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Simple Summary: Abortions are a significant contributor to economic losses in the swine breeding industry. Identifying the factors responsible for abortion outbreaks is crucial for optimizing farm management and implementing preventive measures, though this can be challenging due to their often multifactorial nature. In this study, we retrospectively examined the infectious agents associated with abortion outbreaks from 2011 to 2021 in northern Italy. The most frequently detected pathogens in fetal samples were porcine reproductive and respiratory syndrome virus (PRRSV), porcine circovirus-3 (PCV3), and PCV2, while Chlamydia spp., porcine parvovirus (PPV), and Leptospira spp. were less common. PRRSV prevalence fluctuated yearly without a clear trend, whereas PCV2 showed a slight decline and PCV3 increased over the study period. Our findings suggest a general decrease in abortion outbreaks between 2011 and 2021. PRRSV, PCV2, and PCV3 were commonly detected in aborted fetuses, while pathogens like Chlamydia spp. and Leptospira spp. had a limited impact, possibly due to improved on-farm hygiene and biosecurity measures. The present study retrospectively analyzed the infectious agents associated with 829 abortion outbreaks occurring from 2011 to 2021 in northern Italy. Foetuses were subjected to necropsies, and organ samples were analyzed by direct PCR to screen for six swine pathogens. In 42.0% of the examined outbreaks, at least one infectious agent was found. Porcine reproductive and respiratory syndrome virus (PRRSV) (24.9%) and porcine circovirus-2 (PCV2) (11.5%) were the most frequently detected among the known abortion-inducing pathogens. Chlamydia spp. (5.6%), porcine parvovirus (PPV) (4.0%), and Leptospira spp. (2.6%) were less common. Although its role in swine reproductive disorders is still unclear, PCV3 was detected in 19.6% of the cases. Coinfections were detected in 25.0% of positive outbreaks, and the most frequent coinfection was represented by PRRSV and PCV2 (32.2%), followed by PRRSV and PCV3 (23%). PCV2 prevalence showed a slight but consistent reduction during the study period, while PCV3 increased in frequency. Our data suggest an overall reduction in abortion outbreaks during the study period. PRRSV was confirmed as the main abortion agent detected in the examined area, while PCV2 prevalence showed a decline. Conversely, PCV3 detection has been increasing, supporting its potential role as an abortion agent. Our results highlight the importance of implementing a consistent and standardized sampling procedure, as well as a thorough diagnostic protocol, to reduce the incidence of inconclusive diagnoses. [ABSTRACT FROM AUTHOR]

Simple Summary: Abattoir lung lesion scoring is a common practice to assess the impact of respiratory diseases in pig production, but whether the information obtained could be used to optimize antimicrobial stewardship programs has rarely been investigated. In this study, lung and pleural scores collected at slaughter from Italian heavy pigs were compared with on-farm antimicrobial use during the six months prior to slaughtering. Lung scores were positively associated with the past use of antimicrobials considered critical for human medicine, suggesting that batches with worse scores may have been unsuccessfully treated with first-choice antimicrobials. This result emphasizes the role of abattoirs as strategic observatories for pig respiratory diseases, which may also be helpful for antimicrobial stewardship. The information obtained could provide useful feedback aiding the identification of gaps in biosecurity or inadequate vaccination plans, thus helping to reduce on-farm antimicrobial use. Respiratory diseases significantly affect intensive pig finishing farms, causing production losses and increased antimicrobial use (AMU). Lesion scoring at slaughter has been recognized as a beneficial practice to evaluate herd management. The integrated analysis of abattoir lesion scores and AMU data could improve decision-making by providing feedback to veterinarians and farmers on the effectiveness of antimicrobial treatments, thus rationalizing their use. This study compared lung and pleural lesion scores collected at Italian pig slaughterhouses with on-farm AMU, estimated through a treatment index per 100 days (TI100). Overall, 24,752 pig carcasses, belonging to 236 batches from 113 finishing farms, were inspected. Bronchopneumonia and chronic pleuritis were detected in 55% and 48% of the examined pigs, respectively. Antimicrobials were administered in 97% of the farms during the six months prior to slaughter (median TI100 = 5.2), notwithstanding compliance with the mandatory withdrawal period. EMA category B (critical) antimicrobials were administered in 15.2% of cases (median TI100 = 0.06). The lung score was not associated with the total AMU, but significant, positive associations were found with the past use of critical antimicrobials (p = 0.041) and macrolides (p = 0.044). This result highlights the potential of abattoir lung lesion monitoring to rationalize antimicrobial stewardship efforts, contributing to AMU reduction. [ABSTRACT FROM AUTHOR]

