Genotypic characterization of toxigenic Escherichia coli isolated from pigs with postweaning diarrhea (PWD) and edema disease (ED)

El objetivo del trabajo fue caracterizar mediante PCR 47 aislamientos de Escherichia coli recuperados de 32 cerdos con diagnóstico clínico de diarrea posdestete (DPD) y de 3 cerdos con enfermedad de los edemas (ED). Sobre 44 aislamientos provenientes de cerdos con DPD, 42 (95,5 %) fueron caracterizados como E. coli enterotoxigénicos (ETEC) y 2 (4,5 %) como E. coli productores de toxina Shiga (STEC). Catorce aislamientos de ETEC (33,3 %) fueron positivos para los genes estI/estII/fedA. El genotipo más complejo fue eltA/estII/east1/faeG/aidA. Los aislamientos provenientes de cerdos con ED se clasificaron como STEC porcinos y fueron portadores de stx2e aidA. Once aislamientos (25 %) fueron portadores del gen que codifica la expresión de la adhesina AIDA-I. Sin embargo, en ningún aislamiento se detectaron los genes que codifican la expresión de las adhesinas F5, F6, F41, de intimina y de PAA. La prevención de la DPD y de la ED podría realizarse mediante el desarrollo de vacunas que generen anticuerpos contra las adhesinas de las cepas de E. coli prevalentes en Argentina.The purpose of this work was to characterize 47 Escherichia coli strains isolated from 32 pigs diagnosed with postweaning diarrhea and tree pigs with edema disease by PCR. Forty two (95.5 %) of the strains isolated from diarrheic pigs were characterized as enterotoxigenic E. coli (ETEC) and 2 (4.5 %) as Shiga toxin-producing E. coli (STEC). Fourteen (33.3 %) ETEC strains were positive for est/estII/fedA genes. The most complex genotype was eltA/estI/faeG/aidA. Strains isolated from pigs with ED were classified as porcine STEC and were stx2e/aidA carriers. Eleven (25 %) strains carried the gene encoding adhesin protein AIDA-I. However, genes coding for F5, F6, F41, intimin and Paa were not detected. The development of vaccines generating antibodies against prevalent E. coli adhesins in Argentina could be useful for the prevention of PWD and ED.Fil: Moredo, Fabiana Alicia. Universidad Nacional de La Plata. Facultad de Ciencias Veterinarias; ArgentinaFil: Cappuccio, Javier Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Veterinarias; ArgentinaFil: Insarralde, Lucas. Universidad Nacional de La Plata. Facultad de Ciencias Veterinarias; ArgentinaFil: Perfumo, Carlos Juan. Universidad Nacional de La Plata. Facultad de Ciencias Veterinarias; ArgentinaFil: Quiroga, María A.. Universidad Nacional de La Plata. Facultad de Ciencias Veterinarias; ArgentinaFil: Leotta, Gerardo Anibal. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico CONICET- La Plata. Instituto de Genética Veterinaria "Ing. Fernando Noel Dulout". Universidad Nacional de La Plata. Facultad de Ciencias Veterinarias. Instituto de Genética Veterinaria; Argentin

Wild-type minimal inhibitory concentration distributions in bacteria of animal origin in Argentina

AbstractThe aim of this study was to determine the antimicrobial resistance profiles of indicator bacteria isolated from domestic animal feces. Minimal inhibitory concentration (MIC) was determined by agar dilution. Interpretative criteria on the basis of wild-type MIC distributions and epidemiological cutoff values (ECOFF or ECV) were used according to the ‘European Committee on Antimicrobial Susceptibility Testing’ (EUCAST) data. Results from 237 isolates of Escherichia coli showed reduced susceptibility for ampicillin, streptomycin and tetracycline, the antimicrobials commonly used in intensive breeding of pigs and hens. Regarding all the species of the genus Enterococcus spp., there are only ECOFF or ECV for vancomycin. Of the 173 Enterococcus spp. isolated, only one showed reduced susceptibility to vancomycin and was classified as ‘non-wild-type’ (NWT) population. This is the first report in Argentina showing data of epidemiological cutoff values in animal bacteria

Diarrea en lechones lactantes y posdestete de cuatro criaderos intensivos de la provincia de Buenos Aires, Argentina: identificación e índice de detección de partículas virales en materia fecal por microscopía electrónica

