Search Results (803)

Background: Antimicrobial resistance (AMR) is a major global health threat, particularly in surgical site infections (SSIs), where multidrug-resistant (MDR) pathogens complicate treatment. Objective: This study aimed to identify antimicrobial resistance genes and assess their prevalence in bacterial species causing SSIs in Lebanon. Materials and Methods: The present research is a multicenter and prospective study that included patients who developed SSIs after surgery in seven hospitals, within the period of January 2024–September 2024. Bacterial isolates from wound swabs or tissue samples were identified using standard microbiological methods. Antimicrobial susceptibility was tested by disk diffusion, and resistance genes were detected by PCR. Data were analyzed using Statistical Package for the Social Sciences (SPSS). Results: Among 6933 surgical patients, 63 developed SSIs (0.91%; 95% CI [0.70–1.15]). Gram-negative bacteria predominated (73%), mainly Escherichia coli and Pseudomonas aeruginosa, while Gram-positive isolates accounted for 27%, mostly Staphylococcus aureus. MDR was observed in 71% of Gram-positive and 61% of Gram-negative isolates. The most frequent genes were mecA in S. aureus (100%) and coagulase-negative staphylococci (83.3%); bla_CTX-M in E. coli, Klebsiella pneumoniae, and Enterobacter cloacae (100%); and bla_NDM in E. cloacae (100%) and Acinetobacter baumannii (60%). bla_KPC was less common, and no isolates carried Imipenemase (IMP), Verona integron-encoded metallo-β-lactamase (VIM), and Oxacillinase-48-like β-lactamase (OXA-48). Conclusions: This study highlights the high prevalence of antibiotic resistance in agents causing SSIs in Lebanese hospitals. Resistance genes, particularly mecA, bla_CTX-M, and blaNDM, were highly prevalent in SSI pathogens, underscoring the urgent need for surveillance and judicious antibiotic use in Lebanese hospitals. Full article

Bioactive coatings are of great interest for orthopedic applications, as they combine mechanical stability with biological functionality. In this study, stainless steel discs were coated with 45S5 bioactive glass doped with 1.0 wt% samarium by spin coating, followed by surface functionalization with benfotiamine through spraying. This strategy integrates three components: a metallic substrate as a stable and inexpensive support, a bioactive glass layer with well-known osteogenic potential, and a superficial organic layer of benfotiamine, a lipid-soluble analog of vitamin B1 with higher bioavailability. Samarium doping was selected based on previously reported antimicrobial potential against clinically relevant staphylococci, while the rationale for benfotiamine functionalization derives from literature describing vitamin B1 derivatives with anti-resorptive and osteogenic activity. The coatings were characterized by scanning electron microscopy (SEM) and Fourier-transform infrared (FTIR) microscopy. Bioactivity was assessed by immersion in simulated body fluid (SBF), where phosphate bands indicated the formation of calcium phosphate phases (CaPs). Wettability tests showed a reduced contact angle after benfotiamine functionalization. Cytocompatibility was evaluated by LDH and MTT assays with MC3T3-E1 cells, suggesting overall biocompatibility and enhanced cell viability after 7 days for the benfotiamine-functionalized coatings. The present findings support a simple and cost-effective route to multifunctional coatings with potential relevance for future orthopedic applications. Full article

