Is it possible to shorten serum bactericidal testing?

Serum bactericidal test represents an alternative possibility for optimization of antibiotic treatment. The paper aimed to confirm non-inferiority of bactericidal testing using the broth dilution method according to the CLSI method (M21A) in comparison with turbidimetric and colorimetric modifications. We tested human blood sera (n = 76) of ten hematological patients, their blood was withdrawn prior to and during the course of antibiotic therapy. Testing employed the reference strain Escherichia coli ATCC 25922. The results of the modified turbidimetric method did not differ in a statistically significant way with the use of the wavelengths of 620 nm or 405 nm and the break-point <30% turbidity change after 24-hour incubation. The colorimetric method was also non-inferior from the CLSI method when resazurin was applied after 8-hour incubation and the results of subculture were read after 24-hour incubation. Both tested modifications can represent a shorter alternative to the CLSI reference method.