Search Results (2,092)

Background/Objectives: Multidrug-resistant (MDR) Escherichia coli has increasingly been recognized as a pathogen capable of causing severe systemic infections in various animal species. However, reports describing respiratory and septicemic infections caused by MDR E. coli in guinea pigs remain scarce. The objective of this report was to describe the clinical, pathological, and microbiological findings associated with a fatal infection in a domestic guinea pig. Case Study: A 10-month-old female guinea pig (Cavia porcellus), kept as a companion animal in a household environment, presented with acute respiratory distress, lethargy, and anorexia, progressing rapidly to death within approximately 36 h of onset. Post-mortem examination revealed severe pulmonary congestion, diffuse inflammatory lesions in the trachea, and generalized vascular congestion in multiple organs. Bacteriological cultures obtained from lung and bone marrow samples yielded pure growth of Escherichia coli. Identification was confirmed using MALDI-TOF mass spectrometry. Antimicrobial susceptibility testing demonstrated resistance to several antibiotic classes, including β-lactams, fluoroquinolones, tetracyclines, sulfonamides, and phenicols, while susceptibility was retained only to aminoglycosides. Molecular analysis revealed the presence of virulence genes involved in adhesion and iron acquisition, supporting the pathogenic potential of the isolate. Conclusions: This report highlights the ability of MDR E. coli to cause severe respiratory and systemic infections in guinea pigs. The findings underline the importance of early diagnosis, appropriate antimicrobial stewardship, and improved husbandry conditions in preventing such infections. From a One Health perspective, the circulation of resistant strains in companion animals may represent a potential risk for both environmental and human health. Full article

Background/Objectives: Staphylococcus aureus (S. aureus) intramammary infection remains a major global dairy problem due to its contagious nature, its ability to persist and colonize teat/skin and mucosal niches, and the often-limited bacteriological cure achieved with antimicrobial therapy. Beyond udder health, it is relevant to public health because it can enter raw milk chains and serve as a reservoir for antimicrobial resistance determinants that may circulate between dairy animals and humans. Methods: We assessed S. aureus’ ecology in raw ewe milk from 75 sheep farms in Epirus (Greece) by sampling clinically healthy controls (group A) and clinical mastitis cases pre-treatment (group B), followed by resampling at the first post-withdrawal milking after penicillin/streptomycin treatment (group C1—therapeutic protocol 1), oxytetracycline treatment (group C2—therapeutic protocol 2), or enrofloxacin treatment (group C3—therapeutic protocol 3). Results: S. aureus detection was high and comparable across groups (A 23.0%, B 22.0–30.0%, C 20.0–22.0%), and paired analyses showed no significant pre–post shifts in detection/burden within therapeutic protocols (all p > 0.05). Nevertheless, persistence remained evident. The chromosomal gene mecA was detected in S. aureus strains in all groups, ranging from 13.6% in controls to 54.5% post-withdrawal in group C1, and was also present in the pre-treatment group. In paired sampling animals, mecA was mostly stable, with rare emergence or loss. Across antibiotic classes, within-animal resistance transitions were generally uncommon and non-significant (p > 0.05); β-lactam resistance was fully stable (p = 1.00). Descriptively, resistance to protein synthesis inhibitors tended to decline after therapy in protocol 1 and protocol 3, while protocol 3 showed post-treatment gains in fluoroquinolone resistance. By contrast, virulence-associated phenotype traits shifted after therapy: enterotoxigenicity increased post-withdrawal (especially in the C3 group), Staphylococcal Enterotoxin A (SEA) and Staphylococcal Enterotoxin B (SEB) appeared only post-therapy, Staphylococcal Enterotoxin D (SED) increased significantly in paired isolates (p = 0.002), and strong biofilm adherence increased (in C3, p = 1.5 × 10⁻⁵). Conclusions: The detection of S. aureus after therapy suggests that one possibility is that antimicrobial exposure may select for, or otherwise reshape, the residual intramammary population, rather than reliably eliminating it—an outcome that remains clinically relevant for udder health. Moreover, the persistence of mecA/methicillin-resistant Staphylococcus aureus (MRSA)-compatible profiles indicates that milk released to the food chain after withdrawal compliance may still harbor S. aureus with enhanced preservation capacity and significant food safety relevance. Full article

