Use of organic acids to reduce Salmonella Typhimurium excretion in swine / Uso de ácidos orgânicos para reduzir a excreção de Salmonella Typhimurium em suínos

The use of antimicrobials as growth promoters and disease prevention is being constantly reduced in several animal production systems, including in the swine industry. Therefore, this study aimed to evaluate the effectiveness of using acidifiers to control Salmonella Typhimurium in 65-day-old pigs by detecting the pathogen in organs at euthanasia. For this, 24 piglets were divided into two experimental groups consisting of 12 piglets each. An untreated control group (G1) and a treatment group (G2) received a liquid organic acidifier in the drinking water for 10 days (D-5 to D5). Five days after the start of treatment (D0), all piglets were challenged with 106 CFU of Salmonella Typhimurium and assessed for 12 days (D12). Every three days (D3, D6, D9, and D12), three animals from each experimental group were euthanized and then submitted for necropsy. Samples from the intestines (ileum, cecum, mesenteric lymph nodes, and ileocolic lymph nodes), liver, spleen, and lungs were collected to isolate Salmonella. The results show that, numerically, Salmonellaisolation in the organs of G2 was lower than in G1 and that the number of positive cecum samples in G1 (66.7%; 8/12) was statistically different from the number of positive models in G2 (16.7%; 2/12), with a reduction of 28.6% of the total cecum positive samples in the treated group compared to the control. Therefore, it was observed that the liquid organic acidifier product could reduce the colonization of organs by Salmonella Typhimurium.(AU)

O uso de antimicrobianos como promotores de crescimento e prevenção de doenças vem sendo constantemente reduzido em diversos sistemas de produção animal, inclusive na suinocultura. Portanto, o objetivo do presente estudo foi avaliar a eficácia do uso de acidificantes no controle de Salmonella Typhimurium em suínos de 65 dias de idade, detectando o patógeno em órgãos após a eutanásia. Para isso, 24 leitões foram divididos em dois grupos experimentais constituídos por 12 leitões cada. Um grupo controle não tratado (G1) e um grupo de tratamento (G2) que recebeu um acidificante orgânico líquido na água de beber por 10 dias (D-5 a D5). Cinco dias após o início do tratamento (D0), todos os animais foram inoculados oralmente com 106 UFC de Salmonella Typhimurium e avaliados por 12 dias (D12). A cada três dias (D3, D6, D9 e D12), três leitões de cada grupo experimental foram eutanasiados e posteriormente submetidos à necropsia. Amostras de intestino (íleo, ceco, linfonodos mesentéricos e linfonodos ileocólicos), fígado, baço e pulmões foram coletadas para o isolamento de Salmonella. Os resultados mostram que, numericamente, o isolamento de Salmonella nos órgãos do G2 foi inferior ao G1, e que o número de amostras positivas de ceco no G1 (66,7%; 8/12) foi estatisticamente diferente do número de amostras positivas no G2 (16,7%; 2/12), com redução de 28,6% do total de amostras positivas de ceco no grupo tratado em relação ao controle. Portanto, observou-se que o ácido orgânico líquido foi capaz de reduzir a colonização de órgãos por Salmonella Typhimurium.(AU)

Use of organic acids to reduce Salmonella Typhimurium excretion in swine / Uso de ácidos orgânicos para reduzir a excreção de Salmonella Typhimurium em suínos

The use of antimicrobials as growth promoters and disease prevention is being constantly reduced in several animal production systems, including in the swine industry. Therefore, this study aimed to evaluate the effectiveness of using acidifiers to control Salmonella Typhimurium in 65-day-old pigs by detecting the pathogen in organs at euthanasia. For this, 24 piglets were divided into two experimental groups consisting of 12 piglets each. An untreated control group (G1) and a treatment group (G2) received a liquid organic acidifier in the drinking water for 10 days (D-5 to D5). Five days after the start of treatment (D0), all piglets were challenged with 106 CFU of Salmonella Typhimurium and assessed for 12 days (D12). Every three days (D3, D6, D9, and D12), three animals from each experimental group were euthanized and then submitted for necropsy. Samples from the intestines (ileum, cecum, mesenteric lymph nodes, and ileocolic lymph nodes), liver, spleen, and lungs were collected to isolate Salmonella. The results show that, numerically, Salmonella isolation in the organs of G2 was lower than in G1 and that the number of positive cecum samples in G1 (66.7%; 8/12) was statistically different from the number of positive models in G2 (16.7%; 2/12), with a reduction of 28.6% of the total cecum positive samples in the treated group compared to the control. Therefore, it was observed that the liquid organic acidifier product could reduce the colonization of organs by Salmonella Typhimurium. (AU)

Experimental Infection with Mycoplasma hyopneumoniae Strain 232 in Swine Influences the Lower Respiratory Microbiota.

