Use of COPAN SL Solution For Processing Sputum From Patients With and Without Cystic Fibrosis


Background: COPAN SL solution (SL) is a new device used to homogenize and liquefy sputum for manual processing or processing on the Walk Away Specimen Processor (WASP®) (COPAN, Murrieta, CA). Sputum is transferred with a dipper device to the SL tube (containing dithiothreitol), vortexed and liquefied before plating. We compared standard processing to SL for sputa from patients with cystic fibrosis (CF) and without cystic fibrosis (non-CF).

Method: There were 104 sputum specimens (CF=52 and non-CF=52) included in this study. Sputa were cultured by standard processing and residual samples transferred to the SL solution with the sputum dipper. The SL tube was vortexed for 15 seconds and left undisturbed for 15 minutes. The specimen was then inoculated using a 10uL loop on the same media as used for traditional culture. Standard incubation and identification methods were used. Organisms isolated from each processing method were compared.


CF sputa: There were 140 isolates by standard processing and 158 from SL. Fifteen of 19 additional isolates from SL were identified as Pseudomonas aeruginosa (PA). One additional isolate from standard processing was identified as S. aureus.

Non-CF sputa: Ten cultures contained only normal respiratory flora, 4 showed no growth and 38 cultures had potential respiratory pathogens. There were 50 isolates recovered by standard processing and 56 from SL.

Conclusion: SL processing solution using the sputum dipper is an efficient system to liquefy sputum for manual or automated processing. SL is better than standard processing for CF and non-CF sputum. For CF sputum there was improved recovery of all organisms and significant increase of PA strains.


Copan’s SL solution is a ready to use mucolytic agent for sputum samples with the principle active ingredient being dithiotreitol (DTT). SL solution quickly liquefies sputum specimens without affecting the morphology, growth or microscopic staining of pathogens in the sputum. It enables the emulsification of sputum and mucus resulting in a homogenous suspension allowing for easier, more consistent and reproducible planting and streaking of specimens.