Background/Objectives: Periprosthetic joint infections (PJIs) represent a serious complication following musculoskeletal tumor resection and megaprosthetic reconstruction. Local antibiotic administration may reduce infection risk by achieving high local drug concentrations. The aim of this study was to evaluate whether local vancomycin powder reduces postoperative periprosthetic infections in bone tumor surgeries involving megaprostheses. Methods: This retrospective cohort study included 276 patients who underwent bone tumor resection and megaprosthetic reconstruction. Study subjects were divided into two groups: the control group (n = 142) that received standard perioperative intravenous antibiotics, and the vancomycin group (n = 134) that received an additional 1 g of vancomycin powder locally at wound closure. Periprosthetic joint infections were defined using the 2018 International Consensus Meeting (ICM) criteria and monitored for 2 years. A multivariable competing risks regression model was used to assess the independent effect of local vancomycin on infection risk. Results: Periprosthetic joint infections occurred in 28 patients in the control group (19.7%) vs. eight patients in the vancomycin group (5.9%, p = 0.001). The most frequently isolated pathogens were coagulase-negative staphylococci (52.7%), followed by Staphylococcus aureus (22.2%). Among infected patients in the vancomycin group, only two had Gram-positive infections, suggesting efficacy against staphylococcal PJIs. The multivariable regression confirmed a significantly lower risk of infection in the vancomycin group (hazard ratio [HR]: 0.40, 95% confidence interval [CI]: 0.16–0.95, p = 0.040), while pelvic tumors were associated with a higher infection risk (HR: 5.82, p < 0.001). Conclusions: Our results indicate that local vancomycin may reduce periprosthetic infection rates in oncologic megaprosthetic reconstruction without added complications. Randomized studies are warranted to confirm these findings and refine dosing strategies. Full article

Total joint arthroplasty (TJA) and total joint replacement (TJR) are effective treatments for end-stage osteoarthritis, but prosthetic joint infections (PJIs) remain a significant complication. These infections are often associated with bacteria that form biofilms, which contribute to their persistence and resistance to treatment. The aim of this study was to investigate the biofilm-forming ability, cyclic diguanylic acid (c-di-GMP) production, and the presence of biofilm-associated genes in Staphylococcus aureus and coagulase-negative Staphylococci (CoNS) isolates obtained from synovial fluid samples of patients with PJIs following TJA and TJR. A total of 198 samples were analyzed, with bacterial growth detected in 33 samples (16.7%). Among these, 10 strains of S. aureus and 22 strains of CoNS were identified. Biofilm formation was evaluated using the crystal violet assay, and c-di-GMP levels were measured. A statistically significant linear regression was found between biofilm formation and c-di-GMP production (p = 0.016, R² = 0.18). Genetic analysis revealed the presence of biofilm-associated genes, including icaA, clfA, fnbA in S. aureus, and atlE, fbe in CoNS. Furthermore, there was a statistically significant difference in c-di-GMP production between strains harboring the icaA gene and strains without icaA (p = 0.016), while oxacillin resistance was detected more frequently in strains carrying fbe gene (p = 0.031). The study emphasizes the variability in antibiotic resistance profiles among staphylococcal isolates, underscoring the complexity of managing these infections. Full article

Background: Native joint septic arthritis is a severe infection associated with considerable morbidity. The data about the microbiological spectrum, treatment methods, and long-term outcomes are heterogeneous. Methods: We performed a decade-long retrospective study encompassing all patients with native joint septic arthritis treated at our institution, a tertiary orthopedic center. Data on demographics, clinical parameters, microbiology, surgical interventions, and antibiotic use were gathered. Outcomes included reoperation, persistent infection and mortality during follow-up. We used logistic regression to identify predictors of adverse outcomes, and Kaplan–Meier analyses to evaluate reoperation-free survival among microbiologic groups. Results: A total of 114 patients (103 adults and 11 children) were included. Cultures yielded positive results in 72 out of 103 (70%) adults and 8 out of 11 (73%) children. Staphylococcus aureus was the primary pathogen in adults (49% of positives) and children (88%), followed by coagulase-negative staphylococci. Antibiotics were administered to all patients, with combinations of at least two molecules in 68% of adults and 91% of children, while surgical intervention predominantly consisted of debridement alone. In adults, an elevated preoperative white blood cell count was associated with unfavorable outcomes in univariate analysis (odds ratio 1.14, 95% confidence interval 1.01–1.30, p = 0.040). The Kaplan–Meier analysis revealed no significant differences in reoperation-free survival across microbiologic groups (log-rank p = 0.361). Conclusions: Over a ten-year period, Staphylococcus aureus remained the predominant cause of native joint septic arthritis; however, culture-negative cases and coagulase-negative staphylococci were also common. Only preoperative leukocytosis was a predictor of poor outcomes, while microbiologic etiology did not significantly influence the risk of reoperation, potentially indicating early and effective therapy. These findings highlight the intricacy of native joint septic arthritis and the necessity for enhanced diagnostics and prognostic stratification. Full article

