Antimicrobial use in pigs, broilers and veal calves in Belgium

Given the risks associated with antimicrobial resistance and its link with antimicrobial use, available data on antimicrobial use in the Belgian pig, broiler and veal calf production were compared. Allowing for comparison of the data available from three peer-reviewed scientific articles, the unit of measurement for antimicrobial use was the Treatment Incidence (TI), defined as the number of animals per 1000 treated daily with one 'defined' (DDDA) or 'used daily dose animal' (UDDA). Moreover, extrapolation of farm-level data to national-level data was attempted according to the European Surveillance of Veterinary Antimicrobial Consumption (ESVAC) methodology, to estimate the amount of antimicrobials used in Belgium per species. Although, among the three species, the highest TI was observed in veal calves (TIDDDA=414, TIUDDA=379), based on the extrapolation, it was estimated that most antimicrobials were administered to pigs (159.4 tons). Thus, the most rapid decline in the total use could potentially be achieved by targeting the pig sector. During the process of data collection for comparison and calculation, it became obvious that there is a need for harmonized monitoring programs

Clinical resistance and decreased susceptibility in Streptococcus suis isolates from clinically healthy fattening pigs

Streptococcus suis (S. suis) has often been reported as an important swine pathogen and is considered as a new emerging zoonotic agent. Consequently, it is important to be informed on its susceptibility to antimicrobial agents. In the current study, the Minimum Inhibitory Concentration (MIC) population distribution of nine antimicrobial agents has been determined for nasal S. suis strains, isolated from healthy pigs at the end of the fattening period from 50 closed or semiclosed pig herds. The aim of the study was to report resistance based on both clinical breakpoints (clinical resistance percentage) and epidemiological cutoff values (non-wild-type percentage). Non-wild-type percentages were high for tetracycline (98%), lincomycin (92%), tilmicosin (72%), erythromycin (70%), tylosin (66%), and low for florfenicol (0%) and enrofloxacin (0.3%). Clinical resistance percentages were high for tetracycline (95%), erythromycin (66%), tylosin (66%), and low for florfenicol (0.3%) and enrofloxacin (0.3%). For tiamulin, for which no clinical breakpoint is available, 57% of the isolates did not belong to the wild-type population. Clinical resistance and non-wild-type percentages differed substantially for penicillin. Only 1% of the tested S. suis strains was considered as clinically resistant, whereas 47% of the strains showed acquired resistance when epidemiological cutoff values were used. In conclusion, MIC values for penicillin are gradually increasing, compared to previous reports, although pigs infected with strains showing higher MICs may still respond to treatment with penicillin. The high rate of acquired resistance against tiamulin has not been reported before. Results from this study clearly demonstrate that the use of different interpretive criteria contributes to the extent of differences in reported antimicrobial resistance results. The early detection of small changes in the MIC population distribution of isolates, while clinical failure may not yet be observed, provides the opportunity to implement appropriate risk management steps

Antimicrobial resistance profile in faecal Escherichia coli of sows and their offspring in the farrowing unit and their interaction

C

Antimicrobial resistance prevalence of pathogenic and commensal Escherichia coli in food-producing animals in Belgium

In this article, detailed studies on antimicrobial resistance to commensal E. coli (in pigs, meat-producing bovines, broiler chickens and veal calves) and pathogenic E. coli (in pigs and bovines) in Belgium are presented for 2011. Broiler chicken and veal calf isolates of commensal E. coli demonstrated higher antimicrobial resistance prevalence than isolates from pigs and bovines. Fifty percent of E. coli isolates from broiler chickens were resistant to at least five antimicrobials, whereas sixty-one percent of bovine E. coli isolates were susceptible to all antimicrobials tested. On the other hand, bovine pathogenic E. coli isolates showed an extended resistance profile with more than half of the isolates being resistant to ten or more antimicrobials. The results are not significantly different from the results from previously published studies on commensal bacteria in pigs in Belgium, although different methodologies of sampling and susceptibility testing were used

Relation between antimicrobial use and resistance in Belgian pig herds

The aim of this study was to determine the link between the characteristics of antimicrobial therapy and occurrence of antimicrobial resistance in Escherichia coli of clinically healthy pigs exposed to antimicrobial treatments. A total of 918 Escherichia coli isolates were obtained from faecal samples, collected from 50 pig herds at the end of the fattening period and susceptibility was tested towards 15 different antimicrobial agents, using the disk diffusion method

Effect of antimicrobial consumption and production type on antibacterial resistance in the bovine respiratory and digestive tract

