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 rfb(O157)/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, stx(2e)/estI, stx(2e)/estI/estII, and stx(2e)/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.

[Genotypic characterization of toxigenic Escherichia coli isolated from pigs with postweaning diarrhea (PWD) and edema disease (ED)]. / Caracterización genotípica de aislamientos de Escherichia coli obtenidos de cerdos con diarrea posdestete y enfermedad de los edemas.

The purpose of this work was to characterize 47 Escherichia coli strains isolated from 32 pigs diagnosed with postweaning diarrhea and three 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.

Outbreak of swine influenza in Argentina reveals a non-contemporary human H3N2 virus highly transmissible among pigs.

Sporadic outbreaks of human H3N2 influenza A virus (IAV) infections in swine populations have been reported in Asia, Europe and North America since 1970. In South America, serological surveys in pigs indicate that IAVs of the H3 and H1 subtypes are currently in circulation; however, neither virus isolation nor characterization has been reported. In November 2008, an outbreak of respiratory disease in pigs consistent with swine influenza virus (SIV) infection was detected in Argentina. The current study describes the clinical epidemiology, pathology, and molecular and biological characteristics of the virus. Phylogenetic analysis revealed that the virus isolate shared nucleotide identities of 96-98 % with H3N2 IAVs that circulated in humans from 2000 to 2003. Antigenically, sera from experimentally inoculated animals cross-reacted mainly with non-contemporary human-origin H3N2 influenza viruses. In an experimental infection in a commercial swine breed, the virus was of low virulence but was transmitted efficiently to contact pigs and caused severe disease when an infected animal acquired a secondary bacterial infection. This is the first report of a wholly human H3N2 IAV associated with clinical disease in pigs in South America. These studies highlight the importance of two-way transmission of IAVs and SIVs between pigs and humans, and call for enhanced influenza surveillance in the pig population worldwide.

First detection and genetic characterization of porcine circovirus type 3 (PCV3) in Argentina and its association with reproductive failure.

Porcine circovirus type 3 (PCV3) is considered a new circovirus and since it first description has been widely reported in most of the swine-producing countries. Multisystemic inflammation and reproductive failure are consistent and concerning issues associated with PCV3 infection. This report describes the clinical and pathological features of a chronic reproductive disorder in a swine herd in Argentina associated with the presence of PCV3. Mummified (n = 42) and stillborn piglets (n = 20) from a case of chronic reproductive disorder (Study A) and mummified and stillborn piglets (n = 141) from normal deliveries (Study B) were retrospectively assessed for the presence of multiple reproductive pathogens (PCV3, PCV2, ADV, PPV, Leptospira spp. and Brucella spp). On study, A PCV3 and PPV were detected in 15 and 8 pools, respectively, with a coinfection rate of 100% in all PPV-positive cases. Three out of 131 foetuses from three different sows from Study B were positive only for PCV3. Histological evaluation of hearts from stillborn also showed lesions similar to those previously described in the literature for PCV3-reproductive disease. Partial genome of PCV3 was amplified and phylogenetic analysis showed that strains of Study A and B clustered within the PCV3a and PCV3b clades, respectively. This study demonstrates, for the first time, the PCV3 has been circulating in Argentina at least since 2016 and its potential role in reproductive disorders. Further studies are warranted to determine the role of PCV3 in the reproductive disease complex and its prevalence in the swine industry in Argentina.

Pandemic (H1N1) 2009 outbreak on pig farm, Argentina.

In June-July 2009, an outbreak of pandemic (H1N1) 2009 infection occurred on a pig farm in Argentina. Molecular analysis indicated that the virus was genetically related to the pandemic (H1N1) 2009 influenza virus strain. The outbreak presumably resulted from direct human-to-pig transmission.

Salmonella enterica subclinical infection: bacteriological, serological, pulsed-field gel electrophoresis, and antimicrobial resistance profiles--longitudinal study in a three-site farrow-to-finish farm.

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((R)) 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.

Hemagglutinating encephalomyelitis coronavirus infection in pigs, Argentina.

We describe an outbreak of vomiting, wasting, and encephalomyelitis syndrome in piglets in Argentina, caused by porcine hemagglutinating encephalomyelitis coronavirus (PHE-CoV) infection. Diagnosis was made by epidemiologic factors, pathologic features, immunohistochemistry, reverse transcription-PCR, and genomic sequencing. This study documents PHE-CoV infection in South America.

Seroprevalence of Toxoplasma gondii in sows from slaughterhouses and in pigs from an indoor and an outdoor farm in Argentina.

