Hatrongjit Rujirat, Kerdsin Anusak, Gottschalk Marcelo, Takeuchi Dan, Hamada Shigeyuki, Oishi Kazunori, Akeda Yukihiro
Faculty of Science and Engineering, Kasetsart University Chalermphrakiat Sakon Nakhon Province Campus, Muang, Sakon Nakhon Province, 47000, Thailand.
National Institute of Health, Department of Medical Sciences, Ministry of Public Health, Tiwanon Road, Muang, Nonthaburi Province, 11000, Thailand.
BMC Infect Dis. 2015 Sep 30;15:392. doi: 10.1186/s12879-015-1136-0.
Streptococcus suis is a zoonotic pathogen that causes invasive infections in humans and pigs. It has been reported that S. suis infection in humans is mostly caused by serotype 2. However, human cases caused by other serotypes have rarely been reported. This is the first report of a human case of infection with S. suis serotype 31 in Thailand.
A 55-year-old male alcohol misuser with liver cirrhosis was admitted with sepsis to a hospital in the Central Region of Thailand. He had consumed a homemade, raw pork product prior to the onset of illness. He was alive after treatment with ceftriaxone and no complication occurred. An isolate from blood culture at the hospital was suspected as viridans group Streptococcus. It was confirmed at a reference laboratory as S. suis serotype 31 by biochemical tests, 16S rDNA sequencing, and multiplex polymerase chain reaction for serotyping, but it was untypable by the co-agglutination test with antisera against recognized S. suis serotypes, suggesting loss of capsular material. The absence of a capsule was confirmed by transmission electron microscopy. The isolate was confirmed to be sequence type 221, with 13 putative virulence genes that are usually found in serotype 2 strains.
We should be aware of the emergence of S. suis infections caused by uncommon serotypes in patients with predisposing conditions. Laboratory capacity to identify S. suis in the hospital is needed in developing countries, which can contribute to enhanced surveillance, epidemiological control, and prevention strategies in the prevalent area.
猪链球菌是一种人畜共患病原体，可导致人类和猪发生侵袭性感染。据报道，人类感染猪链球菌主要由2型引起。然而，由其他血清型引起的人类病例鲜有报道。这是泰国首例人类感染31型猪链球菌病例的报告。
一名55岁的男性酒精滥用者，患有肝硬化，因败血症入住泰国中部地区的一家医院。他在发病前食用了自制的生猪肉制品。经头孢曲松治疗后存活，未出现并发症。医院血培养分离出的菌株疑似为草绿色链球菌群。经参考实验室通过生化试验、16S rDNA测序和用于血清分型的多重聚合酶链反应确认为31型猪链球菌，但用针对公认猪链球菌血清型的抗血清进行协同凝集试验无法分型，提示荚膜物质缺失。通过透射电子显微镜证实无荚膜。该分离株被确认为序列型221，具有13个通常在2型菌株中发现的假定毒力基因。
我们应警惕在有易感因素的患者中出现由不常见血清型引起的猪链球菌感染。发展中国家的医院需要具备鉴定猪链球菌的实验室能力，这有助于加强流行地区的监测、流行病学控制和预防策略。
