Search Results (50)

Background: Antimicrobial resistance (AMR) is an escalating concern in both human and veterinary medicine, particularly in the poultry sector, where antibiotic usage is substantial. Streptococcus spp. and Staphylococcus aureus are important pathogens in waterfowl, causing systemic infections. However, there is a significant lack of data regarding their antimicrobial susceptibility patterns in waterfowl populations. This study aims to address this gap by determining the minimum inhibitory concentrations (MICs) of isolates from Hungarian waterfowl farms and evaluating resistance patterns in clinical isolates. Methods: A total of eight S. aureus and 19 Streptococcus isolates were collected from ducks and geese between 2022 and 2023. Antimicrobial susceptibility testing was performed for 15 antimicrobials using the broth microdilution method. Potential associations between MIC values were analyzed using Spearman’s rank correlation test. Results: High MIC values were observed for tetracyclines, phenicols, and fluoroquinolones, in the case of Streptococcus, with 89.5% of isolates exhibiting resistance to doxycycline, 63.2% to florfenicol, and in the case of S. aureus, 25.0% to enrofloxacin. In the case of Streptococcus, a strong positive correlation was identified between tylosin and tiamulin (0.88, p < 0.001), as well as between tylosin and lincomycin (0.75, p < 0.001). A moderate correlation was observed between doxycycline and spectinomycin (0.72, p = 0.03), suggesting potential co-selection mechanisms. Conclusions: Our findings emphasize the necessity of continuous AMR surveillance in the waterfowl industry, particularly for multidrug-resistant strains. Understanding cross-resistance patterns is crucial for developing targeted control measures, and future studies should incorporate whole-genome sequencing to elucidate resistance determinants and co-selection mechanisms. This study highlights the potential public health and veterinary risks associated with AMR in waterfowl and reinforces the importance of responsible antibiotic use and the development of alternative therapeutic strategies in veterinary practice. 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

Background:Riemerella anatipestifer and Erysipelothrix rhusiopathiae remain clinically significant pathogens in the waterfowl industry, causing substantial economic losses and posing potential zoonotic risks. Antimicrobial resistance (AMR) continues to spread in the poultry sector, making regular surveillance of bacterial isolates essential. Methods: In this study, eight R. anatipestifer and eighteen E. rhusiopathiae strains were isolated from clinical cases in Hungarian waterfowl between 2022 and 2023. Minimum inhibitory concentration (MIC) values were determined for antibiotics of veterinary and public health significance. Results: For R. anatipestifer, high resistance rates were observed for spectinomycin, lincomycin, and tiamulin, while beta-lactam antibiotics (amoxicillin, ceftriaxone, and imipenem) demonstrated strong efficacy. Among the E. rhusiopathiae isolates, resistance to amoxicillin (89%) and enrofloxacin (61%) was notable, whereas ceftriaxone and doxycycline exhibited moderate antibacterial effects. Conclusions: Our findings underscore the importance of targeted antimicrobial use in the waterfowl industry. Beta-lactam antibiotics remain effective, whereas rising resistance to fluoroquinolones and aminoglycosides raise serious concerns. Routine AMR surveillance and the adoption of alternative strategies are crucial for controlling infections and maintaining flock health. Full article

