Detection of susceptibility in Enterococcus faecium isolates using the rapid method

Enterococcus faecium is an opportunistic pathogen found in normal intestinal flora of humans and animals. Its resistance ability against antimicrobials has posed a threat to human health. The early identification of a causative agent with a selective antibiotic and its sensitivity result can be important in diagnosis. Our study investigated E.feaecium isolates from blood samples using rapid methods to observe susceptibility. The study collected 112 E. faecium isolates of blood samples from the routine bacteriology laboratory at Ondokuz Mayıs University of Medicine. The resazurin microplate method was used to detect early susceptibility of vancomycin and high-level gentamicin in E. faecium isolates. The microdilution method was used as a reference method. The results of the resazurin microplate method and the reference microdilution method then were compared. The results of the resazurin microplate method were observed at the sixth to seventh hour though the results of the standard microdilution method were evaluated after 24 hours of incubation. The KU rates for the vancomycin antibiotic were 99.1%, and the KU rates for the gentamicin antibiotic were 86.0%, and 95%, respectively. The TU rates for the vancomycin antibiotic were 94.2% and 96.7%, and the TU rates for the gentamicin antibiotic were 76.2% and 83.6%, respectively. The ADR rates for the vancomycin antibiotic were 4.5%, and the ADR rates for the gentamicin antibiotic were 19.2% and 6.0%, respectively. The GH for the vancomycin antibiotic was 0%, and the GH rate for the gentamicin antibiotic was 2.5% respectively. The CH rate of vancomycin and gentamicin antibiotics was not determined. It is anticipated that the resazurin microplate approach will be useful in determining vancomycin and gentamicin susceptibility in E. faecium isolates at 6 to 7-hour intervals. However, it is suggested that doing repeatability tests with several antibiotic groups and many isolates would be advantageous in order to clarify the method's trustworthiness.