Background: The emergence of livestock-associated antimicrobial-resistant staphylococci, particularly non-aureus staphylococci, has become a major public health problem requiring immediate global attention. Methods: In this study, 92 Staphylococcus borealis isolates from 20 different pig farms in Korea were examined to determine the following: (1) antimicrobial-resistance (AMR) profiles of the isolates, (2) prevalence of methicillin resistance and staphylococcal cassette chromosome methicillin resistance gene (SCCmec) types, (3) occurrence of chloramphenicol–florfenicol resistance gene (cfr)-mediated oxazolidinone resistance, and (4) genomic characteristics of cfr-positive methicillin-resistant S. borealis (MRSB) via whole-genome sequence (WGS) analysis. Results: The overall rate of S. borealis isolation was 9.1% (92 isolates/1009 swabs), and 34.8% (32/92) of the isolates were MRSB. Surprisingly, all 32 MRSB isolates carried SCCmec V for methicillin resistance, and 31/32 MRSB isolates displayed multidrug-resistance phenotypes. Although 22 cfr-positive S. borealis isolates (20 MRSB and two methicillin-susceptible S. borealis) were identified, most of the isolates were susceptible to linezolid because they carried the 35-bp insertion sequence in the cfr promoter. Moreover, WGS analyses suggested horizontal transmission of SCCmec V and cfr-containing plasmids among different staphylococci species, including Staphylococcus aureus, S. epidermidis, and S. borealis. Conclusions: To the best of our knowledge, this study is the first to describe the AMR characteristics of livestock-associated S. borealis isolates, particularly the high prevalence of SCCmec V and cfr. Collectively, these results suggest that S. borealis is a crucial reservoir of AMR genes on pig farms in Korea. Full article

This cross-sectional study aimed to (a) determine the apparent prevalence of mastitis pathogens and (b) to identify risk factors for intramammary infections (IMIs) at the herd level in dairy herds in Bavaria, Germany. A stratified random sample of 305 herds was selected based on herd size, administrative district, and season. During the farm visits between July 2023 and July 2024, management data were recorded, quarter milk samples (QMSs) from 14,700 lactating cows were collected aseptically and analyzed, and the somatic cell count (SCC) at the quarter level was determined. Risk factors for the within-herd prevalence of Staphylococcus (S.) aureus, Streptococcus (Strep.) uberis, Strep. dysgalactiae, and non-aureus staphylococci (NAS) were analyzed by negative binomial regression, while risk factors for the presence of Escherichia (E.) coli and Strep. agalactiae IMIs on dairy farms were identified by logistic regression. The most frequently detected pathogens were NAS, found in 5.0% of all QMSs (n = 57,251), followed by Strep. uberis (1.9%) and S. aureus (1.8%), Strep. agalactiae (0.2%), and E. coli (0.1%). At the herd level, NAS, Strep. uberis, S. aureus, and Strep. dysgalactiae were found in 92%, 69%, 67%, and 57% of farms, respectively. Risk factors for increased within-herd prevalence included automated milking systems (NAS), organic production (Strep. uberis, S. aureus), straw bedding (Strep. uberis), and lack of bedding or mattress cubicles (Strep. dysgalactiae). The odds for a herd to be positive were increased with audible liner slips (E. coli) and the irregular cleaning of water troughs (Strep. agalactiae), and without a maintenance agreement for milking equipment (Strep. agalactiae). These results provide valuable insights into options for the targeted prevention of IMI. Full article

