Genomic epidemiology of third-generation cephalosporin-resistant Escherichia coli from Argentinian pig and dairy farms reveals animal-specific patterns of co-resistance and resistance mechanisms.

Control measures are being introduced globally to reduce the prevalence of antibiotic resistance (ABR) in bacteria on farms. However, little is known about the current prevalence and molecular ecology of ABR in bacterial species with the potential to be key opportunistic human pathogens, such as Escherichia coli, on South American farms. Working with 30 dairy cattle farms and 40 pig farms across two provinces in central-eastern Argentina, we report a comprehensive genomic analysis of third-generation cephalosporin-resistant (3GC-R) E. coli, which were recovered from 34.8% (cattle) and 47.8% (pigs) of samples from fecally contaminated sites. Phylogenetic analysis revealed substantial diversity suggestive of long-term horizontal and vertical transmission of 3GC-R mechanisms. CTX-M-15 and CTX-M-2 were more often produced by isolates from dairy farms, while CTX-M-8 and CMY-2 and co-carriage of amoxicillin/clavulanate resistance and florfenicol resistance were more common in isolates from pig farms. This suggests different selective pressures for antibiotic use in these two animal types. We identified the ß-lactamase gene blaROB, which has previously only been reported in the family Pasteurellaceae, in 3GC-R E. coli. blaROB was found alongside a novel florfenicol resistance gene, ydhC, also mobilized from a pig pathogen as part of a new composite transposon. As the first comprehensive genomic survey of 3GC-R E. coli in Argentina, these data set a baseline from which to measure the effects of interventions aimed at reducing on-farm ABR and provide an opportunity to investigate the zoonotic transmission of resistant bacteria in this region. IMPORTANCE: Little is known about the ecology of critically important antibiotic resistance among bacteria with the potential to be opportunistic human pathogens (e.g., Escherichia coli) on South American farms. By studying 70 pig and dairy cattle farms in central-eastern Argentina, we identified that third-generation cephalosporin resistance (3GC-R) in E. coli was mediated by mechanisms seen more often in certain species and that 3GC-R pig E. coli were more likely to be co-resistant to florfenicol and amoxicillin/clavulanate. This suggests that on-farm antibiotic usage is key to selecting the types of E. coli present on these farms. 3GC-R E. coli and 3GC-R plasmids were diverse, suggestive of long-term circulation in this region. We identified the de novo mobilization of the resistance gene blaROB from pig pathogens into E. coli on a novel mobile genetic element, which shows the importance of surveying poorly studied regions for antibiotic resistance that might impact human health.

Pediococcus pentosaceus RC007 and Saccharomyces boulardii RC009 as antibiotic alternatives for gut health in post-weaning pigs.

AIMS: The aim of the present study was to evaluate a novel probiotic Pediococcus pentosaceus RC007 used alone and convined with Saccharomyces cerevisiae var. boulardii RC009, as in-feed additives to substitute the non-therapeutic use of antibiotics, and evaluate the different structural characteristics of intestinal bacterial populations between groups, correlated with pig production performance. METHODS AND RESULTS: The in vivo study was conducted on post-weaning pigs, from 21 to 56 days-old. Three dietary treatments were included: T1- basal diet (BD - Control group); T2- BD with P. pentosaceus RC007; and T3- BD with a mix of P. pentosaceus RC007 and S. boulardii RC009. The weight gain increase of pigs consuming non-therapeutic antibiotics was similar to those that did not consume antibiotics during the study (p=0.0234), but had better health indicators. The use of a probiotic combination increased carcass weight and significantly reduced the lumbar fat thickness. In terms of taxonomic composition, there was a tendency to modify the abundance of Proteobacteria, Cyanobacteria, Enterobacteriaceae and Lactobacillaceae in pigs that consumed the additives. The genus Butyricicoccus, Collinsella and Ruminococcus tended to be more abundant in the microbiota of pigs at T3. CONCLUSIONS: For the first time, the results of the present study indicate that P. pentosaceus RC007 and S. boulardii RC009, a probiotic combination, could be a good substitute for antibiotics in improving pig production performance, while also contributing to a healthier gut microbiota, especially with the reduced abundance of Proteobacteria and Cyanobacteria.

