الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
 |  | from | 94 |  |  |
| | | from | 94 | | |
Abstract
TB is a public health problem in the developing world. It remains a main threat to mankind, ranking at the 8 th position of all causes of deaths in low-income countries. (185)
Despite many advances in its diagnosis and treatment, the problem of tuberculosis is on its rise. Deaths from TB comprise 25% of all avoidable deaths in developing countries. Nearly 95% of all tuberculosis cases and 98% of deaths due to TB are in the developing countries and 75% of tuberculosis cases are in the economically productive age group. (72)
The most effective control measure for the spread of TB is to detect it early and to treat it optimally at the earliest. (157) However, its diagnosis remains an enigma. Although AFB microscopy, and conventional LJM culture are the cornerstone of the diagnosis of TB, these traditional bacteriological methods are either slow or their sensitivity is quite low, especially with clinical samples that contain small number of organisms. This can affect treatment by either delaying it or causing inappropriate empiric therapy for TB to subjects without mycobacterial infections or with atypical mycobacteria. (174) Thus rapid detection and identification of M. tuberculosis is essential both for medical and epidemiological purposes. Under these circumstances, there is a need of a culture method that is reliable and has a short turnaround time. (157)
Among the newly developed culture methods is the BLM which is claimed to be rapid, highly sensitive, specific and does not need any sophisticated instruments in detection of M. tuberculosis. The present study aimed to:
3. To isolate M. tuberculosis on a novel BLM and LJM.
4. To compare between the novel BLM and the conventional LJM as regards:
a. Recovery time.
b. Results in both smear positive and smear negative samples.
c. Contamination.
The current study was carried out on clinically suspected patients at El-Maamorah Chest Hospital during 4 months period from August 2014 to November 2014. This study included:
One hundred and fourteen clinically suspected PTB patients. A full questionnaire was filled for each patient after obtaining their consents.
One early morning sputum sample, spontaneously produced, was obtained from each patient, divided into two portions; one was subjected to ZN staining and the other was digested, decontaminated, centrifuged then further divided into three portions to be inoculated on LJM, LJM with PNB and BLM.
Summary and Conclusion
63
The results of BLM were compared with those of LJM to assess the sensitivities, specificities, and predictive values of both culture media. The results of this study showed that:
1. Out of 37 smear positive sputum samples, only 21were positive on LJM but BLM grew all of them.
2. Out of 77 smear negative sputum samples, only 3 grew on LJM and 9 grew on BLM.
3. BLM and LJM were positive in 23 samples, and both were negative in 67 samples.
4. BLM was positive in 22 samples that were negative on LJM. None of the samples yielded on LJM alone.
5. The highest sensitivity was that of BLM (100%), while LJM showed sensitivity of 55.55%.
6. LJM showed the highest specificity of (90.05%), while BLM specificity was 88.16%.
7. The overall test accuracy in BLM (91.97%) was higher than that of LJM (83.03%).
8. The proportions of specific agreement were higher in BLM (93.05%), (96.79%) than in LJM (88.50%), (67.79%) for negative and positive agreements respectively.
9. The performance of BLM in discriminating between smear positive and smear negative samples was statistically better than that of LJM.
10. The mean time for detection of M. tuberculosis on BLM (5.54 ± 4.95 days) was statistically shorter than that of LJM (21.86±11.56 days).
11. The maximum isolation of M. tuberculosis on BLM was during the first 3 to 6 days (44.44% for smear positive samples, 4.44% for smear negative samples). While LJM showed its maximum isolation (65.22% for smear positive samples, 13.04% for smear negative samples) in the period from 15th day till the last day of incubation.
12. Out of 46 BLM positive cultures, 15 (32.60%) showed colour change only, 10 (21.80%) showed surface colonies, and 21 (45.60%) showed embedded colonies.
13. One of smear positive samples proved to be MOTT on both LJM and BLM.
14. There was only one case of contamination on each of the studied media, which was smear negative.
Summary and Conclusion
64
It was concluded from the study that:
1. When adopting ZN staining results as reference standard, BLM is more sensitive than LJM in diagnosing M. tuberculosis but LJM is more specific.
2. BLM is better than LJM in diagnosing both positive and negative smears.
3. BLM is more rapid in detecting the presence of M. tuberculosis, but it is cumbersome, needs high accuracy and to be freshly prepared.
4. Colonies of BLM are not always easy obtained for staining