Streptococcus suis (ex Elliot 1966, Kilpper-Bälz & Schleifer 1987) is a facultatively anaerobic Gram-positive ovoid or coccal bacterium surrounded by a polysaccharide capsule. Based on the antigenic diversity of the capsule, S. suis strains are classified serologically into 35 serotypes....

Streptococcus suis 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 S. suis 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 S. suis. 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. Streptococcus suis 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, S. suis 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 S. suis 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 S. suis clones, which are more successful in penetration to and propagation within the host's cells, may coexist in the organism of a single host together with those that are encapsulated. Both 'complementary' clones assist each other in the successful colonization of host's tissues and persistence therein. S. suis has an open pan-genome characterized by a frequent gene transfer and a large diversity. Of the genetic determinants of S. suis pathogenicity, the most important are pathogenicity islands (PAI), in particular, a novel DNA segment of 89 kb length with evident pathogenic traits that has been designated as 89K PAI. It has been estimated that more than one-third of the S. suis virulence factors is associated with this PAI. It has been proved that the virulent S. suis strains possess smaller genomes, compared to avirulent ones, but more genes associated with virulence. Overall, the evolution of the species most probably aims towards increased pathogenicity, and hence the most significant task of the current research is an elaboration of a vaccine, efficient both for humans and pigs.

[i]Spiroplasma[/i] is a genus of wall-less, low-GC, small Gram-positive bacteria of the internal contractile cytoskeleton, with helical morphology and motility. The genus is classified within the class Mollicutes. [i]Spiroplasma[/i] / host interactions can be classified as commensal, pathogenic...

Occurrence of co-infections with various pathogens in ixodid ticks creates a risk of increased severity of tick-borne diseases in humans and animals exposed to bite of the ticks carrying multiple pathogens. Accordingly, co-infections in ticks were subject of numerous analyses, but almost...

A total of 853 questing Ixodes ricinus males, females, and nymphs and of 582 questing Dermacentor reticulatus males and females were collected from vegetation on the territory of the Lublin province (eastern Poland). The ticks were examined for the presence of Babesia by PCR detecting part of 18S ribosomal RNA (rRNA) gene and nuclear small subunit rRNA (SS-rDNA) for determining of Babesia spp. and Babesia microti, respectively. The overall incidence of Babesia strains in I. ricinus ticks was 4.6 %. Three species of Babesia were identified. The prevalent species was B. microti which occurred in 2.8 % of ticks, while Babesia venatorum, Babesia divergens, and unidentified Babesia species were found at the frequency of 1.2, 0.2, and 0.3 %, respectively. Altogether, B. microti constituted 61.5 % of the total strains detected in I. ricinus, B. venatorum—25.7 %, B. divergens—5.1 %, and unidentified Babesia species—7.7 %. The prevalence of Babesia species in I. ricinus did not depend significantly on locality (χ ² = 1.885, P = 0.390) nor on the tick stage (χ ² = 4.874, P = 0.087). The incidence of Babesia strains in D. reticulatus ticks was 2.7 %. Two species of Babesia were identified. Again, the prevalent species was B. microti which occurred in 2.1 % of ticks, while B. canis was found in 0.7 % of ticks. In one D. reticulatus female, B. canis and B. microti co-infection was found. Altogether, B. microti constituted 75 % of the total strains detected in D. reticulatus while B. canis formed 25 % of the total strains. The frequency of the occurrence of Babesia species in D. reticulatus did not depend significantly on locality (χ ² = 0.463, P = 0.793). The difference between the prevalence of Babesia in males and females of D. reticulatus was insignificant (P = 0.0954); nymphs were not found. The dominance of B. microti in the species composition of tick-borne Babesia found in this study was typical for eastern Europe. In conclusion, the results revealed that the population inhabiting the forested area of eastern Poland could be exposed to Babesia parasites, especially to those from the species B. microti, by a bite of I. ricinus, a competent vector of human babesiosis, and probably also by a bite of D. reticulatus whose role in the transmission of human babesiosis needs to be clarified.

Objective: The aim of the present work was to determine the presence of various rickettsiae and protozoan in raw milk and the assessment the potential, milk-borne route in the spread of selected zoonotic pathogens. Materials: A total of 119 raw milk samples collected randomly from 63 cows, 29 goats, and 27 sheep bred on 34 farms situated on eight communities in eastern Poland were examined by polymerase chain reaction (PCR) method for the presence of pathogenic rickettsiae (Coxiella burnetii, Anaplasma phagocytophilum, and Rickettsia spp.) and protozoan (Toxoplasma gondii). Results: The only prevalent pathogen was T. gondii, which was found in 10 samples of cow milk (15.9%), in one sample of goat milk (3.4%), and in one sample of sheep milk (3.7%). One sample of cow milk was positive for C. burnetii; however, the sequence analysis did not confirm any species of Coxiella or Coxiella-like organisms, but showed 100% homology to Psychrobacter alimentarius. None of the examined samples showed the presence of A. phagocytophilum or Rickettsia spp. Conclusions: The results of this study suggest a potential hazard of milk-borne Toxoplasma infection, mostly by consumption of raw cow milk. The milk-borne spread seems to be limited or nonsignificant in the case of C. burnetii, A. phagocytophilum, and Rickettsia spp. The false-positive sample for Coxiella spp. suggests that some care should be taken in the interpretation of the results obtained by using the PCR method.