Molecular Characterization and Correlation with ß-lactam Resistance of Streptococcus pneumonia Isolates in Hangzhou, China.

Penicillin-binding proteins (PBPs) are the target of ß-lactam antibiotics (the major treatment for Streptococcus pneumoniae infections), and mutations in PBPs are considered as a primary mechanism for the development of ß-lactam resistance in S. pneumoniae. This study was conducted to investigate the mutations in the PBPs of clinical S. pneumoniae isolates in Hangzhou, China, in correlation with ß-lactam resistance. Results showed that 19F was the predominant serotype (7/27) and 14 of the S. pneumoniae isolates were resistant to both penicillin G and cephalosporin. Genotyping results suggested that ß-lactam-resistant isolates primarily exhibited single-site mutations in both the STMK and SRNVP motifs of pbp1a in combination with double-site mutations in the STMK motif of pbp2x, which might be the primary mechanisms underlying the ß-lactam resistance of the isolates in this study.

[Impact of land use types on soil macropores in the loess region].

Soil hydraulic conductivity and macropores are important parameters for determining the proportion of precipitation infiltration, simulating soil water and solution transport and establishing the hydrologic model. To investigate the effect of land use types on macropores in soils, soil hydraulic properties, macroporosity and macropore connectivity under different land use types (locust forestland, grassland, farmland and apple forestland) in the loess region were measured by Hood infiltrometer and water retention curve. The results showed that the average hydraulic conductivities under locust forestland, grassland, farmland and apple forestland were 58.60 x 10(-6), 54.90 x 10(-6), 35.30 x10(-6), 23.40 x 10(-6) m x s(-1), respectively. The differences among land use types were statistically significant (P < 0.05). The effective macropores per unit area, macroporosity and macropore connectivity were highest in locust forestland and grassland, followed by farmland and apple forestland. As a consequence of vegetation restoration, macropores which developed by plant roots and animal activity had significantly improved the soil infiltration capability. Restoring woods and grasses should persist in the loess region.