Browsing by Author "Tamene, Wegene"

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    Assessment of Blood Agar Media For the Diagnosis of Tuberculosis
    (Addis Ababa University, 2011-01) Tamene, Wegene; Lemma, Eshetu (PhD); Dagne, Kifle (PhD)
    Diagnosing tuberculosis is a challenge because of the complex nature of the bacteria. Recently, the need for TB culture is growing due to the increasing demand for TB drug susceptibility testing(DST) and due to the high incidence of TB/HIV co-infection, which faces a great deal of misdiagnosis. Even though there are a number of better culture technology systems, most of these technologies are not feasible and affordable for resource limited countries like Ethiopia. Therefore, resource limited countries mainly rely on available solid culture system for Mycobacterium isolation and DST despite the fact, they are time consuming, costly and need stringent media preparation procedure. Thus, this study was aimed to assess the performance of 5% sheep blood agar media for the isolation and DST of M. tuberculosis complex. Blood agar is simple to prepare, readily available, and cheap media. 107 clinical specimens were collected from patients referred to EHNRI for TB culture. Specimens were liquefied and decontaminated by N-acetyl L- cysteine sodium hydroxide method and cultured on Lowenstein-Jensen media, blood agar media and BACTEC MGIT 960 system. Species identification was done using Capilla TB-Neo (TAUNS Laboratories Inc, Numazu, Japan). DST for M. tuberculosis complex isolates were performed using proportion method on LJ and blood agar media. From the total 107 specimens cultured, 2 specimens with persistent contamination were excluded from analysis, and analyses were done with the remaining 105 specimens. The sensitivity, specificity, PPV and NPV of blood agar media was 98, 98.2, 98 and 98.2%, respectively, as compared to LJ media, whereas the sensitivity, specificity, positive predictive value and negative predictive value of blood agar media were 87.2, 100, 100 and 87.2% respectively, when compared to MGIT. Mean time for culture positivity was 9.3, 17.3 and 22.7 days for MGIT, blood agar and LJ media, respectively and the difference was statistically significant (P< 0.0001). On the other hand, concordance between blood agar media and LJ media for DST was, 97.7% for Isonizid, 100% for rifampin, 90.7% for streptomycin and 97.7% for etambutol. The contamination rate was 5.1, 9.7 and 14.8% for blood agar media, LJ media and MGIT, respectively. In conclusion, blood agar media was correlated well with LJ media both for the isolation and drug susceptibility testing of M.TB and it was faster than LJ media. Keywords: Blood agar media, Diagnosis, Drug susceptibility testing, Isolation, Tuberculosis