Kittang Bård Reiakvam, Pettersen Veronika Kuchařová, Oppegaard Oddvar, Skutlaberg Dag Harald, Dale Håvard, Wiker Harald G, Skrede Steinar
Department of Medicine, Haraldsplass Deaconess Hospital, Bergen, Norway.
The Gade Research Group for Infection and Immunity, Department of Clinical Science, University of Bergen, Bergen, Norway.
BMC Infect Dis. 2017 Feb 15;17(1):147. doi: 10.1186/s12879-017-2262-7.
Streptococcus equi subsp. zooepidemicus is a beta-hemolytic group C streptococcus mainly causing infections in domesticated animals. Here we describe the first case of zoonotic necrotizing myositis caused by this bacterium.
The patient was a 73-year-old, previously healthy farmer with two asymptomatic Shetland ponies in his stable. After close contact with the ponies while feeding them, he rapidly developed erythema of his left thigh and sepsis with multiple organ failure. The clinical course was severe and complicated, requiring repetitive surgical excision of necrotic muscle, treatment with vasopressors, mechanical ventilation and continuous venovenous hemofiltration, along with adjunctive hyperbaric oxygen therapy. The patient was discharged from hospital at day 30, without obvious sequelae. The streptococcal isolate was identified as Streptococcus equi by MALDI-ToF MS, and was later assigned subspecies identification as S. equi subsp. zooepidemicus. Multilocus sequence typing identified the strain as a novel sequence type (ST 364), closely related to types previously identified in horses and cattle. A focused proteomic analysis revealed that the ST 364 expressed putative virulence factors similar to that of Streptococcus pyogenes, including homologues of the M protein, streptodornases, interleukin 8-protease and proteins involved in the biosynthesis of streptolysin S.
This case illustrates the zoonotic potential of S. equi subsp. zooepidemicus and the importance of early clinical recognition, rapid and radical surgical therapy, appropriate antibiotics and adequate supportive measures when necrotizing soft tissue infection is suspected. The expression of Streptococcus pyogenes-like putative virulence determinants in ST 364 might partially explain the fulminant clinical picture.
马链球菌兽疫亚种是一种β溶血性C群链球菌，主要引起家畜感染。在此，我们描述了首例由该细菌引起的人兽共患坏死性肌炎病例。
患者为一名73岁、既往健康的农民，其马厩中有两匹无症状的设得兰矮种马。在喂马时与其密切接触后，他很快出现左大腿红斑并伴有败血症及多器官功能衰竭。临床过程严重且复杂，需要反复手术切除坏死肌肉，使用血管升压药、机械通气和持续静脉-静脉血液滤过治疗，同时辅助高压氧治疗。患者于第30天出院，无明显后遗症。通过基质辅助激光解吸电离飞行时间质谱（MALDI-ToF MS）鉴定该链球菌分离株为马链球菌，随后确定其亚种为马链球菌兽疫亚种。多位点序列分型确定该菌株为一种新的序列类型（ST 364），与先前在马和牛中鉴定的类型密切相关。一项针对性的蛋白质组学分析显示，ST 364表达的假定毒力因子与化脓性链球菌相似，包括M蛋白、链道酶、白细胞介素8蛋白酶的同源物以及参与链球菌溶血素S生物合成的蛋白质。
该病例说明了马链球菌兽疫亚种的人兽共患潜力，以及在怀疑坏死性软组织感染时早期临床识别、快速彻底的手术治疗、适当的抗生素和充分的支持措施的重要性。ST 364中化脓性链球菌样假定毒力决定因素的表达可能部分解释了其暴发性临床表现。
