• More than half of the E. coli isolates reported to EARS-Net in 2015 were resistant to at least one antimicrobial group under surveillance. As in pre-vious years, resistance to aminopenicillin and fluoroquinolones were most frequently reported, both as single resistance and in combination with other antimicrobial groups.
• The EU/EEA population-weighted mean percentage for third-generation cephalosporin resistance and combined resistance to fluoroquinolones, third-generation cephalosporins and aminoglycosides in E. coli both increased significantly between 2012 and 2015.
• Carbapenem resistance remained rare in E. coli in Europe.
• The highest resistance percentages in E. coli were generally reported from southern and south-east-ern Europe.
Aminopenicillins
• For 2015, 30 countries reported 77 528 E. coli isolates with AST information for aminopenicillins (amoxicil-lin or ampicil(amoxicil-lin). The number of isolates reported per country ranged from 123 to 10 946 (Table 3.1).
The EU/EEA population-weighted mean percentage for aminopenicillin resistance was 57.2 % in 2015. No significant trend was noted between 2012 and 2015 (Table 3.1).
National percentages of resistant isolates ranged from 34.1 % (Sweden) to 73.0 % (Romania) in 2015. Trends for the period 2012–2015 were calculated for the 29 coun-tries reporting data for at least 20 isolates per year during the full reporting period. Significantly increas-ing trends were observed for seven countries (Belgium, France, Lithuania, Luxembourg, Slovenia, Romania and the United Kingdom). For Belgium, the trend did not remain significant when considering only data from laboratories that reported consistently for all four years. Significantly decreasing trends were observed for four countries (the Czech Republic, Finland, Hungary and the Netherlands). For the Czech Republic and the Netherlands, the trends did not remain significant when considering only data from laboratories reporting con-sistently for all four years (Table 3.1).
Fluoroquinolones
For 2015, 30 countries reported 89 850 E. coli iso-lates with AST information for fluoroquinolones (ciprofloxacin, levofloxacin or ofloxacin). The number of isolates reported per country ranged from 123 to 10 998 (Table 3.2).
The EU/EEA population-weighted mean percentage for fluoroquinolone resistance was 22.8 % in 2015. No significant trend was noted between 2012 and 2015 (Table 3.2).
National percentages of resistant isolates ranged from 6.8 % (Iceland) to 45.5 % (Cyprus) in 2015 (Table 3.2 and Figure 3.1). All 30 countries reported data for at least 20 isolates per year during the full reporting period.
Significantly increasing trends were observed for seven countries (Belgium, Croatia, Italy, Latvia, Lithuania, Slovenia and Sweden). For Sweden, the trend did not remain significant when considering only data from laboratories reporting consistently for all four years.
Significantly decreasing trends were observed for four countries (Denmark, Germany, the Netherlands and Spain). For Germany, the trend did not remain significant when considering only data from laboratories reporting consistently for all four years (Table 3.2).
Third-generation cephalosporins
For 2015, 30 countries reported 89 839 E. coli isolates with AST information for third-generation cephalospor-ins (cefotaxime, ceftriaxone or ceftazidime). The number of isolates reported per country ranged from 123 to 11 051 (Table 3.3).
The trend for the EU/EEA population-weighted mean percentage increased significantly for the period 2012–
2015, from 11.9 % in 2012 to 13.1 % in 2015 (Table 3.3).