As demand for sustainable protein sources grows, edible insects like Tenebrio molitor (yellow mealworm) are gaining attention as functional feed ingredients. This study investigated how dietary inclusion of T. molitor meal affects gut microbiota composition and diversity in laboratory rats. Wistar rats were divided into three diet groups: standard feed, 35% chicken meal, and 35% T. molitor meal. Fecal samples were collected at weeks 4, 6, and 8. Microbial populations were assessed using culture-based methods, and community structure was analyzed at week 9 via Illumina MiSeq 16S rRNA sequencing. Bioinformatic analyses evaluated microbial diversity and predicted functions. Rats fed T. molitor meal showed significantly reduced counts of total aerobic/anaerobic bacteria, fungi, and coagulase-positive staphylococci. Metagenomics revealed a Firmicutes-dominated microbiota, with enrichment of protein- and cholesterol-metabolizing taxa (e.g., Eubacterium coprostanoligenes, Oscillospiraceae, Ruminococcaceae), and a decline in fiber- and mucin-degrading bacteria like Akkermansia and Muribaculaceae. Functional predictions indicated upregulated amino acid metabolism and chitin degradation. Despite compositional shifts, microbial diversity remained stable, with no signs of dysbiosis. These findings suggest that T. molitor meal supports a safe, functional adaptation of gut microbiota to high-protein, chitin-rich diets, supporting its potential use in monogastric animal nutrition. Full article

Staphylococcal bacterial biofilm plays an important role in the pathogenesis and bacterial persistence of chronic rhinosinusitis. N-acetyl cysteine (NAC) has an inhibitory role in biofilm formation, suppressing adhesion and matrix production or favoring dispersal of preformed biofilm. The aim of this study was to examine the in vitro effect of NAC on Staphylococcal biofilm formation by bacterial strains isolated from tissue samples of patients with chronic rhinosinusitis with or without nasal polyps (CRSwNP and CRSsNP). Prospective study included 75 patients with CRS. The biofilm-forming capacity of isolated strains was detected by microtiter-plate method and the effects of sub-inhibitory (1/2x, 1/4x, and 1/8x minimal inhibitory concentration, MIC) and supra-inhibitory minimal concentrations (2x, 4x, and 8xMIC) of NAC on biofilm production were investigated. Staphylococcal bacterial strains were isolated in 54 (72%) patients, and the most frequently isolated species were Staphylococcus aureus (40.7%). Coagulase-negative Staphylococci species were weak producers of biofilm, while S. aureus was a strong biofilm producer. Concentration of 3.1 mg/mL (1/2 MIC) was sufficient to completely prevent biofilm formation in 77.8% of the isolates, where 49.6 mg/mL (8xMIC) led to the complete eradication of formed biofilm in 81.5% of the isolates. The subinhibitory and eradication effects were dose- and strain-dependent. There were no significant differences in MIC values between isolates from patients with CRSwNP and CRSsNP isolates. NAC proved to be effective in inhibiting biofilm formation and reducing formed biofilm by Staphylococcal isolates from patients with CRS. A comparable antibiofilm effect was exhibited in both phenotypes of CRS, indicating that NAC’s antibiofilm activity was independent of the underlying clinical phenotype, and more targeted on biofilm matrix components. Full article

Background: Periprosthetic joint infection (PJI) is one of the most serious complications following total joint arthroplasty. The debridement, antibiotics, irrigation, and implant retention (DAIR) procedure is commonly employed to treat acute, early-stage infections, but its success is highly variable, influenced by factors such as pathogen virulence and antibiotic susceptibility profiles. This study aimed to evaluate the impact of pathogens responsible for these infections on the outcome of DAIR. Methods: This retrospective, single-center study analyzed the microbiological profiles of 116 patients (66 hips and 50 knees) treated for acute periprosthetic joint infections (PJIs) with DAIR between 2018 and 2022. Acute PJI was defined as a duration of symptom less than three weeks, according to the criteria established by the Tsukayama and Izakovicova classification. Preoperative joint aspirations, intraoperatively collected tissue samples, and sonication of the exchanged mobile parts were analyzed for each case. We differentiated between monomicrobial PJI, polymicrobial PJI (defined as the identification of more than one microorganism from preoperative joint fluid aspiration or intraoperative samples), and difficult-to-treat (DTT) pathogens. Results: In this cohort, the following pathogen profiles were identified: culture-negative cases accounted for 11.1% of infections, while 64.2% were attributed to Gram-positive bacteria, 19.8% to Gram-negative bacteria, and 4.9% to fungal pathogens. Among the identified microorganisms, coagulase-negative staphylococci (CNS) were the most frequently detected, exhibiting a notable oxacillin resistance rate of 52.9% and rifampicin resistance rate of 28.7%. Additionally, no significant difference in revision-free implant survival was found between patients with DTT pathogens and/or polymicrobial PJI and those without such infections. Conclusions: This study highlights that pathogens in prosthetic joint infections (PJIs) do not solely determine outcomes, as patient-specific factors (comorbidities, implant type) may also play a key role. Regional variations in pathogens and antibiotic resistance patterns should guide empirical therapy. For instance, this study found a high reliance on vancomycin due to high oxacillin resistance in CNS, the most frequent causative pathogen. Full article

