed with pneumonia. Clinical data, including prior antibiotic exposure and treatment history, were collected. PCR diagnostics were used to detect resistance genes in respiratory samples. In this study, we evaluated 14 antibiotic resistance genes in pneumonia pathogens, highlighting their diverse resistance mechanisms. Results: Mec A was the most frequently detected gene, appearing in 87 samples (77.3%). Additionally, Tem in 80 samples (70.2%), Oxa-48-like in 15 samples (13.2%), and Ctx-M-1 in 38 samples (33.3%) were among the most commonly detected genes. In contrast, Oxa-40-like (7.0%), Vim (8.8%), and Imp (4.4%) genes exhibited a lower prevalence. The Oxa-51-like gene showed the only significant association with ertapenem resistance (p-value = 0.046). Further analysis revealed statistically significant associations between Mec A and methicillin resistance (p < 0.001), underscoring its critical role. However, other genes, such as Oxa-40-like and Oxa-48-like, showed no significant correlation with the antibiotic resistance patterns of imipenem and meropenem (p > 0.05). Conclusions: This study demonstrates the utility of PCR-based diagnostics for detecting resistance genes and highlights the critical clinical factors associated with antibiotic resistance in patients with pneumonia. These findings underscore the importance of integrating molecular diagnostics into routine care to improve treatment outcomes and combat the growing threat of antibiotic resistance in Jordan. This highlights PCR’s value in guiding effective treatment strategies and addressing multidrug-resistant pneumonia. Full article

Staphylococcus aureus is a formidable human pathogen responsible for infections ranging from superficial skin lesions to life-threatening systemic diseases. This review synthesizes current knowledge on its pathogenesis, emphasizing colonization dynamics, virulence mechanisms, biofilm formation, and antibiotic resistance. By analyzing studies from PubMed, Scopus, and Web of Science, we highlight the pathogen’s adaptability, driven by surface adhesins (e.g., ClfB, SasG), secreted toxins (e.g., PVL, TSST-1), and metabolic flexibility in iron acquisition and amino acid utilization. Nasal, skin, and oropharyngeal colonization are reservoirs for invasive infections, with biofilm persistence and horizontal gene transfer exacerbating antimicrobial resistance, particularly in methicillin-resistant S. aureus (MRSA). The review underscores the clinical challenges of multidrug-resistant strains, including vancomycin resistance and decolonization strategies’ failure to target single anatomical sites. Key discussions address host–microbiome interactions, immune evasion tactics, and the limitations of current therapies. Future directions advocate for novel anti-virulence therapies, multi-epitope vaccines, and AI-driven diagnostics to combat evolving resistance. Strengthening global surveillance and interdisciplinary collaboration is critical to mitigating the public health burden of S. aureus. Full article

Staphylococcus aureus, particularly methicillin-resistant S. aureus (MRSA), poses significant challenges in healthcare settings due to its ability to form biofilms on various surfaces. These biofilms enhance bacterial survival and increase resistance to conventional treatments, complicating infection control efforts. This study evaluated the efficacy of combined povidone-iodine (PVP-I) and hydrogen peroxide (H₂O₂) to disrupt pre-formed S. aureus biofilms. A series of assays—including crystal violet staining, colony-forming unit (CFU) enumeration, gene expression analysis, and confocal laser scanning microscopy—were performed to assess the effects of each treatment individually and in combination. The combined treatment resulted in significantly greater reductions in biofilm biomass and viable bacteria compared with either agent alone. Gene expression analysis revealed downregulation of key biofilm-associated genes (icaA, icaB, icaD, icaR, and clfA), suggesting interference with biofilm stability and maintenance. While formal synergy quantification was not conducted, the observed effects suggest a potentially synergistic or additive interaction between the two agents. These findings support the use of dual antiseptic strategies as a promising approach to biofilm eradication and highlight the potential clinical utility of dual antiseptic strategies. However, we underscore the need for further optimization and safety evaluation. Full article