National percentages of resistant isolates ranged from 1.7 % (Iceland) to 38.5 % (Bulgaria) in 2015 (Table 3.3 and Figure 3.2). All 30 countries reported data for at
Figure 3.1. Escherichia coli. Percentage (%) of invasive isolates with resistance to fluoroquinolones, by country, EU/EEA countries, 2015
Liechtenstein Luxembourg Malta Non-visible countries
10% to < 25%
25% to < 50%
≥ 50%
No data reported or fewer than 10 isolates Not included
< 1%
1% to < 5%
5% to < 10%
Figure 3.2. Escherichia coli. Percentage (%) of invasive isolates with resistance to third-generation cephalosporins, by country, EU/EEA countries, 2015
Liechtenstein Luxembourg Non-visible countries
10% to < 25%
25% to < 50%
≥ 50%
No data reported or fewer than 10 isolates Not included
< 1%
1% to < 5%
5% to < 10%
least 20 isolates per year during the full reporting period. Significantly increasing trends were observed for 12 countries (Belgium, Croatia, the Czech Republic, France, Greece, Ireland, Italy, Lithuania, Norway, Portugal, Slovenia and Sweden). For Greece and Portugal, the trends did not remain significant when considering only data from laboratories reporting con-sistently for all four years. Significantly decreasing trends were observed for Spain and the United Kingdom.
These trends remained significant when considering only data from laboratories reporting consistently for all four years (Table 3.3).
ESBL percentages for E. coli were calculated based on data from 24 countries. Only data from laboratories reporting ESBL results for all isolates identified as resistant to third-generation cephalosporins (56 % of the laboratories reporting AST data for third-generation cephalosporin in E. coli), and only data from countries reporting at least 10 such isolates were included. Among the E. coli isolates resistant to third-generation cepha-losporins and meeting the inclusion criteria, 88.6 % were ascertained as ESBL-positive by the laboratories in 2015. ESBL results might not be directly comparable between countries as there are national differences in the definition of ESBL. The presence of ESBL might also be masked by some carbapenemases such as MBLs and KPC and/or severe permeability defects [10].
Aminoglycosides
For 2015, 30 countries reported 89 764 E. coli isolates with AST information for aminoglycosides (gentamicin or tobramycin). The number of isolates reported per coun-try ranged from 123 to 11 055 (Table 3.4).
The EU/EEA population-weighted mean percentage for aminoglycoside resistance was 10.4 % in 2015. No significant trend was noted between 2012 and 2015 (Table 3.4).
National percentages of resistant isolates ranged from 2.9 % (Iceland) to 24.2 % (Slovakia) in 2015 (Table 3.4 and Figure 3.3). All 30 countries reported data for at least 20 isolates per year during the full reporting period. Significantly increasing trends were observed for five countries (Belgium, Croatia, the Czech Republic, Slovenia and the United Kingdom). For Belgium, the trend did not remain significant when considering only data from laboratories reporting consistently for all four years. Significantly decreasing trends were observed for four countries (Finland, Hungary, the Netherlands and Portugal). For Finland and the Netherlands, these trends did not remain significant when considering only data from laboratories reporting consistently for all four years (Table 3.4).
Susceptibility data for amikacin were less frequently reported than for gentamicin and/or tobramycin and generally showed lower resistance levels. A total of 52 637 isolates had susceptibility data for both for ami-kacin and gentamicin and/or tobramycin (58.6 % of the isolates included in the aminoglycoside group analysis).
Among isolates with resistance to either gentamicin or
Carbapenems
For 2015, 30 countries reported 86 200 E. coli isolates with AST information for carbapenems (doripenem, imi-penem or meroimi-penem). The number of isolates reported per country ranged from 123 to 10 481 (Table 3.5).
The EU/EEA population-weighted mean percentage for carbapenem resistance was 0.1 % in 2015. No significant trend was noted between 2012 and 2015 (Table 3.5).
E. coli with resistance to carbapenems remained rare in Europe. Twenty-three countries reported carbapenem resistance percentages < 0.01 % in 2015 (Table 3.5 and Figure 3.4). Only two countries – Greece (1.2 %) and Romania (1.9 %) – reported percentages above 1 %. All 30 countries reported data for at least 20 isolates per year during the full reporting period. A significantly increasing trend was observed for Romania, but the trend did not remain significant when considering only data from laboratories reporting consistently for all four years. Significantly decreasing trends were observed for Bulgaria, Italy and Slovakia. For Slovakia, the trend did not remain significant when considering only data from laboratories reporting consistently for all four years (Table 3.5).