The aim of this pilot study was to identify and to determine the detection rate of viral particles in faecal specimens recovered from suckling and postweaning piglets with diarrhoea from 4 pigherds situated in Buenos Aires Province, Argentina. We used the negative staining for electron microscopy (NSEM) technique, which has been applied for decades because of its simplicity, rapidness and sensitivity. One hundred and forty six samples were collected during one year from suckling (50) and postweaning (96) young pigs. Viral particles were identified in 58% and 53.1% of the suckling and postweaning faecal samples, respectively. Rotavirus-like, coronavirus-like, adenovirus- like, parvovirus-like and small round viruses (SRV) were detected in 32% and 34.4%, 18% and 16.7%, 10% and 9.4%, 4% and 3.1% and, 2% and 1% of suckling and postweaning faecal samples, respectively. Viral combinations were observed in 8% and 10.4% of suckling and postweaning samples, respectively. Rotavirus-like and coronavirus-like particles was the most frequent combination in both categories. The present study identified the presence of several viruses known to be linked to diarrhoea in young pigs. Apart from rotavirus, the detected viruses had never been reported previously in Argentina. The NSEM technique demonstrated to be adequate as a screening test to identify viral particles in faecal specimens. However, more specific tests are needed to confirm the presence of these viruses and also to determine the group or variant of the identified viruses.El presente estudio preliminar tuvo como objetivo identificar y determinar el índice de detección de partículas virales en heces diarreicas de lechones de 4 establecimientos intensivos de la Provincia de Buenos Aires, Argentina, empleando la técnica de tinción negativa en microscopía electrónica (TNME). Esta técnica ha venido empleándose durante décadas por su rapidez, sencillez y sensibilidad. Se estudiaron un total de 146 muestras pertenecientes a lechones lactantes (50) y a lechones posdestete (96), detectándose partículas virales en un 58% y en un 53,1% de las heces, respectivamente. Se identificaron partículas virales compatibles con rotavirus, coronavirus, adenovirus, parvovirus y pequeños virus redondos en 32% y 34,4%, 18% y 16,7%, 10% y 9,4%, 4 y 3,1% y 2 y 1% de las muestras de lechones lactantes y posdestete, respectivamente. Se observaron combinaciones virales en un 8% y en un 10,4% de las muestras, respectivamente. En ambas categorías, la combinación más frecuente fue de partículas compatibles con rotavirus y coronavirus. El presente estudio permitió la identificación de diversos géneros de virus considerados agentes causales de diarrea en lechones y que, a excepción de rotavirus, no habían sido previamente descriptos en nuestro país. La técnica de TNME demuestra ser un método adecuado como prueba tamiz para identificar partículas virales en materia fecal; sin embargo, necesita de otras pruebas de mayor especificidad para confirmar los resultados obtenidos y también para determinar a qué grupo o variante pertenecen los virus identificados

Genotypic characterization of toxigenic Escherichia coli isolated from pigs with postweaning diarrhea (PWD) and edema disease (ED)

El objetivo del trabajo fue caracterizar mediante PCR 47 aislamientos de Escherichia coli recuperados de 32 cerdos con diagnóstico clínico de diarrea posdestete (DPD) y de 3 cerdos con enfermedad de los edemas (ED). Sobre 44 aislamientos provenientes de cerdos con DPD, 42 (95,5 %) fueron caracterizados como E. coli enterotoxigénicos (ETEC) y 2 (4,5 %) como E. coli productores de toxina Shiga (STEC). Catorce aislamientos de ETEC (33,3 %) fueron positivos para los genes estI/estII/fedA. El genotipo más complejo fue eltA/estII/east1/faeG/aidA. Los aislamientos provenientes de cerdos con ED se clasificaron como STEC porcinos y fueron portadores de stx2e aidA. Once aislamientos (25 %) fueron portadores del gen que codifica la expresión de la adhesina AIDA-I. Sin embargo, en ningún aislamiento se detectaron los genes que codifican la expresión de las adhesinas F5, F6, F41, de intimina y de PAA. La prevención de la DPD y de la ED podría realizarse mediante el desarrollo de vacunas que generen anticuerpos contra las adhesinas de las cepas de E. coli prevalentes en Argentina.The purpose of this work was to characterize 47 Escherichia coli strains isolated from 32 pigs diagnosed with postweaning diarrhea and tree pigs with edema disease by PCR. Forty two (95.5 %) of the strains isolated from diarrheic pigs were characterized as enterotoxigenic E. coli (ETEC) and 2 (4.5 %) as Shiga toxin-producing E. coli (STEC). Fourteen (33.3 %) ETEC strains were positive for est/estII/fedA genes. The most complex genotype was eltA/estI/faeG/aidA. Strains isolated from pigs with ED were classified as porcine STEC and were stx2e/aidA carriers. Eleven (25 %) strains carried the gene encoding adhesin protein AIDA-I. However, genes coding for F5, F6, F41, intimin and Paa were not detected. The development of vaccines generating antibodies against prevalent E. coli adhesins in Argentina could be useful for the prevention of PWD and ED.Facultad de Ciencias VeterinariasInstituto de Genética Veterinari

