Strong correlation between the rates of intrinsically antibiotic-resistant species and the rates of acquired resistance in Gram-negative species causing bacteraemia, EU/EEA, 2016

Background: Antibiotic resistance, either intrinsic or acquired, is a major obstacle for treating bacterial infections. Aim: Our objective was to compare the countryspecific species distribution of the four Gram-negative species Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and Acinetobacter species and the proportions of selected acquired resistance traits within these species. Method: We used data reported for 2016 to the European Antimicrobial Resistance Surveillance Network (EARS-Net) by 30 countries in the European Union and European Economic Area. Results: The country-specific species distribution varied considerably. While E. coli accounted for 31.9% to 81.0% (median: 69.0%) of all reported isolates, the two most common intrinsically resistant species P. aeruginosa and Acinetobacterspp. combined (PSEACI) accounted for 5.5% to 39.2% of isolates (median: 10.1%). Similarly, large national differences were noted for the percentages of acquired non-susceptibility to third-generation cephalosporins, carbapenems and fluoroquinolones. There was a strong positive rank correlation between the countryspecific percentages of PSEACI and the percentages of non-susceptibility to the above antibiotics in all four species (rho > 0.75 for 10 of the 11 pairs of variables tested). Conclusion: Countries with the highest proportion of P. aeruginosa and Acinetobacter spp. were also those where the rates of acquired non-susceptibility in all four studied species were highest. The differences are probably related to national differences in antibiotic consumption and infection prevention and control routines.