Background: Antimicrobial resistance (AMR) poses an increasing threat to animal health and food safety. In the poultry sector, particularly in waterfowl farming, the widespread use of antibiotics may contribute to the dissemination of resistant Escherichia coli strains. This study aims to map the antibiotic resistance profiles of E. coli isolates from geese in Hungary, determine the prevalence of multidrug-resistant (MDR) and extensively drug-resistant (XDR) strains, and analyze resistance patterns and co-resistance relationships. Methods: E. coli isolates from clinical cases between 2022 and 2023 were examined using minimum inhibitory concentration (MIC) determination. Susceptibility results were evaluated based on the Clinical Laboratory Standard Institute (CLSI) breakpoints. Cluster analysis and principal component analysis (PCA) were applied to identify resistance patterns. Co-resistance relationships were examined through network analysis, while Monte Carlo simulations were used to estimate the expected prevalence of MDR strains. Results: Among the examined isolates, neomycin resistance was particularly high (86.8%), while florfenicol (73.6%) and amoxicillin (65.9%) resistance levels were also significant. The prevalence of MDR strains was 86.8%, and XDR strains accounted for 38.5%. Co-resistance analysis revealed a strong correlation between neomycin and spectinomycin resistance, as well as amoxicillin and doxycycline resistance. Monte Carlo simulations estimated that the expected range of MDR strain prevalence could vary between 80.2% and 92.3%. Conclusions: The high prevalence of MDR and XDR strains highlights the urgent need to reassess antibiotic usage strategies in goose farming. These findings underscore the importance of targeted antibiotic use, continuous microbiological surveillance, and the exploration of alternative therapeutic approaches to mitigate AMR. Full article

Neisseria gonorrhoeae (NG) is a globally significant sexually transmitted infection (STI) with increasing antimicrobial resistance (AMR), posing a serious threat to public health. Between 2016 and 2022, the Israeli National NG Reference Center (INNGRC) comprehensively analyzed NG isolates in Israel to determine AMR patterns and sequence types (STs). Antimicrobial susceptibility testing (AST) was performed on 1205 NG isolates using E-test gradient strips, and NG-MAST analysis was conducted on 279 isolates via Sanger sequencing and whole genome sequencing (WGS). Surveillance revealed high resistance rates to ciprofloxacin (54.4%), azithromycin (41.3%), tetracycline, and benzylpenicillin, while all isolates remained susceptible to ceftriaxone and spectinomycin. Multi-drug resistance (MDR) was observed in 8.6% of isolates, and 3% were classified as extensively drug-resistant (XDR). NG-MAST analysis identified 72 distinct STs, with ST292, ST4269, and ST5441 being the most prevalent. ST19665 and ST11461 predominated in 2022, while ST292, ST5441, and ST16169 were more abundant in 2018. The findings highlight the increasing prevalence of AMR in NG in Israel and underscore the importance of continuous surveillance and molecular characterization by reference laboratories like the INNGRC to inform treatment strategies and public health interventions, ultimately reducing the burden of this critical STI. Full article

The objective of this study was to determine the frequency of Salmonella in pig samples analyzed at the Veterinary Diagnostic Unit of the Faculty of Agricultural Sciences of the University of Antioquia, Colombia, between 2022 and 2023. Out of 5820 serum samples analyzed using indirect enzyme-linked immunosorbent assay, 63.76% were positive. Additionally, Salmonella was isolated and identified in a separate group of 848 samples (feces, tissues, etc.) with a positivity rate of 23.47%. Eight serotypes were identified, with the most common being Salmonella enterica subsp. enterica serotype Typhimurium (49.2%), followed by its monophasic variant I 4,[5],12:i:- (23%), and serotype Choleraesuis (18%). Antimicrobial susceptibility profiles of 105 isolates were evaluated using the Kirby–Bauer method, which demonstrated higher resistance (100%) to ampicillin, tiamulin, penicillin, tylosin, and erythromycin (these were the least tested), followed by florfenicol (44/54), doxycycline (4/5), spectinomycin (18/25), amoxicillin (32/46), chloramphenicol (2/3), tetracycline (2/3), and enrofloxacin (34/64), with lower resistance observed for fosfomycin (2/38) and ceftiofur (5/35). Multi-drug resistance was observed in 59% (62/105) of the isolates. The high proportion of Salmonella and the levels of resistance to various drugs raise significant concerns, indicating potential deficiencies in responsible antimicrobial use and management practices on pig farms in the region. Full article

