Background: Antimicrobial resistance is the ability of a microorganism to resist the effects of medication intended to be used against them. Resistance arises in three ways: natural (intrinsic) resistance in certain types of bacteria, or acquired via either genetic mutation, or by horizontal gene transfer. The European Antimicrobial Resistance Surveillance Network (EARS-Net) monitors the evolution of acquired antimicrobial resistance at the European level. The Scientific Institute of Public Health (WIV-ISP) is the nominated focal contact point for Belgium (BE), and collects data from the clinical laboratories through its national surveillance EARS-Net BE.
Results: In 2016, 31 clinical laboratories voluntarily reported results on Antimicrobial susceptibility tests (AST) in 8 pathogens isolated from blood or cerebrospinal fluid samples. For Streptococcus pneumonia isolates, national AST data for 2016 from 97 laboratories was provided by the National Reference Center (NRC) at the Catholic University of Leuven (KUL). We observed an increase in antimicrobial resistance for Escherichia coli to third-generation cephalosporins and to fluoroquinolones, leading to countrywide resistance percentages in 2016 of 10.5% and 24.5%, respectively. An increasing trend could also be observed for antimicrobial resistance of Klebsiella pneumoniae to third-generation cephalosporins and to carbapenems, resulting in mean resistance percentages of 22.9% and 2.4%, respectively. Extended-spectrum beta-lactamase (ESBL) was detected in 83.5% of the additionally tested samples that were resistant to third-generation cephalosporins. Pseudomonas aeruginosa showed resistance to almost all antimicrobial groups. The predominant resistance in P. aeruginosa was to fluoroquinolones (14.5%), followed by resistance to aminoglycosides (11.0%), piperacillin-tazobactam (9.8%) and carbapenems (9.6%). The highest resistance levels in Acinetobacter species were observed to fluoroquinolones (7.7%), followed by aminoglycosides (5.1%) and carbapenems (2.6%). Apart from macrolides (15.9% intermediary resistant + resistant strains), non-susceptibility was rare in Streptococcus pneumoniae: 0.4% of the samples were non-susceptible to penicillins or to third-generation cephalosporins, and 0.2% was non-susceptible to fluoroquinolones. Over the period 2012-2016, we observed a strong decreasing trend for non-susceptibility to macrolides. In 2016, 12.2% of all tested Staphylococcus aureus samples were non-susceptible to meticillin (MRSA) and 12.7% were resistant to fluoroquinolones. For both antimicrobial 9 groups, we could observe a decreasing trend between 2012 and 2016. For MRSA, the decreasing trend up till 2015 did not continue in 2016. No E. faecalis isolates were found resistant to vancomycin and 1.7% of E. faecium isolates tested resistant to this antibiotic. Resistance to linezolid remained almost non-existent in both Enterococci, with none of the E. faecalis, and 0.5% of E. faecium isolates testing resistant. High-level gentamicin resistance was common in both Enterococcus faecalis (19.8%) and Enterococcus faecium (19.7%).
Conclusions: Klebsiella pneumoniae isolates have continuously lost susceptibility for third-generation cephalosporins over the last 5 years, resulting in a mean resistance percentage of 22.9% in 2016. Resistance of these isolates to carbapenems is emerging, with 2.4% resistance in 2016. A majority of third-generation cephalosporins resistant E. coli and K. pneumoniae isolates produced ESBL. Resistance of P. aeruginosa to ceftazidime, carbapenems, aminoglycosides and fluoroquinolones was common in 2016. The decreasing trend between 2012 and 2015 for meticillin non-susceptibility of S. aureus (MRSA) stabilized in 2016 around 12.2%. No E. faecalis isolates and 1.7% of E. faecium isolates tested resistant to vancomycin. Resistance to linezolid remained very low in both Enterococci. For upcoming data calls, we encourage laboratories to submit quantitative results on AST (next to the current final interpretations of susceptibility), to improve standardization of national results on AMR. We also encourage harmonization of case and data definitions used for national AMR surveillance in Belgium, to reduce workload and increase internal validation.