Mycobacterium avium sp. avium (MAA), M. avium sp. hominissuis (MAH), and M. avium sp. paratuberculosis (MAP) are the main members of the M. avium complex (MAC) causing diseases in several hosts. The aim of this study was to describe the genetic diversity of MAC isolated from different hosts. Twenty-six MAH and 61 MAP isolates were recovered from humans and cattle, respectively. GenoType CM® and IS1311-PCR were used to identify Mycobacterium species. The IS901-PCR was used to differentiate between MAH and MAA, while IS900-PCR was used to identify MAP. Genotyping was performed using a mycobacterial interspersed repetitive-unit-variable-number tandem-repeat (MIRU-VNTR) scheme (loci: 292, X3, 25, 47, 3, 7, 10, 32) and patterns (INMV) were assigned according to the MAC-INMV database (http://mac-inmv.tours.inra.fr/). Twenty-two (22/26, 84·6%) MAH isolates were genotyped and 16 were grouped into the following, INMV 92, INMV 121, INMV 97, INMV 103, INMV 50, and INMV 40. The loci X3 and 25 showed the largest diversity (D: 0·5844), and the global discriminatory index (Hunter and Gaston discriminatory index, HGDI) was 0·9300. MAP (100%) isolates were grouped into INMV 1, INMV 2, INMV 11, INMV 8, and INMV 5. The HGDI was 0·6984 and loci 292 and 7 had the largest D (0·6980 and 0·5050). MAH presented a higher D when compared with MAP. The MIRU-VNTR was a useful tool to describe the genetic diversity of both MAH and MAP as well as to identify six new MAH patterns that were conveniently reported to the MAC-INMV database. It was also demonstrated that, in the geographical region studied, human MAC cases were produced by MAH as there was no MAA found among the human clinical samples.

Multiple-locus variable number-tandem repeat analysis (MLVA) of Mycobacterium avium subspecies paratuberculosis (MAP) isolates may contribute to the knowledge of strain diversity in Argentina. Although the diversity of MAP has been previously investigated in Argentina using IS900-RFLP, a small number of isolates were employed, and a low discriminative power was reached. The aim of the present study was to test the genetic diversity among MAP isolates using an MLVA approach based on 8 repetitive loci. We studied 97 isolates from cattle, goat and sheep and could describe 7 different patterns: INMV1, INMV2, INMV11, INMV13, INMV16, INMV33 and one incomplete pattern. INMV1 and INMV2 were the most frequent patterns, grouping 76.3% of the isolates. We were also able to demonstrate the coexistence of genotypes in herds and co-infection at the organism level. This study shows that all the patterns described are common to those described in Europe, suggesting an epidemiological link between the continents.

We here identified for the first time the presence of Mycobacterium avium paratuberculosis (MAP) sheep (S) strain in Argentina. IS900 polymerase chain reaction (PCR) was positive. The S strain was compared with MAP cattle (C) strains by using IS1311 PCR-restriction endonuclease analysis (PCR-REA), multiplex PCR and restriction fragment length polymorphism (RFLP) analysis.

Bovine paratuberculosis (PTB) is caused by Mycobacterium avium subsp. paratuberculosis (MAP). The optimization of detection tests specific for MAP is crucial to improve PTB control. In this work, we aimed to develop and validate a diagnostic tool based on an ELISA to specifically detect anti-MAP antibodies from bovine serum samples. For that purpose, we designed a recombinant polyprotein containing four specific antigens from MAP and optimized the ELISA. The validation consisted of the assessment of 10 sera from PTB-infected and healthy bovines with different OD values. The diagnostic performance of the polyprotein-ELISA was evaluated by testing 130 bovine serum samples (47 healthy, 48 MAP-infected, and 35 M. bovis-infected bovines). The ELISA using the polyprotein yielded an area under the ROC curve (AUC) of 0.9912 (95% CI, 0.9758–1.007; P  < 0.0001). Moreover, for this ELISA, the cut-off selected from the ROC curve based on the point with a sensitivity of 95.56% (95% CI, 0.8485–0.9946) and specificity of 97.92 (95% CI, 0.8893–0.9995) was 0.3328. Similar results were obtained with an ELISA using the commercial Paratuberculosis Protoplasmatic Antigen (PPA). However, the ELISA with the polyprotein antigen showed a better performance against sera from animals infected with Mycobacterium bovis compared to the ELISA with PPA: lower cross-reactivity (2.85% versus 25.71%). These results demonstrate a very low cross-reactivity of the polyprotein with antibodies present in serum samples from animals infected with M. bovis. The designed polyprotein and the validated ELISA could be very useful for the specific identification of MAP-infected animals in herds.

