Search Results (743)

Respiratory diseases in poultry caused by Ornithobacterium rhinotracheale represent a significant challenge from both therapeutic and economic perspectives. Treatment of them, which uses antimicrobial agents, improperly contributes to the emergence and dissemination of multidrug-resistant strains within avian populations. The present study, based on O. rhinotracheale isolates (n = 733) obtained from the respiratory tract, joints, and organs of turkeys in Poland between 2016 and 2022, was conducted to assess the antimicrobial resistance of the strains and identify their serotypes. All O. rhinotracheale isolates were tested for antimicrobial susceptibility using the disk-diffusion method. The results of this study indicated that amoxicillin/clavulanic acid, doxycycline, florfenicol, and lincomycin/spectinomycin were the most effective agents against the isolates from turkeys. The findings showed that serotype I was the most prevalent among the tested turkey strains in Poland and was the serotype to which 29% of the O. rhinotracheale isolates affiliated. Full article

Background/Objectives: Antimicrobial resistance (AMR) in wildlife is an emerging public health concern due to the risk of zoonotic transmission, especially through the food chain, yet data on free-ranging animals remain scarce. This study examined the presence and patterns of AMR among bacteria isolated from hunted wild boars in the Campania region of Italy. Methods: Matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS) was used to identify bacterial isolates from wild boar meat and carcass swabs to the species level, and the Kirby–Bauer disk diffusion test was applied to screen 205 isolates, spanning 20 bacterial genera, against a panel of clinically relevant antibiotics. Resistance metrics were analyzed at genus and antibiotic levels, and patterns were visualized using a hierarchically clustered heatmap. Results: Resistance was detected in 15 of the 20 genera, with full susceptibility observed in Acinetobacter, Arthrobacter, Glutamicibacter, Leclercia, and Rahnella. Overall, 67.3% (138/205) of the isolates showed resistance to at least one antibiotic, with 33.7% (69/205) classified as multidrug-resistant (MDR). Carbapenems retained the highest activity (≥95% susceptibility) among all genera tested, while amoxicillin/clavulanate (78.4%) and aztreonam (57.4%) exhibited the highest mean resistance. Among potential pathogens, Escherichia coli exhibited an extended-spectrum β-lactamase (ESBL)-like phenotype, with resistance to amoxicillin/clavulanate (67%), aztreonam (54%), and ceftazidime (47%) but preserved carbapenem susceptibility. Staphylococcus spp. showed pronounced resistance to linezolid (57%) and erythromycin (52%), whereas Pseudomonas isolates demonstrated elevated resistance to aztreonam and ceftazidime (57% each). Opportunistic pathogens such as Alcaligenes faecalis and Pantoea agglomerans showed peak resistance to ciprofloxacin and amoxicillin/clavulanate. Pathogens and opportunistic pathogens demonstrated higher mean resistance (>30%) than commensals (≤32%), but the difference in mean and median resistance levels was not statistically significant (Mann–Whitney’s U test, W = 4, p = 0.39). Conclusions: These findings highlight the widespread occurrence of AMR and MDR phenotypes, with clinically significant resistance patterns in wild-boar-associated bacteria, including non-pathogenic strains, highlighting their role in the amplification of AMR. Although the preservation of carbapenem susceptibility underscores their potential as last-line antibiotics, the high resistance to commonly used antibiotics raises concerns for zoonotic transmission. Surveillance of wildlife reservoirs therefore remains critical for integrated AMR control. Full article