The rise in antimicrobial resistance and strict milk withdrawal regulations drive the search for safe, non-antibiotic intramammary therapies. This pilot field study focused on clinical parameters, including the somatic cell count (SCC) and the assessment of changes, as well as overall safety, which together enabled a prospective evaluation of whether the substance exerted any therapeutic effect. In this study, 48 Holstein–Friesian cows with naturally occurring clinical mastitis (somatic cell count > 400,000 cells/mL; single quarter) were randomized to receive either seven daily infusions of 10% pectin (n = 24) or two standard intramammary doses of a licensed multi-component antibiotic formulation (n = 24). The clinical severity scores (0–3) and SCC were monitored from 72 h before to 168 h after treatment initiation; the bacteriological cultures, milk TNF-α, milk yield, and blood hematology/biochemistry were also assessed. Both groups exhibited comparable and significant reductions in the mastitis scores and log₂-transformed SCC by 48 h post-treatment, with equivalent bacteriological cure rates and pathogen profiles (predominantly Streptococcus uberis, coagulase-negative staphylococci, and Escherichia coli) and no local irritation, systemic adverse effects, or alterations in the milk yield, TNF-α, or blood parameters. These findings indicate that intramammary pectin at a 10% concentration is safe and well tolerated and that it provides efficacy equivalent to standard antibiotic therapy, supporting its potential as an alternative mastitis treatment that avoids antibiotic residues and contributes to antimicrobial stewardship. Full article

Toxic shock syndrome (TSS) is a serious, often fatal disease, rarely occurring in dogs via infection with Staphylococcus and Streptococcus. The development of TSS is mainly dependent on the presence of bacterial toxins recognized to be potent superantigens causing the release of massive amounts of host inflammatory cytokines, notably TNF-α, progressing to high fever, hypotension, haemoconcentration, thrombosis and neutrophil and endothelial activation with multiple organ failure. Rarely, TSS is associated with erythematous and exfoliative dermatitis progressing to ulceration with extremely extensive dermo-epidermal detachment, which is often very painful. Like in humans, very little is known about the transmission and prevention of this condition. In our paper, a case of TSS-like caused by a mixed bacterial infection with Staphylococcus aureus, Streptococcus halichoeri and Dermatophilus spp. has been described in an 11 year-old, cross-breed male dog, most probably following injury due to biting and fighting. Lesions consisted of severe and diffuse ulceration on the dorsum, and bacterial culture/cytology led to the isolation and identification of Gram-positive staphylococci and streptococci associated with an intense neutrophil reaction. Dermatophilus spp. was presumed morphologically based on cytological preps, not by culture or molecular analysis. PCR demonstrated the presence of the nuc thermonucleaze gene (for S. aureus confirmation) together with the genes encoding enterotoxin H (seh), protein A (spa), toxic shock syndrome toxin TSST-1 (tst) and methicillin resistance (mecC); the exfoliative toxins (eta, etb) were detected. Clinical signs, cytology, bacterial culture and the response to systemic antibiotic therapy were compatible with a TSS-like diagnosis. The patient has completely recovered after 1 year of treatment. Full article