The objective of the present study was to determine the prevalence of Toxoplasma gondii antibodies from slaughter sows and from pigs raised at an indoor and an outdoor swine farm. Serum samples were obtained from 230 slaughter sows belonging to 83 farms distributed in 5 provinces. Blood samples were collected monthly from pigs of different ages from an intensive management indoor farm (farm 1). A cross-sectional study was carried-out from an outdoor farm (farm 2). All sera were tested for T. gondii antibodies by the modified agglutination test (MAT), using formalin-fixed tachyzoites as antigen. An antibody titer > or =1:25 was considered positive. Antibodies to T. gondii were detected in 87 (37.8%) of 230 sows sera. Distribution among provinces was: 37.1% from Santa Fe, 62.8% from Buenos Aires, 3.3% from San Luis, 58.7% from La Pampa and 24% from Córdoba. Four of 88 (4.5%) serum samples from farm 1 had antibodies to T. gondii and none of the negative pigs seroconverted. However, 45 of 112 samples from farm 2 were positive (40.2%) with the following distribution: sows 100%; nursery 40%; growers 13.8% and fatteners 20%. It is concluded that the prevalence of T.gondii antibodies among sows seems to be quite variable. T. gondii prevalence was related to the facilities and management of the farm.

Caracterización genotipica de aislamientos de Escherichia coli obtenidos de cerdos con diarrea posdestete y enfermedad de los edemas / 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 Escheríchia 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 estl/estlI/fedA. El genotipo más complejo fue eltA/estll/east1/faeG/aidA. Los aislamientos provenientes de cerdos con ED se clasificaron como STEC porcinos y fueron portadores de stxJaidA. 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 la Argentina.(AU)

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/estll/fedA genes. The most complex genotype was eltA/estl/faeG/aidA. Strains isolated from pigs with ED were classified as porcine STEC and were stxjaidA carriers. Eleven (25 %) strains carried the gene encoding adhesln 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.(AU)

Caracterización genotipica de aislamientos de Escherichia coli obtenidos de cerdos con diarrea posdestete y enfermedad de los edemas / 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 Escheríchia 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 estl/estlI/fedA. El genotipo más complejo fue eltA/estll/east1/faeG/aidA. Los aislamientos provenientes de cerdos con ED se clasificaron como STEC porcinos y fueron portadores de stxJaidA. 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 la 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/estll/fedA genes. The most complex genotype was eltA/estl/faeG/aidA. Strains isolated from pigs with ED were classified as porcine STEC and were stxjaidA carriers. Eleven (25 %) strains carried the gene encoding adhesln 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.

Fibrinonecrotic enteritis of piglets in a commercial farm: a postmortem study of the prevalence and the role of lesion associated agents Isospora suis and Clostridium perfringens

The objectives were to determine the prevalence of fibrinonecrotic enteritis (FNE) on a farrow-to-finish farm of 1,000 sows, to categorize the pathological changes, and to to investigate the lesion associated agents Isospora suis and Clostridium perfringens. Causes of preweaning mortality (PWM) were classified into 8 categories including FNE. Obtained data were evaluated for statistical significance by adjusted Chi-square analysis. Samples of FNE were taken for complementary studies including a PCR technique for genotyping toxin genes of Clostridium perfringens from gut samples fixed in 10 percent neutral formalin. From 3,153 piglets examined, less than 1 percent was classified as FNE. FNE prevalence increased progressively from the first to the third week, the last differing statistically from the others. Eighty percent of gut samples with FNE lesions were positive to Isospora suis, when examined by PCR from 9 severe FNE lesions detected 7 positive samples only for a toxin gene, characteristic of C. perfringens type-A.

Os objetivos deste trabalho foram determinar a prevalência de enterite fibrinonecrótica (EFN) em uma granja tecnificada com 1000 matrizes, classificar as mudanças patológicas e investigar a lesão decorrente da associação dos agentes Clostri-dium perfringens e Isospora suis. As lesões macroscópicas devidas à mortalidade pré-desmame (MPD) foram classificadas em oito categorias incluindo EFN. Os dados obtidos foram avaliados pelo teste Qui-quadrado. Amostras de EFN foram colhidas para estudos complementares incluindo uma técnica de reação em cadeia da polimerase (PCR) para identificação dos genes codificadores de toxinas de C. perfringens a partir de amostras do intestino fixadas em formalina a 10 por cento. Dos 3.153 leitões examinados, menos que 1 por cento foram classificados como EFN. As análises estatísticas revelaram que a EFN aumentou progressivamente a partir da primeira para a terceira semana, sendo que a última semana diferiu estatisticamente das demais. Oitenta porcento das amostras do intestino com EFN foram positivas para I. suis. Por meio da PCR a partir dos 9 casos de EFN severa, 7 foram positivos somente para o gene da toxina alfa, característico de C. perfringens tipo A.

Mycoplasma suis in naturally infected pigs: an ultrastructural and morphometric study

A eperitrozoonose suína é uma doença hemotrópica causada por Eperitrozoon suis, atualmente denominado Mycoplasma suis, uma bactéria extracelular que, aparentemente, adere à membrana dos eritrócitos suínos, induzindo sua deformação e lesionando-os. O presente trabalho busca estabelecer os aspectos estruturais e ultra-estruturais, pouco conhecidos, deste microorganismo. O estudo ultra-estrutural revelou a presença de estruturas correspondentes a túbulos disseminados no soma bacteriano. Observou-se também uma separação variável entre a membrana do microorganismo e a parede do eritrócito. O estudo morfométrico e a localização de M. suis pode permitir especulação sobre seu mecanismo de ação.