Background/Objectives: Although vonoprazan-based triple therapy has improved the first- and second-line Helicobacter pylori eradication rates, a subset of patients still require third-line or later treatments. The present study aimed to evaluate the efficacy and safety of susceptibility-guided eradication strategies from third-line or later treatments in a multicenter setting. Methods: This retrospective multicenter study (2019–2024) enrolled 94 patients who had failed second-line eradication therapy and underwent H. pylori isolation and susceptibility testing. Based on sitafloxacin sensitivity, patients received vonoprazan, amoxicillin, and sitafloxacin (VAS) if sensitive, or vonoprazan, amoxicillin, and rifabutin (VAR) if resistant. Altogether, 75 patients received treatment according to this protocol. Results: Among the 75 patients, 61.3% were sitafloxacin-sensitive (VAS group), and 38.7% were resistant (VAR group). All strains were rifabutin-sensitive. The overall eradication rates were 92.0% and 95.8% in the intention-to-treat and per-protocol analyses, respectively. Adverse events occurred in 17.3% of cases. One patient in the VAR group discontinued therapy due to dizziness, whereas all other adverse events were mild and did not require treatment cessation. Subgroup analysis showed eradication rates of 93.5% (43/46) and 89.7% (26/29) for the VAS and VAR groups, respectively. The eradication rate for third-line therapy was 96.2% (50/52), whereas that for fourth-line therapy was 85.7% (18/21). Fifth-line therapy showed an eradication rate of 50.0% (1/2). Conclusions: Susceptibility-guided vonoprazan-based regimens from the third-line treatment onward achieved high eradication and tolerability in a multicenter cohort. This approach may offer a valuable treatment option for patients with refractory H. pylori infections. Full article

Raw meat can act as a reservoir and vehicle for antimicrobial-resistant foodborne Escherichia coli, particularly when sold under poor hygienic conditions, as is often the case in informal markets in many developing countries, thereby representing a significant public health risk. This study aimed to characterize the antibiotic resistance patterns and virulence of E. coli isolated from raw meat sold in informal markets in Luanda, Angola. A total of 99 E. coli isolates were recovered from fresh beef, pork and goat meat in five informal markets. DNA macrorestriction analysis by Pulsed-Field Gel Electrophoresis (PFGE) was used to evaluate the genetic diversity of isolates. Multiplex PCR was performed to detect virulent and antibiotic resistance genes. Antibiotic susceptibility was tested using the disk diffusion method. PFGE analysis showed high genotypic diversity. Virulence genes were found in 46% of the isolates, with astA (32.3%) being the most frequent. The results also showed high resistance to cefotaxime (67.7%), ampicillin (56.7%) and amoxicillin/clavulanic acid (56.6%). Resistance to imipenem, a last-resort antibiotic, was observed in 30.3% of the isolates. The most prevalent resistance genes were CTX-M group 1 (10.1%) and FOX variants (27.3%). The presence of multidrug-resistant and potentially pathogenic E. coli strains in raw meat sold in informal markets in Luanda represents a significant threat to public health. These findings underscore the urgent need to improve surveillance, hygiene practices, and antimicrobial use regulation policies in animal production in Angola. Full article

Background: Canine skin and ear infections are common in small-animal practice and increasingly complicated by multidrug resistance (MDR), yet data from Serbia are limited. This study aimed to describe the bacterial etiology and antimicrobial resistance patterns in canine otitis externa and pyoderma. Methods: We retrospectively reviewed laboratory records from the Clinical Bacteriology and Mycology Laboratory, Faculty of Veterinary Medicine, University of Belgrade (January 2017–August 2024). A total of 422 non-invasive swabs from clinically ill dogs were included (ears: n = 210; skin: n = 212). Bacterial identification used conventional methods and commercial systems, and disk-diffusion susceptibility testing followed CLSI/EUCAST guidance. Methicillin resistance in staphylococci was assessed by cefoxitin/oxacillin screening; MRSA was confirmed by PCR and PBP2a detection. Resistance trends were compared between 2017–2020 and 2021–2024. Results: The leading pathogens were Staphylococcus pseudintermedius (ears 48.1%; skin 79.7%) and Pseudomonas aeruginosa (ears 29.1%; skin 7.6%). Staphylococci showed high resistance to macrolides, clindamycin, tetracycline, and first-line β-lactams (amoxicillin–clavulanate, cephalexin), with the highest susceptibilities to amikacin, florfenicol, and rifampicin. P. aeruginosa remained most susceptible to amikacin, polymyxin B, and imipenem. Between the two periods, S. pseudintermedius resistance increased to amikacin, fusidic acid, and cephalexin, while resistance to florfenicol decreased. P. aeruginosa resistance to imipenem increased. The prevalence of methicillin-resistant S. pseudintermedius (MRSP) was 27.4% (74/270). MDR S. pseudintermedius and MDR P. aeruginosa were identified in 38.5% and 53.3% of isolates, respectively. One isolate of each species was resistant to all tested drugs. Conclusions: These findings confirm high levels of antimicrobial resistance in major canine skin and ear pathogens and emphasize the need for susceptibility-based therapy, rational antimicrobial use, and ongoing surveillance in small-animal practice. Full article