Enterotoxigenic Escherichia Coli subclinical infection in pigs: bacteriological and genotypic characterization and antimicrobial resistance profiles

Enterotoxigenic Escherichia coli (ETEC) is the major pathogen responsible for neonatal diarrhea, postweaning diarrhea, and edema disease in pigs. Although it can be harmless, ETEC is also present in the intestines of other animal species and humans, causing occasional diarrhea outbreaks. The evaluation of this pathogen’s presence in food sources is becoming an increasingly important issue in human health. In order to determine the prevalence of ETEC in nondiarrheic pigs, 990 animals from 11 pig farms were sampled. Using end-time polymerase chain reaction (PCR), eltA, estI genes, or both, were detected in 150 (15.2%) animals. From the positive samples, 40 (26.6%) ETEC strains were isolated, showing 19 antibiotic-resistance patterns; 52.5% of these strains had multiple antibiotic resistances, and 17.5% carried the intI2 gene. The most prevalent genotypes were rfbO157/estII/aidA (32.5%) and estI/estII (25.0%). The estII gene was identified most frequently (97.5%), followed by estI (37.5%), astA (20.0%), and eltA (12.5%). The genes coding the fimbriae F5, F6, and F18 were detected in three single isolates. The aidA gene was detected in 20 ETEC strains associated with the estII gene. Among the isolated ETEC strains, stx2e/estI, stx2e/estI/estII, and stx2e/estI/estII/intI2 genotypes were identified. The ETEC belonged to 12 different serogroups; 37.5% of them belonged to serotype O157:H19. Isolates were grouped by enterobacterial repetitive intergenic consensus–PCR into 5 clusters with 100.0% similarity. In this study, we demonstrated that numerous ETEC genotypes cohabit and circulate in swine populations without clinical manifestation of neonatal diarrhea, postweaning diarrhea, or edema disease in different production stages. The information generated is important not only for diagnostic and epidemiological purposes, but also for understanding the dynamics and ecology of ETEC in pigs in different production stages that can be potentially transmitted to humans from food animals.Fil: Moredo, Fabiana A.. Universidad Nacional de la Plata. Facultad de Cs.veterinarias. Departamento de Microbiologia. Catedra de Microbiologia; ArgentinaFil: Piñeyro Piñeiro, Pablo Enrique. University of Iowa; Estados UnidosFil: Márquez, Gabriela C.. Virginia Polytechnic Institute; Estados UnidosFil: Sanz, Marcelo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tandil. Centro de Investigacion Veterinaria de Tandil; Argentina. Universidad Nacional del Centro de la Provincia de Buenos Aires; ArgentinaFil: Colello, Rocío. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tandil. Centro de Investigacion Veterinaria de Tandil; Argentina. Universidad Nacional del Centro de la Provincia de Buenos Aires; ArgentinaFil: Etcheverría, Analía Inés. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tandil. Centro de Investigacion Veterinaria de Tandil; Argentina. Universidad Nacional del Centro de la Provincia de Buenos Aires; ArgentinaFil: Padola, Nora L.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tandil. Centro de Investigacion Veterinaria de Tandil; Argentina. Universidad Nacional del Centro de la Provincia de Buenos Aires; ArgentinaFil: Quiroga, Maria A.. Universidad Nacional de la Plata. Facultad de Cs.veterinarias. Departamento de Patologia. Laboratorio de Patolog. Espec. Veterinaria "dr. Bernardo Epstein"; ArgentinaFil: Perfumo, Carlos J.. Universidad Nacional de la Plata. Facultad de Cs.veterinarias. Departamento de Patologia. Laboratorio de Patolog. Espec. Veterinaria "dr. Bernardo Epstein"; ArgentinaFil: Galli, Lucía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico La Plata. Instituto de Genética Veterinaria "Ingeniero Fernando Noel Dulout"; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Veterinarias; ArgentinaFil: Leotta, Gerardo Anibal. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico La Plata. Instituto de Genética Veterinaria "Ingeniero Fernando Noel Dulout"; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Veterinarias; Argentin

