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Introduction: Streptococcus suis is a major pathogen for swine and human. Here we aimed to know the rates of antimicrobial resistance (AMR) in invasive S. suis isolates recovered along Spain between 2016 - 2021 and elucidate their genetic origin., Methods: Antibiotic susceptibility testing was performed for 116 isolates of different genetic backgrounds and geographic origins against 18 antibiotics of 9 families. The association between AMR and genotypes and the origin of the isolates were statistically analyzed using Pearson´s chi-square test and the likelihood ratio. The antimicrobial resistant genes were identified by whole genome sequencing analysis and PCR screenings., Results: High AMR rates (>80%) were detected for tetracyclines, spectinomycin, lincosamides, and marbofloxacin, medium (20-40%) for sulphonamides/trimethoprim, tiamulin, penicillin G, and enrofloxacin, and low (< 20%) for florfenicol, and four additional β-lactams. The occurrence of multidrug resistance was observed in 90% of isolates. For certain antibiotics (penicillin G, enrofloxacin, marbofloxacin, tilmicosin, and erythromycin), AMR was significantly associated with particular sequence types (STs), geographic regions, age of pigs, and time course. Whole genome sequencing comparisons and PCR screenings identified 23 AMR genes, of which 19 were previously reported in S. suis ( aph (3')-IIIa, sat4, aadE, spw , aac(6')-Ie- aph (2'')-Ia, fexA, optrA, erm (B), mef (A/E), mrs (D), mph (C), lnu (B), lsa (E), vga (F), tet (M), tet (O), tet (O/W/32/O), tet (W)), and 4 were novel ( aph (2'')-IIIa, apmA, erm (47), tet (T)). These AMR genes explained the AMR to spectinomycin, macrolides, lincosamides, tiamulin, and tetracyclines. Several genes were located on mobile genetic elements which showed a variable organization and composition. As AMR gene homologs were identified in many human and animal pathogens, the resistome of S. suis has a different phylogenetic origin. Moreover, AMR to penicillin G, fluoroquinolones, and trimethoprim related to mutations in genes coding for target enzymes ( pbp1a, pbp2b, pbp2x, mraY, gyrA , parC , and dhfr) . Bioinformatic analysis estimated traits of recombination on target genes, also indicative of gene transfer events., Conclusions: Our work evidences that S. suis is a major contributor to AMR dissemination across veterinary and human pathogens. Therefore, control of AMR in S. suis should be considered from a One Health approach in regions with high pig production to properly tackle the issue of antimicrobial drug resistance., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Uruén, Gimeno, Sanz, Fraile, Marín and Arenas.)

Due to the possible toxicological impact, the accumulation of pharmaceuticals in wildlife as a consequence of human practices is of growing concern. The consumption of carrion at feeding stations – the so-called ‘vulture restaurants’ – with no management of the veterinary drugs it contains may expose scavengers to pharmaceuticals. To demonstrate this, we analyzed plasma from Eurasian griffon vultures ( Gyps fulvus ) originating from two different areas of Spain for antibiotics such as enrofloxacin and ciprofloxacin, its primary metabolite. Quinolone residues were detected in about 65% ( n = 106) of birds, of which 15.1% (16/106) had quantifiable amounts of enrofloxacin (0.049 ± 0.102 μg/mL) and 5.7% (6/106) of ciprofloxacin (0.009 ± 0.007 μg/mL). The differences in exposure between the two sampled areas are attributable to different types of carrion management: the vultures that fed in areas with a high density of dead livestock (supplied directly to feeding stations) were more prone to exposure than those that sought food in areas where carcass availability is more unpredictable. Our findings are evidence that vultures have access to medicated livestock and that there are quantifiable levels of livestock antibiotics in vulture plasma. However, the vultures analyzed in this study had maximum antibiotic concentrations of only 0.4 μg/mL, much less than the concentrations used in the clinical treatment of scavengers and a level that is probably too small to cause intoxication. [ABSTRACT FROM AUTHOR]

The spread of antibiotic resistance in bacteria is a matter of global concern, and the identification of possible sources of the associated genetic elements (antibiotic resistance genes -ARGs-, components of the horizontal gene transfer mechanism), is becoming an urgent need. While the transmission of ARGs in medical settings have been adequately characterized, ARG propagation in agroecosystems remains insufficiently studied. Particularly crucial is the determination of potential risks associated to the use of swine slurries and related products as component of organic fertilizers, an increasingly used farming practice. We determined ARGs and antibiotic loads analysed from swine slurries and digestates from eight farms from Catalonia (NE Spain), and compared the results with their microbiome composition. Both ARGs and antibiotic were conspicuous in farm organic wastes, and the levels of some antibiotics exceeded currently accepted minimum inhibitory concentrations. Particularly, the presence of high loads of fluoroquinolones was directly correlated to the prevalence of the related qnrS 1 ARG in the slurry. We also found evidence that ARG loads were directly correlated to the prevalence of determined bacterial taxa (Actinobacteria, Proteobacteria, Spirochaeta), a parameter that could be potentially modulated by the processing of the raw slurry prior to their use as fertilizer. • ARG, AB, and microbiomes analysed in slurries from currently operting pig farms. • High prevalence for some ARGs, surpassing 90% of bacterial cells in some cases. • AB concentrations amply surpassing MIC in some samples, particularly fluoroquinolones. • Evidence for positive selective pressure for fluoroquinolone resistance. • Bacterial composition related to ARG prevalence and to slurry processing methods. [ABSTRACT FROM AUTHOR]

Red-legged partridges (Alectoris rufa) are a significant part of the culture, diet and income for many people in central and southern Spain. Due to declining populations in the wild, intensive farming is common and 4 million juvenile partridges are released each autumn. Intensive management and high densities result in high prevalence of enteric disease and the use of antimicrobials as preventive measures on partridge farms and prior to restocking in the wild. We determined the occurrence of avian pathogenic Escherichia coli (APEC), and screened phenotypic resistance of E. coli against enrofloxacin, gentamicin and cefotaxim in farmed, restocked and wild partridges. Prevalence of APEC in farmed and restocked red-legged partridges was significantly higher than in natural populations. Phenotypic resistance against both gentamicin and enrofloxacin was significantly more frequent in farmed (75%) and restocked (43%) partridges than in wild partridges, while most E. coli isolated from natural populations were susceptible to all three antimicrobials tested (65%). This indicates that farmed and restocked partridges carry APEC that could be a reason for disease outbreaks on farms, and that E. coli carried by farmed and restocked partridges can acquire resistance to frequently used antimicrobials, thus being a concern for the environment, wild birds and consumers. Management in farms and restocking procedures may create a hazard not only for spreading APEC, but also as a potential source of resistant E. coli in the environment.