Selective Inhibition of <i>Mycobacterium tuberculosis</i> by Para-Nitrobenzoic Acid (PNB) used in Lowenstein-Jensen Medium

Authors

  • S Nepali Central Department of Microbiology, Tribhuvan University, Kirtipur, Kathmandu
  • P Ghimire Central Department of Microbiology, Tribhuvan University, Kirtipur, Kathmandu
  • DK Khadka SAARC Tuberculosis and HIV/AIDS Centre, Thimi, Bhaktapur
  • S Acharya Central Department of Microbiology, Tribhuvan University, Kirtipur, Kathmandu

DOI:

https://doi.org/10.3126/saarctb.v5i1.3080

Keywords:

PNB, AFB, LJ medium, Mycobacterium tuberculosis

Abstract

Background: Mycobacterial growth in media to which inhibitory substances are added has been used in species identification. Mycobacterium tuberculosis does not grow in Lowenstein-Jensen (LJ) medium containing para-nitrobenzoic acid (PNB); which can be a basis for its identification from other mycobacteria.

Setting: National Tuberculosis Centre (NTC), Thimi, Bhaktapur, Nepal.

Objectives: To evaluate usefulness of PNB containing LJ medium in identifying mycobacterial isolates.

Methodology: This diagnostic evaluation study based at NTC was conducted from Sep 2006-Jun 2007. During the study period, a total of 857 sputum samples collected from patients attending NTC were analyzed using fluorescence microscopy. The smear positive samples were confirmed by Ziehl-Neelsen (ZN) staining. Smear positive samples were cultured on LJ media with and without PNB; followed by biochemical tests.

Results: Out of total 857 sputum samples analyzed, 246 (28.7%) were positive for AFB on fluorescence staining and 214 (87%) of smear positive samples were also positive in culture. All the isolates which grow on LJ media without PNB did not grow on LJ media containing PNB.

Conclusion: Mycobacterium tuberculosis can be identified and differentiated from non-tuberculous mycobacteria using PNB containing media, easily in labs where culture is being done.

Keywords: PNB; AFB; LJ medium; Mycobacterium tuberculosis

DOI: 10.3126/saarctb.v5i1.3080

SAARC J. Tuber. Lung Dis. HIV/AIDS 2008 Vol.5(1) 25-28

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Published

2010-05-07

How to Cite

Nepali, S., Ghimire, P., Khadka, D., & Acharya, S. (2010). Selective Inhibition of <i>Mycobacterium tuberculosis</i> by Para-Nitrobenzoic Acid (PNB) used in Lowenstein-Jensen Medium. SAARC Journal of Tuberculosis, Lung Diseases and HIV/AIDS, 5(1), 25–28. https://doi.org/10.3126/saarctb.v5i1.3080

Issue

Vol. 5 No. 1 (2008)

Section

Articles

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