Ureaplasma diversum-Ureaplasma sp. alone or concomitantly with Mycoplasma hyopneumoniae in pig lungs with and without pneumonia: A descriptive exploratory study in abattoirs.

Occurrence of Ureaplasma diversum (U. diversum) has been associated with reproductive failures in cattle and detected in pigs with and without pneumonia. However, its role in the porcine respiratory disease complex (PRDC) is unclear. A cross-sectional study was conducted in abattoirs, inspecting 280 pig lungs from eight herds. All the lungs were inspected, processed and classified according to the histopathological analysis. Moreover, bronchoalveolar lavage (BAL) specimens were collected and processed by PCR for detection of U. diversum and Mycoplasma hyopneumoniae (M. hyopneumoniae). Ureaplasma sp.-U. diversum and M. hyopneumoniae were detected in 17.1% and 29.3% of the analyzed BAL specimens, respectively. The concomitant presence of both microorganisms was detected in 12.5% of the inspected lungs. Both agents were found in lungs with and without pneumonia. M. hyopneumoniae was detected in 31.8% of pig lungs with enzootic pneumonia-like lesions, while Ureaplasma sp.-U. diversum was detected in 27.5% of lungs with these lesions. This descriptive exploratory study provides information for future experimental and field-based studies to better define the pathogenic role of this organism within the PRDC.

Ureaplasma diversum and Ureaplasma sp. in nasal cavity of pigs: Distribution among herds and individual frequency based on pooled samples.

The role of Ureaplasma diversum in the porcine respiratory disease complex (PRDC), its circulation among herds and prevalence in live pigs is unknown; thus, the objectives of this study were: to determine the presence of U. diversum in indoor intensive pig herds and to determine the individual frequency of pigs with U. diversum from pooled samples. A cross sectional study was carried out in 16 indoor intensive herds from Córdoba and La Pampa provinces, collecting eight nasal swabs specimens that were further processed by two pools of four specimens each by a PCR targeting a fragment of 16S ribosomal RNA gene. Four PCR products were sequenced and aligned against data bases. U. diversum - Ureaplasma sp. were detected in 56.3% of the analyzed herds, with 16.5% (95% CI 8.2-30.8) of positive pigs. It was concluded that U. diversum - Ureaplasma sp. are present in the nasal cavity of live pigs, being widely distributed among herds.

Persistence of the same genetic type of Mycoplasma hyopneumoniae in a closed herd for at least two years.

Two cross-sectional studies were carried out in 2013 and 2015 monitoring for Mycoplasma hyopneumoniae presence in a swine farm. In these studies, the genetic diversity of M. hyopneumoniae was assessed in clinical specimens using a Multiple Locus Variable-number tandem repeat Analysis (MLVA) targeting P97 R1, P146 R3 and H4 loci. The samples from August 2015 showed the MLVA profile prevalent in June 2013, therefore it can be concluded that a same genetic type of M. hyopneumoniae can persist for at least two years in a closed herd. In addition, the nested PCR reactions implemented in this study showed to be useful for MLVA typing in non-invasive clinical samples.

First detection of PCV4 in swine in the United States: codetection with PCV2 and PCV3 and direct detection within tissues.

Since PCV4 was first described in 2019, the virus has been identified in several countries in Southeast Asia and Europe. Most studies have been limited to detecting PCV4 by PCR. Thus, PCV4 has an unclear association with clinical disease. This study utilized 512 porcine clinical lung, feces, spleen, serum, lymphoid tissue, and fetus samples submitted to the ISU-VDL from June-September 2023. PCV4 was detected in 8.6% of samples with an average Ct value of 33. While detection rates among sample types were variable, lymphoid tissue had the highest detection rate (18.7%). Two ORF2 sequences were obtained from lymphoid tissue samples and had 96.36-98.98% nucleotide identity with reference sequences. Direct detection of PCV4 by RNAscope revealed viral replication in B lymphocytes and macrophages in lymph node germinal centers and histiocytic and T lymphocyte infiltration in the lamina propria of the small intestine. PCV4 detection was most commonly observed in nursery to finishing aged pigs displaying respiratory and enteric disease. Coinfection with PCV2, PCV3, and other endemic pathogens was frequently observed, highlighting the complex interplay between different PCVs and their potential roles in disease pathogenesis. This study provides insights into the frequency of detection, tissue distribution, and genetic characteristics of PCV4 in the US.

