Sputum is an important biological material for the investigation of respiratory disease, but is notoriously difficult to work with. Various reagents have been used over the years to liquefy sputum specimens to make them suitable for inoculation onto agar. Some of these reagents must be prepared in caustic solutions, and can be unsafe and unpleasant to handle, with limited stability. They are normally kept lyophilised and prepared when required.

Modern microbiology laboratories use automated processing platforms for the inoculation of agar plates, but the current methods of preparation of sputum specimens are not well suited to such processing. Specimens are loaded in large numbers onto the equipment, but may wait for several hours before being processed. Reagents such as dithiothreitol are detrimental to the survival of important respiratory pathogens such as Haemophilus influenzae. MWE’s new Sigma SP™ resolves all of these issues.

Sigma SP™ contains a novel reagent which is not only a more powerful mucolytic, but comes in a simple, ready to use liquid format, ready to load onto the automated platforms. It is not directly harmful to any of the target bacteria, so specimens can be safely left in the queue for several hours. The solution has a neutral pH, and can be safely stored prior to use at ambient temperature for many months.

To use, simply add 1ml of sputum directly to the Sigma SP™ vial, recap, vortex and allow to stand for about 15 minutes before processing.

Initial studies show that Sigma SP™ liquid does not interfere with molecular diagnostic test systems.