Use of vancomycin in the culture of Mycobacterium tuberculosis from gastric lavage.

Mathew, S.; Paramasivan, C.N.

Indian Journal of Medical Research; 2001; 113; 125-128.          

Background & objectives : Earlier studies from the Tuberculosis Research Centre, Chennai, on culture of Mycobacterium tuberculosis from gastric lavage (GL) specimens in selective Kirchner's medium (SK) resulted in a loss of 60 per cent culture results due to contamination with aerobic spore bearers (ASB). Addition of vancomycin to SK (SKV) effectively reduced the contamination rate to 20 per cent. The objective of the present study was to further reduce the contamination by collecting the specimens in bottles containing vancomycin, thus providing continuous exposure of the sample to the drug, which is bactericidal to ASB.

Methods : One thousand GL specimens collected from children in vancomycin containing bottles were decontaminated and cultured in SK medium, with and without vancomycin, subcultured on Lowenstein Jensen (LJ) medium and the culture results compared.

Results : The contamination of cultures in SK and SKV was 15 and 4 per cent respectively when the specimens were collected in bottles containing vancomycin compared to 60 and 20 per cent contamination reported in the earlier studies.

Interpretation & conclusion : The reduced contamination in SK and SKV is mostly likely due to the collection of samples in vancomycin containing bottles. Although a concurrent comparison of samples processed in vancomycin free conditions would have been ideal, it could not be done due to practical difficulties. The study thus confirms the value of vancomycin as a major deterrent for contamination due to aerobic spores and better results can be obtained if vancomycin is used in sample collection bottles, transport media and liquid culture media used in mycobacteriology laboratories particularly in humid and tropical environment.

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