Reducción de la excreción de Salmonella spp en cerdos antes del sacrificio en matadero

La salmonelosis es una de las enfermedades de transmisión alimentaria de mayor incidencia en los países desarrollados, suponiendo un importante problema para la salud publica. En Europa el ganado porcino se sitúa como la segunda fuente más importante de infección humana, por detrás de las aves y los huevos. El estrés producido en los cerdos antes de llegar al matadero, debido al transporte, cambio de su ambiente habitual y otros factores, favorece una mayor excreción de Salmonella a través de las heces, produciendo así, un problema a nivel higiénico en el matadero. El objetivo es evaluar la posibilidad de reducir la excreción de Salmonella en el matadero mediante la adición de ácidos orgánicos al agua de estos en los corrales de espera. Se utilizarán cerdos procedentes de la misma explotación que al llegar al matadero se separarán en dos corrales de 40 animales cada uno. En uno de los corrales, se les ofrecerá agua tratada con un ácido orgánico (MOLI MC1), en la otra cuadra los cerdos beberán agua sin tratar. Tras una espera de entre 8 a 12 horas, los cerdos serán sacrificados y eviscerados y se recogerán muestras fecales de los 80 animales directamente del intestino grueso. Se analizará la presencia de Salmonella en las heces mediante bacteriología (ISO 6579:2002/Amd 1:2007) y se evaluará si existen diferencias significativas en la proporción de animales excretores entre los dos grupos. Se realizarán un total de 5 réplicas de este estudio

Wild griffon vultures (Gyps fulvus) fed at supplementary feeding stations: Potential carriers of pig pathogens and pig-derived antimicrobial resistance?

The carriage of two important pathogens of pigs, that is enterotoxigenic Escherichia coli (ETEC) and Clostridioides difficile, was investigated in 104 cloacal samples from wild griffon vultures (Gyps fulvus) fed on pig carcasses at supplementary feeding stations (SFS), along with their level of antimicrobial resistance (AMR). E. coli was isolated from 90 (86.5%) samples, but no ETEC was detected, likely because ETEC fimbriae confer the species specificity of the pathogen. Resistance to at least one antimicrobial agent was detected in 89.9% of E. coli isolates, with AMR levels being extremely high (>70%) for tetracycline and streptomycin and very high (>50%) for ampicillin and sulfamethoxazole–trimethoprim. Resistance to other critically important antimicrobials such as colistin and extended-spectrum cephalosporins was 2.2% and 1.1%, respectively, and was encoded by the mcr-1 and blaSHV-12 genes. Multidrug resistance was displayed by 80% of the resistant E. coli, and blaSHV-12 gene shared plasmid with other AMR genes. In general, resistance patterns in E. coli from vultures mirrored those found in pigs. Clostridioides difficile was detected in three samples (2.9%); two of them belonged to PCR ribotype 078 and one to PCR ribotype 126, both commonly found in pigs. All C. difficile isolates were characterized by a moderate-to-high level of resistance to fluoroquinolones and macrolides but susceptible to metronidazole or vancomycin, similar to what is usually found in C. difficile isolates from pigs. Thus, vultures may contribute somewhat to the environmental dissemination of some pig pathogens through their acquisition from pig carcasses and, more importantly, of AMR for antibiotics of critical importance for humans. However, the role of vultures would likely be much lesser than that of disposing pig carcasses at the SFS. The monitoring of AMR, and particularly of colistin-resistant and ESBL-producing E. coli, should be considered in pig farms used as sources of carcasses for SFS

Simultaneous infections by different Salmonella strains in mesenteric lymph nodes of finishing pigs

