Antimicrobial sensitivity of Dutch porcine A. pleuropneumoniae, E. coli and S. suis 2016 - 2020

AHEAD

ANIMAL HEALTH

Access to representative, reliable antimicrobial susceptibility testing (AST) data is a prerequisite for further promotion of prudent use of antimicrobials and provision of solid evidence for policies aimed at reducing antimicrobial resistance levels in bacterial pathogens. Therefore, this study aimed to assess the effect of several potential factors on representativeness and reliability of AST results of Actinobacillus pleuropneumoniae (APP), Escherichia coli (ECO), and Streptococcus suis (SSU) from pigs.

Materials & Methods

AST results (Minimal Inhibitory Concentration (MIC)) were extracted from the Laboratory Information Management System of GD for the period 2016-2020. Next, additional data (age category, farm and province of origin) were collected and merged with the MIC databases. Subsequently statistical analyses were carried out using STATA 15.1 (StataCorp, 2017).

Results

• Overall, the number of APP (n=761), ECO (n=1141) and SSU (n=2816) isolates were well representative considering the number of pigs and number of farms per province they originated from. Although less APP isolates were available compared to ECO and SSU, for all bacterial species fairly precise estimations of resistance levels were determined as shown by the confidence intervals in the MIC distributions (<17% but most <9%).

• The dataset also allows for detection of year-to-year trends in resistance; hardly any significant changes in resistance percentages in time were found.

• Multilevel analyses revealed significant associations between resistance levels and age category (ECO and SSU); generally, resistance levels decreased with increasing age.

• For several antimicrobials a significant association between farm of origin and level of resistance was shown.

Conclusions

All factors associated with susceptibility levels should be considered before sharing aggregated susceptibility patterns for use in antimicrobial treatment guidelines and in veterinary practice.

This project was funded by The Netherlands Organisation for Health Research and Development (ZonMw); Dossier number: 541003007.

Table 2a - 2c

Dilution series applied for each individual antimicrobial are marked white, green vertical lines indicate the breakpoint/cut off used for interpretation. To the right of the dilution ranges,

Jobke van Hout1,3, Marieke Augustijn1, Els Broens2, Maaike Gonggrijp1, Annet Heuvelink1 1 Royal GD, 2 Utrecht University, 3 Presenting author

