Sydney School of Veterinary Science, The University of Sydney, Camperdown NSW, Australia.
School of Veterinary Science, Massey University, Palmerston North, New Zealand.
PLoS One. 2022 Mar 3;17(3):e0264582. doi: 10.1371/journal.pone.0264582. eCollection 2022.
Hypervirulent Klebsiella pneumoniae infection causes significant mortality of endangered New Zealand sea lion pups at Enderby Island, Auckland Islands. Gross necropsy and histopathology findings are well reported, but little is known about the clinical course of disease in affected pups. To determine factors feasible as clinical screening tools for hypervirulent K. pneumoniae in live pups, 150 pups over two field seasons (2016-18) were recruited shortly after birth for a prospective cohort study. A randomised controlled clinical treatment trial with the anthelmintic ivermectin was conducted concurrently and risk factor data and biological samples were collected approximately fortnightly. Treatment with ivermectin has been demonstrated to reduce the risk of hypervirulent K. pneumoniae mortality in pups, so effects on clinical parameters between the treated and control cohorts were also investigated. A broader sample of pups were monitored for clinical signs to investigate the course of disease in affected pups. Clinical signs, haematology and oral and rectal swabs to detect gastrointestinal carriage of hypervirulent K. pneumoniae were not useful for detection of disease prior to death. Of those pups that died due to hypervirulent K. pneumoniae, only 26.1% (18/69) had any clinical signs prior, likely a reflection of the peracute course of disease. On comparison of haematological parameters between ivermectin-treated and control pups, significantly lower total plasma protein and higher eosinophil counts were seen in control versus treated pups, however standard length as a surrogate for age was a more important influence on parameters overall than ivermectin treatment. This study also highlighted a cohort of pups with severe clinical signs suggestive of hypervirulent K. pneumoniae infection were lost to follow up at the end of the monitored season, which could be contributing to cryptic juvenile mortality.
高毒力肺炎克雷伯菌感染导致奥克兰群岛恩德比岛濒危新西兰海狮幼崽大量死亡。大体剖检和组织病理学发现已有详细报道，但对于受感染幼崽的疾病临床过程知之甚少。为了确定作为活幼崽中高毒力肺炎克雷伯菌临床筛查工具可行的因素，在两个野外季节（2016-18 年）中，在幼崽出生后不久招募了 150 只幼崽进行前瞻性队列研究。同时进行了随机对照临床试验，用驱虫药伊维菌素进行治疗，并定期收集风险因素数据和生物样本。伊维菌素治疗已被证明可降低幼崽感染高毒力肺炎克雷伯菌的死亡率，因此还研究了治疗组和对照组之间的临床参数的影响。对更广泛的幼崽监测临床症状，以调查受感染幼崽的疾病过程。在死亡前，临床症状、血液学检查以及口腔和直肠拭子检测高毒力肺炎克雷伯菌的胃肠道携带情况对于疾病的检测均无帮助。死于高毒力肺炎克雷伯菌的幼崽中，只有 26.1%（18/69）在死亡前有任何临床症状，这可能反映了疾病的超急性病程。在伊维菌素治疗组和对照组幼崽的血液学参数比较中，对照组幼崽的总血浆蛋白明显较低，嗜酸性粒细胞计数较高，但标准长度作为年龄的替代指标对参数的影响总体上比伊维菌素治疗更为重要。本研究还突出了一组具有严重临床症状的幼崽，这些幼崽提示存在高毒力肺炎克雷伯菌感染，但在监测季节结束时失去了随访，这可能导致隐匿性幼崽死亡。