Background: Salmonellosis is a major worldwide zoonosis, and Salmonella-infected finishing pigs are considered one of the major sources of human infections in developed countries. Baseline studies on salmonellosis prevalence in fattening pigs in Europe are based on direct pathogen isolation from mesenteric lymph nodes (MLN). This procedure is considered the most reliable for diagnosing salmonellosis in apparently healthy pigs. The presence of simultaneous infections by different Salmonella strains in the same animal has never been reported and could have important epidemiological implications. Results: Fourteen finishing pigs belonging to 14 farms that showed high salmonellosis prevalence and a variety of circulating Salmonella strains, were found infected by Salmonella spp, and 7 of them were simultaneously infected with strains of 2 or 3 different serotypes. Typhimurium isolates showing resistance to several antimicrobials and carrying mobile integrons were the most frequently identified in the colonized MLN. Four animals were found infected by Salmonella spp. of a single serotype (Rissen or Derby) but showing 2 or 3 different antimicrobial resistance profiles, without evidence of mobile genetic element exchange in vivo. Conclusion: This is the first report clearly demonstrating that pigs naturally infected by Salmonella may harbour different Salmonella strains simultaneously. This may have implications in the interpretation of results from baseline studies, and also help to better understand human salmonellosis outbreaks and the horizontal transmission of antimicrobial resistance genes.The work was financed by Gobierno de Navarra (project reference IIQ14064.RI1) and INIA (project reference RTA2007-65). Contracts were funded by UPNA (VG postdoctoral contract, and AZB predoctoral fellowship), EMUNDUS18 program (SS) and CSIC in collaboration with the European Social Fund (BSR “Programa JAE-Doc” contract)

Reduction of subclinical Salmonella infection in fattening pigs after dietary supplementation with a ß-galactomannan oligosaccharide

Aims: To assess the efficacy of a b-galactomannan oligosaccharide (ß-GMOS)for the control of Salmonella infection in fattening pigs.Methods and Results: Three different doses (05, 3 and 2 kg ß-GMOS per tonof feed) were used during the entire period of growing in three similar andindependent field trials carried out in a small fattening unit (100 pigs).Treatment was randomly assigned to half of the pens. Individual serumsamples (20–25 per group) were collected at different times during thefattening period and a similar number of faecal samples during the fatteningperiod and at slaughter. In addition, mesenteric lymph nodes were collected atslaughter. HerdcheckâSwine Salmonella ELISA was used for serologicalanalyses, the ISO 6579:2002/Amd 1 : 2007 for bacteriology and the PFGE formolecular characterization of Salmonella strains. The addition of ≥2kgt1ofß-GMOS to the pig diet during the entire fattening period was associated witha reduction in Salmonella prevalence, shedding and seroconversion.Conclusions: Feed supplementation with ß-GMOS may be a usefulcomplementary tool for the control of salmonellosis in fattening pigs.Significance and Impact of the Study: ß-GMOS may be a complementary wayof reducing Salmonella shedding and infection in fattening pigs.This study was partially funded by INIA (ref.RTA2012-24) and Gobierno de Aragón/Fondos FEADER(EU) (ref. DRU-2012-02-22-541-00-IFO-00770020052).Peer reviewe

Sensitivity of the ISO 6579:2002/Amd 1:2007 standard method for detection of Salmonella spp. on mesenteric lymph nodes from slaughter pigs

The ISO 6579:2002/Amd 1:2007 (ISO) standard has been the bacteriological standard method used in the European Union for the detection of Salmonella spp. in pig mesenteric lymph nodes (MLN), but there are no published estimates of the diagnostic sensitivity (Se) of the method in this matrix. Here, the Se of the ISO (SeISO) was estimated on 675 samples selected from two populations with different Salmonella prevalences (14 farms with a ≥20% prevalence and 13 farms with a <20% prevalence) and through the use of latent-class models in concert with Bayesian inference, assuming 100% ISO specificity, and an invA-based PCR as the second diagnostic method. The Se ISO was estimated to be close to 87%, while the sensitivity of the PCR reached up to 83.6% and its specificity was 97.4%. Interestingly, the bacteriological reanalysis of 33 potential false-negative (PCR-positive) samples allowed isolation of 19 (57.5%) new Salmonella strains, improving the overall diagnostic accuracy of the bacteriology. Considering the usual limitations of bacteriology regarding Se, these results support the adequacy of the ISO for the detection of Salmonella spp. from MLN and also that of the PCR-based method as an alternative or complementary (screening) test for the diagnosis of pig salmonellosis, particularly considering the cost and time benefits of the molecular procedure. Copyright © 2013, American Society for Microbiology. All Rights Reserved.This study was funded by the Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA) of Spain (research grants no. RTA2007-65 and FAU2008-16) and the Gobierno de Navarra (project reference IIQ14064.RI1).Peer Reviewe

