الفهرس 
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Abstract
Egypt is one of the developing countries that suffers from chronic infectious diseases such as bovine tuberculosis, and constitutes a risk for public health. Tuberc ulin test detects TB infections, but it does not differentiate infection from diseased animals. Consequently, the present
study showed the following :
from 225 cross-breed dairy cattle tested by single intradermal cervical tuberculin test, using human PPD, 66 animals (29.3 %) gave positive reactors. The post mortem examination carried out on 60 animals showed that 44 animals (73.4 %) have visible lesions while the other 16 animals (26.6 %) failed to show any visible lesions.
Out of 190 buffaloes, 17 (8.9 %) gave positive reactors. The post mortem examination of the 16 slaughtered animals, showed that 5 (31.2 %) have visible lesions and 11 (68.7 %) failed to show any
visible lesions.
The bacteriological examination of the positive reactors cleared that. 45 out of 60 cattle and 7 out of 16 buffaloes gave positive isolation.
Biochemical typing of mycobacterial isolates in cattle revealed that 33 (55 %) M. bovis and 12 (20 %) atypical mycobacteria. The 12 atypical mycobacteria identified as : 3 M. scrofulaceum, 2 M. intracellulare, 1 M. fortuitum, 1 M. plisli, 2 M. gordonae and unidentified rapid grower ”one non chromogenic and 2 chromogenic”). While, in buffaloes, the isolates identified as 2 (12.5%) M. bovis and 5 (31.2 %) atypical mycobacteria.
In cattle, the 33 isolated M. bovis were 31 from visible lesions and 2
from non visible lesion. The 12 atypical mycobacteria were 4 from
tuberculous lesions (extrapulmonary) and 8 from NVL reactors.
•In buffaloes, 2 M. bovis were isolated from pulmonary lesion
infection, and 5 atypical mycobacteria were isolated as following, 3 isolated from extrapulmonary and 2 isolates from non visible lesions.
•The results of radiometric method for isolation of mycobacteria from
slaughtered tuberculin reactor animals, by using improved BACTEC TB system and BACTEC NAP differentiation test on 25 animals (9 animals with visible lesions and 16 animals with non visible lesions) 20 animals (80%) give positive cultures. The 20 isolates identified as 8 mycobacteria tuberculosis complex (88.8 %) out of 9 animals showing visible lesions, 4 (25%) mycobacteria tuberculosis complex and 8 (50 %) atypical from 16 animals with non visible lesion. At the same time, the average time for isolation of mycobacteria tuberculosis complex were 14 days and 7.5 days for isolation of atypical mycobacteria. On the other hand, by using conventional culture method for isolation of the same samples, only 16 (64 %) gave positive result. These isolates identified as 6 (66.9%) from visible lesions and 2 (12.5 %) TB complex and 8 (50 %) atypical from 16 non visible lesions with the average time for detection: 0 days for mycobacteria tuberculosis complex and 23.5 days or detection of atypical mycobacteria.
•The results of ELISA on sera of tuberculin reactor cattle in field for evaluation of unheated tuberculin and heated tuberculin showed that the sensitivity was 88.6 % and 79.5 %, the specificity was 81.3 % and 68.8 %, the positive predictive value was 92.8 %, 87.5 %. The negative predictive value was 72.2 % and 55 % and the accuracy index was 86.7%, 76.7% , respectively.
•The results of tuberculin test for evaluation of unheated and heated tuberculin on Guinea pigs infected with M. bovis and differents atypical mycobacteria showed that no significant difference between heated and unheated tuberculin for identification of acid fast bacilli on the basis of sensitin specificity. But, the unheated tuberculin gave more specific reaction by using ELISA test on the sera of the same previously infected Guinea pigs for differentiation of infection with M. bovis and atypical mycobacteria.
•The results of positive gelification time of gluteraldehyde test which carried out on blood from tuberculin reaction cattle was (70 %) and 8.5 % in tuberculin negative cattle, while 12.5 % in tuberculin negative animal and positive brucella test at the same time.
The results of the relation between the positive gelification time of gluteraldehyde test and post mortem finding on tuberculin reactor cattle was found to be 100 % in generalized infection, pulmonary infection and mixed infection. But in extrapulmonary infection, the positive gelification time of gluteraldehyde test was found to be 50%, while in non visible lesion infected animals was 20%. Therefore, the sensitivity of gluteraldehyde test was found to be 86.6 % in tuberculin reactor animals.
•The result of positive gelification time of gluteraldehyde test in experimentally infected Guinea pigs with typical mycobacteria (M. bovis) was 100 % and 25 % in different atypical mycobacteria infected groups.
•The results of susceptibility test of M. bovis to specific anti-tuberculosis antibiotics by proportional method as following : 60 % to isoniazide 65 % to streptomycin, 80 % to ethambutol, 75 % to rifampin, lastly 80 % to thiacetazone.
•The results of susceptibility test of atypical mycobacteria to specific anti-tuberculosis antibiotics as following 0 %, 12.5 %, 31.5 %, 43.7% and 50 % to isoniazide, streptomycin, ethambutol, rifampin and thiacetazone, respectively.
•The susceptibility test of atypical mycobacteria to non specific antibiotics and sulphonamides showed that the M. scrofulaceum was susceptible to Amikacin, Tetracycline and Spiramycin.
•The M. intracellulare was susceptible to Amikacin, Tetracycline and Spiramycin.
The M. gordonae was susceptible to Spiramycin, Amikacin and Tetracycline.
•M. fortuitum was susceptible to Amikacin, Kanamycin, Tetracycline and Spiramycin.
•M. Abeli was susceptible to Amikacin, Erythromycin and Spiramycin. Finally, all atypical isolates were susceptible in moderate degree with sulphamethazole, sulphadimidine and polymixin.
•The results of susceptibility test of improved BACTEC TB system tb specific antituberculosis drug was the same results which obtained by using proportional method. But the results of BACTEC susceptibility take mean average time (5 days) but 30 days by using proportional methods.
from the present study, it can be concluded that :
The incidence of atypical mycobacteria in tuberculin positive cattle increased especially in animals showing the non visible lesions and consider the main cause of non specific reaction to tuberculin test.
The high percentage of buffaloes showing non visible lesions, clearly indicates that there is an urgent need of an interpretation key for tuberculin test in Egyptian buffaloes.
•Heated PPD tuberculin are most suitable for tuberculin test in animals, while unheated tuberculin may be of more benefit on humoral immune response (ELISA test).
The improved BACTEC TB system is a rapid, sensitive and efficient method for the isolation, differentiation and susceptibility testing of mycobacteria in a clinical laboratory.
The gluteraldehyde test is simple rapid, easy to perform, sensitive and specific and its use as screening test or in conjunction with tuberculin test will lead to decrease in false positive cases that may be slaughtered, and at the same time to eliminate the active or heavy infected animals which cause the main source of infection.
Finally, the susceptibility test of mycobacteria showed that the high resistant of atypical mycobacteria to specific anti tuberculosis antibiotics as streptomycin, isoniazid, ethambutol, rifampin, thiacetazone. At the same time, atypical mycobacteria are markedly heterogenous in their susceptibility to other antibiotics and sulphonamides such as amikacin, tetracycline, spiromycin, sulphonamides group. So that, there cannot exist a universal antibodies for the control of mycobacterial infection.
The present study is considered one of the modern studies on the uses of advancing methods for the rapid isolation and identification of typical and atypical mycobacteria as well as consider a better study on the uses of different antibiotics for typical and atypical mycobacteria. So, this study aid in the decrease of such infection among animals and humans.