Mycoplasma (M.) hyopneumoniae, the etiological agent of swine enzootic pneumonia, has been reported to increase the susceptibility to secondary infections and modulate the respiratory microbiota in infected pigs. However, no studies have assessed the influence of M. hyopneumoniae on the respiratory microbiota diversity under experimental conditions. Therefore, this study evaluated the impact of M. hyopneumoniae infection on the respiratory microbiota of experimentally infected swine over time. To accomplish this, 12 weaned pigs from a M. hyopneumoniae-free farm were divided into two groups: M. hyopneumoniae strain 232 infected (n = 8) and non-infected (n = 4). The first group received 10 mL of Friis medium containing 107 CCU/mL of M. hyopneumoniae while the control group received 10 mL of sterile Friis medium. Inoculation of both groups was performed intratracheally when the animals were 35 days old (d0). At 28 days post-inoculation (dpi) and 56 dpi, 4 infected animals plus 2 controls were humanely euthanized, and biopsy samples of nasal turbinates (NT) and bronchus-alveolar lavage fluid (BALF) samples were collected. The DNA was extracted from the individual samples, and each group had the samples pooled and submitted to next-generation sequencing. Taxonomic analysis, alpha and beta diversity indexes, weighted unifrac, and unweighted unifrac distances were calculated. A high relative frequency (99%) of M. hyopneumoniae in BALF samples from infected animals was observed with no significant variation between time points. The infection did not seem to alter the diversity and evenness of bacterial communities in NT, thus, M. hyopneumoniae relative frequency was low in NT pools from infected animals (28 dpi-0.83%; 56 dpi-0.89%). PCoA diagrams showed that BALF samples from infected pigs were grouped and far from the control samples, whereas NT from infected animals were not separated from the control. Under the present coditions, M. hyopneumoniae infection influenced the lower respiratory microbiota, which could contribute to the increased susceptibility of infected animals to respiratory infections.

Chemotherapeutic Strategies with Valnemulin, Tilmicosin, and Tulathromycin to Control Mycoplasma hyopneumoniae Infection in Pigs.

Mycoplasma hyopneumoniae is the primary agent of Swine Enzootic Pneumonia (SEP). Vaccines reduce the clinical manifestation of the disease but do not prevent infection. The present study aimed to evaluate the use of antimicrobial drugs to minimize the impact of M. hyopneumoniae. For this, 32 pregnant female pigs and their litters were selected and then followed from birth to slaughter. The study involved three experimental groups that received metaphylactic treatment with different protocols involving tilmicosin, valnemulin, tulathromycin, and a control group to compare the effect of treatments against M. hyopneumoniae infection throughout the phases. Performance data were recorded, and the piglets were evaluated for the occurrence of cough. Nasal swab and blood collection was conducted periodically to detect M. hyopneumoniae shedding and anti-M. hyopneumoniae IgG, respectively. At slaughter, the lungs of animals from all groups were evaluated, and samples were collected for histopathological examination and qPCR for M. hyopneumoniae detection. All protocols promoted a reduction in consolidation lung lesions when compared to the control group. Individuals treated with valnemulin showed increased performance results, lower mortality, and low bacterial load in the lung. The results are promising and may indicate an alternative in the strategic control of M. hyopneumoniae infection in pigs.

Salmonella Bacterin Vaccination Decreases Shedding and Colonization of Salmonella Typhimurium in Pigs.