Background: Antimicrobial resistance (AMR) has become a serious global challenge in the 21st century. Poultry, including turkeys, are a vital source of animal-derived protein worldwide. Commensal bacterial strains in poultry can act as reservoirs for AMR, making monitoring them crucial for both veterinary and public health. Enterococcus species are emerging pathogens, particularly in severe nosocomial infections. Methods: This study aimed to assess the resistance profiles of commensal Enterococcus strains isolated (n = 470) from large-scale turkey flocks in Hungary. From each animal, two swab samples were collected: one from the oropharyngeal region near the tracheal entrance and one from the cloaca. The samples were subsequently processed, and the minimum inhibitory concentration (MIC) was determined following the Clinical and Laboratory Standards Institute (CLSI) guidelines. The tested antibiotics included amoxicillin, amoxicillin–clavulanic acid, imipenem, neomycin, doxycycline, florfenicol, tylosin, enrofloxacin, potentiated sulfonamide, vancomycin, ceftriaxone, spectinomycin, tiamulin, lincomycin, and colistin. The dilution range for MIC determination was set between 512 and 0.001 µg/mL. Results: Resistance to amoxicillin, a first-line treatment for Enterococcus infections, was low (11.1%). However, high resistance levels were observed for tylosin (62.6%), florfenicol (51.1%), doxycycline (48.7%), and enrofloxacin (45.5%). Notably, vancomycin resistance reached 15.5%, a finding consistent with global trends. Compared to human-derived Enterococcus data, resistance to aminopenicillins was significantly lower in turkey isolates, while neomycin resistance levels were comparable to those observed in human E. faecalis strains. Conclusions: The findings underscore the necessity of continuous surveillance of AMR trends in poultry production. While amoxicillin remains an effective treatment, the presence of multidrug-resistant strains and vancomycin-resistant isolates raises concerns regarding the potential dissemination of resistance genes. Future studies should incorporate next-generation sequencing to elucidate the genetic mechanisms underlying resistance. Additionally, integrating antibiotic usage data from farms may provide further insights into resistance dynamics. Strengthening antibiotic stewardship programs and fostering collaboration between veterinary and human medicine are crucial steps in addressing AMR under the One Health framework. Full article

CRISPR/Cas9, as a well-established gene editing technology, has been applied in numerous model organisms, but its application in wild-type E. coli remains limited. Pathogenic wild-type E. coli, a major cause of foodborne illnesses and intestinal inflammation in humans and animals, poses a significant global public health threat. The valine-glycine repeat protein G (VgrG) is a key virulence factor that enhances E. coli pathogenicity. In this study, PCR was used to identify 50 strains carrying the virulence gene VgrG2 out of 83 wild pathogenic E. coli strains, with only one strain sensitive to kanamycin and spectinomycin. A homologous repair template for VgrG2 was constructed using overlap PCR. A dual-plasmid CRISPR/Cas9 system, combining pTarget (spectinomycin resistance) and pCas (kanamycin resistance) with Red homologous recombination, was then used to induce genomic cleavage and knock out VgrG2. PCR and sequencing confirmed the deletion of a 1708 bp fragment of the VgrG2 gene in wild-type E. coli. IPEC-J2 cells were infected with E. coli-WT and E. coli ∆VgrG2, and treated with the mTOR inhibitor rapamycin to study the effects of VgrG2 on the mTOR signaling pathway. The qPCR results showed that VgrG2 activated the mTOR pathway, suppressed mTOR and p62 mRNA levels, and upregulated the autophagy-related genes and LC3-II protein expression. In conclusion, we utilized CRISPR/Cas9 technology to achieve large-fragment deletions in wild-type E. coli, revealing that VgrG2 activates the mTOR signaling pathway and upregulates autophagy markers. These findings offer new insights into E. coli genome editing and clarifies the pathogenic mechanisms through which VgrG2 induces cellular damage. Full article

