[A study by the National Reference Center for Antibiotics on inocula for antibiotic sensitivity testing]

We compared the diameters of inhibition zones obtained during antibiotic sensitivity testing using two different techniques for preparing and seeding the inoculum, i.e. photometric adjustment followed by flooding, and turbidity adjustment followed by swab streaking. There was no significant difference between the results recorded following photometry-flooding of a light inoculum (2 to 3 X 10(6) CFU/ml) and following swab seeding of a bacterial suspension with a turbidity equal to 0.5 Mac Farland unit. These results indicate that both methods tested answer the NCCLS performance standards for disc antibiotic sensitivity testing and the critical values of the S.F.M. Antibiotic Sensitivity Testing Committee.