Streptococcus suis in Hong Kong.

Streptococcus suis was isolated from 6.1% of raw pork meat from 3 of the 6 wet markets in 6 districts in Hong Kong. S. suis was particularly isolated in sites from the tongue, tonsil, bone, and tail, but not from lean meat/minced pork or internal organs. Isolates were confirmed by polymerase chain reaction using S. suis-specific primers, did not belong to serotype 2 using serotype 2-specific antiserum, and were clustered closely with other known serotypes by phylogenetic analysis. Ten strains from patients admitted to Hong Kong hospitals with sepsis or meningitis in the past 10 years all belonged to type 2, with closely related pulsed-field gel electrophoresis types that were distinct from the S. suis strains isolated from pork in this study. These methods may serve as useful tools in studying and enhancing our understanding of these infections in Hong Kong.

Quick identification of kuraridin, a noncytotoxic anti-MRSA (methicillin-resistant Staphylococcus aureus) agent from Sophora flavescens using high-speed counter-current chromatography.

Bacterial resistance to antibiotics has become a serious problem of public health that concerns almost all currently used antibacterial agents and that manifests in all fields of their application. To find more antibacterial agents from natural resources is all the time considered as an important strategy. Sophora flavescens is a popularly used antibacterial herb in Chinese Medicine, from which prenylated flavones were reported as the antibacterial ingredients but with a major concern of toxicity. In our screening on the antibacterial activities of various chemicals of this herb, 18 fractions were obtained from 8 g of 50% ethanol extract on a preparative high-speed counter-current chromatography (HSCCC, 1000 ml). The system of n-hexane/ethyl acetate/methanol/water (1:1:1:1) was used as the two-phase separation solvent. A chalcone named kuraridin was isolated from the best anti-MRSA fraction, together with sophoraflavanone G, a known active ingredient of S. flavescens. Their structures were elucidated by analysis of the NMR spectra. Both compounds exhibited significant anti-MRSA effects, compared to baicalein that is a well known anti-MRSA natural product. More important, kuraridin showed no toxicity on human peripheral blood mononuclear cells (PBMC) at the concentration up to 64 µg/ml while sophoraflavanone G inhibited over 50% of cellular activity at 4 µg/ml or higher concentration. These data suggested that opening of ring A of the prenylated flavones might decrease the toxicity and remain the anti-MRSA effect, from a viewpoint of structure-activity relationship.