S. suis strain P1/7 was isolated from an ante-mortem blood culture from a pig dying with meningitis [9] , and is ST1 by MLST [10] (link). S. suis strain BM407 is also ST1, and was isolated from CSF from a human case of meningitis in Ho Chi Minh City, Vietnam in 2004 [3] (link). S. suis strain SC84 is ST7, which is closely related to ST1, and was isolated from a case of streptococcal toxic shock-like syndrome in Sichuan Province, China in 2005 [8] (link). Strain P1/7 is resistant to gentamycin, streptomycin, neomycin, nalidixic acid, and sulfamethoxazole, and sensitive to penicillin, ampicillin, cephalotin, erythromycin, tulathromycin, clarythromycin, lincomycin, clindamycin, pirlimicin, tetracycline, trimethoprim-sulfa, ciprofloxacin, and chloramphenicol. Strain BM407 is resistant to trimethoprim-sulfamethoxazole, tetracycline, erythromycin, azithromycin and chloramphenicol and susceptible to penicillin, ceftriaxone and vancomycin. Strain SC84 is resistant to tetracycline, and susceptible to penicillin, ampicillin, cefotaxime, ceftriaxone, cefepime, meropenem, levofloxacin, chloramphenicol, erythromycin, azithromycin, clindamycin, and vancomycin [11] (link).
Bacteria were cultured in Todd-Hewitt-broth at 37°C for 18 h and pelleted at 10,000×g. The cells were resuspended in 30 ml of lysis solution (10 mM NaCl, 20 mM Tris HCl pH 8, 1 mM EDTA, 0.5% SDS) and incubated at 50°C overnight. Three ml of 5 M sodium perchlorate was added and incubated for 1 h at ambient temperature. After phenol chloroform extraction the DNA was precipitated with ethanol, spooled into deionised water and stored at −20°C. DNA was also extracted using a genomic DNA extraction kit (G-500, Qiagen).
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