Oliver Amb, Pomroy W E, Leathwick D M
a Animal Health, AgResearch Grasslands , Private Bag 11008, Palmerston North 4442 , New Zealand.
b Institute for Veterinary, Animal and Biomedical Science , Massey University , Private Bag 11222, Palmerston North 4442 , New Zealand.
N Z Vet J. 2016 Jul;64(4):201-6. doi: 10.1080/00480169.2016.1149117. Epub 2016 Feb 22.
To determine the prevalence of benzimidazole resistance in Nematodirus spathiger and N. filicollis from a sample of New Zealand farms.
The efficacy of albendazole (ABZ) against Nematodirus spp. was assessed by faecal nematode egg count reduction (FECR) tests undertaken in lambs aged 3-8 months old on 27 sheep farms throughout New Zealand. On each farm, groups of 10-16 lambs were either treated with ABZ (4.75 mg/kg) or remained as untreated controls. Faecal samples were collected from all animals at the time of treatment and 7-10 days later. Faecal nematode egg counts (FEC) were performed using a modified McMaster technique. Larvae were cultured from pooled faecal samples, collected 7-10 days after treatment from each group, by incubation at 20°C for 6 weeks, 4°C for 26 weeks then 13°C for 2 weeks. The resulting third stage larvae were identified to species using a multiplex PCR assay, that identified species-specific sequences in the second internal transcribed spacer region of ribosomal DNA. The efficacy of ABZ for N. spathiger and N. filicollis was calculated from the proportion of the two species in culture and the group mean FEC before and after treatment. Only farms with a mean of 10 epg for each species in untreated samples were included for analysis. Resistance was defined as an efficacy <95%.
On farms that met the threshold of 10 epg in faecal samples, benzimidazole resistance was found on 20/21 (95%) farms for N. spathiger compared with 4/10 (40%) farms for N. filicollis (p<0.05). In samples collected following treatment, a mean of 83 (min 46, max 100)% of Nematodirus spp. larvae recovered from the untreated groups were N. spathiger, compared with 94 (min 45, max 100)% in the ABZ treated groups (p=0.03). This change in percentage was not influenced by the overall efficacy of treatment based on the FECR test (p=0.324).
The results confirm the high level of resistance in N. spathiger in New Zealand and that benzimidazole resistance was more common in N. spathiger than N. filicollis. While resistance to benzimidazole anthelmintics has been reported previously in New Zealand, this is the first report of N. filicollis being resistant to benzimidazole anthelmintics.
确定来自新西兰农场样本中的斯氏细颈线虫和丝状细颈线虫对苯并咪唑的耐药率。
通过在新西兰27个养羊场对3至8月龄羔羊进行粪便线虫虫卵计数减少（FECR）试验，评估阿苯达唑（ABZ）对细颈线虫属的疗效。在每个农场，将10 - 16只羔羊分为两组，一组用ABZ（4.75 mg/kg）治疗，另一组作为未治疗的对照。在治疗时和7 - 10天后从所有动物采集粪便样本。使用改良的麦克马斯特技术进行粪便线虫虫卵计数（FEC）。从每组治疗后7 - 10天收集的混合粪便样本中培养幼虫，在20°C孵育6周，4°C孵育26周，然后13°C孵育2周。使用多重PCR检测法将所得的第三期幼虫鉴定到种，该检测法可鉴定核糖体DNA第二内部转录间隔区中的种特异性序列。根据培养物中这两个种的比例以及治疗前后的组平均FEC计算ABZ对斯氏细颈线虫和丝状细颈线虫的疗效。仅将未治疗样本中每个种平均虫卵数为10 epg的农场纳入分析。耐药性定义为疗效<95%。
在粪便样本达到10 epg阈值的农场中，斯氏细颈线虫在20/21（95%）的农场中出现苯并咪唑耐药，而丝状细颈线虫在4/10（40%）的农场中出现耐药（p<0.05）。在治疗后采集的样本中，从未治疗组回收的细颈线虫属幼虫平均83%（最小值46%，最大值100%）为斯氏细颈线虫，而在ABZ治疗组中为94%（最小值45%，最大值100%）（p = 0.03）。基于FECR试验，这种百分比变化不受治疗总体疗效的影响（p = 0.324）。
结果证实新西兰斯氏细颈线虫的耐药水平很高，且苯并咪唑耐药在斯氏细颈线虫中比在丝状细颈线虫中更常见。虽然此前在新西兰已报道过对苯并咪唑驱虫药的耐药性，但这是丝状细颈线虫对苯并咪唑驱虫药耐药的首次报道。