In-feed nutritional additive probiotic Saccharomyces boulardii RC009 can substitute for prophylactic antibiotics and improve the production and health of weaning pigs.

Background and Aims: Non-therapeutic antibiotic use is associated with the current decrease in antibiotic therapeutic efficiency and the emergence of a wide range of resistant strains, which constitutes a public health risk. This study aimed to evaluate the use of Saccharomyces cerevisiae var. boulardii RC009 as a nutritional feed additive to substitute the prophylactic use of antibiotics and improve the productive performance and health of post-weaning piglets. Materials and Methods: Four regular nutritional phases were prepared. Post-weaning pigs (21-70 days old) received one of two dietary treatments: T1-basal diet (BD-control group) with in-feed antibiotics as a prophylactic medication (one pulse of Tiamulin in P3 and one pulse of Amoxicillin in P4); and T2-BD without in-feed antibiotics but with Saccharomyces boulardii RC009 (1 × 1012 colony forming unit/T feed). The feed conversion ratio (FCR), total weight gain (TWG-kg), and daily weight gain (DWG-kg) were determined. A post-weaning growth index (GI) was calculated and animals (160 days old) from each treatment were analyzed at the abattoir after sacrifice for carcass weight and respiratory tract lesions. Results: Pigs consuming probiotics had higher TWG and DWG than the control group. The group of animals with low body weight obtained the same results. Saccharomyces boulardii administration decreased diarrhea, and FCR reduction was related to a GI improvement. A significant increase in carcass weight and muscle thickness reduction was observed in animals received the probiotic post-weaning. Conclusion: Saccharomyces boulardii RC009, a probiotic additive, was found to improve the production parameters of pigs post-weaning and enhance their health status, indicating that it may be a promising alternative to prophylactic antibiotics.

Antibiotic resistance and associated resistance determinants in different Salmonella enterica serovars isolated from pigs in Argentina.

Background and Aim: Salmonellosis is one of the most common foodborne diseases in the world, and the increasing antibiotic resistance in Salmonella enterica subsp. enterica recovered from food animals constitutes an important risk from a One Health approach. This study aimed to characterize antibiotic resistance and some of its associated resistance determinants in different S. enterica serovars isolated from pigs in Argentina. Materials and Methods: A retrospective study was conducted on Salmonella strains isolated between 2011 and 2015 from pigs in the Pampean region of Argentina. The antimicrobial susceptibility patterns to 21 antimicrobials and some antibiotic resistance determinants were characterized in 55 Salmonella isolates, representing 58 farms. Results: We identified 56% (n=30) of the strains as multidrug-resistant, where resistance to tetracycline (62%, n=34), ampicillin (53%, n=29), nalidixic acid (53%, n=29), chloramphenicol (33%, n=18), and trimethoprim-sulfamethoxazole (31%, n=17) was most common. The wide range of resistance to ampicillin correlates with the presence of TEM type ß-lactamases in the strains. However, high susceptibility was found in the new generation of ß-lactams. Fluoroquinolone resistance is a major concern. Most strains with decreased susceptibility to ciprofloxacin showed gyrA mutations and plasmid-mediated quinolone resistance gene qnrB. Conclusion: Here, we identified broad resistance to some antibiotics frequently used in human therapeutics and several easily transferable resistance mechanisms that could endanger public health.

Respiratory tract clinometry, fat thickness, haematology and productive parameters associated with direct-fed microbials used as growth promoter antibiotic alternative in weaned piglets.

