Differentiating between Mycobacterium tuberculosis complex and atypical mycobacteria, by culturing samples in gels containing different levels of resazurin

摘要

Differentiating between the Mycobacterium tuberculosis complex (MTC) and other atypical mycobacteria (aM) in biological samples by culturing samples in gels containing different levels of resazurin, is new. Two aliquots of the sample are used to inoculate a gel tube (1) containing, in a sterile gel phase, a mycobacterial culture medium that includes a mixture of antibiotics to inhibit contaminating bacteria and resazurin (I) at a concentration (C1) below the MIC for MTC but sufficient for revealing microorganisms, and a second similar tube (2) in which either the concentration (C2) of (I) is at least equal to the MIC for MTC but below that for other mycobacterial species, or the concentration (C'2) of (I) is not over the MIC for MTC (but sufficient to reveal microorganisms) and (I) is used together with enough of a specific inhibitor (II) of MTC to inhibit its growth. The samples are mixed immediately after inoculation then incubated at 37 deg C and results read. Independent claims are also included for the following: (a) similar method for differentiating between mycobacteria that are respiratory pathogens and those that are not pathogenic, using, instead of (2), a third tube (3) containing (I) at a concentration (C3) greater than C1 and also a concentration (C4) of a specific inhibitor (III) of mycobacteria, with C3 and C4 selected so that pathogenic aM are inhibited but non-pathogenic aM are not; (b) similar method for differentiating MTC from pathogenic mycobacteria and other non-pathogenic aM which uses all three tubes; and (c) kit for the process containing tube (1) and at least one of (2) and (3).