The aim of this study was to investigate the relationship between antimicrobial use and the occurrence of antimicrobial resistance in the digestive and respiratory tract in three different production systems of food producing animals. A longitudinal study was set up in 25 Belgian bovine herds (10 dairy, 10 beef, and 5 veal herds) for a 2 year monitoring of antimicrobial susceptibilities in E. coli and Pasteurellaceae retrieved from the rectum and the nasal cavity, respectively. During the first year of observation, the antimicrobial use was prospectively recorded on 15 of these farms (5 of each production type) and transformed into the treatment incidences according to the (animal) defined daily dose (TIADD) and (actually) used daily dose (TIUDD). Antimicrobial resistance rates of 4,174 E. coli (all herds) and 474 Pasteurellaceae (beef and veal herds only) isolates for 12 antimicrobial agents demonstrated large differences between intensively reared veal calves (abundant and inconstant) and more extensively reared dairy and beef cattle (sparse and relatively stable). Using linear mixed effect models, a strong relation was found between antimicrobial treatment incidences and resistance profiles of 1,639 E. coli strains (p< 0.0001) and 309 Pasteurellaceae (p <= 0.012). These results indicate that a high antimicrobial selection pressure, here found to be represented by low dosages of oral prophylactic and therapeutic group medication, converts not only the commensal microbiota from the digestive tract but also the opportunistic pathogenic bacteria in the respiratory tract into reservoirs of multi-resistance

Correlation between veterinary antimicrobial use and antimicrobial resistance in food-producing animals: a report on seven countries

Objectives: To evaluate correlations between antimicrobial use and the prevalence of resistance in commensal Escherichia coli isolates from pigs, poultry and cattle, using data from publicly available national or international reports from seven European countries. Methods: The link between the quantities of different classes of antimicrobials administered to food-producing animals per country(expressed in mg/population correction unit) and the prevalence of resistance to the different antimicrobial classes (interpreted by EUCAST epidemiological cut-off values) in E. coli isolates (4831 isolates in total) was assessed by means of polynomial regression analysis and determination of Spearman's rank correlation coefficient. Results: A quadratic regression best fitted the antimicrobial use and antimicrobial resistance data. The coefficient of determination was, in decreasing order, 0.99 for fluoroquinolones and amphenicols, 0.94 for third-generation cephalosporins and sulphonamides, 0.93 for aminopenicillins, 0.86 for fluoroquinolones, 0.81 for streptomycin and 0.80 for gentamicin and tetracycline. Spearman's rank correlation coefficient was 1 for amphenicols, 0.96 for sulphonamides, 0.93 for streptomycin and tetracycline, 0.89 for aminopenicillins, 0.71 for gentamicin and 0.70 for third-generation cephalosporins. Conclusions: These remarkably high coefficients indicate that, at a national level, the level of use of specific antimicrobials strongly correlates to the level of resistance towards these agents in commensal E. coli isolates in pigs, poultry and cattle. However, data restraints reveal the need for further detail in collection and harmonization of antimicrobial resistance and use data in Europe

Antimicrobial resistance in E. coli isolated from lettuce, irrigation water and soil

Introduction: Fresh vegetables normally carry natural non-pathogenic epiphytic microorganisms, but during growth, and harvest, the produce might become contaminated with antibiotic resistant pathogens or commensals from animal and human sources. The contamination of produce by resistant bacteria can occur in the field by contaminated soil, by exposure to contaminated water (such as crop irrigation, application of pesticides or flooding) or by deposition of feces by livestock or wild animals. In this study was investigated whether lettuce or its production environment (irrigation water, soil) was able to act as a vector or reservoir of antimicrobial resistant E. coli. Materials and Methods: Over a one year period, eight lettuce farms were visited on multiple times and a total of 738 samples among which lettuce seedlings (leaves and soil), soil, irrigation water and lettuce crops were collected. From these samples, 473 isolates of Escherichia coli were obtained and tested for resistance against 14 antimicrobials. Results: A total of 54 isolates (11.4%) were resistant to one or more antimicrobials. The highest resistance rate was observed for ampicillin (7%), followed by cephalothin, amoxicillin/clavulanic acid, tetracycline, trimethoprim and streptomycin with resistance rates between 4.4 % and 3.6 %. No resistance was observed for amikacin, ciprofloxacin, gentamicin and kanamycin. One isolate showed resistance for cefotaxim. Among the multi-resistant isolates (n = 37), ampicillin and cephalothin showed the highest resistance rate, respectively 76 % and 52 %. The E. coli isolated from the lettuce showed higher resistance rates compared to E. coli isolates obtained from the soil or irrigation water samples. Discussion: Because fresh produce (such as lettuce) is directly consumed without further microbial inactivation treatment, it may directly contribute to the human exposure of antimicrobial resistant bacteria. The study emphasizes the need for ‘good agricultural practices’ to keep the fecal contamination and E. coli levels low and thus not only reducing the probability of exposure to human zoonotic pathogens but also to the exposure of antimicrobial resistant commensal E. coli. The percentage of multi-resistance to antibiotics occurring among the E. coli isolates in the present study was lower compared to other publications involving E. coli isolates from a variety of animal species (Casteleyn et al., 2006; Persoons et al., 2010). The antimicrobial resistance patterns suggested cattle as the main source for commensal resistant E. coli contamination as the presence of resistance and resistance patterns with animal profiles were the most comparable with what is found in cattle