The objective was to evaluate the effect of two probiotic yeast strains (Saccharomyces. cerevisiae RC016 and Kluyveromyces marxianus VM004) as a substitute of growth promoter antibiotics on health status and productive parameters in weaned piglets. Commercial line hybrid piglets (Choice n=200), weaned at 21 d age were allotted by sex, and assigned in 4 pens per treatment (2 pens males and 2 pens females), 10 pigs per pen divided into 2 blocks (with or without antibiotics). Dietary treatments included a basal diet (BD) supplemented with probiotic Saccharomyces cerevisiae RC016 and Kluyveromyces marxianus VM004 (100 g, 1 × 1010 CFU/g, respectively), with or without antibiotics, mixed per ton of growth phases diets. Pigs were fed ad libitum with treatments T1) BD with antibiotics (BD); T2) BD with antibiotics + Saccharomyces cerevisiae; T3) BD without antibiotics + Saccharomyces cerevisiae; T4) BD with antibiotics + Kluyveromyces marxianus; T5) BD without antibiotics + Kluyveromyces marxianus. The effects on respiratory tract clinometry, carcass quality, organs weight, blood haematology and productive parameters were evaluated. When clinical signs occurred (diarrhoea, stomach ulcers, respiratory signs), they decreased with both probiotics addition, mainly Saccharomyces cerevisiae. The productive parameters promotion by both probiotics was similar than that using antibiotics. The probiotics inclusion increased the carcass weight and significantly reduced the lumbar fat thickness (P ≤ 0.05). Supplementation with both probiotics demonstrated their ability to substitute the antibiotics use on clinometry, carcass quality and on the productive parameters promotion of weaned piglets.

Identification and distribution of Brachyspira species in feces from finishing pigs in Argentina.

BACKGROUND AND AIM: Brachyspira are Gram-negative, aerotolerant spirochetes that colonize the large intestine of various species of domestic animals and humans. The aim of this study was to determine the presence and distribution of different species of Brachyspira presents in feces from finishing pigs in Argentina. MATERIALS AND METHODS: Fecal samples (n=1550) were collected from finishing pigs in 53 farms of the most important swine production areas of Argentina, and Brachyspiras species were identified by bacteriological and molecular methods. RESULTS: The regional prevalence of Brachyspira spp. was at the level of 75.5% (confidence interval 95%, 62.9-87.9), and it was lower among those farms with >1001 sows. One hundred and twenty-eight isolates of Brachyspira were properly identified and the species found were: Brachyspira hyodysenteriae, Brachyspira pilosicoli, Brachyspira innocens, and Brachyspira murdochii. B. hyodysenteriae and B. pilosicoli had low prevalence (1.9% and 7.5%, respectively), B. innocens was isolated from 34% of the farms and B. murdochii was found in 39.6%. CONCLUSION: The present study provides epidemiological data about herd prevalence of the different Brachyspira species in Argentina, showing that the prevalence figure seems to be higher than that reported in other countries.

Effect of soybean expeller supplementation during the final phase of sow gestation on litter birth weight.

AIM: Nutrition plays a key role in the production of pigs, especially in pregnant sows, where modifications in nutritional requirements can affect their productive performance. The aim of this study was to evaluate nutritional supplementation with soybean expeller in sows during the last third of the gestation period and its effect on litter birth weight. MATERIALS AND METHODS: A quasi-experimental study was conducted on a farrow-to-finish farm, where 192 sows were equally assigned to treatment and control groups. Several variables were recorded at both the sow and piglet level. The treatment group consisted of piglets from 95 sows supplemented with soybean expeller during the final phase of gestation (20 days), and the comparison group consisted of piglets from 97 sows fed only with a commercial balanced ration (control group). RESULTS: Soybean expeller supplementation increased individual piglet weight by 190-270 g, and the increased number of live piglets could decrease the weight of each piglet. Moreover, the number of piglets weighing <900 g decreased by 10% as compared to the control group, indicating that supplementation could improve pre-weaning mortality. CONCLUSION: Our results suggest that soybean expeller supplementation in sows during the last third of the gestation period could improve production performance, especially on organic farms.

Detection of Mycoplasma hyopneumoniae in nasal and laryngeal swab specimens in endemically infected pig herds.