Combined resistance to third-generation cephalospor-ins, fluoroquinolones and aminoglycosides
For 2015, 30 countries reported 87 798 E. coli isolates with sufficient AST information to determine combined resistance to third-generation cephalosporins, fluo-roquinolones and aminoglycosides. The number of isolates reported per country ranged from 123 to 10 988 (Table 3.6).
The trend for the EU/EEA population-weighted mean percentage increased significantly for the period 2012–
2015, from 4.9 % in 2012 to 5.3 % in 2015 (Table 3.6).
National percentages of resistant isolates ranged from zero (Iceland) to 17.1 % (Slovakia) in 2015 (Table 3.6 and Figure 3.5). All 30 countries reported data for at least 20 isolates per year during the full reporting period. Significantly increasing trends were observed for 10 countries (Belgium, Croatia, the Czech Republic, Estonia, France, Ireland, Lithuania, Luxembourg, Slovenia and Sweden). For Belgium, France and Sweden, the trends did not remain significant when consider-ing only data from laboratories reportconsider-ing consistently for all four years. Significantly decreasing trends were observed for Finland, Hungary and Portugal. For Finland, the trend did not remain significant when considering only data from laboratories reporting consistently for all four years (Table 3.6).
Other resistance combinations and resistance to other antimicrobial groups
Of the 72 123 isolates (78.2 % of all E. coli isolates) tested for all antimicrobial groups under regular EARS-Net surveillance (aminopenicillins, fluoroquinolones, third-generation cephalosporins, aminoglycosides and carbapenems) in 2015, more than half (53.7 %) were
Figure 3.3. Escherichia coli. Percentage (%) of invasive isolates with resistance to aminoglycosides, by country, EU/EEA countries, 2015
Liechtenstein Luxembourg Malta Non-visible countries
10% to < 25%
25% to < 50%
≥ 50%
No data reported or fewer than 10 isolates Not included
< 1%
1% to < 5%
5% to < 10%
Figure 3.4. Escherichia coli. Percentage (%) of invasive isolates with resistance to carbapenems, by country, EU/EEA countries, 2015
Liechtenstein Luxembourg Non-visible countries
10% to < 25%
25% to < 50%
≥ 50%
No data reported or fewer than 10 isolates Not included
< 1%
1% to < 5%
5% to < 10%
group (mainly aminopenicillins) was the most common (34.2 %). For isolates with resistance to two antimi-crobial groups (11.4 %), combined aminopenicillin and fluoroquinolone resistance was the most common, and for those with resistance to three antimicrobial groups (7.6 %), combined aminopenicillin, fluoroqui-nolone and third-generation cephalosporin resistance accounted for the majority. Antimicrobial resistance to four antimicrobial groups were less frequent (5.2 %), the vast majority of these isolates was resistant to aminopenicillins, third-generation cephalosporins, fluoroquinolones and aminoglycosides. As carbapenem resistance remained rare in E. coli, resistance combina-tions including this antimicrobial group were uncommon (Table 3.7).
Twenty countries reported AST data for polymyxins for a total of 14 518 isolates (15.7 % of all reported E. coli isolates) in 2015. Only five countries reported polymyxin AST data for more than half of the reported E. coli iso-lates. Only a small proportion (1.1 %) was resistant to polymyxin. Among carbapenem-resistant isolates also tested for resistance to polymyxins (30 out of 69 iso-lates), 6.2 % were resistant to polymyxins, whereas only 1.1 % of the carbapenem-susceptible isolates were resistant to polymyxins. The small number of isolates, the rare occurrence of both carbapenem and polymyxin
resistance in E. coli, and potential differences in the use of laboratory methodology used to determine suscep-tibility mean that these findings should be interpreted with caution and may not be representative for Europe as a whole.