Since the occurrence of swine salmonellosis has increased over time and control strategies other than biosecurity are highly recommended, the present study aimed to evaluate the efficacy of vaccination with Salmonella Choleraesuis and Salmonella Typhimurium bacterins in pigs. Two experimental groups were formed: G1, animals immunized with two doses of a commercial vaccine (n = 20); G2, control group (n = 20). After vaccination, all pigs were orally challenged (D0) with 108 CFU of Salmonella Typhimurium and evaluated for 40 days. Every 10 days after D0, five piglets from each experimental group were euthanized and submitted to the necroscopic examination, when organ samples were collected. Blood samples and rectal swabs were collected before the first dose of the vaccine (D-42), before the second dose (D-21), before the challenge (D0), and thereafter, every three days until D39. Blood count, serum IgG measurement by ELISA, and the excretion of Salmonella Typhimurium in feces were evaluated. While the results from blood count and serum IgG concentration did not differ, the detection and excretion of Salmonella between G1 and G2 differed (p < 0.05). Therefore, it was observed that this vaccine partially protected the animals against experimental infection with Salmonella Typhimurium, reducing the excretion of bacteria in feces.

Co-infections by Mycoplasma hyopneumoniae, Mycoplasma hyorhinis and Mycoplasma flocculare in macroscopic lesions of lung consolidation of pigs at slaughter.

Infections with Mycoplasma hyopneumoniae (Mhyo), Mycoplasma hyorhinis (Mhr) and Mycoplasma flocculare (Mfloc) are common in swine. However, the degree of co-infections and the correlations between these mycoplasma co-infection and the severity of macroscopic lung consolidation lesions (MLCL) have not yet been explored in Brazil.The objectives were to quantify Mhyo, Mhr, and Mfloc in MLCL of slaughter pigs in Brazil, and to assess correlations with the degree of MLCL in slaughter pigs. To this end, five groups of lungs were made based on severity of lung lesions, and 80 lungs were collected for each group (400 lungs in total). The Mycoplasmas were quantified using a multiplex qPCR. Statistical differences and comparison between the groups were evaluated, respectively, by the Kruskal-Wallis test (p < 0.05) and Dunn's test (p < 0.05), and the correlation between the data was performed by Spearman's method (p < 0.05). The results revealed that the extent of MLCL showed a positive correlation with the Mhyo estimate (rho = 0.26; p < 0.05), a negative correlation with the Mfloc estimate (rho= -0.15; p < 0.05), and no significant correlation with the Mhr estimate (p = 0, 12). The extension of MLCL showed a positive correlation with the co-infection by Mfloc and Mhr (rho = 0.17; p < 0.05), and no significant correlation with Mhyo and Mhr (p = 0.87), and a negative correlation with Mhyo and Mfloc (rho= -0.28; p < 0.05). This study allowed to infer that, regarding the extension of MLCL, Mhr and Mfloc did not present opportunistic activity in relation to primary infection by Mhyo, but revealed some potential aggravation of these lesions. In addition, Mhyo expressed inhibitory behavior towards Mfloc, suggesting that one can compete with the other's presence.

Investigation of hemotropic Mycoplasmas in fetuses and sows with reproductive failure.

Swine eperythrozoonosis or porcine hemoplasmosis is an infectious disease caused mainly by Mycoplasma suis and is distributed worldwide. This study investigated the occurrence of porcine hemothropic mycoplasmas (PHMs) in fetuses and sows with reproductive failure. Two hundred and seventy-six samples (80 sows' blood and 196 fetal tissue samples) from 27 farms with reproductive disorders were evaluated. The PHMs DNA was detected in 15 out of 80 (18.7%) sows but it was not detected in the fetuses. The bacterial load ranged from 1.32 × 102 to 2.61 × 105 copies/µL. From the 27 tested herds, 11 (40.7%) showed at least one positive sow per farm. The majority of the reproductive problems observed in PMHs positive sows were stillborn fetuses (46.7%) and stillborn associated with fetal mummification (26.7%). So, we evidenced that porcine hemoplasmas circulate among sows in Brazilian herds, however, its real impact on reproductive problems remains unknown.

Cross-sectional study of Leptospira spp. in commercial pig farms in the state of Goiás, Brazil.

