Audit of Staphylococcus aureus bacteraemia management in NHS Tayside and comparison with European Antibiotic Strategies study group international quality standards

TEM/SHV+ ESBL+ E. coli. There is no immediate explanation for these results, particularly since several other TEM, SHV and CTX-M ESBL+ isolates were correctly identified as ‘exhibiting another resistance mechanism’. The ESBL activity might have been masked by the AmpC inducer (incorporated into all three discs), and hence these results highlight an important limitation of the D69C kit, i.e. it is solely a method for AmpC detection, and its use cannot be extrapolated to ESBL detection. The ESBL inhibitor is incorporated into discs B and C to improve the performance of the kit in detecting AmpC, not to adapt it for ESBL detection. In conclusion, this study indicates that the D69C AmpC Detection Disc Set provides a simple, economical, convenient and accurate means of detecting AmpC production by organisms exhibiting plasmid-mediated as well as chromosomal AmpC, whether inducible or derepressed. Results are easily interpreted, and the methodology is suitable for use by any clinical microbiology laboratory. The D69C kit is a promising development in a difficult area—broader experience will hopefully pave the way for its wide adoption in routine laboratories.