Human infection caused by Streptococcus suis serotype 2 in China: report of two cases and epidemic distribution based on sequence type

Abstract

Background: Streptococcus suis is a zoonotic pathogen that causes serious systemic infections in pigs and occupation-related infections in humans who contact with pigs or pork products. In China, it has caused two outbreaks of human infection and surveillance for S.suis has been ongoing since last time. Case presentation: Two cases of meningitis and sepsis caused by S. suis were reported in this study. Both patients work in relation to the pork trade, a risk factor for S. suis infection. The outcome was favorable after a prolonged ceftriaxone therapy but one patient was left with mild hearing loss. Two isolates were identified as sequencing type (ST) 7, S. suis serotype 2 (SS2), which is one the most prevalent and cause two outbreaks in China. Whole-genome sequencing (WGS) revealed that a high degree identity was noted in the genome organizations and sequences between two sporadic ST7 SS2 isolates in this study and representative epidemic virulent isolates. Major differences among them are two sporadic ST7 SS2 isolates lacked a virulence factor called agglutinin receptor and an 89 K pathogenicity island (PAI), which plays important role in the pathogenesis of streptococcal toxic shock syndrome (STSS). A summary about STs of human infection with S. suis in China was completed. The result showed ST1 and ST7 were still the major STs and several novel STs were successfully discovered in different provinces. Conclusions: Our results enhanced the understanding of the ability to cause life-threatening infections in humans and the distribution and evolution of the S. suis in China.

Pathogenicity and drug resistance of animal streptococci responsible for human infections

“…This species is characterized by α-haemolysis on blood agar, and its identification should be based on the MALDI-TOF MS due to the variability of biochemical features. Serological methods and serotyping with the use of multiplex PCR are also in use [156].…”

“…Endocarditis is associated with a mortality of 50 % [173,174]. Deafness or impaired hearing are the most common complications of meningitis [156,158]. Hearing loss is usually irreversible.…”

Streptococcus suis serotype 2 enolase interaction with host brain microvascular endothelial cells and RPSA-induced apoptosis lead to loss of BBB integrity

“…In the case of BMECs, SS2 interaction induces serine/threonine kinase activity that affects the expression of E3 ubiquitin ligase HECTD1, which subsequently increases the degradation of claudin-5, thus enabling SS2 to traverse the BBB [ 6 ]. Once bacteria enter the brain tissue, meningitis is the most serious clinical manifestation of SS2 infection; which is difficult to treat because of the difficulty of delivery of therapeutic drugs to the brain, but also the associated long term sequelse [ 7 ]. The SS virulence factor suilysin may also have a role in inducing BMEC injury, and passage across the BBB to the central nervous system (CNS) [ 8 , 9 ].…”

Transcriptomic Analysis of Streptococcus suis in Response to Ferrous Iron and Cobalt Toxicity

“…In China, two large outbreaks of S. suis infection in humans occurred in 1998 and 2005, leading to 240 cases with 53 deaths in total [6]. More recently, sporadic cases of human infection of S. suis have been reported worldwide [7][8][9][10]. Moreover, it was the most prevalent bacterial pathogen in Chinese pig farms from 2013 to 2017 [11].…”