Search Results (174)

Introduction: Haemolytic Escherichia coli (E. coli) is commonly associated with enteric disease in pigs and is frequently used as a phenotypic marker for enterotoxigenic E. coli (ETEC). This study aimed to characterise the resistance and virulence profiles of haemolytic E. coli isolated from Colombian pig farms. Methods: A total of 367 faecal samples from sows and pigs across all production stages were collected and analysed for the presence of haemolytic E. coli. Resistance and virulence genes associated with ETEC was detected by multiplex PCR, and antimicrobial susceptibility profiles were determined using broth microdilution and disc diffusion. Results: Haemolytic E. coli were identified in 40.3% of samples (n = 148 non-duplicate isolates), with the highest prevalence observed in growing piglets (47.1%). ETEC occurred in 5.4% of isolates. All isolates exhibited resistance to at least three antimicrobial classes (MDR), with high levels of resistance to tetracycline (98.0%), neomycin (97.3%), chloramphenicol (95.9%), sulfamethoxazole (93.9%), trimethoprim (91.9%), ampicillin (91.9%), nalidixic acid (82.4%), and ciprofloxacin (79.7%). Colistin resistance was observed in 5.4% of isolates, mediated by mcr1 or mcr3, while cefotaxime resistance (8.8%) was extensively associated with blaCTX-M. Conclusions: These findings reveal a concerning burden of MDR E. coli in Colombia’s pig-producing regions and indicate that haemolysis alone is a poor indicator of ETEC. Integrating farm-level antimicrobial use data with genomic analyses will be essential to identify drivers of AMR and guide effective stewardship in the Colombian pig industry. Full article

Topical antibiotics have long been used for the prevention and treatment of superficial skin and soft tissue infections; however, increasing evidence indicates that their clinical value is undermined by rising antimicrobial resistance, high rates of allergic sensitization, inadequate activity against biofilms, and a lack of wound-healing properties. Agents such as bacitracin, neomycin, polymyxin B, mupirocin, and fusidic acid act through narrow, target-specific mechanisms that facilitate resistance selection and provide limited benefit in chronic or polymicrobial wound environments. Contemporary antimicrobial stewardship frameworks therefore discourage routine use of topical antibiotics and increasingly favor non-antibiotic antiseptics with broad-spectrum activity and low resistance risk, including silver, iodine, polyhexamethylene biguanide, octenidine, and medical-grade honey. These modalities, however, primarily serve to reduce microbial burden and do not directly address the underlying biological impairments that prevent healing. Nitric oxide-releasing gels (NORGs) represent a novel class of topical antimicrobials that combine multi-target bactericidal activity with physiologic pro-healing effects. Nitric oxide exerts potent antimicrobial and antibiofilm effects via oxidative and nitrosative stress, disruption of metabolic pathways, inhibition of DNA replication, and interference with quorum sensing. Simultaneously, nitric oxide enhances angiogenesis, modulates inflammation, improves microvascular perfusion, and promotes fibroblast and keratinocyte function. Preclinical models and early-phase clinical studies demonstrate broad-spectrum efficacy—including activity against multidrug-resistant organisms—with favorable tolerability and minimal risk of resistance development. Although the current evidence base remains preliminary, NORGs offer a promising antimicrobial platform with the potential to reduce reliance on topical antibiotics while simultaneously addressing key barriers to wound healing. Larger randomized controlled trials, direct comparisons with established advanced dressings, and robust pharmacoeconomic evaluations are needed to define their optimal role within stewardship-aligned wound-care practice. Full article