This cross-sectional study assessed the prevalence, bacterial distribution, antimicrobial susceptibility, and potential risk factors associated with subclinical mastitis (SCM) in small-holder dairy herds in Gansu Province, Northwest China. Forty small-holder cow farms were randomly selected from eight cities/counties in six districts of Gansu Province, and a total of n = 530 lactating cows were included in this study. SCM prevalence was noted at 38.87% and 9.72% at the cow and quarter levels, respectively, based on the California Mastitis Test (CMT). The prevalence of the recovered bacterial species was noted as follows: S. agalactiae (36.02%), S. aureus (19.43%), coagulase-negative staphylococci (CNS) (16.11%), S. dysgalactiae (12.80%), E. coli (9.00%), and S. uberis (6.64%). All isolated bacteria were 100% multi-drug-resistant (MDR) except S. aureus (87.8% MDR). Antimicrobial susceptibility profiles revealed the increased resistance (>85%) of these pathogens to penicillin, streptomycin, trimethoprim–sulfamethoxazole, vancomycin, and erythromycin. However, these pathogens showed increased susceptibility to ampicillin, amoxicillin–sulbactam, ceftazidime, neomycin, kanamycin, spectinomycin, norfloxacin, ciprofloxacin, and doxycycline. The multivariate regression analysis demonstrated that old age, high parity, late lactation, lesions on teats, previous history of clinical mastitis, higher milk yield, and milking training were found to be potential risk factors (p < 0.001) associated with developing SCM in small-holder dairy cows in Gansu Province, China. These findings highlight the need for routine surveillance, antimicrobial stewardship, and effective preventive strategies to mitigate SCM in small-holder dairy production and their possible impacts, i.e., increased antimicrobial resistance and infection, on public health. Full article

Mycoplasma hyopneumoniae, an important cause of enzootic pneumonia in pigs in many countries, has recently been shown to exhibit reduced susceptibility to several antimicrobial classes. In the present study, a total of 185 pig lung tissue samples were collected from abattoirs in Australia, from which 21 isolates of M. hyopneumoniae were obtained. The antimicrobial resistance profile of the isolates was determined for 12 antimicrobials using minimum inhibitory concentration (MIC) testing, and a subset (n = 14) underwent whole-genome sequence analysis. MIC testing revealed uniformly low values for enrofloxacin (≤1 μg/mL), florfenicol (≤8 μg/mL), lincomycin (≤4 μg/mL), spectinomycin (≤4 μg/mL), tetracycline (≤0.5 μg/mL), tiamulin (≤2 μg/mL), tildipirosin (≤4 μg/mL), tilmicosin (≤16 μg/mL) tulathromycin (≤2 μg/mL), and tylosin (≤2 μg/mL). Higher MICs were observed for erythromycin (MIC range: 16–32 μg/mL), gamithromycin, and tilmicosin (MIC range of both: 32–64 μg/mL). Whole-genome sequencing of the isolates and additional screening using mismatch amplification mutation assay PCR did not identify any known genetic resistance markers within 23S rRNA (macrolides), DNA gyrase A, and topoisomerase IV genes (fluoroquinolones). The WGS data also indicated that the Australian M. hyopneumoniae isolates exhibited limited genetic diversity and formed a distinct monophylectic clade when compared to isolates from other countries. These findings indicate that Australian M. hyopneumoniae likely remains susceptible to the major antimicrobials used to treat enzootic pneumonia in pigs and have evolved in isolation from strains identified in other pig-producing countries. Full article

