Surveillance of antimicrobial resistance in clinical isolates of Pasteurella multocida and Streptococcus suis from Ontario swine.

Susceptibility results for Pasteurella multocida and Streptococcus suis isolated from swine clinical samples were obtained from January 1998 to October 2010 from the Animal Health Laboratory at the University of Guelph, Guelph, Ontario, and used to describe variation in antimicrobial resistance (AMR) to 4 drugs of importance in the Ontario swine industry: ampicillin, tetracycline, tiamulin, and trimethoprim-sulfamethoxazole. Four temporal data-analysis options were used: visualization of trends in 12-month rolling averages, logistic-regression modeling, temporal-scan statistics, and a scan with the "What's strange about recent events?" (WSARE) algorithm. The AMR trends varied among the antimicrobial drugs for a single pathogen and between pathogens for a single antimicrobial, suggesting that pathogen-specific AMR surveillance may be preferable to indicator data. The 4 methods provided complementary and, at times, redundant results. The most appropriate combination of analysis methods for surveillance using these data included temporal-scan statistics with a visualization method (rolling-average or predicted-probability plots following logistic-regression models). The WSARE algorithm provided interesting results for quality control and has the potential to detect new resistance patterns; however, missing data created problems for displaying the results in a way that would be meaningful to all surveillance stakeholders.

Les résultats de sensibilité pour des isolats de Pasteurella multocida et Streptococcus suis provenant d'échantillons cliniques de porcs furent obtenus du Animal Health Laboratory de l'Université de Guelph pour la période de janvier 1998 à octobre 2010, et utilisés pour décrire la variation dans la résistance antimicrobienne (AMR) à quatre antibiotiques d'importance dans l'industrie porcine en Ontario : l'ampicilline, la tétracycline, la tiamuline, et le trimethoprime-sulfaméthoxazole. Quatre options temporelles d'analyse des données ont été utilisées : visualisation des tendances des moyennes mobiles de 12 mois, modélisation de régression logistique, statistiques d'un scan temporel, et un scan avec l'algorithme «Qu'y a-t-il d'étrange avec des évènements récents?¼ (WSARE). Les tendances d'AMR variaient entre les antibiotiques pour un agent pathogène et entre les agents pathogènes pour un antibiotique unique, ce qui suggère que la surveillance AMR pour un agent pathogène spécifique serait préférable à des données indicatrices. Les quatre méthodes ont fourni des données complémentaires, et parfois des résultats redondants. La combinaison la plus appropriée de méthodes d'analyse pour la surveillance en utilisant ces données incluait les statistiques d'un scan temporel avec une méthode de visualisation (moyenne mobile ou graphes de probabilité prédite suite à des modèles de régression logistique). L'algorithme WSARE a fourni des résultats intéressants pour le contrôle de qualité et a le potentiel de détecter des nouveaux patrons de résistance; toutefois, des données manquantes ont causé des problèmes pour montrer les résultats d'une manière qui serait signifiante pour toutes les personnes concernées par la surveillance.(Traduit par Docteur Serge Messier).

Characteristics of drug use on sheep farms in Ontario, Canada.

This study examined characteristics of the use of drugs, especially antimicrobials, on Ontario sheep farms. Forty-nine sheep farms participated in a 12-month prospective study. Producers documented treatment events during the study period and drug use data from the records were summarized. The most frequently used drugs of the 15 drug categories used by producers belonged to the following categories: antimicrobial (40.7%, n=2710), vitamin/mineral (12.0%), and biological (11.1%). Short-acting penicillin (27.2%, n=1103), long-acting oxytetracycline (22.9%), and long-acting penicillin (21.9%) were the most frequently used antimicrobials. The drugs that were used most frequently on sheep farms were antimicrobials, of which 93% of treatments were extra-label. Extensive extra-label drug use may be the result of the limited number of drugs that are approved in Canada for use in sheep.

Antimicrobial resistance: its emergence and transmission.

New concepts have emerged in the past few years that help us to better understand the emergence and spread of antimicrobial resistance (AMR). These include, among others, the discovery of the mutator state and the concept of mutant selection window for resistances emerging primarily through mutations in existing genes. Our understanding of horizontal gene transfer has also evolved significantly in the past few years, and important new mechanisms of AMR transfer have been discovered, including, among others, integrative conjugative elements and ISCR (insertion sequences with common regions) elements. Simultaneously, large-scale studies have helped us to start comprehending the immense and yet untapped reservoir of both AMR genes and mobile genetic elements present in the environment. Finally, new PCR- and DNA sequencing-based techniques are being developed that will allow us to better understand the epidemiology of classical vectors of AMR genes, such as plasmids, and to monitor them in a more global and systematic way.