A definitive diagnosis of M. bovis infection in animals depends on the isolation of the organism, as the
optimum condition for the primary isolation of M. bovis infection has not been determined. In this study
a total number of 2550 cattle from different governorates in Egypt were tested by Single Intradermal
Cervical (SID) tuberculin skin test. Positive reacted cattle (no= 42, 1.6%) were slaughtered and
suspected lesions were collected, these samples were decontaminated by using three different methods,
which were 0.75 % Hexadecyl Pyridinium Chloride (HPC), 5% oxalic acid and 6 % sulphuric acid.
Isolation of mycobacteria from 42 samples by using these decontaminated methods were of 34 (80.9
%), 30 (71.4 %) and 28 (66.6 %), respectively. So it could be concluded that using HPC method as
decontaminated agent revealed high rate of isolation of mycobacteria with less contamination (7.1 %)
than the other two methods