Simple Summary: Processing fluids (PFs) are novel diagnostic specimens consisting of serosanguineous exudate obtained from tissues after piglets' castration. PFs can be used for some diagnostic tests that would otherwise require a blood sample. This has the advantage of not subjecting piglets to an additional stressful procedure and, at the same time, reducing sampling costs. In the present study, the efficacy and reliability of a monitoring plan for porcine reproductive and respiratory syndrome (PRRS), one of the main pig diseases, based on PF sampling has been assessed in the Italian swine production system. Twenty-five breeding herds were monitored for 4–5 months by RT-PCR performed on both PFs and blood serum (the standard specimen used for monitoring). Based on the results obtained from each method, the herds were classified following the standard PRRS status categories. The two methods fully agreed in discriminating between herds with stable and unstable PRRSV circulation. However, we observed a slight discrepancy in classifying high- and low-prevalence herds within unstable herds. We conclude that PFs are a reliable material for the PRRSV surveillance and classification of breeding herds, but in case of unstable circulation, a strategy combining blood and PF sampling is recommended. The porcine reproductive and respiratory syndrome (PRRS) control strategy within swine breeding farms is based on herd classification relative to PRRSV infection status. This study aims to assess the efficacy of a monitoring plan based on processing fluids (PFs) by comparing it with the classification of herds based on the analysis of blood serum. Twenty-five breeding herds were enrolled in the study, with at least five consecutive batches sampled from each herd. Each batch was tested for PRRSV by RT-PCR performed on (i) pre-weaning blood serum from 30 piglets and (ii) PFs from all the male piglets in the batch. PRRS categories following the Holtkamp classification were assigned based on the results of each testing protocol. The two protocols assigned the same category to 18 out of 25 herds: while they showed perfect agreement in identifying positive unstable and stable herds, we observed some discrepancy in discriminating between low- and high-prevalence classes within unstable herds. PFs are thus a reliable sample to assign PRRS categories in Italian breeding herds characterized by widespread PRRSV circulation. However, in case of an unstable epidemiological scenario, we recommend the adoption of an integrated monitoring strategy that combines blood sampling with PFs. [ABSTRACT FROM AUTHOR]

The emergence of colistin resistance raises growing concerns because of its use as a last-resort antimicrobial for the treatment of severe gram-negative bacterial infections in humans. Plasmid-borne mobile colistin resistance genes (mcr) are particularly worrisome due to their high propensity to spread. An mcr-9-positive Escherichia coli was isolated from a piglet in Italy, representing the first isolation of this gene from an E. coli of animal origin in the country. Whole genome sequencing (WGS) revealed that mcr-9 was borne by an IncHI2 plasmid carrying several other resistance genes. The strain was indeed phenotypically resistant to six different antimicrobial classes, including 3rd and 4th generation cephalosporins. Despite the presence of mcr-9, the isolate was susceptible to colistin, probably because of a genetic background unfavourable to mcr-9 expression. The lack of colistin resistance, coupled with the fact that the farm of origin had not used colistin in years, suggests that mcr-9 in such a multidrug-resistant strain can be maintained thanks to the co-selection of neighbouring resistance genes, following usage of different antimicrobials. Our findings highlight how a comprehensive approach, integrating phenotypical testing, targeted PCR, WGS-based techniques, and information on antimicrobial usage is crucial to shed light on antimicrobial resistance. [ABSTRACT FROM AUTHOR]

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