Synergic activity of D-cycloserine and β-chloro-D-alanine against Mycobacterium tuberculosis

David, Suzana

Unit of Mycobacteriology and Centro de Malária e outras Doenças Tropicais /IHMT/Universidade Nova de Lisboa, Rua da Junqueira 96, 1349-008 Lisbon, Portugal

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Received 29 June 2000; returned 12 September 2000; revised 30 October 2000; accepted 31 October 2000

Journal of Antimicrobial Chemotherapy 47(2):p 203-206, February 2001.

D-Cycloserine (DCS) is a peptidoglycan inhibitor. Although very effective against Mycobacterium tuberculosis, it is seldom employed in the management of this infection due to its high toxicity. β-Chloro-D-alanine (another peptidoglycan inhibitor) reduces the MIC of DCS from 50 to 2.5 mg/L at a concentration significantly below its MIC for this organism. A reduction in bacterial viability and significant growth inhibition (as quantified by the X/Y quotient for the Bactec radiometric procedure) were observed with subinhibitory concentrations of both drugs. It is suggested that this powerful synergic effect should be the object of in vivo and eventually clinical trials.