Non-typhoidal Salmonella (NTS) is an important poultry-associated pathogen with major One Health and economic impacts, but data on its epidemiology and antimicrobial resistance in Nigeria remain limited. This study investigated the prevalence, serovar distribution, clonal relatedness, and antimicrobial resistance of NTS along the poultry production chain in Enugu State, southeastern Nigeria. A total of 2400 samples were collected, comprising feces (cecal content)/cloacal swabs from chickens (n = 1100), eggs (n = 400), chicken meat (n = 600), and stool samples from poultry workers (n = 300). Isolation and identification were performed using standard bacteriological methods, with confirmation by serotyping and polymerase chain reaction (PCR) targeting the invA gene. Genetic relatedness was assessed using enterobacterial repetitive intergenic consensus (ERIC)-PCR, and antimicrobial susceptibility was determined by the disk diffusion method. Overall, 47 (2.0%) Salmonella enterica isolates were recovered from 2400 samples, with the highest prevalence observed in eggs (3.5%), followed by human stool (3.3%), chicken meat (1.8%), and chicken feces (1.1%). Only 35 (11.8%) of the 297 sampled farms were positive for Salmonella, and recovery rates differed significantly (p = 0.0065) among sample sources. Five serotypes were identified, dominated by S. Typhimurium (57.4%), followed by S. Enteritidis (14.9%), S. Anatum (12.8%), S. Stanley (8.5%), and S. Agona (6.3%). ERIC-PCR revealed multiple clonal clusters, many containing isolates from mixed sources, indicating circulation of related strains between poultry and humans. All isolates were resistant to ampicillin, with high resistance to tetracycline (76.6%), sulphamethoxazole–trimethoprim (51.1%), and fluoroquinolones. Overall, 80.9% of isolates were multidrug-resistant, with a mean Multiple Antibiotic Resistance Index of 0.29, highest among isolates from chicken feces. Although the prevalence of NTS was low, the presence of genetically related multidrug-resistant strains across the production chain underscores the role of poultry as a reservoir for zoonotic transmission and highlights the need for coordinated One Health surveillance and antimicrobial stewardship strategies in Nigeria. Full article

The objective of this study is to evaluate the efficiency of surgical instruments’ manual cleaning versus automated cleaning in an ultrasonic cleaner for the removal of biofilms on surgical forceps contaminated with Staphylococcus epidermidis and Pseudomonas aeruginosa. Subsequently, the residual microbial load was quantified through microbiological culture, aiming to evaluate the effectiveness of biofilm removal under different reprocessing conditions. Cleaning is an essential step in the processing of surgical instruments to ensure the effective removal of dirt and microorganisms. Through adhesion, microorganisms can attach to surfaces and form biofilms, organized structures surrounded by an extracellular matrix consisting of various components, which favor metabolic exchanges, adaptation, resistance, and bacterial dispersion. These biofilms increase the pathogenic potential of microorganisms, contributing to the occurrence of Healthcare-Associated Infections, and to avoid these, it is essential that preventive measures aimed at microbial reduction are adopted. Automated cleaning proved more effective than manual cleaning, and the combined approach achieved the greatest microbial reduction, though persistent contamination was still observed. The ability of adhesion and biofilm formation on the surfaces of surgical instruments is regarded as a challenge for complete microbial removal. These findings enhance the need for more rigorous reprocessing protocols and complementary strategies to ensure greater safety in the use of reusable instruments in clinical practice. Full article

Antimicrobial resistance (AMR) is a silently escalating global crisis, presenting a specific challenge for the One Health approach. Landscapes can serve as reservoirs of AMR bacteria and genes, while synurban wildlife may act as vectors of bidirectional exchange. However, these species can also be utilised as sentinels of landscape AMR load. Herbivorous avian bioindicators, such as the Common Wood Pigeon (Columba palumbus), continuously sample the landscape during foraging and drinking, providing a homogenous spatial overview on the state of AMR. This study aimed to investigate the potential of this species for assessing the impact of landscape diversity on bacterial communities and their AMR patterns. Toward this objective, two spatial units of 4 km in diameter located at an upstream and a downstream section of a river, relative to a provincial town, were compared using 16 cloacal samples per site. Heterotrophic plate count techniques resulted in 60 isolates, of which 48 were identified, and 35 were tested for AMR using the VITEK 2 Compact system. The association between bacteriological findings and landscape diversity was analysed using Rényi diversity profiles. The Gram-positive/Gram-negative ratio was the only parameter that proved to be significantly different between the two study sites. The investigation detected six MDR isolates, with two methicillin-resistant phenotypes (Staphylococcus gallinarum, Mammaliicoccus lentus) and two carbapenem-resistant Pseudomonas fluorescens isolates. We established that the small sample size limits drawing definitive conclusions. However, exploring the link between landscape diversity and the cultivable faecal microbiota of herbivorous birds is a promising approach for more extensive research. Full article

