For example, acid-fast staining is rapid, inexpensive, technically simple, and highly specific for acid-fast bacilli (AFB), but it lacks sensitivity. As with most diagnostic methods, each technique has its advantages and disadvantages. The principal methods include microscopic, cultural, and molecular techniques. Several diagnostic techniques are currently used to evaluate the presence of mycobacteria in respiratory specimens. Examination of the relationship between increasing CB-18 and lecithin concentrations suggested that lecithin could not overcome the deleterious effects of CB-18 in liquid culture at these higher concentrations. Increasing the CB-18 concentration to 4 mM provided quantitative recovery on solid medium however, higher concentrations of CB-18 were not compatible with liquid culture.

The tuberculocidal effect was time dependent but independent of concentration, whereas recovery was directly proportional to concentration. Other parameters of the CB-18 method were also examined, including recovery versus CB-18 concentration and the relationship between CB-18 concentration and the tuberculocidal effect. Recovery of the tuberculous and nontuberculous mycobacteria following CB-18 processing averaged 86 and 73%, respectively, with ranges from 61 to over 100% and from 43 to over 100%, respectively. Recovery of the tuberculous and nontuberculous isolates by the Tween 80-based method ranged from 22 to 92% and 27 to 93%, respectively, with averages of 58 and 65%, respectively. Recovery of the tuberculous isolates following NALC-NaOH processing averaged 20% and ranged from 1.6 to 45%, whereas recovery of the nontuberculous isolates averaged 11% and ranged from 0.1 to 55%. Subsequently, recovery of several mycobacterial isolates by the CB-18 method was compared to a contemporary processing method that combines NALC and NaOH (NALC-NaOH) and a Tween 80-based method. First, eliminating the incubation step was shown to further improve culture sensitivity.

Additional significant parameters of the CB-18 processing method are identified herein. 36:2004–2013, 1998) described initial improvements to this method.

This method used C 18-carboxypropylbetaine (CB-18) and increased both smear and culture sensitivity.

36:1996–2003, 1998) reported a new specimen-processing method for improved recovery of mycobacteria.

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