Comparison of the Lowenstein-Jensen Medium, the Middlebrook 7H10 Medium and MB/BacT for the Isolation of Mycobacterium Tuberculosis (MTB) from Clinical Specimens

Abstract

Introduction: Tuberculosis (TB) is the most common cause of death due to a single infectious agent worldwide in adults. India alone accounts for 30% of the global tuberculosis burden. There is a need for a method of cultivation of mycobacteria that is reliable and economical and has a short turnaround time.Objective: The present study was attempted to assess the feasibility of using MB BACT and Middlebrook 7h10(MB7H10) as primary isolation media for mycobacteria. They were compared with the LJ medium, which was the gold standard. Materials and Methods:Various clinical specimens from a total of 236 clinically suspected cases of TB were studied. All the samples were decontaminated by using the modified Petroff's method. Each sample was subjected to ZN staining and it was simultaneously inoculated onto the LJ medium, the MB7H10 medium and MB BACT. The growth from the cultures were confirmed by ZN staining and they were speciated by using biochemical reactions.Results: Out of the 236 samples which were screened, 116 isolates were obtained. All the 116 were isolated from MB BACT, 82 were isolated from the LJ medium and 62 were isolated from MB7H10. 82 isolates were obtained from MB BACT and the LJ medium, 62 were obtained from MB7H10 and MB BACT, 58 were isolated from LJ and MB7H10 and 58 were isolated from LJ medium, MB7H10 and MB bact. Neither the L J medium nor the Middlebrook 7h 10 medium could isolate mycobacteria exclusively. It showed that the combination of media did not prove to be superior over the use of MB BACT alone. The average isolation time of L J, the MB7H10 medium and MB BACT was 30

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“…Direct smears prepared from of all specimens and Ziehl-Neelsen staining was done. Processing was done by modified Petroff's method 5 . In the case of sterile fluids, the specimen was transferred into a 50 ml sterile conical bottom graduated centrifuge tubes.…”

“…Subculture was done on LJ medium and blood agar from positive bottles. BacT/ALERT MP Bottles were declared negative for AFB after 42 days of incubation and the corresponding LJ slopes after 12 weeks of incubation 5 . MTB was differentiated from Nontuberculosis mycobacterium by the heat stable catalase test.…”

Microscopic Observation Drug Susceptibility (MODS) Assay: A Convenient Method for Determining Antibiogram of Clinical Isolates of Mycobacterium tuberculosis in Ghana

“…The L-J solid culture method is relatively simpler and cheaper, but it is slow, requiring longer culture periods (4-8 weeks) for DST determination. The period can be shortened with the use of Middlebrook and Cohn's solid media using agar [11]; however, its long turnaround time makes it unreliable, in addition to this media not being easily available in some locations. In the midst of these challenges, new cases of tuberculosis continue to be reported annually [4].…”

Fluoromycobacteriophages Can Detect Viable Mycobacterium tuberculosis and Determine Phenotypic Rifampicin Resistance in 3–5 Days From Sputum Collection

“…in sputum, with subsequent culture to determine viable bacilli and DST using the proportion method is often the method of choice. Culture methodology is laborious and takes 3–6 weeks to report the presence of viable mycobacteria in the sample and a few additional weeks for DST ( Naveen and Peerapur, 2012 ).…”