Background/Objectives: The emergence of hypervirulent Pseudomonas aeruginosa strains resistant to β-lactamase inhibitor antibiotics is a critical health problem as they impede the treatment of infections. The objective of this study was to determine the different molecular arrangements of the virulence genotype related to β-lactamase genotype and the resistance phenotype to a combination of β-lactam antibiotics and β-lactamase inhibitors, and the phylogroups in P. aeruginosa strains isolated from patients with healthcare-associated infections and community-acquired infections. Methods: P. aeruginosa, virulence genes, β-lactamase genes and phylogroups were identified using polymerase chain reaction. Resistance to β-lactam antibiotics and β-lactamase inhibitors was determined using the disk diffusion method. The MIC determination of ticarcillin/clavulanic acid and piperacillin/tazobactam was performed using the MIC test strip for antimicrobial susceptibility testing. Results: In total, 124 P. aeruginosa strains from patients with healthcare-associated (67/124) and community-acquired infections (57/124) were analyzed. Most strains from patients with healthcare-associated infections and community-acquired infections harbored genes for proteases (aprA), phospholipases (pIcH and pIcN), elastases (lasA and lasB), rhamnolipids (rhLA), quorum-sensing system (lasI and rhII), and β-lactamase (bla_oxa-4, bla_oxa-1, and bla_GES). In total, 100% (124/124) and 99.1% (123/124) of the strains isolated from patients with healthcare-associated and community-acquired infections were resistant to the β-lactamase inhibitor antibiotics, amoxicillin/clavulanic acid and ampicillin/sulbactam, respectively, while 54% (67/124) of the strains were resistant to piperacillin/tazobactam. Phylogroup 1 (22/124) was detected more frequently among the strains in relation to phylogroup 2 (8/12). Conclusions: We demonstrated different association profiles of virulence genotype related to the β-lactamase genotype, the β-lactamase inhibitor resistome, phylogroups, and clinical origin of the strains. Therefore, medical treatment regimens against infections caused by P. aeruginosa should be improved. Full article

Subclinical mastitis is a major but often overlooked constraint to dairy productivity, causing economic losses through reduced milk yield and quality. In Romania, comprehensive data on the bacterial etiology and antimicrobial resistance (AMR) of subclinical mastitis are limited. This study aimed to characterize the etiological agents and antimicrobial susceptibility profiles of major bacterial pathogens isolated from subclinical mastitis cases in dairy cows from Western Romania. Between 2021 and 2022, milk samples were collected from 117 lactating cows diagnosed with subclinical mastitis on three dairy farms. Bacterial isolation and differentiation were performed on ChromID^® CPS^® Elite Agar, and isolates were confirmed by standard biochemical tests. Antimicrobial susceptibility testing of Staphylococcus aureus and Escherichia coli isolates was conducted using the automated Vitek^®2 system, interpreted according to CLSI veterinary standards. Multidrug resistance (MDR) was defined as resistance to at least one agent in three or more antimicrobial classes. Bacterial growth occurred in 51 of 117 samples (43.6%). S. aureus subsp. aureus predominated (28.2%), followed by E. coli (4.3%), Klebsiella pneumoniae subsp. pneumoniae (2.3%), and Streptococcus uberis (2.3%). Mixed infections occurred in 6.0% of positive samples. Among S. aureus, the highest resistance rates were to fosfomycin (58.3%), penicillin (44.4%), clindamycin (44.4%), and tetracycline (41.7%), with 47.2% MDR isolates. E. coli showed resistance to amoxicillin/clavulanic acid (88.9%), ampicillin (55.6%), and cefotaxime (55.6%), with 66.6% MDR. S. aureus remains the leading cause of subclinical mastitis in Western Romania. The high MDR rates highlight the need for targeted antimicrobial stewardship, culture-based therapy, and continuous AMR monitoring under the “One Health” framework. Full article