BACKGROUND: Apparently, laryngeal swabs (LS) are more sensitive than nasal swabs (NS) and allow earlier detection of Mycoplasma hyopneumoniae by PCR. However, antecedents about the compared detection of M hyopneumoniae with NS and LS in growing pigs, from naturally infected herds, are lacking in the literature. Thus, this study compared the PCR detection of M hyopneumoniae from NS and LS in pigs of various ages. METHODS: A longitudinal study was performed at two farms where NS and LS were collected from three consecutive groups of 20 pigs at 3, 6, 10, 16 and 22 weeks of age. All samples were analysed by nested PCR for M hyopneumoniae detection. RESULTS: The probability of PCR detection of M hyopneumoniae was higher in LS for pigs of all ages (odds ratio (OR)=1.87; 95 per cent confidence interval (CI) 1.31-2.67) and in 22-week-old pigs (OR=4.87; 95 per cent CI 2.86-8.30). The agreement between both sample types was low to moderate (kappa 0.087-0.508), highlighting that M hyopneumoniae does not appear to colonise the respiratory tract in a generalised and consistent fashion. CONCLUSIONS: The results suggest that LS could be employed at different ages to achieve greater bacterial detection. Considering that LS is a minimally invasive, highly sensitive sample compared with the traditional NS, it could be suggested to employ this sample type for M hyopneumoniae detection in naturally infected pigs.

Ureaplasma diversum-Ureaplasma sp. alone or concomitantly with Mycoplasma hyopneumoniae in pig lungs with and without pneumonia: A descriptive exploratory study in abattoirs / Presencia de Ureaplasma diversum-Ureaplasma sp. solo o junto con Mycoplasma hyopneumoniae en pulmones de cerdos con y sin neumonía: un estudio exploratorio descriptivo en frigorífico

Abstract Occurrence of Ureaplasma diversum (U. diversum) has been associated with repro-ductive failures in cattle and detected in pigs with and without pneumonia. However, its rolein the porcine respiratory disease complex (PRDC) is unclear. A cross-sectional study was con-ducted in abattoirs, inspecting 280 pig lungs from eight herds. All the lungs were inspected,processed and classified according to the histopathological analysis. Moreover, bronchoalveolarlavage (BAL) specimens were collected and processed by PCR for detection of U. diversum andMycoplasma hyopneumoniae (M. hyopneumoniae). Ureaplasma sp.---U. diversum and M. hyop-neumoniae were detected in 17.1% and 29.3% of the analyzed BAL specimens, respectively. Theconcomitant presence of both microorganisms was detected in 12.5% of the inspected lungs.Both agents were found in lungs with and without pneumonia. M. hyopneumoniae was detectedin 31.8% of pig lungs with enzootic pneumonia-like lesions, while Ureaplasma sp.---U. diversumwas detected in 27.5% of lungs with these lesions. This descriptive exploratory study providesinformation for future experimental and field-based studies to better define the pathogenicrole of this organism within the PRDC.

Resumen La presencia de Ureaplasma diversum se ha asociado a fallas reproductivas en el ganado bovino y se ha detectado en cerdos con y sin neumonía. Sin embargo, su participación en el complejo de enfermedades respiratorias porcinas (CERP) no es clara. Se llevó a cabo un estudio transversal en matadero, inspeccionando 280 pulmones de cerdo provenientes de ocho piaras. Todos los pulmones fueron inspeccionados, procesados y clasificados según el análisis histopatológico. También se colectaron muestras de lavado broncoalveolar (LBA) y se procesaron mediante PCR para la detección de U. diversum y Mycoplasma hyopneumoniae. Ureaplasma sp.-U. diversum y M. hyopneumoniae se detectaron en el 17,1% y en el 29,3% de los LBA analizados, respectivamente. La presencia concomitante de ambos microorganismos se detectó en el 12,5% de los pulmones inspeccionados. Ambos agentes se encontraron en pulmones con y sin neumonía. M. hyopneumoniae se detectó en el 31,8% de los pulmones con lesiones compatibles con neumonía enzoótica, mientras que Ureaplasma sp.-U. diversum se detectó en el 27,5% de los pulmones con estas lesiones. Este estudio exploratorio descriptivo proporciona información para futuros estudios experimentales y de campo tendentes a definir mejor el papel patógeno de este organismo dentro del CERP.

Assessment of a segregated medicated early weaning protocol for elimination of Actinobacillus pleuropneumoniae / Avaliação de um protocolo de desmame precoce segregado medicado para a eliminação de Actinobacillus pleuropneumoniae

ABSTRACT: To assess the success of a segregated medicated early weaning protocol for elimination of Actinobacillus pleuropneumoniae, ten consecutive batches of 100 pigs per batch weaned at 7-9 days of age were monitored at 21-22 weeks of age looking for presence of productive cough, presence of antibodies against the agent and pleuropneumonia-compatible lung lesions at slaughter. Also, whole tonsils were processed for A. pleuropneumoniae identification by both bacteriological isolation and nested-PCR using a direct method. Positive serological test (1.4%) and PCR (3.5%) results, suggested that A. pleuropneumoniae could not be eradicated in all batches, even using segregated medicated early weaning protocol.

