Finding and characterizing new bacterial strains, including probiotic strains, is a crucial task in today’s world to expand the genetic data pool and identify new genes. In this study, we investigated the gut microbiota of one industrial species, Cyprinus carpio, and identified representatives of various microbial genera, including Citrobacter, Serratia, Bacillus, Enterococcus, and Kocuria. Notably, we discovered two strains of Hafnia with potentially probiotic properties. We conducted next-generation sequencing (NGS) of these strains, described their antibiotic resistance and antibacterial activity, and compared them with other representatives of the Hafnia genus. These strains, characterized by rapid growth, the presence of the ClpB heat shock protein gene, and genes associated with microplastic degradation, provide a promising basis for further research, including studies on their potential application in plastic biodegradation.

Airborne pathogens, though a minor fraction of airborne particles, can cause infections, intoxications, or allergic reactions through respiration, dermal contact, or ingestion. The SARS-CoV-2 pandemic has underscored the significance of mitigating airborne microbial threats. Traditional air ionization methods, such as dielectric barrier discharge and metal tip corona discharge, produce ozone, a reactive and potentially harmful byproduct. However, carbon-fiber ionizers (CFIs) generate high concentrations of ions with minimal ozone production, making them a safer alternative. Operating at voltages below 5 kV, CFIs are more efficient than their metallic counterparts. This review focuses on the antimicrobial efficacy of CFIs, which produce unipolar ions that can disrupt microbial membranes, leading to cell death. Compared to ultraviolet light sterilization, CFIs are cost-effective and suitable for small spaces. The literature review highlights the need for comprehensive studies to evaluate the real-world application and effectiveness of CFIs. Many existing studies are limited by small-scale testing and insufficient data reporting, complicating comparative analyses. Our work aims to provide a detailed perspective on CFIs, examining their impact on various microorganisms, ion efficacy, ionization outcomes, and ozone generation levels. By addressing these aspects, the review seeks to offer an updated understanding of CFIs’ antimicrobial capabilities and to identify limitations in current research, paving the way for more informed and effective air purification strategies.

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.

Contagious equine metritis (CEM), caused by the bacterium Taylorella equigenitalis, is a clinically important disease of equids that can induce transient infertility and impair reproductive performance. To date, no studies have investigated the presence of this pathogen in the Serbian horse population. To obtain a preliminary estimate of T. equigenitalis prevalence, genital tract swabs were collected from clinically healthy mares across various regions of Serbia. Detection was performed using quantitative real-time PCR to avoid the nonspecific amplifications sometimes encountered with conventional PCR assays. The results confirmed the presence of T. equigenitalis in the sampled population, marking the first report of this pathogen in Serbia and providing a foundation for future investigations. These findings highlight a potential risk for further dissemination of infection and underscore the need to introduce systematic surveillance together with diagnostic and control measures consistent with international guidelines.

Porcine circovirus 2 (PCV2) and porcine circovirus 3 (PCV3) are widespread in domestic pigs and common in wild boar, but Serbian wild boar data come predominantly from the east. Tissue pools from 90 wild boar hunted in West Bačka District, Vojvodina, in 2021 and 2022, collected within national swine fever surveillance, were screened by real-time PCR. PCV2 was detected in 17 animals (18.9%; 95% CI 11.4–28.5) and PCV3 in 12 (13.3%; 95% CI 7.1–22.1), with no co-infection. Four partial PCV2 capsid sequences were obtained, three PCV2b and one PCV2d, all within the diversity already reported from Serbian wild boar and European domestic pigs. Five complete PCV3 genomes differed by no more than 1.46% and met the distance criteria for PCV3-a; at the complete-genome level, the closest reference sequences came mainly from domestic pigs in Serbia and Hungary. Neither of the two PCV3 recombination signals met the acceptance criteria, so no event could be attributed to these sequences; breakpoint analysis of the combined reference-and-study alignment detected topological incongruence at the Cap coding-region boundary, an exploratory finding that does not demonstrate recombination in these genomes. Both viruses circulate in this population, carrying diversity that these data do not separate from that of European domestic pigs.