Phenotypic antimicrobial resistance in Escherichia coli strains isolated from swine husbandries in North Western Germany - temporal patterns in samples from laboratory practice from 2006 to 2017.

BACKGROUND: Since 2011, antibiotic usage has decreased continuously in livestock in Germany. Whether this is accompanied by a reduction in bacterial antimicrobial resistance has not been proven so far. In this study 3054 Escherichia coli (E. coli) isolates from pigs which had suffered from disease on 2161 farms in North Western Germany were evaluated retrospectively from 2006 to 2017 for trends in their antimicrobial resistance pattern. Data were substantially related to the "pre-reduction period" and were therefore suggested as a basis for this task. Minimal inhibitory concentrations for selected antimicrobial substances were evaluated for E. coli strains isolated from different organs of diseased swine sampled for routine diagnostic. In total, 81% of E. coli were isolated from faeces or the gastrointestinal tract, 11% from the genito-urinary tract and 8% from other organs. Susceptibility testing and classification of isolates in accordance with clinical cut-offs followed the Clinical and Laboratory Standards Institute (CLSI). If no clinical cut-offs were available for the respective combination of species, substance and organ, other published clinical cut-offs were used. RESULTS: Differences in susceptibility patterns between isolates from the gastrointestinal and genito-urinary tract were found for most substances. Isolates from the genito-urinary tract were less frequently resistant to ampicillin, apramycin, colistin, neomycin, spectinomycin and tetracycline and more frequently resistant to enrofloxacin and florfenicol. A multifactorial logistic regression model revealed time-dependent decreases in frequency of resistant isolates for neomycin, spectinomycin and tetracycline. For colistin, the highest percentage of resistant isolates with 16.0% was found in 2015 followed by a decrease to the level of 2009-2010 in 2017. A decrease in frequencies of ampicillin-resistant isolates was dependent on the age-group and time period. Irrespective of the year, less than 15% E. coli isolates were resistant to apramycin, cephalosporins, colistin, enrofloxacin, florfenicol, gentamicin and neomycin. CONCLUSION: An overall time-dependent decrease in the percentage of resistant E. coli isolates was found for some substances. These data from diseased animals indicate an impact of a general reduction in antibiotic usage on development of bacterial antimicrobial resistance in the field and can support the decision-making of swine practitioners for treatment options in swine.

Survey of systems for comparative ranking of agents that pose a bioterroristic threat.

Strong efforts are made to improve preparedness for the prevention and counteraction of possible deliberate release of highly pathogenic biological agents at national and international level. An objective risk assessment for highly pathogenic biological agents is urgently needed for the purpose of prioritizing measures, evaluating the vulnerabilities and supporting rapid decisions on a scientific base in case of an emergency. Hitherto, several differing ranking schemes were developed. In general, the purpose of such ranking schemes is a comparative classification of agents under consideration of different transmission paths as well as agents threatening human and/or animal health. The analysed prioritization methods differ from qualitative to (semi-)quantitative with each its benefits and disadvantages in preciseness of the result, complexity and duration of the assessment but also in comprehensibility. Mainly, risk was defined as the product of probability and impact. In this survey, factors frequently used for the assessment of the probability and impact of a deliberate agent release were identified. Main criteria for the probability of an application were the history of use, the accessibility of the agent and possible paths of introduction and contamination as well as the feasibility of agent production. For the estimation of the impact, mainly the agent's effects on human and/or veterinary public health, depending on the target population, were examined. This includes the morbidity and mortality rates as well as the severity of induced illness, possible measures for diagnosis, and treatment and prevention. Furthermore, the economic and socioeconomic consequences were considered. In this review, the authors give an overview on open-source publications dealing with risk ranking of biological agents by outlining the criteria that were applied for risk ranking.