Detection, Isolation and Identification of Streptococcus suis in A Slaughterhouse in Dongguan

Objective Streptococcus suis (SS) is an important porcine pathogen and a zoonotic pathogen. Among various types, Streptococcus suis type 2 (SS2) has the strongest pathogenicity. It can not only cause acute sepsis, meningitis, arthritis and even death in pigs, but also lead to human infection and death. In order to evaluate the transmission risks of SS in slaughterhouses, the sampling, detection, isolation and identification of SS were carried out in a slaughterhouse in Dongguan.

Method The synovial fluid and tonsils of 40 pigs were collected for PCR detection and SS isolation. The isolated strains were used for morphology, physiology and biochemistry identification, 16S rDNA PCR amplification, typing PCR detection and antibiotic sensitivity test.

Result The nucleic acids extracted from the synovial fluid and tonsils of 40 pigs were detected by PCR. In 40 synovial fluids, the positive rate of SS was 22.5%, but no SS2 was detected. In 40 tonsil samples, the positive rate of SS was 32.5%, in which the positive rate of SS2 was 7.5%. Three strains of SS were isolated from 80 tonsil and synovial fluid samples of 40 pigs. The PCR results showed that one of the three strains was SS type 4, and the genotype was epf-mrp+gdh+gapdh+fbps-orf2+sly-; while the other two strains were SS type 9, and the genotypes were epfmrp+gdh+gapdh+fbps-orf2+sly-and epf-mrp-gdh+gapdh+fbps-orf2+sly+, respectively. The drug sensitivity test showed that the three SS strains were resistant to penicillin G, lincomycin, polymyxin B and sulfaisoxazole, and sensitive to enrofloxacin, ciprofloxacin, spectinomycin and amoxicillin.

Conclusion The results suggest that there are a large number of recessive infection of SS in the pigs of the slaughterhouse, and there is a risk of human infection by SS2.