Infectious abortions of goats in Argentina are mainly associated with brucellosis and toxoplasmosis. In this paper, we describe an abortion outbreak in goats caused by Chlamydia abortus . Seventy out of 400 goats aborted. Placental smears stained with modified Ziehl‐Neelsen stain showed many chlamydia‐like bodies within trophoblasts. One stillborn fetus was necropsied and the placenta was examined. No gross lesions were seen in the fetus, but the inter‐cotyledonary areas of the placenta were thickened and covered by fibrino‐suppurative exudate. The most consistent microscopic finding was found in the placenta and consisted of fibrinoid necrotic vasculitis, with mixed inflammatory infiltration in the tunica media. Immunohistochemistry of the placenta was positive for Chlamydia spp. The results of polymerase chain reaction targeting 23S rRNA gene performed on placenta were positive for Chlamydia spp. An analysis of 417 amplified nucleotide sequences revealed 99% identity to those of C. abortus pm225 (GenBank AJ 005617) and pm112 (GenBank AJ 005613) isolates. To the best of our knowledge, this is the first report of abortion associated with C. abortus in Argentina.

La paratuberculosis es una enfermedad crónica producida por un bacilo ácidoalcohol resistente (BAAR), el Mycobacterium avium subsp. paratuberculosis (Map). No existe tratamiento ni vacuna aprobada por SENASA para esta enfermedad, por lo que es imprescindible el diagnóstico de los animales positivos para controlar la enfermedad antes de que infecten a otros. Se probó la implementación de un medio de cultivo líquido para el diagnóstico de paratuberculosis en bovinos, modificado a partir del medio Middlebrook M7H9 caldo. Para probar la efectividad del medio se realizó la siembra pareada de muestras de materia fecal y tejidos animales en el medio de cultivo sólido de Herrold con micobactina (HEYM) y en el medio de cultivo líquido modificado a partir del M7H9 caldo. Además, se lograron comparar el tiempo de detección de colonias en el medio sólido con el de detección de BAAR formando grupos en el medio de cultivo líquido en estudio. Se corroboró que hay diferencias significativas entre el medio de cultivo líquido y el medio HEYM, tanto en el tiempo de detección como en la cantidad de muestras positivas detectadas, observando BAAR en el medio líquido o colonias bacterianas en el medio HEYM. Sobre la base de estos resultados se concluye que el medio líquido probado posee una mayor sensibilidad analítica y un tiempo de detección del crecimiento menor con respecto a los del medio HEYM.

RESUMENEl presente trabajo analiza las asociaciones observadas entre las densidades ópticas de las muestras de sueros analizados por la técnica de ELISA indirecto para el diagnóstico de paratuberculosis bovina, con el denominado índice urea, el cual se obtiene de comparar las densidades ópticas de sueros expuestos y no expuestos a dicha sustancia. Se analizaron 592 muestras de sueros de tres establecimientos ganaderos, dos dedicados a la producción de carne y uno de leche, ubicados en la Provincia de Buenos Aires, Argentina. En todos los casos se halló correlación positiva entre las variables. Se discute el uso del índice urea como mejorador de la especificidad del ELISA convencional.

Se presentan los resultados obtenidos en 17.747 sueros analizados para el diagnóstico serológico de paratuberculosis bovina, provenientes de 85 rodeos de cría y 5 de leche, ubicados en 14 partidos de la provincia de Buenos Aires. La prueba de ELISA permite diagnosticar esta enfermedad en estadio subclínico, y la incorporación de urea mejora la eficiencia para detectar los anticuerpos específicos contra el Mycobacterium avium subsp. paratuberculosis (MAP). Se estimó la seroprevalencia sobre la base de los resultados obtenidos de animales caracterizados como positivos y sospechosos en la prueba de ELISA urea. Se observó una seroprevalencia individual del 5,5 % en los rodeos de cría y del 13,6 % en los rodeos lecheros, siendo la seroprevalencia predial del 78,8 %. De 425 muestras de heces cultivadas se aisló MAP en el 67,6 % de los animales positivos, del 52,7 % de los sospechosos y del 7 % de los negativos por la prueba de ELISA urea. Mediante estadística bayesiana, el valor predictivo positivo de esta prueba fue de 0,61 y el valor predictivo negativo de 0,93. Nuestros resultados aportan información actualizada sobre la estimación de la seroprevalencia regional de paratuberculosis bovina, la cual es elevada, y confirma la utilidad de la prueba de ELISA urea, desarrollada localmente, en el diagnóstico y control de la enfermedad.