Preparation of the Blood-Enriched Agar with the Use of Red Cell Suspension

A culture medium is said to support the growth and development of different microorganisms. Certain bacteria like Staphylococcus aureus and Staphylococcus epidermidis entail hemoglobin found in the red blood cells. Because of its cost effectiveness and availability, expired human blood is being utilized in some developing countries. Despite the widely accepted disadvantages of using human blood as enrichment agent, many laboratories still opt to use it due to the unavailability of sheep blood or due to budgetary reasons. This study determined if the washed expired human blood can be used as an alternative enrichment agent in the preparation of Blood Agar Plate (BAP) culture medium in the isolation of Staphylococcus aureus ATCC 25923 and Staphylococcus epidermidis ATCC 12228. The cultural characteristics and hemolytic reactions of the selected microorganisms were recorded, assessed and compared with their growth in BAP. The stability of the washed expired human blood was evaluated in terms of temperature and storage period. Results reveal that expired human blood with washing improved the morphologic and hemolytic pattern of Staphylococcus aureus. The washing of blood had no effect on Staphylococcus epidermidis because it is a gamma hemolytic bacterium. Both unwashed expired and fresh human blood produced gamma hemolysis due to the interferences still present in them. Both washed expired human blood and washed fresh human blood produced beta hemolysis. Washed expired human blood could be stored for seven days and still could be used for microbial culture.

 

Keywords - Blood, Blood Enriched Agar, Red Cell Suspension