[Linezolid-resistant enterococci]

To assess the occurrence of linezolid-resistant enterococci (E. faecalis and E. faecium) in patients hospitalized at the centers and clinics of the Institute for Clinical and Experimental Medicine (IKEM).

For the period from 1. 1. 2017 to 31. 12. 2022, isolates of E. faecalis and E. faecium, which were tested for sensitivity to antibiotics, were retrospectively evaluated. Microbiological data were obtained from the laboratory information system ENVIS LIMS, and clinical data from the hospital information system IKEM. Enterococci were identified using a MALDI-TOF mass spectrometer. Susceptibility testing was performed using the disc diffusion method according to EUCAST criteria. Minimum inhibitory concentrations were determined by the Vitek automated system using the P592 card. Verification of resistance to linezolid and determination of the resistance mechanism took place at the National Reference Laboratory for Antibiotics of the National Institute of Public Health in Prague.

In the monitored period, the sensitivity of 6900 strains of E. feacalis (67,0 %) and 3356 strains of E. faecium (33,0 %) was examined. A total of 14 linezolid-resistant enterococci (LRE) were identified - 5x E. faecalis (35,7 %) and 9x E. faecium (64,3 %). The most common mechanism of resistance to linezolid was the presence of the optrA gene in E. faecalis, and 23S rRNA mutation in E. faecium. The material with the largest LRE capture was urine (35,7 %) and secrets or punctates (28,6 %). Only in the species E. faecium, resistance to vancomycin and teicoplanin (LVRE) occurred at the same time. Three patients (21,4 %) developed an LRE infection requiring antibiotic treatment, the remaining eleven patients (78,6 %) were colonized.

The proportion of linezolid-resistant enterococci was in the mentioned period low - 0,14 %. Linezolid therefore remains a safe therapeutic alternative for enterococcal infections when first-line drugs cannot be used.