RNA triple helices are relatively understudied, including their interactions with small molecules. In this study, we evaluated eight previously reported triplex-binding molecules (TBMs) for their functional effects on the premature and mature MALAT1 triple helix. Based on UV thermal denaturation experiments, the TBMs berberine, coralyne, sanguinarine, berenil, and neomycin selectively stabilize the Hoogsteen interface of the MALAT1 triple helix. Moreover, fisetin, luteolin, and quercetin were more sensitive to nucleotide composition, whereas berberine, coralyne, sanguinarine, and berenil were more sensitive to changes in the length of the major-groove triple helix. Most TBMs could not outcompete MALAT1 triple helix-binding proteins, except for neomycin. Surface plasmon resonance experiments demonstrated that berberine and sanguinarine display relatively quick association and dissociation binding profiles. Treating human colorectal carcinoma cells with each of the TBMs reduced MALAT1 levels by ~20–60%. This study demonstrates that TBMs broadly recognize the premature and mature MALAT1 triple helix but exhibit subtle sensitivities, suggesting that TBMs can be designed to selectively bind triple helices based on nucleotide composition, length, and structural context. Full article

Neuromast cells are specialized mechanosensory receptor cells embedded within the lateral line system of aquatic vertebrates, enabling the detection of water movement and vibration that are essential for navigation, prey capture, and predator avoidance. These cells share common evolutionary and functional homology with mammalian inner ear hair cells, both of which rely on stereocilia-mediated mechano-transduction and ion channel activation to convert mechanical stimuli into neural signals. Unlike their mammalian counterparts, neuromast hair cells possess a regenerative capacity following damage, making the lateral line system a unique model for studying hair cell regeneration and sensory restoration. This study examines the potential of the Mexican tetra (Astyanax mexicanus) as a novel model organism for investigating ototoxicity and regeneration of neurosensory hair cells. Here, we explore the cranial and trunk lateral line neuromasts, including deep canal neuromast cells located in facial bones, such as the mandible and circumorbital bones. In the present study, juvenile surface-dwelling Mexican tetra were exposed to a 500 µM neomycin for 4 h to induce targeted hair cell damage. The samples were collected at 4-, 12-, 24-, and 72 h post-exposure. Furthermore, neuromast cell viability was assessed using [2-(4-(Dimethylamino) styryl)-N-ethylpyridinium iodide] (DASPEI). Gene expression analysis revealed a modest increase in Fibroblast Growth Factor 1 (fgf1) and Axis Inhibition Protein 2 (axin2) expression following treatment; however, these changes were not statistically significant. The SRY-box transcription factor 2 (sox2) remains constant throughout the exposure and recovery period. These findings highlighted the regenerative dynamics of neuromast cells in Mexican tetra. This work lays the foundation for future therapeutic strategies targeting human sensory deficits, particularly those involving inner ear hair cell degeneration. Full article

Background: Skin infections caused by Staphylococcus aureus represent a major public health concern, and plant extracts, such as those from Cochlospermum regium, have emerged as promising therapeutic alternatives. Methods: This study developed carbopol-based gel formulations containing ethanolic leaf extracts of C. regium (CRG 0.5% and 1%) and evaluated their physicochemical stability, antibacterial activity against S. aureus and a methicillin-resistant wound isolate, antioxidant potential, and biocompatibility. Results: Both CRG 0.5% and 1% were physically stable and maintained antibacterial activity for up to 90 days at 8 °C, while at 25 °C only CRG 1% retained activity throughout the evaluation period. In ex vivo pig skin assays, CRG 1% reduced methicillin-resistant S. aureus contamination by 99%, outperforming the conventional topical antibacterial agent (neomycin + bacitracin), which achieved 66% inhibition. The extract also exhibited high antioxidant activity without mutagenic or hemolytic effects. Although phenolic and flavonoid contents decreased over time, CRG 1% preserved adequate levels for therapeutic application. Conclusions: These findings indicate that CRG 1% has potential as a stable, safe, and effective alternative for the treatment of topical infections, particularly those caused by methicillin-resistant S. aureus. Full article