Background: Erysipelothrix rhusiopathiae is an important zoonotic pathogen in poultry, yet little is known about its antimicrobial resistance (AMR) dynamics in avian hosts. With growing concerns about subtherapeutic antimicrobial use in animal agriculture, poultry-origin isolates represent a potential but under-characterized reservoir of resistance genes. Methods: We phenotypically tested 38 E. rhusiopathiae strains isolated from geese, ducks, and turkeys in Hungary (2024) using broth microdilution against 18 antimicrobial agents, following Clinical Laboratory Standards Institute (CLSI) guidelines. Nineteen phenotypically resistant strains were selected for whole-genome sequencing (Illumina platform), followed by de novo hybrid assembly, gene annotation (Prokka, CARD, VFDB), mobile element detection (Mobile Element Finder), and phylogenetic inference (autoMLST). Results: All isolates were susceptible to β-lactams, including penicillin, amoxicillin, and third-generation cephalosporins. Resistance to tetracyclines (up to 10.5%) and florfenicol (5.3%) was most frequently detected. Genomic analysis revealed the presence of tetM (9/19), tetT (2/19), and erm(47) (2/19) genes, all associated with chromosomally integrated mobile elements, ICE Tn6009 and IS ISErh6. Phylogenomic analysis demonstrated tight clustering into four clades, suggesting clonal expansion. Notably, one strain harbored a 64.8 kb genomic island carrying ermC, the first such finding in poultry-derived E. rhusiopathiae. Conclusions: Our data highlights the early emergence of mobile AMR determinants in E. rhusiopathiae from poultry and suggests that horizontal gene transfer may drive resistance even in chromosomally encoded contexts. The genomic stability and phylogenetic homogeneity of avian isolates underscore the need for targeted AMR surveillance in poultry sectors to mitigate potential zoonotic transmission risks. Full article

Background: The inappropriate and empirical use of antibiotics in early childhood remains a major global public health concern, contributing significantly to the rise of antimicrobial resistance (AMR). In Kosovo, the COVID-19 pandemic further influenced prescribing behaviors in primary care, increasing the reliance on symptom-based treatment in the absence of laboratory confirmation and age-appropriate formulations. Aim: This study aimed to assess the prevalence and patterns of antibiotic prescribing among children aged 1–7 years in primary health care centers in Prishtina and Ferizaj from January 2022 to December 2025, and to compare regional differences in prescribing practices and guideline adherence. Methods: A retrospective observational study was conducted using data from the national electronic health record system and protocol books. All pediatric visits for children aged 1–7 years with infectious diagnoses were included. Descriptive statistics, Chi-square tests, and multivariable logistic regression were used to evaluate prescribing prevalence, demographic and seasonal variations, and independent predictors of antibiotic use, including assessment of appropriateness based on international pediatric guidelines. Results: Of 4320 pediatric visits, 1328 (30.7%) resulted in an antibiotic prescription. Prescribing prevalence was higher in Ferizaj (34.2%) than in Prishtina (28.5%, p < 0.01). Amoxicillin–clavulanic acid (42.9%) and amoxicillin (21.5%) were the most frequently prescribed agents, while macrolides (11.7% vs. 6.2%) and cephalosporins (7.9% vs. 3.4%) were more common in Ferizaj. Only 61.4% of prescriptions were fully guideline-concordant. Younger age (1–3 years), winter season, and residence in Ferizaj were independently associated with higher odds of receiving an antibiotic. Conclusions: Pediatric antibiotic prescribing in Kosovo remains high and predominantly empirical, reflecting real-world limitations in diagnostic capacity and formulation availability. Significant proportions of partially appropriate and inappropriate prescriptions highlight the need for standardized pediatric guidelines, improved diagnostic support, and strengthened stewardship initiatives within primary care. Full article

