Hernandez-Garcia Juan, Wang Jinhong, Restif Olivier, Holmes Mark A, Mather Alison E, Weinert Lucy A, Wileman Thomas M, Thomson Jill R, Langford Paul R, Wren Brendan W, Rycroft Andrew, Maskell Duncan J, Tucker Alexander W
Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge, CB3 0ES, UK.
SAC Consulting: Veterinary Services, Bush State, Penicuik, EH26 0QE, Scotland, UK.
Vet Microbiol. 2017 Aug;207:117-124. doi: 10.1016/j.vetmic.2017.06.002. Epub 2017 Jun 13.
Antimicrobial resistance in Streptococcus suis, a global zoonotic pathogen of pigs, has been mostly studied only in diseased animals using surveys that have not evaluated changes over time. We compared patterns of resistance between S. suis isolates from clinical cases of disease (CC) and non-clinical case (NCC) pigs in England, collected over two discrete periods, 2009-2011 and 2013-2014. Minimum inhibitory concentrations (MIC) of 17 antimicrobials (nine classes) were determined on 405 S. suis isolates categorised by sampling period and disease association to assess changes in resistance over time and association with disease. First, isolates were characterized as resistant or susceptible using published clinical breakpoints. Second, epidemiological cut-offs (ECOFF) were derived from MIC values, and isolates classified as wild type (WT) below the ECOFF and non-wild type (NWT) above the ECOFF. Finally, isolate subsets were analysed for shifts in MIC distribution. NCC isolates were more resistant than CC isolates to cephalosporins, penams, pleuromutilins, potentiated sulphonamides and tetracyclines in both study periods. Resistance levels among CC isolates increased in 2013-2014 relative to 2009-2011 for antimicrobials including aminoglycosides, cephalosporins, fluoroquinolones, pleuromutilins, potentiated sulphonamides and tetracyclines. The prevalence of isolates categorised as NWT for five or more classes of antimicrobials was greater among NCC than CC isolates for both time periods, and increased with time. This study used standardised methods to identify significant shifts in antimicrobial resistance phenotypes of S. suis isolated from pigs in England, not only over time but also between isolates from known clinical cases or disease-free pigs.
猪链球菌是一种全球范围内感染猪的人畜共患病原体，目前对其耐药性的研究大多仅针对患病动物，且相关调查未评估随时间的变化情况。我们比较了在两个不同时间段（2009 - 2011年和2013 - 2014年）收集的英格兰临床病例（CC）猪和非临床病例（NCC）猪的猪链球菌分离株之间的耐药模式。对405株猪链球菌分离株测定了17种抗菌药物（九类）的最低抑菌浓度（MIC），这些分离株按采样时间和疾病关联进行分类，以评估耐药性随时间的变化以及与疾病的关联。首先，使用已发表的临床断点将分离株表征为耐药或敏感。其次，从MIC值推导出流行病学临界值（ECOFF），ECOFF以下的分离株分类为野生型（WT），ECOFF以上的分离株分类为非野生型（NWT）。最后，分析分离株亚组的MIC分布变化。在两个研究时间段内，NCC分离株对头孢菌素、青霉素类、截短侧耳素类、增效磺胺类和四环素类的耐药性均高于CC分离株。相对于2009 - 2011年，2013 - 2014年CC分离株中包括氨基糖苷类、头孢菌素类、氟喹诺酮类、截短侧耳素类、增效磺胺类和四环素类在内的抗菌药物耐药水平有所增加。在两个时间段内，NCC分离株中被分类为对五类或更多类抗菌药物呈NWT的分离株患病率均高于CC分离株，且随时间增加。本研究采用标准化方法，不仅确定了随时间推移，而且确定了来自已知临床病例或无病猪的分离株之间，英格兰猪源猪链球菌抗菌药物耐药表型的显著变化。
