Streptococcus suis: a re-emerging pathogen associated with occupational exposure to pigs or pork products. Part II - Pathogenesis

• Published in: Annals of Agricultural and Environmental Medicine 2018-03, Vol.25 (1), p.186-203
• Main Authors: Dutkiewicz, Jacek, Zając, Violetta, Sroka, Jacek, Wasiński, Bernard, Cisak, Ewa, Sawczyn, Anna, Kloc, Anna, Wójcik-Fatla, Angelina
• Format: Article
• Language: English
• Subjects: Agricultural Workers' Diseases - microbiology; Animals; Astrocytes; biofilm formation; Biofilms; Blood-brain barrier; Capsular polysaccharides; Cell activation; Central nervous system; Cerebrospinal fluid; Cloning; Cochlea; Colonization; Cytokines; Deafness; Dendritic cells; Environmental stress; Genomes; genomic determinants of pathogenicity; Hogs; Humans; infection stages; Inflammation; interaction with host cells and tissues; Leukocytes; Lymphocytes; Meningitis; Microglia; Mucosa; Occupational exposure; Occupational Exposure - adverse effects; pathogenesis; Pathogenicity; Pathogens; Phagocytosis; Pork; Streptococcal Infections - microbiology; Streptococcal Infections - transmission; Streptococcus infections; Streptococcus suis; Streptococcus suis - genetics; Streptococcus suis - isolation & purification; Streptococcus suis - pathogenicity; Streptococcus suis - physiology; Swine; Swine Diseases - microbiology; Transcription factors; Translocation; Virulence; Virulence factors; Virulence Factors - genetics; Virulence Factors - metabolism; Zoonoses; Zoonoses - microbiology; Zoonoses - transmission
• ISSN: 1232-1966; 1898-2263
• DOI: 10.26444/aaem/85651

is a re-emerging zoonotic pathogen that may cause severe disease, mostly meningitis, in pigs and in humans having occupational contact with pigs and pork, such as farmers, slaughterhose workers and butchers. The first stage of the pathogenic process, similar in pigs and humans, is adherence to and colonisation of mucosal and/or epithelial surface(s) of the host. The second stage is invasion into deeper tissue and extracellular translocation of bacterium in the bloodstream, either free in circulation or attached to the surface of monocytes. If present in blood fails to cause fatal septicaemia, it is able to progress into the third stage comprising penetration into host's organs, mostly by crossing the blood-brain barrier and/or blood-cerebrospinal fluid barrier to gain access to the central nervous system (CNS) and cause meningitis. The fourth stage is inflammation that plays a key role in the pathogen esis of both systemic and CNS infections caused by . The pathogen may induce the overproduction of pro-inflammatory cytokines that cause septic shock and/or the recruitment and activation of different leukocyte populations, causing acute inflammation of the CNS. can also evoke - through activation of microglial cells, astrocytes and possibly other cell types - a fulminant inflammatory reaction of the brain which leads to intracranial complications, including brain oedema, increased intracranial pressure, cerebrovascular insults, and deafness, as a result of cochlear sepsis. In all stages of the pathogenic process, interacts with many types of immunocompetent host's cells, such as polymorphonuclear leukocytes, mononuclear macrophages, lymphocytes, dendritic cells and microglia, using a range of versatile virulence factors for evasion of the innate and adaptive immune defence of the host, and for overcoming environmental stress. It is estimated that produces more than 100 different virulence factors that could be classified into 4 groups: surface components or secreted elements, enzymes, transcription factors or regulatory systems and transporter factors or secretion systems. A major virulence factor is capsular polysaccharide (CPS) that protects bacteria from phagocytosis. However, it hampers adhesion to and invasion of host's cells, release of inflammatory cytokines and formation of the resistant biofilm which, in many cases, is vital for the persistence of bacteria. It has been demonstrated that the arising by mutation unencapsulated clones, which are more s