Aeromonas salmonicida is a major pathogen in aquaculture, and its ability to form biofilms contributes significantly to antibiotic resistance and chronic infections. This study investigated the effects of four antibiotics—ampicillin, amoxicillin, oxytetracycline, and doxycycline—at various concentrations on bacterial growth, biofilm formation, and gene expression related to antibiotic resistance and quorum sensing (QS) in two subspecies: A. salmonicida subsp. masoucida (ASM) and A. salmonicida subsp. salmonicida (ASS). Bacterial isolates from Atlantic salmon were identified using 16S rRNA and vapA gene sequencing. Growth inhibition was more pronounced in ASS than ASM under high antibiotic concentrations. Conversely, sub-inhibitory concentrations (sub-MICs) enhanced biofilm formation in both subspecies, particularly in ASM. PCR results showed that tetA and tetE resistance genes were present only in ASM. qRT-PCR analysis revealed that expression of QS-related genes (ahyI and ahyR) was generally downregulated under tetracycline treatment, while litR expression varied across antibiotic conditions and strains. Some isolates showed increased litR expression alongside elevated biofilm formation, suggesting involvement of additional regulatory mechanisms. These results highlight the potential for sub-MIC antibiotic exposure to promote biofilm development and modulate gene expression, emphasizing the need for careful antibiotic use in aquaculture and providing insight into alternative pathogen control strategies. Full article

Methicillin-resistant Staphylococcus aureus (MRSA) poses a significant clinical challenge due to its multidrug resistance, particularly to β-lactam antibiotics. This study comprehensively evaluated the natural compound emodin for its anti-MRSA activity, mechanisms of action, and potential for synergy with β-lactam antibiotics. Our findings demonstrate that emodin dose-dependently inhibits MRSA growth and abrogates biofilm formation at 2× MIC. Mechanistic studies revealed that emodin compromises cell membrane and wall integrity, induces oxidative stress, and downregulates the virulence factors SPA and EsxA. Furthermore, emodin acted synergistically with β-lactam antibiotics: it enhanced the ability of cefalexin to block bacterial adhesion and invasion of HaCat cells, and potentiated the efficacy of amoxicillin in clearing MRSA from infected macrophages. In conclusion, emodin employs a multi-target mechanism against MRSA and can resensitize the bacterium to conventional β-lactam antibiotics, presenting a promising strategy for combination therapy that may help curb antibiotic use and resistance development. Full article

Mastitis remains a major constraint to dairy production in Bangladesh, particularly in high-demand regions. This study investigated the prevalence, risk factors, and antimicrobial resistance patterns of major pathogens associated with bovine mastitis in Northern Bangladesh. A total of 488 milk samples from 122 randomly selected milking cows were tested through clinical inspection and the California Mastitis Test (CMT). Positive samples were subjected to bacterial culture and antimicrobial susceptibility testing using the disc diffusion method. The overall cow-level prevalence was 35.24%, with 27.86% sub-clinical and 7.37% clinical cases. At the quarter level, prevalence was 21.72%. Among 166 bacterial isolates, Staphylococcus spp. (41.56%) was predominant, followed by Streptococcus spp. (23.49%), E. coli (17.47%), Klebsiella spp. (12.65%) and Bacillus spp. (4.82%). Gentamicin (100%) and Streptomycin (92.20%) were the most effective antibiotics, whereas Cefixime (100%) and Amoxicillin (87.40%) showed the highest resistance rates. Major risk factors included late lactation stage, high milk yield, previous mastitis history, and poor hygiene. In contrast, breed, age, and parity were not significant. These findings highlight a high prevalence of mastitis, predominance of Staphylococcus spp., and rising antimicrobial resistance, identify associated risk factors, and rising antimicrobial resistance profiles in Northern Bangladesh. Full article