Livestock-associated Staphylococcus species—particularly Staphylococcus aureus (S. aureus), Staphylococcus pseudintermedius (S. pseudintermedius), and coagulase-negative staphylococci (CoNS)—pose escalating threats to animal health, food safety, and public health due to their evolving antimicrobial resistance (AMR) profiles. This review synthesizes recent insights into the molecular epidemiology, resistance determinants, and host adaptation strategies of these pathogens across food-producing animals. We highlight the role of mobile genetic elements (MGEs), clonal dissemination, and biofilm formation in shaping multidrug resistance (MDR) patterns. Diagnostic advancements, including MALDI-TOF MS, whole-genome sequencing (WGS), and PCR-based assays, are discussed alongside treatment challenges arising from therapeutic failures and limited vaccine efficacy. The review critically examines current AMR surveillance gaps and the need for integrative One Health frameworks that encompass animals, humans, and the environment. Novel tools such as metagenomics, real-time genomic surveillance, and artificial intelligence (AI)-driven analytics are proposed to enhance predictive monitoring and resistance management. Together, these insights underscore the urgency of coordinated, evidence-based interventions to curb the spread of MDR staphylococci and safeguard One Health. Full article

Staphylococcus species are often the cause of implant-related infections, posing a significant clinical challenge in orthopedics. Antimicrobial peptides (AMPs) like LL-37-derived FK-16 and GF-17 offer promising alternatives to conventional antibiotics; however, they require suitable delivery systems to overcome rapid degradation. The aim of this study was to develop and evaluate silk fibroin (SF) and osteoinductive peptide-enriched silk fibroin (PSF) sponges that can be used locally for FK-16 and GF-17 delivery. Two concentrations of FK-16 or GF-17 were loaded into SF and PSF sponges. Swelling behavior and AMP release profiles were analyzed for 72 h. Time-kill assays were conducted on MRSE and MRSA clinical strains to assess antimicrobial activity. FK-16 released quickly (>90% within 24 h) and then maintained a stable plateau from both SF and PSF matrices, which was associated with bactericidal activity against MRSE strains. In contrast, the release efficiency of GF-17 was lower and did not achieve significant antimicrobial effects. Neither peptide exhibited effective activity against MRSA under the tested conditions. PSF sponges showed higher swelling and enhanced FK-16-mediated antibacterial performance compared to SF counterparts. FK-16-loaded PSF sponges are a promising biomaterial for treating local orthopedic infections related to MRSE. The findings underscore the significance of peptide–matrix interactions in determining therapeutic outcomes and suggest the need for more in vivo evaluation of AMP-functionalized PSF scaffolds. Full article

Antimicrobial peptides (AMPs) are increasingly emerging as alternatives to conventional antibiotics. This study compared the antibacterial activity of two decapeptides, KSL and KSL-W, and a 23-residue peptide, Dadapin-1, against bacterial species that colonize orthopedic implants, with the aim of identifying the most effective peptide for future AMP-based anti-infective orthopedic biomaterials. Staphylococcus aureus ATCC 25923 was the reference strain. The minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and minimum biofilm inhibitory concentration (MBIC) of the AMPs were determined in both undiluted and diluted Mueller–Hinton Broth II (MHB II) to gain a simplified perspective on the potential interference of bioenvironments. The MBICs of the AMPs were close to their MICs. In diluted broth, a concentration of 3.91 μg/mL of KSL or KSL-W was bactericidal against staphylococci and prevented biofilm formation. An eight-fold higher concentration of Dadapin-1 was required to achieve bactericidal activity. Undiluted MHB II significantly hindered the antibacterial activity of KSL and Dadapin-1, while KSL-W was notably less affected. The values of LoA, a newly developed indicator of loss of activity, confirmed these findings. Bacterial species and strain influenced LoA. Furthermore, KSL-W exhibited a protective effect on osteoblasts co-cultured with S. aureus ATCC 25923. Overall, KSL-W emerged as the most promising candidate for AMP-based anti-infective orthopedic biomaterials. Full article