Antimicrobial Actinobacillus pleuropneumoniae 2020 (n=151) MIC values (µg/mL) MIC50 MIC90 S R R CI 0.125 0.25 0.5 1 2 4 8 16 32 64 128 256 512 (μg/mL) (μg/mL) (%) (%) Amoxicillin/Clavulanic acid 98.0 2.0 0.0 0.0 0.0 0.0 0.0 0.0 ≤0.25 ≤0.25 - -Ampicillin 0.0 90.1 2.6 0.0 0.0 0.0 0.7 0.0 2.6 4.0 0.25 0.25 92.7 7.3 3.7 - 12.7 Apramycin 16.6 68.2 15.2 0.0 16 32 - -Cefepime 100.0 0.0 0.0 0.0 0.0 0.0 0.0 ≤1 ≤1 - -Cefotaxime 98.7 1.3 0.0 0.0 ≤1 ≤1 - -Colistin 96.0 2.6 1.3 0.0 0.0 0.0 0.0 ≤0.5 ≤0.5 - -Enrofloxacin 100.0 0.0 0.0 0.0 0.0 ≤0.25 ≤0.25 100.0 0.0 0.0 - 2.4 Florfenicol 99.3 0.7 0.0 0.0 ≤2 ≤2 99.3 0.7 0.0 - 3.6 Flumequine 98.7 1.3 0.0 0.0 0.0 ≤2 2 - -Gentamicin 71.5 23.2 5.3 0.0 ≤2 4 - -Neomycin 0.0 15.9 72.8 11.3 16 >16 - -Spectinomycin 0.7 0.0 6.0 82.1 10.6 0.7 64 128 - -Streptomycin 2.0 10.6 51.0 27.2 4.0 1.3 4.0 8 16 - -Sulfamethoxazole 3.3 6.6 8.6 81.5 >256 >256 - -Tetracycline 4.0 4.0 66.9 12.6 0.7 4.6 2.6 4.6 1 8 8.0 92.0 86.5 - 95.8 Tiamulin 99.3 0.7 0.0 0.0 ≤8 ≤8 100.0 0.0 0.0 - 2.4 Tilmicosin 49.0 47.7 3.3 0.0 0.0 0.0 4 4 100.0 0.0 0.0 - 2.4 Trimethoprim 39.7 9.9 11.9 10.6 11.3 4.6 11.9 2 >16 - -Trimethoprim/Sulfamethoxazoleb 43.0 15.2 17.9 13.9 8.6 1.3 0.5 2 - -Tylosin 0.7 0.0 0.0 0.0 1.3 98.0 >4 >4 - -Antimicrobial Escherichia coli 2020 (n=143) MIC values (µg/mL) MIC50 MIC90 S R R CI 0.125 0.25 0.5 1 2 4 8 16 32 64 128 256 512 (μg/mL) (μg/mL) (%) (%) Amoxicillin/Clavulanic acid 0.0 0.7 7.0 22.4 35.7 33.6 0.7 0.0 0.0 4 8 99.3 0.7 0.0 - 3.8 Ampicillin 0.0 0.7 8.4 21.7 2.8 0.0 0.7 0.0 65.7 >32 >32 33.6 66.4 58.1 - 74.1 Apramycin 95.1 4.9 0.0 ≤8 ≤8 - -Cefepime 99.3 0.0 0.7 0.0 0.0 0.0 0.0 ≤1 ≤1 99.3 0.7 0.0 - 3.8 Cefotaxime 99.3 0.0 0.0 0.7 ≤1 ≤1 99.3 0.7 0.0 - 3.8 Colistin 88.1 5.6 2.1 2.1 2.1 0.0 0.0 ≤0.5 1 95.8 4.2 1.6 - 8.9 Enrofloxacin 97.2 2.1 0.7 0.0 0.0 ≤0.25 ≤0.25 - -Florfenicol 4.2 48.3 35.7 11.9 4 >8 - -Flumequine 91.6 4.9 3.5 0.0 0.0 ≤2 ≤2 91.6 8.4 4.4 - 14.2 Gentamicin 100.0 0.0 0.0 0.0 ≤2 ≤2 100.0 0.0 0.0 - 2.5 Neomycin 93.7 0.0 2.1 4.2 ≤4 ≤4 93.7 6.3 2.9 - 11.6 Spectinomycin 0.7 1.4 36.4 21.7 10.5 29.4 64 >128 60.1 39.9 31.8 - 48.4 Streptomycin 33.6 5.6 4.9 8.4 4.9 6.3 36.4 16 >64 52.4 47.6 39.1 - 56.1 Sulfamethoxazole 10.5 2.1 2.8 84.6 >256 >256 - -Tetracycline 0.0 2.8 33.6 2.8 0.0 0.7 0.0 60.1 >16 >16 39.2 60.8 52.3 - 68.9 Tiamulin 0.7 0.0 3.5 95.8 >32 >32 - -Tilmicosin 0.0 0.0 0.0 0.0 9.1 90.9 >32 >32 - -Trimethoprim 37.1 0.0 0.0 0.7 0.0 0.0 62.2 >16 >16 37.8 62.2 53.8 - 70.2 Trimethoprim/Sulfamethoxazoleb 36.4 0.7 0.0 1.4 0.0 61.5 >4 >4 38.5 61.5 53.0 - 69.5 Tylosin 0.0 0.0 0.0 0.0 0.0 100.0 >4 >4 - -Antimicrobial Streptoccus suis 2020 (n=505) MIC values (µg/mL) MIC MIC S R R CI 0.03125 0.0625 0.125 0.25 0.5 1 2 4 8 16 32 64 128 256 512 1024 (μg/mL) (μg/mL) (%) (%) Amoxicillin/Clavulanic acid 97.8 0.6 0.2 0.8 0.4 0.2 0.0 0.0 0.0 ≤0.25 ≤0.25 - -Ampicillin 96.0 2.0 0.0 0.4 0.2 0.8 0.4 0.0 0.2 0.0 0.0 ≤0.0625 ≤0.0625 98.4 1.6 0.7 – 3.1 Cefepime 99.0 0.6 0.4 0.0 0.0 0.0 0.0 ≤0.5 ≤0.5 - -Ceftiofur 94.7 2.8 0.8 0.8 0.4 0.4 0.2 ≤0.25 ≤0.25 99.0 1.0 0.3 – 2.3 Clindamycin 51.9 0.8 0.2 0.8 1.6 44.8 ≤0.25 >4 - -Enrofloxacin 86.7 12.9 0.2 0.0 0.0 0.2 ≤0.25 0.5 99.6 0.4 0.04 – 1.4 Erythromycin 51.3 2.0 0.4 0.4 0.4 0.4 1.4 43.8 ≤0.125 >8 53.3 46.7 42.3 – 51.2 Florfenicol 97.8 1.8 0.0 0.2 0.2 ≤2 ≤2 97.8 2.2 1.1 – 3.9 Neomycin 9.3 9.3 39.6 41.8 16 >16 - -Oxacillin 68.1 28.9 1.8 0.8 0.2 0.2 0.0 ≤0.25 0.5 - -Penicillin G 89.1 4.2 2.0 2.8 0.6 1.2 0.0 0.2 0.0 0.0 0.0 ≤0.0625 0.125 95.3 4.7 3.1 – 7.0 Sulfamethoxazole 3.4 0.4 0.4 0.0 0.0 0.8 95.0 >512 >512 - -Tetracycline 4.2 5.0 18.6 5.1 1.0 3.8 15.0 47.3 16 >16 9.2 90.8 88.0 – 93.3 Tilmicosin 15.4 35.0 3.8 0.2 45.5 8 >32 - -Trimethoprim/Sulfamethoxazoleb 50.5 1.6 10.5 1.2 13.5 1.8 6.9 2.0 12.1 ≤0.0313 >4 63.8 36.2 32.0 – 40.6 A B C D