Isolation of Mycobacterium paratuberculosis from apparently Healthy Sheep and Goats

A total of 260 tissue specimens (from the last portion of the small intestine, ileo-cecal valve and corresponding lymph nodes) were collected from apparently healthy sheep and goats in the slaughter houses. The specimens were prepared and inoculated on Middle Brook 7H10 agar base M199 media with and without mycobactin J. All the specimens were pre-treated with 5% oxalic acid. Direct smears were also prepared from intestinal scrapings and lymph nodes parenchyma and stained with Zeihl Neelsen (acid-fast stain). The cultures were monitored carefully and results were recorded throughout the incubation period, among which 23 (9%) of them showed growth after the 16th week. The culture Results were recorded considering the long incubation period, colony appearance and acid fastness of the bacteria. The direct smear result revealed 55 (21%) positivity. Sensitivity and specificity of the culture method was determined taking histopathological examination as a reference. It is concluded that the conventional culture method is laborious and time consuming for sub clinical paratuberculosis in small ruminants.