Growing evidence suggests that chronic kidney disease (CKD) profoundly disrupts gut microbiome and its activity. This study explores how CKD affects colon microbial metabolism, focusing on (1) the representativeness of fecal metabolomics, (2) saccharolytic and proteolytic fermentation metabolites, and (3) the gut microbiome’s role in the partitioning of tryptophan in its metabolic pathways. Tryptophan’s main metabolic pathways include the indolic and the kynurenine pathways, which lead, respectively, to the formation of indoxyl sulfate and kynurenine, both contributing to uremic toxicity. Using a rat model of CKD, we evaluated whether fecal concentrations of microbial compounds, on which most studies are based, reflect the colonic concentrations in contact with the gut mucosa. Thus, we quantified the concentration and content of amino acids, indole, p-cresol, and also short-chain fatty acids, in different colon sections. We demonstrated that CKD promotes increased proteolytic fermentation and an augmented tryptophan partitioning into both the indolic and kynurenine pathways. Depletion of the indolic pathway obtained upon antibiotic treatment leads to a further enhancement of the kynurenine pathway. Full article

Background: Inducible macrolide–lincosamide–streptogramin B (iMLSB) resistance is well defined in Gram-positive aerobes but remains poorly characterized in anaerobes, where standardized detection strategies are lacking. Following withdrawal of EUCAST guidance to infer clindamycin resistance from erythromycin resistance in Peptostreptococcus and Bacteroides spp. because of inconsistent species-specific performance, a diagnostic gap persists. Methods: We therefore assessed the accuracy of the D-test for detecting iMLSB resistance in anaerobes by correlating phenotypic results with whole-genome sequencing data. Fifty clinical anaerobic isolates, including Finegoldia magna, Peptostreptococcus anaerobius, and Bacteroides spp., were included in the analysis. Antimicrobial susceptibility testing was performed using gradient diffusion to determine minimum inhibitory concentrations of erythromycin and clindamycin, complemented by D-test analysis for phenotypic detection of inducible resistance. Whole-genome sequencing was undertaken to identify erm genes encoding ribosomal methyltransferases associated with the iMLSB phenotype. Results: Among the 50 isolates, erm genes were detected in 16 strains (32.0%). The prevalence of erm positivity was highest among Gram-positive cocci (50%), followed by Gram-positive rods (35.3%) and Gram-negative rods (11.8%). Five erm-positive isolates exhibited a characteristic D-shaped growth pattern, with high erythromycin MICs (>256 mg/L) and low clindamycin MICs (≤2 mg/L), consistent with an inducible iMLSB phenotype, whereas the remaining eleven demonstrated constitutive resistance. Conclusions: The D-test accurately identified inducible iMLSB resistance among Gram-positive anaerobic cocci and, if confirmed in larger studies, could form the basis of an accessible and pragmatic screening strategy for this subgroup. Integration of molecular analyses seems essential for the evidence-based refinement of diagnostic algorithms, particularly in the absence of robust, species-specific guidance. Full article

Leptospirosis is a neglected zoonosis causing significant economic losses in livestock, primarily through Bovine Genital Leptospirosis (BGL). While current vaccines prevent clinical disease, they typically fail to provide sterilizing immunity against adapted strains. This allows Leptospira to persist in the genitourinary tract, maintaining environmental shedding and zoonotic risk. Achieving sterilizing immunity remains a challenge, and this gap may be closely related to the immune response pattern of ruminants, where effective protection against chronic colonization requires, besides the humoral response, a robust cellular immune response (Th1/IgG2). Recent studies indicate that adjuvants based on oil emulsions or biodegradable polymers are better at inducing Th1/IgG2 responses and the proliferation of CD4⁺ T cells, as well as WC1⁺ γδ T cells, which may be essential for eliminating Leptospira from renal and probably also genital tissues. Thus, overcoming chronic colonization through inducing the Th1-type immune response may be the main challenge for vaccination to fulfill its role in sustaining herd immunity and mitigation of zoonotic risk, in line with the One Health approach. In this context, we aimed to critically examine immune mechanisms in ruminants, advances in vaccine platforms and adjuvant strategies against bovine leptospirosis and outline the challenges that must be overcome to achieve sterilizing immunity. Full article