Biofilms as Promoters of Bacterial Antibiotic Resistance and Tolerance

Multidrug resistant bacteria are a global threat for human and animal health. However, they are only part of the problem of antibiotic failure. Another bacterial strategy that contributes to their capacity to withstand antimicrobials is the formation of biofilms. Biofilms are associations of microorganisms embedded a self-produced extracellular matrix. They create particular environments that confer bacterial tolerance and resistance to antibiotics by different mechanisms that depend upon factors such as biofilm composition, architecture, the stage of biofilm development, and growth conditions. The biofilm structure hinders the penetration of antibiotics and may prevent the accumulation of bactericidal concentrations throughout the entire biofilm. In addition, gradients of dispersion of nutrients and oxygen within the biofilm generate different metabolic states of individual cells and favor the development of antibiotic tolerance and bacterial persistence. Furthermore, antimicrobial resistance may develop within biofilms through a variety of mechanisms. The expression of efflux pumps may be induced in various parts of the biofilm and the mutation frequency is induced, while the presence of extracellular DNA and the close contact between cells favor horizontal gene transfer. A deep understanding of the mechanisms by which biofilms cause tolerance/resistance to antibiotics helps to develop novel strategies to fight these infections

Biofilms as promoters of bacterial antibiotic resistance and tolerance

Multidrug resistant bacteria are a global threat for human and animal health. However, they are only part of the problem of antibiotic failure. Another bacterial strategy that contributes to their capacity to withstand antimicrobials is the formation of biofilms. Biofilms are associations of microorganisms embedded a self-produced extracellular matrix. They create particular environments that confer bacterial tolerance and resistance to antibiotics by different mechanisms that depend upon factors such as biofilm composition, architecture, the stage of biofilm development, and growth condi-tions. The biofilm structure hinders the penetration of antibiotics and may prevent the accumulation of bactericidal concentrations throughout the entire biofilm. In addition, gradients of dispersion of nutrients and oxygen within the biofilm generate different metabolic states of individual cells and favor the development of antibiotic tolerance and bacterial persistence. Furthermore, antimicrobial resistance may develop within biofilms through a variety of mechanisms. The expression of efflux pumps may be induced in various parts of the biofilm and the mutation frequency is induced, while the presence of extracellular DNA and the close contact between cells favor horizontal gene transfer. A deep understanding of the mechanisms by which biofilms cause tolerance/resistance to antibiotics helps to develop novel strategies to fight these infections

Whole-cell and acellular pertussis vaccination programs and rates of pertussis among infants and young children

BACKGROUND: The transition from a whole-cell to a 5-component acellular pertussis vaccine provided a unique opportunity to compare the effect that each type of vaccine had on the incidence of pertussis, under routine conditions, among children less than 10 years of age. METHODS: Analyses were based on passive surveillance data collected between 1995 and 2005. The incidence of pertussis by year and birth cohort was compiled according to age during the surveillance period. We determined the association between vaccine type (whole-cell, acellular or a combination of both) and the incidence of pertussis using Poisson regression analysis after controlling for age (< 1 year, 1–4 years and 5–9 years) and vaccination history (i.e., partial or complete). RESULTS: During 7 of the 11 years surveyed, infants (< 1 year of age) had the highest incidence of pertussis. Among children born after 1997, when acellular vaccines were introduced, the rates of pertussis were highest among infants and preschool children (1–4 years of age). Poisson regression analysis revealed that, in the group given either the whole-cell vaccine or a combination of both vaccines, the incidence of pertussis was lower among infants and preschool children than among school-aged children (5–9 years). The reverse was true in the group given only an acellular vaccine, with a higher incidence among infants and preschool children than among school-aged children. INTERPRETATION: These results suggest that current immunization practices may not be adequate in protecting infants and children less than 5 years of age against pertussis. Altering available acellular formulations or adopting immunization practices used in some European countries may increase the clinical effectiveness of routine pertussis vaccination programs among infants and preschool children

Effect of protected sodium butyrate on Salmonella spp. excretion in a pig fattening unit

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