Mycobacterium porcinum strains isolated from bovine bulk milk: implications for Mycobacterium avium subsp. paratuberculosis detection by PCR and culture.
Vet Microbiol
; 130(3-4): 338-47, 2008 Aug 25.
Article
en En
| MEDLINE
| ID: mdl-18378411
ABSTRACT
In this study, the isolation of 52 mycobactin-independent fast growing mycobacteria from 631 bulk milk samples (8.2%), is reported. These strains, isolated during a bulk milk survey for Mycobacterium avium subsp. paratuberculosis (Map), strongly affected Map detection both by PCR and by culture, as they gave a positive IS900 PCR signal and resulted to totally inhibit the growth of Map when spotted on HEYM slants already inoculated with 200 microl of 10-fold dilutions containing from 5 x 10 to 5 x 10(3)Map cells/ml. 16S rRNA gene sequencing, using the MicroSeq 500 16S rDNA Bacterial Sequencing Kit (Applied Biosystems), was performed on a subset of six strains, identifying Mycobacterium porcinum with 100% homology in all six cases. The 52 strains were characterized by PCR-restriction fragment length polymorphism (RFLP) analysis of the hsp65 gene, which confirmed the identification of M. porcinum for all the isolates. Using specific primers designed on the Map-IS900 sequence and on the M. porcinum sequence determined in this study, a 1385bp sequence from the M. porcinum genome was characterized. This IS900-like sequence showed 82% homology with Map IS900. From our findings the following results emerged (a) any culture showing one or more M. porcinum colonies represents a potential "false negative" result and should therefore be considered as contaminated; (b) IS900-like elements could be more widespread than was previously thought; (c) IS900 PCR positive results should be interpreted cautiously, as confirmed by the evidence that the primer pair used in this study resulted not to be specific.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Reacción en Cadena de la Polimerasa
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Técnicas Bacteriológicas
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Mycobacterium avium subsp. paratuberculosis
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Leche
Tipo de estudio:
Diagnostic_studies
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Prognostic_studies
Límite:
Animals
Idioma:
En
Revista:
Vet Microbiol
Año:
2008
Tipo del documento:
Article
País de afiliación:
Italia