Acta Microbiologica Hellenica

The European catfish (Silurus glanis, Linnaeus 1758), commonly known as the wels catfish, is one of the largest freshwater fish in Europe and an ecologically and economically important species in both natural ecosystems and aquaculture. Its broad native distribution, together with the rapid growth of farming practices, increases concerns about pathogen dissemination and their potential impact on biodiversity, animal health, and potential risks to human healthcare. This review is based on a structured literature search following PRISMA recommendations for narrative reviews and summarizes current knowledge on the main pathogen groups affecting S. glanis—viruses (ranaviruses, alloherpesviruses), bacteria (Aeromonas spp., Edwardsiella spp.), protozoan and metazoan parasites (Ichthyophthirius multifiliis, Thaparocleidus spp., Eustrongylides spp., Contracaecum larvae), and oomycetes (Saprolegnia spp., Branchiomyces spp.). Within the One Health approach, particular attention is given to zoonotic pathogens such as Aeromonas spp., Edwardsiella tarda, and helminths like Eustrongylides and Contracaecum, which may cause risks to human health through contaminated water or consumption of raw or undercooked fish. The review integrates findings from field surveys, regional case studies such as those from the Danube basin, and data from the authors’ doctoral research. Because the wels catfish is increasingly cultivated and serves as an apex predator in natural habitats, its effective disease management is critical for both aquaculture and wild populations, and also for the food chains at all. Strengthened surveillance, health monitoring, and biosecurity measures are essential preventing the introduction and spread of pathogens into new hosts and habitats. Through the underlining of major catfish pathogen groups, this review highlights key challenges within the One Health approach and underscores the need for integrated health monitoring, biosecurity, and environmental management strategies.

Linezolid (LZD) is an oxazolidinone antibiotic effective in the treatment of infection with Gram-positive bacteria, including methicillin-resistant Staphylococcus aureus (MRSA). The decline in susceptibility to linezolid is a concern for antimicrobial chemotherapy. In this study, the prevalence of the LZD minimum inhibitory concentration (MIC) of 2 mg/L (LZD-MIC2), which represents a slightly high value within a range of susceptibility for S. aureus (≤4 mg/L), was investigated retrospectively for staphylococcal species from different sources. We collected the records of LZD MIC of Staphylococcus/Mammaliicoccus that had been obtained in our previous studies on isolates from patients, healthy individuals, and foodstuff. Prevalence of isolates showing LZD-MIC2 was analyzed depending on the type of staphylococcal species and S. aureus clones. In clinical isolates, methicillin-susceptible S. aureus (MSSA) and S. argenteus showed significantly higher LZD-MIC2 rates (20.0% and 21.5%, respectively) than MRSA (7.3%). Among clinical and colonizing isolates of MSSA, LZD-MIC2 was more commonly found in CC1 (ST188, ST2990, etc.), CC8, CC15, ST30, ST97, and ST121 than other lineages. In S. argenteus isolates, which were mostly methicillin-susceptible, there was no significant difference in the LZD-MIC2 prevalence among the three genotypes. The LZD-MIC2 was detected in 18.3% of coagulase-negative staphylococci (CoNS), with S. saprophyticus, S. pasteuri, and M. sciuri showing higher prevalence (30–57%) than other species. The present study revealed that the prevalence of the LZD-MIC2 is different depending on staphylococcal species/types, as they are more common in specific MSSA lineages and some CoNS species.

West Nile Virus (WNV), a mosquito-borne flavivirus first identified in Uganda in 1937, has emerged over the past quarter century as a major global public health threat. Since its introduction into North America in 1999, WNV has become the leading cause of arboviral neuroinvasive disease, with recurrent outbreaks continuing across Europe, Africa, and the Americas. This review provides a comprehensive overview of the microbiology, epidemiology, and clinical impact of WNV. We discuss the molecular biology of the virus, highlighting its genomic organization, replication strategies, and the structural and non-structural proteins that underpin viral pathogenesis and immune evasion. The complex enzootic transmission cycle, involving Culex mosquitoes and diverse avian reservoir hosts, is examined alongside ecological and climatic determinants of viral amplification and spillover into humans and equines. The clinical spectrum of WNV infection is outlined, ranging from asymptomatic seroconversion to West Nile fever and life-threatening neuroinvasive disease, with particular emphasis on risk factors for severe outcomes in older and immunocompromised individuals. Current approaches to diagnosis, supportive management, and vector control are critically reviewed, while challenges in vaccine development and the absence of effective antiviral therapy are underscored. Finally, we address future research priorities, including therapeutic innovation, predictive outbreak modeling, and genomic surveillance of viral evolution. WNV exemplifies the dynamics of emerging zoonotic diseases, and its persistence underscores the necessity of a coordinated One Health approach integrating human, animal, and environmental health. Continued scientific advances and public health commitment remain essential to mitigate its enduring global impact.