New application note demonstrates how combining petri dish filler with peristaltic pump provides an optimized and automated solution for production of high-quality blood agar.
The quality of blood agar plates is of prime importance for the reliable determination of haemolysis type – a common technique in medical diagnostics to classify Gram positive cocci. High-quality agar plates have a typical light red colour – a characteristic feature of intact erythrocytes. Agar plates with lysed red blood cells appear brown coloured, a feature that complicates the reading of haemolysis pattern. To avoid spontaneous lysis of erythrocytes, it is important to keep the temperature of the agar as low as possible. In addition to minimize cell lysis, the time the blood remains in the hot agar has to be as short as possible. Meeting these requirements is a challenge for most laboratories.
The application note describes an automated protocol that minimizes the time that the blood is exposed to hot agar medium and thus efficiently reduces thermally induced lysis of erythrocytes. By combining the petri dish filler together with a peristaltic pump and a special tubing set for blood agar the experimenters were able to add blood to the agar immediately before pouring the plate thereby reducing blood cell lysis significantly.