Diarrhoea in suckling and postweaning piglets from four pigherds situated in Buenos Aires province, Argentina: identification and detection rate of viral particles in faecal samples by electron microscopy

El presente estudio preliminar tuvo como objetivo identificar y determinar el índice de detección de partículas virales en heces diarreicas de lechones de 4 establecimientos intensivos de la Provincia de Buenos Aires, Argentina, empleando la técnica de tinción negativa en microscopía electrónica (TNME). Esta técnica ha venido empleándose durante décadas por su rapidez, sencillez y sensibilidad. Se estudiaron un total de 146 muestras pertenecientes a lechones lactantes (50) y a lechones posdestete (96), detectándose partículas virales en un 58% y en un 53,1% de las heces, respectivamente. Se identificaron partículas virales compatibles con rotavirus, coronavirus, adenovirus, parvovirus y pequeños virus redondos en 32% y 34,4%, 18% y 16,7%, 10% y 9,4%, 4 y 3,1% y 2 y 1% de las muestras de lechones lactantes y posdestete, respectivamente. Se observaron combinaciones virales en un 8% y en un 10,4% de las muestras, respectivamente. En ambas categorías, la combinación más frecuente fue de partículas compatibles con rotavirus y coronavirus. El presente estudio permitió la identificación de diversos géneros de virus considerados agentes causales de diarrea en lechones y que, a excepción de rotavirus, no habían sido previamente descriptos en nuestro país. La técnica de TNME demuestra ser un método adecuado como prueba tamiz para identificar partículas virales en materia fecal; sin embargo, necesita de otras pruebas de mayor especificidad para confirmar los resultados obtenidos y también para determinar a qué grupo o variante pertenecen los virus identificados.The aim of this pilot study was to identify and to determine the detection rate of viral particles in faecal specimens recovered from suckling and postweaning piglets with diarrhoea from 4 pigherds situated in Buenos Aires Province, Argentina. We used the negative staining for electron microscopy (NSEM) technique, which has been applied for decades because of its simplicity, rapidness and sensitivity. One hundred and forty six samples were collected during one year from suckling (50) and postweaning (96) young pigs. Viral particles were identified in 58% and 53.1% of the suckling and postweaning faecal samples, respectively. Rotavirus-like, coronavirus-like, adenovirus- like, parvovirus-like and small round viruses (SRV) were detected in 32% and 34.4%, 18% and 16.7%, 10% and 9.4%, 4% and 3.1% and, 2% and 1% of suckling and postweaning faecal samples, respectively. Viral combinations were observed in 8% and 10.4% of suckling and postweaning samples, respectively. Rotavirus-like and coronavirus-like particles was the most frequent combination in both categories. The present study identified the presence of several viruses known to be linked to diarrhoea in young pigs. Apart from rotavirus, the detected viruses had never been reported previously in Argentina. The NSEM technique demonstrated to be adequate as a screening test to identify viral particles in faecal specimens. However, more specific tests are needed to confirm the presence of these viruses and also to determine the group or variant of the identified viruses.Facultad de Ciencias Veterinaria

Diarrhoea in suckling and postweaning piglets from four pigherds situated in Buenos Aires province, Argentina: identification and detection rate of viral particles in faecal samples by electron microscopy