Leptospirosis is an infectious, contagious disease highly important to the world pig industry, which causes reproductive loss in breeding herds. Endemic infections in a herd may produce little evidence of clinical disease despite resulting in economic losses. However, some epidemiological features of leptospirosis in midwestern Brazil, such as risk factors and prevalence of the disease, remain unclear. Therefore, this study focused on assessing the prevalence of the Leptospira spp. in intensive pig herds and associating its risk factors. A set of 900 blood samples, equally distributed between nursery, growing, and finishing pigs of 30 intensive farrow-to-finish farms, were analyzed using the microagglutination test (MAT), in order to detect anti-Leptospira spp. antibodies for 24 different Leptospira spp. serovars. An occurrence of 4.67% (55/342) seropositive samples were detected in fattening pigs. The variables associated with the disease occurrence were animals per square meter at fattening (OR 0.006, CI 95% 0.004-0.42, p = 0.0105) and pen division between growing and fattening pigs (OR 3.56, CI 95% 0.563-22.541, p = 0.185). Thus, the variables semi-hollow floor in the maternity (OR 16.66; CI 95%: 2.17-128.2 and p = 0.006) and animals per trough at fattening (OR: 0.08, CI 95% 0.009-0.87 and p = 0.025), observed in this study, highlight the importance of the fattening phase in the epidemiology of the disease, bringing information on risk factors involved in the occurrence and dissemination of leptospirosis in intensive pig herds.

Achievements and Challenges of Classical Swine Fever Eradication in Brazil.

Classical swine fever virus (CSFV) causes one of the most critical diseases in the porcine industry worldwide. In Brazil, the first description of the infection was reported in 1888, and the national recognition of the first free zone (FZ) occurred in 2001. Brazil has been recently recognized (2015-2016) by the World Organisation for Animal Health (OIE) with an FZ involving 15 states and the Federal District, corresponding to 95% of the industrial production of pigs in the country, and a non-free zone (NFZ), comprised by the North and Northeast regions of the country, with approximately 18% of the national pig herd and 5% of industrial production. This review aims to describe the history, the control and eradication actions, the recent occurrence of outbreaks in the NFZ, and the results obtained by the surveillance systems' action in the FZ for CSF in Brazil since its creation. In the passive surveillance system, the notification of the suspect cases of classical swine fever (CSF) is mandatory while in the active surveillance system adopted in the FZ consists of serological monitoring of certified swine breeding farms (CSBFs), intensive pig farming (IPF), non-technified pig herds (NTPig), surveillance in slaughterhouses and monitoring the populations of wild pigs. In this region, the last outbreaks of the disease occurred in 1998, while in the NFZ, 28 outbreaks were detected from 2005 to 2017, with an apparent lethality rate of 93.96% (840/894). However, in 2018 and 2019, 68 new outbreaks were registered with an apparent lethality rate of 75.05% (1095/1459). Therefore, in 2019, the Brazil CSF-Free Strategic Plan was created to eradicate the infection from the country's NFZ, since outbreaks in this region present a risk of reintroducing the disease FZ. Finally, differences in characteristics between the regions show factors that still need to be considered for the construction of a robust surveillance system in the NFZ and some improvements in the FZ. Thus, the control of CSF throughout the Brazilian territory requires strict sanitary guidelines, promoting animal health and, consequently, the national production chain's competitiveness.

Experimental inoculation and nose-to-nose transmission of Clostridioides difficile between weaned piglets.

In piglets, Clostridioides (C.) difficile infection presents mostly subclinical manifestation. As this agent became important in veterinary medicine due to a hypothesis of zoonosis, the objective of this study was to evaluate the transmission of C. difficile by nose-to-nose contact in young piglets. Six 20-day-old piglets were separated into three groups (infected, sentinel and control), and distributed in different isolation cabinets which allowed nose-to-nose contact only between infected and sentinel groups. The challenged group received an inoculum 106 CFU/mL of C. difficile 096 by oropharyngeal route. Rectal swab samples were daily collected for microbiological and molecular analysis. Euthanasia of all piglets was performed 18 days after challenge to evaluate anatomical, histological and microbiological lesions of the organs of these animals. The challenged and sentinel groups showed clinical signs of infection and genes encoding TcdB were detected by conventional PCR in both groups, confirming the transmission of the pathogen from the challenged to the sentinel piglets. At necropsy, tonsil, liver, spleen, mesenteric lymph nodes, ileocolic lymph nodes, jejunum, ileum, proximal colon, distal colon and cecum were collected for microbiological analysis; lesions were observed varying in degree and intensity. This study demonstrated a novel route of transmission of C. difficile between young piglets, which was proven to occur by nose-to-nose contact.