Paediatric osteoarticular infections (OAIs) encompass a heterogeneous group of musculoskeletal infections associated with acute septic complications, prolonged morbidity and potentially long-term sequelae. Over the past two decades, advances in microbiological diagnostics—particularly nucleic acid amplification assays—have refined the aetiological understanding of OAIs and started a new therapeutic debate regarding the most appropriate routes of antibiotic administration. Clinicians now evaluate which children can be treated safely using oral antibiotics from the outset (oral-first), which require an initial intravenous (IV) phase before a step-down to oral therapy, and which will need IV therapy all along their care pathway. Treatment debates are particularly relevant in contexts involving constrained healthcare resources and limited hospital bed availability. This narrative review summarises the essential prerequisites for prescribing oral antibiotic therapy for paediatric OAIs and proposes a pharmacokinetic/pharmacodynamic (PK/PD) framework for guiding clinical decision-making. Key considerations include: pathogen identification and resistance profiling; contemporary bacteriological epidemiology; the comparative effectiveness of IV versus oral therapy; the availability of active oral antibiotics and their penetration into bone and joint compartments; achieving adequate systemic exposure and hitting PK/PD targets after oral administration; and the clinical limitations of oral antibiotic therapy, including patient selection criteria. We argue that oral-first and early-switch strategies are best framed as structured selection processes that integrate clinical severity and source control, pathogen/minimal inhibitory concentration constraints, the feasibility of attaining PK/PD targets orally and the reliability of follow-up. No single strategy should be seen as a universal default strategy. Full article

Klebsiella species, particularly Klebsiella pneumoniae, are among the most frequently isolated Gram-negative pathogens in surgical departments, associated with a growing trend in multidrug resistance. To identify the types of infections caused by Klebsiella spp. in a general surgery department and to analyze their antimicrobial susceptibility patterns. This retrospective observational study includes bacteriological cultures collected from surgical inpatients between October 2016 and December 2024. Only cases with confirmed Klebsiella spp. isolation were included. Specimen types, infection categories, and antibiotic susceptibility profiles were extracted and analyzed. A total of 138 Klebsiella-positive cultures were identified. Clinical characteristics were analyzed in 38 patients with complete records. The most common infection types included surgical site infections (SSIs), intra-abdominal infections, and biliary tract infections. Sensitivity was highest to carbapenems, while marked resistance was observed to ampicillin-sulbactam and third-generation cephalosporins. Some isolates exhibited ESBL or carbapenemase-producing phenotypes. Reported colistin non-susceptibility was elevated in our cohort; however, these results should be interpreted cautiously because the reference broth microdilution method was not systematically documented. The findings underscore the importance of local surveillance of Klebsiella spp. in surgical settings to info rm empirical treatment and control the spread of multidrug-resistant organisms. Full article

Helicobacter pylori is a Gram-negative bacterium that inhabits the gastric mucosa, with a global prevalence in humans of approximately 40%. It is likely the cause of 90% of gastric cancer (GC) cases and thus considered the most prominent driver of GC development. However, during gastric mucosal atrophy, other bacteria such as nitrate-reducing bacteria (NRB) also proliferate. In this study, we isolated NRB from patients with gastritis and GC to examine their effects on the epithelial cell cycle and production of various cytokines in monocytic cell lines. Bacterial counts (excluding H. pylori and NRB) increased with the progression of gastric mucosal atrophy and were significantly higher in patients with GC. Gastric epithelial cell lines were stimulated with isolated NRB, and the proportion of cells in each cell cycle was measured. Strains from patients with open-type gastritis progressed more rapidly through cell cycles than those from patients with GC. NRB isolated from gastric cancer had high nitrate-reducing activity. Thus, NRB may contribute to GC progression during H. pylori-induced carcinogenesis. Therefore, evaluating gastric atrophy and microbiota may be important for managing the risk of GC. Full article

Bacterial resistance on farms can be driven by antimicrobial use. Less is known about inter-farm transfer of resistance genes and their persistence under low antimicrobial pressure. Over two years and nine visits, we examined the shedding of resistant indicator bacteria (Escherichia coli) on one lower- and one higher-antimicrobial-usage pig farm. There was a unidirectional transfer of some less healthy pigs from the former to the latter. Faecal pools (180) were cultured on Chromagar ECC, with and without added cefotaxime or ciprofloxacin. Presumptive E. coli were phenotyped, and many ciprofloxacin-resistant isolates were whole-genome sequenced. Comparing farms, there was more (p < 0.0001) phenotypic resistance to the antimicrobial panel from the higher-usage unit, and markedly more (about ten-fold) multi-resistance. Significantly elevated individual drug resistances on this unit correlated with recently used antimicrobials. Ciprofloxacin and/or cefotaxime-resistant isolates were often present, although in low proportions. Neither of these antimicrobial classes had been administered recently, except for one fluoroquinolone course late in the study. AMR genes were more diverse from the higher-usage farm, but some resistant and multi-resistant isolates were closely related between farms. Thus, we demonstrated the maintenance of resistance genes in strains present on farms, even where selective pressure was low. Full article

