Many recent articles dealing with bacterial sensitivity to antibacterial agents have been very misleading. Each of these reports various percentages of bacterial pathogens which are susceptible, or "resistant" to certain antibacterial drugs. The definition of resistance evidently has not been standardized, for, according to Rodger et al.,1 each laboratory may modify a standard test to suit its particular need, and therefore there is no one standard in relation to therapy or for comparing results of percentages of resistant strains from different parts of the country. Indeed, in a review, Power2 discovered that what was considered "resistant" in one laboratory was 40 times the "resistant" level of another.
Much of this confusion comes from the use of varying techniques of testing bacterial sensitivity, and the nonstandard way of reporting the sensitivity of those organisms by these various methods, such as the disc, agar-well, and the tube-dilution methods. These methods
PULLEN FW. Bacterial Resistance to AntibioticsA Correlation of Clinically Attainable Blood Levels with in Vitro Sensitivity Tests. Arch Surg. 1960;81(6):942-952. doi:10.1001/archsurg.1960.01300060088017