Comparison of the Swedish Reference Group of antibiotics and Clinical and Laboratory Standards Institute sensitivity testing methods

Abstract: The aim of this project was to compare the use of the Swedish Reference Group of Antibiotics and the Clinical Laboratory standard institute disc diffusions method using a variety of antibiotics on Klebsiella species and Pseudomonas aeruginosa. After the disc diffusions methods a Vitek system and Etest where preformed on those isolates with a different or abnormal result. Klebsiella spp. and P. aeruginosa was colleted in St James’s hospital over a period of four months. These two isolates were chosen because of their resistance pattern to many commonly used antibiotics and the threat of upcoming resistance to other antibiotics. The SRGA method is know to have lower breakpoints to catch low degree of resistance bacteria, while the CLSI often is blamed for not having species specific MIC breakpoints. The results in this study showed that the SRGA-m often caught more resistant and intermediate isolates then the CLSI-m.