El presente estudio preliminar tuvo como objetivo identificar y determinar el índice de detección de partículas virales en heces diarreicas de lechones de 4 establecimientos intensivos de la Provincia de Buenos Aires, Argentina, empleando la técnica de tinción negativa en microscopía electrónica (TNME). Esta técnica ha venido empleándose durante décadas por su rapidez, sencillez y sensibilidad. Se estudiaron un total de 146 muestras pertenecientes a lechones lactantes (50) y a lechones posdestete (96), detectándose partículas virales en un 58% y en un 53,1% de las heces, respectivamente. Se identificaron partículas virales compatibles con rotavirus, coronavirus, adenovirus, parvovirus y pequeños virus redondos en 32% y 34,4%, 18% y 16,7%, 10% y 9,4%, 4 y 3,1% y 2 y 1% de las muestras de lechones lactantes y posdestete, respectivamente. Se observaron combinaciones virales en un 8% y en un 10,4% de las muestras, respectivamente. En ambas categorías, la combinación más frecuente fue de partículas compatibles con rotavirus y coronavirus. El presente estudio permitió la identificación de diversos géneros de virus considerados agentes causales de diarrea en lechones y que, a excepción de rotavirus, no habían sido previamente descriptos en nuestro país. La técnica de TNME demuestra ser un método adecuado como prueba tamiz para identificar partículas virales en materia fecal; sin embargo, necesita de otras pruebas de mayor especificidad para confirmar los resultados obtenidos y también para determinar a qué grupo o variante pertenecen los virus identificados.The aim of this pilot study was to identify and to determine the detection rate of viral particles in faecal specimens recovered from suckling and postweaning piglets with diarrhoea from 4 pigherds situated in Buenos Aires Province, Argentina. We used the negative staining for electron microscopy (NSEM) technique, which has been applied for decades because of its simplicity, rapidness and sensitivity. One hundred and forty six samples were collected during one year from suckling (50) and postweaning (96) young pigs. Viral particles were identified in 58% and 53.1% of the suckling and postweaning faecal samples, respectively. Rotavirus-like, coronavirus-like, adenovirus- like, parvovirus-like and small round viruses (SRV) were detected in 32% and 34.4%, 18% and 16.7%, 10% and 9.4%, 4% and 3.1% and, 2% and 1% of suckling and postweaning faecal samples, respectively. Viral combinations were observed in 8% and 10.4% of suckling and postweaning samples, respectively. Rotavirus-like and coronavirus-like particles was the most frequent combination in both categories. The present study identified the presence of several viruses known to be linked to diarrhoea in young pigs. Apart from rotavirus, the detected viruses had never been reported previously in Argentina. The NSEM technique demonstrated to be adequate as a screening test to identify viral particles in faecal specimens. However, more specific tests are needed to confirm the presence of these viruses and also to determine the group or variant of the identified viruses.Facultad de Ciencias Veterinaria

Salmonella enterica Subclinical Infection: Bacteriological, Serological, Pulsed-Field Gel Electrophoresis, and Antimicrobial Resistance Profiles-Longitudinal Study in a Three-Site Farrow-to-Finish Farm

Fil: Vigo, German B. Universidad Nacional de La Plata. Laboratorio de Diagnóstico e Investigaciones Bacteriológicas; Argentina.Fil: Cappuccio, J. A. Universidad Nacional de La Plata. Cátedra de Patología Especial; Argentina.Fil: Pineyro, Pablo E. Universidad Nacional de La Plata. Cátedra de Patología Especial; Argentina.Fil: Salve, Angela. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Departamento de Bacteriología; Argentina.Fil: Machuca, Mariana A. Universidad Nacional de La Plata. Cátedra de Patología Especial; Argentina.Fil: Quiroga, Maria A. Universidad Nacional de La Plata. Cátedra de Patología Especial; Argentina.Fil: Moredo, Fabiana. Universidad Nacional de La Plata. Laboratorio de Diagnóstico e Investigaciones Bacteriológicas; Argentina.Fil: Giacoboni, Gabriel. Universidad Nacional de La Plata. Laboratorio de Diagnóstico e Investigaciones Bacteriológicas; Argentina.Fil: Cancer, Jose L. Private practitioner; Argentina.Fil: Caffer, María Ines. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Departamento de Bacteriología; Argentina.Fil: Binsztein, Norma. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Departamento de Bacteriología; Argentina.Fil: Pichel, Mariana. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Departamento de Bacteriología; Argentina.Fil: Perfumo, Carlos J. Universidad Nacional de La Plata. Cátedra de Patología Especial; Argentina.The aim of this surveillance was to study both Salmonella spp. shedding patterns and the time course of serological response in farrow-to-finish reared pigs from a subclinically infected farm. Antimicrobial resistance profile, molecular subtyping, and the relationship among the isolates were determined by pulsed-field gel electrophoresis (PFGE). A farrow-to-finish farm of 6000 sows, with a history of Salmonella Typhimurium septicemia, was selected. A longitudinal bacteriological and serological study was conducted in 25 sows before farrowing (M=S1) and in 50 offspring at 21 (M=S2), 35 (M=S3), 65 (M=S4), 86 (M=S5), 128 (M=S6), and 165 (M=S7) days of age. Serum antibodies were tested using Herdcheck Swine Salmonella antibody test kit (Idexx Laboratories, ME). Bacteria were isolated from pooled fecal samples. Suspected isolates were confirmed by conventional biochemical assays, and those identified as Salmonella spp. were serotyped. A variation between seropositive percentages and positive fecal samples was observed. Serologically positive pigs decreased from S1 to S4, and subsequently increased from S4 to S7. The percentages of fecal positive culture increased from M1 to M3, and then declined in M4, increased in M5, and were negative in M6 and M7. In the study three serovars, Salmonella 3,10:e,h:-, Salmonella Muenster, and Salmonella Bovismorbificans, were identified with low pathogenicity for swine. Three multidrug resistance strains (one belonged to Salmonella 3,10:e,h:- and two belonged to Salmonella Muenster) were found. PFGE results showed three different but closely related patterns among the 13 isolates of Salmonella Bovismorbificans, and two patterns for the three Salmonella Muenster and Salmonella 3,10:e,h:- isolates. This longitudinal study established critical points of Salmonella spp. infection in the farm and the production stages, where appropriate control measures must be taken. PFGE showed clonal relationships in each serovar. Antibiotic resistance profiles should be periodically included due to public health concerns

