Introduction: Germany has lower antibiotic resistance rates than the European average, with the exception of Enterococcus faecium (ENCFAC) vancomycin (vanco).

Goal: The aim is to compare the trend of resistance of ENCFAC against vanco in different surveillance systems and to investigate the development of the phenotypic ratio of vanco-resistant isolates to teicoplanin (teico) resistance in Bavaria.

Material/method: From 2020 to 2023, 24 to 30 Bavarian laboratories submitted their resistance data to BARDa, evaluated according to the EUCAST standard, anonymized as SIR assessment. For each patient, only the first isolate in 90 days is included. Screening samples are excluded. Confidence intervals are calculated using Wilson score method. The resistance data of 11 bacterial pathogens are evaluated and compared with other German (ARS by RKI, ARMIN by Lower Saxony) and European (EARS-NET by ECDC) surveillance systems. For the latter, data for 2023 are not yet available.

Results: From 2020 to 2023 1,855,256 isolates were included in the BARDa reports with Escherichia coli (712,971; 38.4%) as the most prevalent species. ENCFAC isolates count for 54,948 (3.0%). Resistance rates of ENCFAC for vanco and teico show a significant decrease in Bavaria according to BARDa data since 2022 to 17.9% and 10.1% in 2023 respectively, approaching ARMIN and ARS levels. In general, German resistance values to vanco are above the European average (17.6% in 2022). In BARDa, the phenotypic combined resistance of vanco and teico (as encoded in the vanA gene) increases from 45% in 2020 to 55% in 2023.

Discussion: ENCFAC resistance rates for vanco in Bavaria and Germany are higher than the European average, but seem to converge slowly. In 2023, a significant decrease is observed in BARDa data in invasive isolates and all materials since 2022. This may be due to an increase of the vanA-gene in the Bavarian ENFAC population. Studies at the University Hospitals of Regensburg and Erlangen, where invasive isolates from 2020 and 2022 were analyzed using (core genome) multilocus sequence typing, show that a novel vanA lineage was an important driver of the increasing vanco-resistant ENCFAC rates.