Hearing loss affects millions and is often caused by irreversible damage to mechanosensory hair cells. Humans and other mammals lack the capacity to regenerate damaged hair cells; however zebrafish, Danio rerio, can regenerate hair cells that are present in the ear and mechanosensory neuromasts, making this animal an ideal model for understanding hair cell regenerative mechanisms. This study investigates the role of the GDP-fucose biosynthesis gene GDP-mannose 4,6-dehydratase (gmds) in regulating neuromast hair cell regeneration in zebrafish. Fucosylation is required for Notch signalling, a critical negative regulator of hair cell regeneration, and we therefore hypothesized that loss of gmds function would enhance hair cell regeneration. We demonstrate increased hair cell number in gmds mutants, and increased hair cell number following chemical ablation of hair cells with neomycin. Additionally, gmds mutants exhibited accelerated neuromast and hair cell regeneration, achieving complete restoration faster than wild-type siblings. Pharmacological inhibition of Notch signalling further enhanced hair cell regeneration in wild-type siblings but less so in gmds mutants, indicating that Notch signalling may partially regulate hair cell regeneration downstream of gmds. These findings highlight the importance of GDP-fucose biosynthesis in regulating hair cell number and regeneration, likely partially dependent on Notch signalling. Full article

Background: The incidence of chemical ocular trauma after accidentally instilling the “wrong” eyedrops is still frequent, but cases resulting from stamper ink refills are rare. Case Presentation: A 73-year-old man presented to our emergency department with a history of inadvertently instilling stamper ink refill into both eyes (BEs) instead of artificial tears. Immediate irrigation and evaluation were performed. The initial visual acuity (VA) was 0.4 in the right eye (RE) and 0.8 in the left eye (LE). Slit lamp examination showed edema palpebra with periocular blue staining in BEs, chemotic conjunctiva with a much darker color in the RE than the LE, and epithelial defects with a positive fluorescein test in BEs. A diagnosis of bilateral corneal abrasion and chemotic conjunctiva was established. Ten hours after the emergency visit, RE VA decreased to 0.2, and corneal edema was found during the follow-up examination. Medications including levofloxacin antibiotic, sodium hyaluronate, sodium chloride, combined polymyxin sulfate–neomycin sulfate and dexamethasone eyedrops, mefenamic acid, and ascorbic acid tablets were prescribed. The RE corneal edema still occurred, and the endothelial cell count was 1952 and 987 cells/mm² in the RE and LE at the one-week follow-up. After three weeks, corneal edema had fully resolved, and the VA was 0.4 and 0.8 in the RE and LE, respectively. Conclusions: This case report adds to the spectrum of the continuing problem of chemical ocular trauma after mistakenly instilling the eyedrops. Promoting and changing to different packages for non-ophthalmic products in plastic bottles mimicking eyedroppers is essential to minimize these injuries. Full article

In the process of chicken breeding, there has been a great deal of abuse of antibiotics. Antibiotics can enter the human body along with the chicken meat, comprising a possible risk to human health. In this paper, principal component analysis (PCA)–linear discriminant analysis (LDA) was chosen to classify neomycin (NEO) and chloramphenicol (CAP) residues in chicken meat. A total of 400 chicken meat samples were used for the classification, of which 268 samples and 132 samples were used as the training sets and the test sets, respectively. The experimental condition of SERS spectrum collection was optimized, including the use of a gold colloid and active agent, and an improvement in the adsorption time. The optimal measurement conditions for the SERS spectra were an adsorption time of 4 min and the use of a 14th-generation gold colloid as the enhanced substrate without a surfactant. For three groups of different spectral preprocessing methods, the classification accuracies of PCA-LDA models for test sets were 78.79% for baseline correction, 84.85% for the second derivative and 100% for the second derivative combined with baseline correction. LDA was used to establish a classification model to realize the quick determination of NEO and CAP residues in chicken meat by SERS. The results showed that the characteristic peaks at 546 and 666 cm⁻¹ could be used to distinguish NEO and CAP residues in chicken meat. The classification model based on PCA-LDA had higher classification accuracy, sensitivity and specificity using a second derivative combined with baseline correction as the spectral preprocessing method, which shows that the SERS method based on PCA-LDA could be used to perform the classification of NEO and CAP residues in chicken meat quickly and effectively. It also verified the feasibility of PCA-LDA to effectively classify chicken meat samples into four types. This research method could provide a reference for the measurement of such antibiotic residues in chicken meat in the future. Full article