RESUMO: Para avaliar o sucesso de um protocolo de desmame precoce segregado medicado para a eliminação de Actinobacillus pleuropneumoniae, dez lotes consecutivos de 100 suínos por lote desmamados aos 7-9 dias de idade foram monitorados às 21-22 semanas de idade procurando a presença de tosse produtiva, presença de anticorpos contra o agente e lesões pulmonares compatíveis com pleuropneumonia no abate. Além disso, as tonsilas inteiras foram processadas para a identificação de A. pleuropneumoniae por isolamento bacteriológico e nested PCR usando um método direto. Os resultados serológicos (1,4%) e PCR (3,5%) positivos sugerem que não foi possível erradicar em todos os lotes, mesmo usando um protocolo de desmame precoce segregado medicado.

Factores asociados a la aparición de mediastinitis en 2073 revascularizaciones miocárdicas / Factors associated with the onset of mediastinitis in 2073 myocardial revascularizations

Introducción: La mediastinitis, entidad de etiología multifactorial, ocurre hasta en 4% de los pacientes sometidos a revascularización miocárdica, y se reporta una mortalidad hospitalaria de 14% a 47%, que genera aumento en los costos de atención y deterioro de la calidad de vida así como de la sobrevida del paciente a largo plazo. Objetivo: Determinar cuáles antecedentes clínicos del paciente y factores relacionados con el procedimiento quirúrgico se asocian con la aparición de mediastinitis. Materiales y métodos: Diseño de casos y controles anidado en una cohorte histórica de pacientes sometidos a revascularización miocárdica en el periodo de enero de 2005 a julio de 2011. Los pacientes con mediastinitis se compararon con un grupo control sin mediastinitis tomados del mismo grupo de riesgo en una relación 1:4, y pareados por fecha de cirugía. El diagnóstico de mediastinitis se hizo con criterios clínicos, de laboratorio y hallazgos quirúrgicos. Resultados: Se identificaron treinta casos en el periodo relacionado. Los factores asociados a la aparición del evento fueron: diabetes mellitus OR 2,3 (1,1-4,9), uso de circulación extracorpórea OR 2,4 (1,1-5,5), tiempo de perfusión OR 1,1 (1,1-1,3) y pacientes mayores de 70 años OR 1,1 (1,2-1,4). Conclusiones: La mediastinitis sigue siendo una complicación de baja prevalencia con consecuencias devastadoras. El impacto clínico y económico de esta complicación debe obligar a los grupos quirúrgicos a crear estrategias de prevención con base en el conocimiento de los factores de riesgo de su población.

Introduction: Mediastinitis is a multifactorial entity which occurs in up to 4% of patients undergoing coronary artery bypass graft (CABG). It has a hospital mortality of 14% to 47%, which generates increased costs of care and deterioration of the quality of life and patient survival in the long term. Objective: To determine which clinical antecedents and factors related to the surgical procedure are associated with the occurrence of mediastinitis. Materials and methods: A nested case control study in a historical cohort of patients undergoing CABG in the period January 2005 to July 2011. Patients with mediastinitis were compared with a control group without mediastinitis taken from the same risk group in a 1:4 ratio and matched for date of surgery. The diagnosis of mediastinitis was made on clinical and laboratory criteria and surgical findings. Results: Thirty cases were identified in the related period. Factors associated with the occurrence of the event were: diabetes mellitus OR 2.3 (1.1 to 4.9), use of extracorporeal circulation OR 2.4 (1.1-5.5), OR 1 perfusion time, 1 (1.1 to 1.3) and patients older than 70 years OR 1.1 (1.2-1.4). Conclusions: Mediastinitis remains complications of low prevalence with devastating consequences. The clinical and economic impact of this complication should compel surgical groups to create prevention strategies based on knowledge of the risk factors of the population.