Antibiotic resistance in cyanobacteria represents a global threat to public health. The widespread presence of cyanobacteria in aquatic environments exposes them to antibiotic contamination. Cyanobacteria are also in direct contact with pathogenic bacteria containing antibiotic-resistance genes (ARGs), which impart these characteristics to them. This study aims to examine the presence of some ARGs in locally isolated cyanobacteria species, Spirulina laxa, Chroococcus minutes, Oscillatoria princeps, Oscillatoria proteus, Oscillatoria terebriformis, and Lyngbya epiphytica, and compare the presence of these genes in two pathogenic bacteria, Escherichia coli and Klebsiella pneumoniae. Ampicillin (Ap) and erythromycin (Em) resistance genes were detected in five algal samples. Meanwhile, Chloramphenicol (Cm) and gentamicin (Gm) resistance genes were apparent in only two species. Genes encoding resistance towards kanamycin (Km) and spectinomycin (Sp) were recorded in three specimens. It was also found that E. coli possessed resistance genes for four antibiotics, ampicillin (Ap), erythromycin (Em), gentamicin (Gm), and kanamycin (Km), whereas K. pneumoniae was resistant towards three antibiotics, ampicillin (Ap), gentamicin (Gm), and kanamycin (Km). The results show that there is a match in antibiotic-resistance genes in both cyanobacteria and pathogenic bacteria. Suggesting the possibility that cyanobacteria could acquire ARGs from the environment through horizontal gene transfer. Thus, freshwater cyanobacteria may play a significant role in the prevalence of ARGs in their environment. Full article

Streptococcus dysgalactiae infection can cause bovine mastitis and lead to huge economic losses for the dairy industry. The abuse of antibiotics has resulted in growing drug resistance of S. dysgalactiae, which causes hard-to-treat infections. Bacteriophage lysin, as a novel antibacterial agent, has great potential for application against drug-resistant gram-positive bacteria. However, few studies have been conducted on the prophage lysin of S. dysgalactiae. In this study, we mined a novel prophage lysin, named Lys1644, from a clinical S. dysgalactiae isolate by genome sequencing and bioinformatic analysis. Lys1644 was expressed and purified, and the lytic activity, antibacterial spectrum, optimal pH and temperature, lytic activity in milk in vitro, and synergistic bacteriostasis with antibiotics were assessed. The Lys1644 prophage lysin showed high bacteriolysis activity specifically on S. dysgalactiae, which resulted in CFU 100-fold reduction in milk. Moreover, Lys1644 maintained high activity over a wide pH range (pH 5–10) and a wide temperature range (4–42 °C). Synergistic bacteriostatic experiments showed that the combination of low-dose Lys1644 (50 μg/mL) with a subinhibitory concentration of aminoglycoside antibiotics (kanamycin or spectinomycin) can completely inhibit bacterial growth, suggesting that the combination of Lys1644 and antibiotics could be an effective therapeutic strategy against S. dysgalactiae infection. Full article

Salmonella spp. pose a global threat as a leading cause of foodborne illnesses, particularly prevalent in the European Union (EU), where it remains the second cause of foodborne outbreaks. The emergence of antimicrobial resistance (AMR) in Salmonella spp. has become a critical concern, complicating treatment strategies and escalating the risk of severe infections. The study focuses on large and small ruminants, identifying a prevalence of Salmonella spp. in slaughterhouses and revealing varied AMR rates across antimicrobial families throughout a meta-analysis. Also, comparison with AMR in human medicine was carried out by a systematic review. The results of the present meta-analysis displayed a prevalence of Salmonella spp. in large and small ruminants at slaughterhouses of 8.01% (8.31%, cattle; 7.04%, goats; 6.12%, sheep). According to the AMR of Salmonella spp., 20, 14, and 13 out of 62 antimicrobials studied were classified as low (<5%), high (>5% but <10%), and very high (>10%), respectively. Salmonella spp. did not display AMR against aztreonam, mezlocillin, ertapenem, meropenem, cefoxitin, ceftazidime, levofloxacin, tilmicosin, linezolid, fosfomycin, furazolidone, quinupristin, trimethoprim and spectinomycin. In contrast, a prevalence of 100% of AMR has been described against ofloxacin, lincomycin, and cloxacillin. In the context of the main antibiotics used in the treatment of human salmonellosis, azithromycin was shown to have the highest resistance among Salmonella spp. isolates from humans. Regarding cephalosporins, which are also used for the treatment of salmonellosis in humans, the prevalence of Salmonella spp. resistance to this class of antibiotics was similar in both human and animal samples. Concerning quinolones, despite a heightened resistance profile in Salmonella spp. isolates from ruminant samples, there appears to be no discernible compromise to the efficacy of salmonellosis treatment in humans since lower prevalences of AMR in Salmonella spp. isolated from human specimens were observed. Although the resistance of Salmonella spp. indicates some degree of concern, most antibiotics are not used in veterinary medicine. Thus, the contribution of cattle, sheep and goats to the rise of antibiotic resistance of Salmonella spp. and its potential impact on public health appears to be relatively insignificant, due to their low prevalence in carcasses and organs. Nevertheless, the observed low prevalence of Salmonella spp. in ruminants at slaughterhouse and the correspondingly low AMR rates of Salmonella spp. to key antibiotics employed in human medicine do not indicate that ruminant livestock poses a substantial public health risk concerning the transmission of AMR. Thus, the results observed in both the meta-analysis and systematic review suggests that AMR is not solely attributed to veterinary antibiotic use but is also influenced by factors such as animal health management (i.e., biosecurity measures, prophylactic schemes) and human medicine. Full article

