title: Analysis of genetic diversity of Streptococcus suis clinical isolates from pigs in Spain by pulsed-field gel electrophoresis.
abstract: Pulsed-field gel electrophoresis (PFGE) was used to investigate the diversity of Streptococcus suis isolates of various serotypes recovered from swine clinical samples in Spain. Capsular types 9 (64.9%) and 2 (14.8%) were the most frequently isolated serotypes followed by serotype 7 (5.9%) and serotype 8 (4.3%). The PFGE results of this study with 60 different pulsotypes indicate a great genetic diversity among the S. suis isolates, which is consistent with the broad distribution of S. suis in the swine population. Forty-five percent of the pulsotypes corresponded to single isolates, no pulsotype was common to all farms, and at least 3 different pulsotypes were isolated in 56% of herds in which more than 3 clinical isolates were analyzed. These results reveal a great diversity both between and within herds throughout the strains of S. suis studied, demonstrating that different strains of S. suis are associated with infection in pigs. Some pulsotypes were more frequently isolated and exhibited a wider distribution over herds than others, and were the unique or predominant strains in several herds, suggesting the existence of a prevalent or a few prevalent clones responsible for a large proportion of clinical cases. Overall, the great genetic heterogeneity of the clinical strains of S. suis, the isolation of different strains within the same herd, and the predominance of particular strains in some herds are evidence that infection by S. suis is a dynamic process and reinforce the idea that the epidemiology of S. suis infection is very complex.
authors.affiliation: Departamento de Patología Animal I (Sanidad Animal), Facultad de Veterinaria, Universidad Complutense, 28040 Madrid, Spain.
authors.forename: Ana I
authors.initials: AI
authors.lastname: Vela
authors.forename: Joaquin
authors.initials: J
authors.lastname: Goyache
authors.forename: Carmen
authors.initials: C
authors.lastname: Tarradas
authors.forename: Inmaculada
authors.initials: I
authors.lastname: Luque
authors.forename: Ana
authors.initials: A
authors.lastname: Mateos
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Moreno
authors.forename: Carmen
authors.initials: C
authors.lastname: Borge
authors.forename: J Anselmo
authors.initials: JA
authors.lastname: Perea
authors.forename: Lucas
authors.initials: L
authors.lastname: Domínguez
authors.forename: José F
authors.initials: JF
authors.lastname: Fernández-Garayzábal
mesh_terms: D000818:Animals; D015373:Bacterial Typing Techniques; D015252:Deoxyribonucleases, Type II Site-Specific / Q000378:metabolism; D016521:Electrophoresis, Gel, Pulsed-Field; D014644:Genetic Variation; D012703:Serotyping; D013030:Spain / Q000453:epidemiology; D013290:Streptococcal Infections / Q000453:epidemiology / Q000382:microbiology / Q000662:veterinary*; D017011:Streptococcus suis / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification; D013552:Swine; D013553:Swine Diseases / Q000453:epidemiology* / Q000382:microbiology
chemical_list: D015252:Deoxyribonucleases, Type II Site-Specific; C038485:GGGCCC-specific type II deoxyribonucleases