No effects of noncytopathic bovine viral diarrhea virus type 2 on the reproductive tract of experimentally inoculated boars.

Bovine viral diarrhea virus (BVDV) infections in pigs may result in transient leukopenia, chronic gastroenteritis, septicemia, and hemorrhagic lesions. Both classical swine fever virus (CSF) and the atypical porcine pestivirus (APPV) are shed in the semen of infected boars. Because these viruses share conserved regions and present antigenic similarity, they may not be the only species belonging to the genus Pestivirus that can be shed in the semen of infected pigs. The objective of this study was to evaluate the testicular and epididymal changes, seminal parameters, and viral shedding in the reproductive tract of boars experimentally inoculated with noncytopathic BVDV-2. Six males were selected, and samples of blood, semen, and preputial swabs were collected every four days until the 52nd day after inoculation. The samples were tested for the presence of viral RNA by RT-PCR. An aliquot of whole blood was used to perform hematological analyses, which showed a significant reduction in monocyte counts and a significant increase in lymphocyte counts when comparing the pre- and postinoculation periods. The neutralizing antibody titers were determined by the virus neutralization test. None of the animals presented clinical signs or worsening of the seminal parameters that were evaluated. Moreover, BVDV-2 shedding by the reproductive route was not observed.

Cross-sectional study of seropositivity, lung lesions and associated risk factors of the main pathogens of Porcine Respiratory Diseases Complex (PRDC) in Goiás, Brazil.

BACKGROUND: The objective of the study was to evaluate the occurrence and severity of Porcine Respiratory Diseases Complex (PRDC) pathogens in the Goiás State, Brazil. Were assessed the serological antibodies occurrency of Mycoplasma hyopneumoniae, Actinobacillus pleuropneumoniae and swine influenza virus (SIV), as well as the evaluation of pulmonary Mycoplasma-like lung lesions, pleuritis, histopathological lesions and diseases occurrence associated with risk factors, such as management, housing and productive indexes. We conveniently selected 2536 animals for serology testing, and 900 lungs at slaughtering of animals from 30 multisite herds in Goiás State, Brazil. RESULTS: For M. hyopneumoniae, all herds presented seropositive animals at some stage of production. Even though most herds (29/30) vaccinated against this pathogen, 90.0% (27/30) of the herds presented at least 50.0% of seropositive animals in finishing and slaughter. Overall, antibodies against A. pleuropneumoniae were present in lower occurrence, varying from 22.4% of the animals in the nursery phase to 1.3% of the animals at slaughter. Conversely, SIV circulated in most herds, with 29 seropositive herds without vaccination. The occurrence of anti-SIV antibodies was higher at slaughter (74.5% of the animals) than nursery (41.8% of the animals), and at slaughter, 23 herds (76.7%) presented at least 50.0% of seropositive animals. All herds presented animals with pulmonary Mycoplasma-like lung lesions, and of the 900 lungs evaluated in the slaughterhouse, 665 (73.9%) presented an average Mycoplasma-like lung lesions of 7.3%. Evaluations of the pneumonia index (PI) showed that 73.3% of the herds were strongly affected by a pathology that manifested itself in different presentation forms. Microscopically, there was a predominance of bronchopneumonia lesions (74.6% of affected lungs), with a high occurrence of the chronic form (57.1%), and there was a moderate to marked proliferation of bronchial associated lymphoid tissue (BALT) in 64.1% of the affected lungs. Pleuritis were observed in 13.5% of the animals. CONCLUSION: Serological tests evidenced that antibodies against App and SIV were present in the Goiás State herds, and high occurrence of M. hyopneumoniae antibodies in finishing phases and slaughter may be influenced by pathogen circulation in vaccinated herds, leading to respiratory lesions at slaughter. Additionally, swine influenza virus was broadly disseminated in technified herds in Goiás State.