Background/Objectives: Antimicrobial resistance is a major global health threat. Among the most problematic pathogens are carbapenem-resistant Acinetobacter baumannii and Klebsiella pneumoniae, which are significant causes of mortality in humans, particularly in the context of nosocomial infections. In companion animals, these bacteria have been reported mainly as colonizers of healthy animals or, less frequently, in community-acquired infections. However, no confirmed cases of healthcare-associated infections caused by these species have been documented in this population. This study reports the first confirmed fatal cases of infection with carbapenem-resistant A. baumannii and KPC-producing K. pneumoniae in dogs. Methods: Three hospitalized dogs developed infections associated with distinct anatomical devices, including a venous catheter, an endotracheal tube, and a Penrose drain. Bacterial isolation followed by antimicrobial susceptibility testing identified carbapenem-resistant A. baumannii and K. pneumoniae. The isolates were subsequently subjected to additional antimicrobial resistance tests and whole-genome sequencing (WGS). Results: WGS confirmed the presence of the OXA-23 carbapenemase gene in both A. baumannii isolates and the KPC-2 carbapenemase gene was detected in the K. pneumoniae strain. All three strains exhibited resistance to multiple antimicrobial classes, including β-lactams (amoxicillin-clavulanic acid, ampicillin, cephalotin, piperacillin-tazobactam, cefoxitin, ceftiofur, cefotaxime, ertapenem, imipenem and meropenem), aminoglycosides (gentamicin, neomycin), tetracyclines (doxycycline, tetracycline and oxytetracycline), fluoroquinolones (ciprofloxacin, enrofloxacin), and folate pathway antagonists (trimethoprim-sulfamethoxazole). Multilocus sequence typing identified two high-risk clones: K. pneumoniae ST340 (CC258) and A. baumannii ST15 (CC15). Single nucleotide polymorphism analysis confirmed a high degree of genetic similarity between these isolates and strains previously associated with human infections in Brazil. Conclusions: These findings provide the first evidence of fatal, healthcare-associated infections caused by these multidrug-resistant pathogens in dogs and underscore the need to strengthen surveillance and infection control practices in veterinary hospitals. Furthermore, the results raise concerns about the potential of companion animals to act as reservoirs for multidrug-resistant organisms of public health relevance. Full article

Background: Shiga toxin-producing E. coli (STEC) are important foodborne pathogens that cause serious public health consequences worldwide. This study conducted a systematic review and meta-analysis of the global prevalence of antibiotic resistance and STEC in chickens. Methods: The assessment of previous study records was carried out following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Heterogeneity between studies was assessed using Cochrane’s Q test and I² test statistics based on the random effects model, and comprehensive meta-analysis (CMA) software v4.0 was used to analyse the pooled prevalence estimate (PPE) of antibiotic resistance and STEC in chickens. Results: A total of 61 studies comprising 823 STEC from 18 countries were included in this study. The overall pooled prevalence of STEC was 8.9% (95% CI: 0.620–0.126). m-PCR assay showed the highest PPE of 21.0% (95%: 0.088–0.420). stx1 had the higher PPE of 12.9% (95%: 0.081–0.199), while stx2 had a PPE of 11.8% (95%: 0.077–0.176). Furthermore, the serotype O157 had the higher PPE of 80.5% (95%: 0.520–0.940). The isolates were resistant to the following antibiotics: amoxicillin and clavulanic acid, chloramphenicol, tetracycline, ciprofloxacin, gentamycin, ampicillin, neomycin, and amoxicillin. Conclusions: These findings may assist in the prevention and control of STEC in chickens globally. To minimise the spread of STEC and antibiotic resistance, future foodborne pathogen prevention and control programmes should prioritise increasing laboratory capacity for the early identification of antibiotic resistance. Full article