Salmonella enterica Subclinical Infection: Bacteriological, Serological, Pulsed-Field Gel Electrophoresis, and Antimicrobial Resistance Profiles-Longitudinal Study in a Three-Site Farrow-to-Finish Farm

Fil: Vigo, German B. Universidad Nacional de La Plata. Laboratorio de Diagnóstico e Investigaciones Bacteriológicas; Argentina.Fil: Cappuccio, J. A. Universidad Nacional de La Plata. Cátedra de Patología Especial; Argentina.Fil: Pineyro, Pablo E. Universidad Nacional de La Plata. Cátedra de Patología Especial; Argentina.Fil: Salve, Angela. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Departamento de Bacteriología; Argentina.Fil: Machuca, Mariana A. Universidad Nacional de La Plata. Cátedra de Patología Especial; Argentina.Fil: Quiroga, Maria A. Universidad Nacional de La Plata. Cátedra de Patología Especial; Argentina.Fil: Moredo, Fabiana. Universidad Nacional de La Plata. Laboratorio de Diagnóstico e Investigaciones Bacteriológicas; Argentina.Fil: Giacoboni, Gabriel. Universidad Nacional de La Plata. Laboratorio de Diagnóstico e Investigaciones Bacteriológicas; Argentina.Fil: Cancer, Jose L. Private practitioner; Argentina.Fil: Caffer, María Ines. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Departamento de Bacteriología; Argentina.Fil: Binsztein, Norma. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Departamento de Bacteriología; Argentina.Fil: Pichel, Mariana. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Departamento de Bacteriología; Argentina.Fil: Perfumo, Carlos J. Universidad Nacional de La Plata. Cátedra de Patología Especial; Argentina.The aim of this surveillance was to study both Salmonella spp. shedding patterns and the time course of serological response in farrow-to-finish reared pigs from a subclinically infected farm. Antimicrobial resistance profile, molecular subtyping, and the relationship among the isolates were determined by pulsed-field gel electrophoresis (PFGE). A farrow-to-finish farm of 6000 sows, with a history of Salmonella Typhimurium septicemia, was selected. A longitudinal bacteriological and serological study was conducted in 25 sows before farrowing (M=S1) and in 50 offspring at 21 (M=S2), 35 (M=S3), 65 (M=S4), 86 (M=S5), 128 (M=S6), and 165 (M=S7) days of age. Serum antibodies were tested using Herdcheck Swine Salmonella antibody test kit (Idexx Laboratories, ME). Bacteria were isolated from pooled fecal samples. Suspected isolates were confirmed by conventional biochemical assays, and those identified as Salmonella spp. were serotyped. A variation between seropositive percentages and positive fecal samples was observed. Serologically positive pigs decreased from S1 to S4, and subsequently increased from S4 to S7. The percentages of fecal positive culture increased from M1 to M3, and then declined in M4, increased in M5, and were negative in M6 and M7. In the study three serovars, Salmonella 3,10:e,h:-, Salmonella Muenster, and Salmonella Bovismorbificans, were identified with low pathogenicity for swine. Three multidrug resistance strains (one belonged to Salmonella 3,10:e,h:- and two belonged to Salmonella Muenster) were found. PFGE results showed three different but closely related patterns among the 13 isolates of Salmonella Bovismorbificans, and two patterns for the three Salmonella Muenster and Salmonella 3,10:e,h:- isolates. This longitudinal study established critical points of Salmonella spp. infection in the farm and the production stages, where appropriate control measures must be taken. PFGE showed clonal relationships in each serovar. Antibiotic resistance profiles should be periodically included due to public health concerns

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 β-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