Enterococcus cecorum is associated with bacterial chondronecrosis with osteomyelitis (BCO) in broilers. Prophylactic treatment with antimicrobials is common in the poultry industry, and, in the case of outbreaks, antimicrobial treatment is needed. In this study, the minimum inhibitory concentrations (MICs) and epidemiological cutoff (ECOFF) values (CO_WT) for ten antimicrobials were determined in a collection of E. cecorum strains. Whole-genome sequencing data were analyzed for a selection of these E. cecorum strains to identify resistance determinants involved in the observed phenotypes. Wild-type and non-wild-type isolates were observed for the investigated antimicrobial agents. Several antimicrobial resistance genes (ARGs) were detected in the isolates, linking phenotypes with genotypes for the resistance to vancomycin, tetracycline, lincomycin, spectinomycin, and tylosin. These detected resistance genes were located on mobile genetic elements (MGEs). Point mutations were found in isolates with a non-wild-type phenotype for enrofloxacin and ampicillin/ceftiofur. Isolates showing non-wild-type phenotypes for enrofloxacin had point mutations within the GyrA, GyrB, and ParC proteins, while five amino acid changes in penicillin-binding proteins (PBP2x superfamily) were observed in non-wild-type phenotypes for the tested β-lactam antimicrobials. This study is one of the first that describes the genetic landscape of ARGs within MGEs in E. cecorum, in association with phenotypical resistance determination. Full article

Pathogenic Staphylococcus spp. strains are significant agents involved in mastitis and in skin and limb infections in dairy cattle. The aim of this study was to assess the antibacterial effectiveness of bacteriophages isolated from dairy cattle housing as potential tools for maintaining environmental homeostasis. The research will contribute to the use of phages as alternatives to antibiotics. The material was 56 samples obtained from dairy cows with signs of limb and hoof injuries. Staphylococcus species were identified by phenotypic, MALDI-TOF MS and PCR methods. Antibiotic resistance was determined by the disc diffusion method. Phages were isolated from cattle housing systems. Phage activity (plaque forming units, PFU/mL) was determined on double-layer agar plates. Morphology was examined using TEM microscopy, and molecular characteristics were determined with PCR. Among 52 strains of Staphylococcus spp., 16 were used as hosts for bacteriophages. Nearly all isolates (94%, 15/16) showed resistance to neomycin, and 87% were resistant to spectinomycin. Cefuroxime and vancomycin were the most effective antibiotics. On the basis of their morphology, bacteriophages were identified as class Caudoviricetes, formerly Caudovirales, families Myoviridae-like (6), and Siphoviridae-like (9). Three bacteriophages of the family Myoviridae-like, with the broadest spectrum of activity, were used for further analysis. This study showed a wide spectrum of activity against the Staphylococcus spp. strains tested. The positive results indicate that bacteriophages can be used to improve the welfare of cattle. Full article