Background: Stenotrophomonas maltophilia is one of the common causative agents of hospital-acquired infections worldwide. The major concern regarding S. maltophilia infections is its extreme resistance to multiple antibiotics. Methods: Enrofloxacin-resistant mutants of S. maltophilia K279a were selected using a serial passage technique. Results: In this study, we showed that one of the mutant strains, KE507, which was selected from S. maltophilia K279a for its resistance to the veterinary drug enrofloxacin, conferred resistance to trimethoprim/sulfamethoxazole (co-trimoxazole), levofloxacin, and minocycline as per the Clinical and Laboratory Standards Institute guideline. These antibiotics are the first-line drugs routinely used to treat S. maltophilia infections. The KE507 mutant also showed increased resistance to all tested quinolones, azithromycin, and neomycin. Molecular characterization using whole genome sequencing, antibiotic resistance gene expression profiles, and mutational analysis indicated that inactivation of SmeRv (Q208insHSPRFTW), a transcriptional regulator of the SmeVWX multidrug efflux pump, contributes to resistance to quinolones (including levofloxacin), co-trimoxazole, and partially to neomycin, but not to azithromycin or minocycline. These data, together with in silico structural analysis, suggest that the mutation of SmeRv causes a conformational change in the SmeRv structure, which leads to the activation of SmeVWX efflux transporter expression and subsequent resistance to co-trimoxazole and quinolone antibiotics. Conclusion:S. maltophilia can thus acquire resistance to the antibiotics primarily used to treat S. maltophilia infections through the mutation of SmeRv. Full article

Mastitis is defined as mammary gland inflammation and is one of the most common and economically significant diseases affecting dairy cows. Bacteria are the most frequently reported agents responsible for mastitis, while other pathogens are often overlooked due to insufficient routine investigation. Incomplete diagnoses can result in inappropriate antimicrobial treatments, treatment failures, antimicrobial resistance, the spread of pathogens, and the recurrence of mastitis. Background/Objectives: This study aimed to investigate the presence of Staphylococcus spp. associated with Romanian buffalo mastitis on dairy farms in Western Romania via a bacteriological analysis of mastitis milk and determine antimicrobial susceptibility profiles. Methods: Bacterial culture was performed according to the guidelines described by the National Mastitis Council. Vitek 2 Compact systems (Bio Mérieux, France), with the GP ID cards, were used to confirm the species of the isolates. Antibiotic susceptibility testing was conducted by utilizing Vitek^® 2 preset antimicrobial card AST-GP79 Gram-positive Livestock WW. Results: Of all the milk samples (n = 115) analyzed, 83 were positive for Staphylococcus spp. (72.17%) and were evaluated for their antimicrobial susceptibility profiles. The most common microorganism found was S. aureus (n = 46; 55.42%), followed by S. hyicus (n = 28; 33.73%) and S. schleiferi (n = 9; 10.84%). These pathogens demonstrated significant resistance to the tetracycline, neomycin, benzylpenicillin, and erythromycin. Conclusions: Current control measures for mastitis caused by S. aureus are ineffective. A better understanding of the virulence factors in Romanian buffalo-adapted strains of S. aureus, their pathogenesis, and host immunological responses is essential for developing effective and sustainable non-antibiotic control tools such as vaccines, prophylactic therapies, and other innovative approaches. Full article

The rapid increase in drug resistance in recent years has become a significant global public health concern. Escherichia coli are ubiquitous bacteria, widely distributed in various environments. This study isolated a bacterial strain (HD-593) from diseased Chinese soft-shelled turtles (Pelodiscus sinensis). The bacterium was identified based on morphology, biochemical tests, and 16S rRNA sequencing, confirming it as E. coli. Drug susceptibility tests revealed that the HD-593 strain was highly resistant to ceftriaxone, enrofloxacin, doxycycline, sulfadiazine, gentamicin, neomycin, florfenicol, carbenicillin, cefradine, erythromycin, penicillin, ampicillin, midecamycin, and streptomycin. Resistance gene analysis confirmed the presence of quinolone resistance genes (oqxA and oqxB), aminoglycoside resistance genes (aac(3)-II and aphA1), a β-lactam resistance gene (blaTEM), and an acylaminol resistance gene (floR) in HD-593. The median lethal dose (LD50) of HD-593 for P. sinensis was 6.53 × 10⁵ CFU/g. Biochemical analysis of serum revealed that HD-593 infection caused a significant reduction in total protein, albumin, and globulin levels, while markedly increasing the levels of aspartate aminotransferase, alanine aminotransferase, and alkaline phosphatase. Histopathological analysis revealed severe intestinal damage characterized by villi detachment and muscle cell necrosis. Additionally, extensive splenocyte necrosis with nuclear marginalization, glomerular swelling, and pronounced hepatic steatosis accompanied by distended sinusoids were observed. This study identified a multidrug-resistant E. coli strain from deceased P. sinensis, suggesting that drug resistance genes may circulate in aquaculture ecosystems, posing potential risks to aquaculture. Full article

