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Epidemiological relationship of human and swine Streptococcus suis isolates
C Tarradas1, I Luque, D de Andrés
1Dpto. Patología Infecciosa, Edificio Sanidad Animal, Ctra. de Madrid, Córdoba, Spain. sa1taigc@lucano.uco.es
Abstract:
Two cases of meningitis due to Streptococcus suis in humans are reported here. A butcher and an abattoir worker were referred to a health centre in Castellón (Spain) with fever and symptoms of meningitis. After adequate treatment, a slight hipoacusia persisted as sequelae in both cases. Colonies of S. suis group R, serotype 2 and phenotype MRP+EF+ were isolated from cerebroespinal fluid. Epidemiological studies showed that both workers had in common the handling of pork meat of slaughtered healthy pigs from three closed farms. A study of the tonsils from apparently healthy, slaughtered pigs was carried out. A total of 234 tonsillar samples were obtained and 81 strains of S. suis were isolated from them. Serotype 2 appeared to be the most frequent (50.6%), and the analysis for phenotype showed a high percentage of tonsillar strains with the phenotype MRP+EF+ (35.9%). The humans and 28 tonsillar swine strains showed a similar profile (S. suis group R, serotype 2 and phenotype MRP+EF+). A total of 26 of the swine isolates were analysed by ribotyping using EcoRI. The human strains showed the same six-band hybridization pattern that shared five bands with the pattern most frequently shown by most of the tonsillar N. suis group R, serotype 2 and phenotype MRP+EF+ strains, differing only in the lightest, faintest band which was slightly less anodical in human (> or = 1.8 kb) than in swine (approximately 1.8 kb). From these results, both groups of strains, humans and porcine, showed differences; how can these differences in the pattern of ribotyping be explained if they should have the same origin? Is it possible that they have undergone an adaptation to the new host or perhaps the modification is due to other unknown causes? Further studies in this area are required in order to answer these questions.
Insights
Two human meningitis cases linked to Streptococcus suis were reported. Pork handlers developed meningitis, with similar S. suis strains found in humans and pigs, suggesting a potential zoonotic link.
Area of Science:
- Microbiology
- Infectious Diseases
- Zoonotic Infections
Background:
- Streptococcus suis is an emerging zoonotic pathogen.
- Meningitis is a severe infection of the central nervous system.
Purpose of the Study:
- To investigate two cases of Streptococcus suis meningitis in human patients.
- To identify the source and characteristics of the S. suis strains involved.
Main Methods:
- Case reporting and clinical observation.
- Bacteriological isolation and characterization (serotyping, phenotyping).
- Epidemiological investigation and pig tonsil sampling.
- Ribotyping analysis of human and swine S. suis strains.
Main Results:
- Two human meningitis cases were linked to S. suis group R, serotype 2, phenotype MRP+EF+.
- Similar S. suis strains were isolated from the patients' cerebrospinal fluid and from apparently healthy pigs.
- Serotype 2 was the most frequent in pigs (50.6%), with a high prevalence of the MRP+EF+ phenotype (35.9%).
- Ribotyping showed distinct but related patterns between human and swine strains, suggesting possible host adaptation.
Conclusions:
- The study highlights Streptococcus suis as a cause of meningitis in humans.
- A common origin between human and swine S. suis strains is suggested, with potential for host adaptation.
- Further research is needed to understand the genetic modifications and transmission dynamics.