Onchocerca flexuosa is a vector-borne filarial nematode infecting red deer (Cervus elaphus) throughout Europe. Despite numerous reports from Central, Northern, and Southern Europe, its occurrence in South-Eastern Europe has remained largely undocumented. This study provides the first molecularly confirmed report and the first systematic epidemiological assessment of O. flexuosa in red deer in Croatia. During the 2024–2025 hunting season, 110 legally harvested red deer from central Croatia were examined for subcutaneous nodules. Nodules were evaluated morphologically, and adult nematodes were identified and confirmed by sequencing of a fragment of the mitochondrial cytochrome c oxidase subunit I (COI) gene. Subcutaneous nodules were detected in 53.6% (59/110) of examined animals. O. flexuosa was confirmed in 52 deer, corresponding to an overall prevalence of 47.3%. Co-infection with Hypoderma diana occurred in 21.2% of infected animals. Sequence similarity ranged from 96.37% to 99.85% compared to published European O. flexuosa isolates. Phylogenetic analysis placed Croatian sequences within the established European lineage, without evidence of regional genetic divergence. The observed prevalence falls within the intermediate range reported across Europe and indicates stable local transmission. These findings close an important geographical knowledge gap and demonstrate that nodular onchocercosis is established in red deer populations in South-Eastern Europe. Full article

Malignant catarrhal fever (MCF) is a highly lethal viral disease of cattle that poses a persistent threat to livestock production in wildlife–livestock interface areas of Southern Africa. Despite its recognized clinical severity, the economic burden of the disease remains poorly quantified in South African production systems. This study assessed the long-term economic impact of malignant catarrhal fever on cattle production in Lephalale Municipality, Limpopo Province, South Africa, using a retrospective analysis covering the period from 2001 to 2021. The study combined confirmed case records, estimated mortalities, and region-specific production parameters to quantify both direct and indirect economic losses. Direct losses included mortality-related financial costs and the expenditure on treatment, while indirect losses encompassed reduced productivity, diminished milk yields, and associated declines in overall herd performance. The results show that MCF imposed substantial financial burdens on cattle producers, with mortality contributing to more than ninety percent of total losses. The total economic losses over the study period were substantial, amounting to approximately R 1.55 million, driven primarily by high mortality-related costs. Annual losses displayed considerable variability, reflecting the sporadic nature of the outbreaks and the fluctuations in the wildlife–livestock interactions. The spatial analysis revealed that most cases occur in wards situated adjacent to wildlife conservation areas, where cattle are exposed to virus-carrying wildebeest populations. Seasonal patterns indicated a higher disease occurrence during the spring and winter, aligning with established transmission dynamics. Although a gradual decline in both cases and associated losses was observed over the study period, episodic outbreaks continued to exert significant economic shocks on affected farming households. The findings reaffirm MCF as a persistent and high-impact constraint to cattle production in interface zones and highlight the need for improved surveillance, integrated land-use planning, and sustained investment in targeted disease control measures. Full article

Anthrax is one of the most significant zoonotic diseases in Albania due to its endemic presence in livestock, the potential for occupational exposure, and human cases. Although the implementation of risk-based livestock immunization, animal movement restrictions, and appropriate carcass disposal, the efficacy of targeted management remains limited in certain outbreaks due to insufficient enforcement of these measures. Their efficacy is specifically diminished by insufficient disinfection, the absence of grazing bans in contaminated pastures, and the absence of designated burial sites for the safe disposal of dead animals. District-level data on animal anthrax control programs were collected and analyzed for the period 2021–2025. In addition, a retrospective analysis of national datasets covering the same period was conducted using data from the national surveillance system, alongside a review of the relevant scientific and grey literature and aggregated program and routine surveillance data. Analysis showed that anthrax affected 149 animals in 97 farms, and the average number of animals per infected farm declined from 1.70 to 1.08, indicating a slight reduction within-farm outbreak. Hotspots for human anthrax were aligned with the animal cases and persisted particularly in the southern districts. The peak of outbreaks was in 2023, primarily driven by cattle (n = 32) and sheep (n = 24). Equine cases appeared only in 2024, with small clusters of 3 cases in both 2024 and 2025. Caprine cases remained consistently low throughout the period. Nevertheless, the number of outbreaks and within-herd cases are decreasing due to more rapid identification and response. Targeted surveillance on animal outbreaks provides critical insights into disease spread and links among affected farms in Albania. Therefore, One Health genomic surveillance and antibiotic susceptibility testing of Bacillus anthracis isolates are essential for understanding its epidemiology, transmission routes, and for tracing the sources of infection across humans, animals, and the environment. Full article