Background: Antimicrobial resistance (AMR) poses a growing threat to veterinary medicine and food safety. This study examines Escherichia coli antibiotic resistance patterns in ducks, focusing on multidrug-resistant (MDR) strains. Understanding resistance patterns and predicting MDR occurrence are critical for effective intervention strategies. Methods: E. coli isolates were collected from duck samples across multiple regions. Descriptive statistics and resistance frequency analyses were conducted. A decision tree classifier and a neural network were trained to predict MDR status. Cross-resistance relationships were visualized using graph-based models, and Monte Carlo simulations estimated MDR prevalence variations. Results: Monte Carlo simulations estimated an average MDR prevalence of 79.6% (95% CI: 73.1–86.1%). Key predictors in MDR classification models were enrofloxacin, neomycin, amoxicillin, and florfenicol. Strong cross-resistance associations were detected between neomycin and spectinomycin, as well as amoxicillin and doxycycline. Conclusions: The high prevalence of MDR strains underscores the urgent need to revise antibiotic usage guidelines in veterinary settings. The effectiveness of predictive models suggests that machine learning tools can aid in the early detection of MDR, contributing to the optimization of treatment strategies and the mitigation of resistance spread. The alarming MDR prevalence in E. coli isolates from ducks reinforces the importance of targeted surveillance and antimicrobial stewardship. Predictive models, including decision trees and neural networks, provide valuable insights into resistance trends, while Monte Carlo simulations further validate these findings, emphasizing the need for proactive antimicrobial management. Full article

Lactobacillaceae is a large family of bacteria from which probiotic strains often originate. Microorganisms used as feed additives in the EU must meet a number of formal criteria, some of which concern antimicrobial susceptibility. In this study, we determined the susceptibility of 19 reference strains and 121 wild-type strains of Lactobacillaceae to aminoglycoside antibiotics using the broth microdilution method based on the ISO 10932:2010/IDF 223:2010 standard. Strains were categorized as resistant or susceptible according to European Food Safety Authority (EFSA) guidelines. Resistance genes were detected by whole genome sequence (WGS) analysis or by PCR. The MICs read after 48 h of incubation showed that 36.8% of reference strains were resistant to kanamycin, 26.3% to streptomycin, and 5.3% to gentamicin, with no aminoglycoside resistance genes detected in any genome. As many as 93.2% of field isolates of Ligilactobacillus salivarius, 85% of Ligilactobacillus agilis, and 58.8% of Lactiplantibacillus plantarum were classified as resistant to kanamycin, with the aac(6)-Ie-aph(2)-Ia gene detected only in two isolates. In six of 12 streptomycin-resistant strains, the ant(6)-Ia gene was identified, which usually coexisted with the spw gene. Three isolates with high neomycin MICs harbored the ant(4′)-Ia gene. In Lactobacillus gallinarum strain LMG 9435, characterized by streptomycin MIC value > 1024 µg/mL, a potential resistance-causing mutation in the rpsL gene (Lys56 → Arg) was detected. The results of the study indicate that some genera of Lactobacillaceae, in particular L. salivarius and L. agilis, exhibit natural resistance to aminoglycoside antibiotics, mainly kanamycin. Therefore, there is a need to update the EFSA guidelines on antimicrobial susceptibility testing of Lactobacillaceae, so that strains lacking resistance genes and/or chromosomal mutations are not considered to be resistant. Full article