Serum bactericidal testing with quality control organisms

Measurements of serum bacteriostatic and bactericidal titers were compared using common quality control organisms. Oxacillin or vancomycin was added to normal sera for duplicate testing against Staphylococcus aureus ATCC 25923 while gentamicin or ampicillin was added for duplicate testing against Escherichia coli ATCC 25922. Recommendations of acceptable ranges are presented in the text. Establishment of acceptable ranges for serum bactericidal assay results could improve accuracy, allow comparisons of data from different studies and help reduce intralaboratory variations.