The One Health approach emphasizes the importance of zoonoses due to their pandemic potential, highlighting the need to characterize emerging bacterial pathogens across animal reservoirs. Non-typhoidal Salmonella (NTS) species are among the most common zoonotic agents and can be transmitted by various reservoirs, including reptiles. Both direct and indirect contact with reptiles may result in Reptile-Associated Salmonellosis (RAS), which mainly affects children, immunocompromised individuals, pregnant women, and the elderly. This study aimed to isolate and characterize the Gram-negative intestinal microbiota from free-living snakes in Poland (Natrix natrix, Natrix tessellata, Coronella austriaca, Zamenis longissimus, and Elaphe dione) and to determine the prevalence and virulence potential of Salmonella. Using MALDI-TOF Mass Spectrometry, 432 isolates were identified. Serological analysis of 62 Salmonella isolates revealed 10 distinct O-antigen groups, and rare serovars O:38, O:48, O:57 and others were confirmed. Salmonella isolates were tested for antibiotic susceptibility and resistance to Human Serum; most isolates survived exposure to serum while remaining susceptible to antibiotics. One isolate was classified as multidrug-resistant (MDR), showing resistance to amoxicillin/clavulanic acid, ampicillin, cefuroxime, cephalexin, tigecycline, and fosfomycin. These findings demonstrate that wild snakes in Poland can act as reservoirs of pathogenic and zoonotic Salmonella, emphasizing their epidemiological significance in natural ecosystems. Full article

Background/Objectives: Helicobacter pylori infection remains a significant health concern, as increasing antimicrobial resistance compromises the efficacy of eradication. Understanding regional antimicrobial resistance profiles is crucial for optimizing eradication strategies. In this study, we aimed to evaluate the antimicrobial susceptibility patterns and identify the factors influencing H. pylori culture success. Methods: In this prospective study, 697 gastric tissue samples were collected from consecutive patients who underwent upper endoscopy between November 2023 and May 2025. Tissue samples obtained by forceps biopsy or recovered from rapid urease test kits were cultured for H. pylori. Antimicrobial susceptibility testing was performed using the agar dilution method; factors associated with successful culture were analyzed using logistic regression. Results: Among 488 patients with H. pylori infection, culture and antimicrobial susceptibility testing were successful in 387 (79.3%). The overall antimicrobial resistance rates were 17.8%, 27.1%, 29.5%, 0.3%, and 32.8% for amoxicillin, clarithromycin, metronidazole, tetracycline, and levofloxacin, respectively. Notably, 27.6% (107/387) of the isolates were resistant to two or more antibiotics. Using multivariate analysis, the use of fresh biopsy tissue (odds ratio [OR]: 1.646, 95% confidence interval [CI]: 1.046–2.591, p = 0.031), transport interval (OR: 0.911, 95% CI: 0.853–0.973, p = 0.005), and presence of prior eradication therapy (OR: 0.318, 95% CI: 0.156–0.648, p = 0.002) were identified as significant predictors of culture success. Conclusions: The high rate of clarithromycin resistance underscores the need for susceptibility-guided eradication strategies in this region. Optimizing sample handling, particularly by minimizing transport time and using fresh biopsy tissue, may improve culture yields. Full article

V. furnissii is a marine bacterium capable of infecting both invertebrates and humans. However, the mechanisms underlying its drug resistance and virulence remain largely elusive. In this study, we isolated a multidrug-resistant V. furnissii strain, MT14, from bivalve mollusks. Genomic analysis revealed that MT14 carries a novel pAQU-type plasmid, designated pMT14, which harbors six antibiotic resistance genes: qnrS2, qnrVC6, dfrA31, tetA; sul2, and bla_GMA-1. Notably, bla_GMA-1 and its variants confer resistance to penicillin-class antibiotics, including ampicillin, amoxicillin, and carbenicillin. Comparative genomic analysis further revealed that V. furnissii strains commonly encode T6SS1, T6SS2, and the hemolysin gene vfh, while only five sequenced strains carry zot toxin gene. To our knowledge, this is the first report of zot in V. furnissii. In addition, the absence of drug resistance genes in the majority of genomes (73.3%, 22/30) suggests that such traits are not intrinsic to the species but have been acquired by specific strains, likely through plasmid transfer or other mobile genetic elements. The emergence of bla_GMA-1 and zot in V. furnissii represents a potential public health concern, underscoring the need for enhanced surveillance of antimicrobial resistance in marine pathogens. Full article