Epidemiological study of community- and hospital-acquired intraabdominal infections

Purpose： To investigate and analyze the clinical and etiological characteristics of community-acquired intraabdominal infections （CIAIs） and hospital-acquired or nosocomial intraabdominal infections （NIAIs） in a comprehensive hospital, to understand the characteristics, pathogen composition, and drug resistance of CIAls as well as NIAIs, and to provide a reference for clinical treatment. Methods： We collected the clinical data of patients with intraabdominal infections admitted to our hospital from June 2013 to June 2014. In vitro drug sensitivity tests were conducted to separate pathogens, and the data were analyzed using the WHONET 5.4 software and SPSS 13.0 software. Results： A total of 221 patients were enrolled in the study, including 144 with CIAls （55 mild-moderate and 89 severe） and 77 with NIAIs. We isolated 322 pathogenic strains, including 234 strains of gramnegative bacteria, 82 strains of gram-positive bacteria, and 6 strains of fungi. Based on clinical features, NIAIs and severe ClAls presented significantly higher values in age, length of hospital stay, mortality, and the incidence of severe intra-abdominal infection than mild-moderate CIAIs （p 〈 0.05）. There was no significant difference in the prognosis between NIAIs and severe CIAIs. Primary diseases leading to CIAIs and NIAIs mostly were hepatobiliary diseases and gastrointestinal diseases respectively. Bacteria isolated from various types of IAls mainly were Enterobacteriaceae; mild-moderate CIAIs mostly were mono-infection of gram-negative bacteria; NIAIs mostly were mixed infections of gram-negative and grampositive bacteria; and severe CIAls were from either type of infection. The rate of Extended Spectrum β-Lactamase-producing Escherichia coil and Klebsiella pneurnoniae was much higher in NIAIs than in CIAIs （p 〈 0.05）. The antimicrobial drug sensitivity of gram-negative bacteria isolated from NIAIs was significantly lower than that of CIAIs. Conclusion： CIAIs and NIAIs have their own unique clinical features and epidemiological features of pathogens which should be considered during the initial empiric therapy for the rational use of anti- microbial drugs. Regional IAls pathogenic bacteria have their own features in drug resistance, slightly different from some recommendations of 2010 Infectious Diseases Society of America guidelines.

Effects of Temperature and Moisture on Soil Organic Matter Decomposition Along Elevation Gradients on the Changbai Mountains, Northeast China

Decomposition of soil organic matter(SOM) is of importance for CO_2 exchange between soil and atmosphere and soil temperature and moisture are considered as two important factors controlling SOM decomposition. In this study, soil samples were collected at 5 elevations ranging from 753 to 2 357 m on the Changbai Mountains in Northeast China, and incubated under different temperatures(5, 10, 15, 20, 25, and 30?C) and soil moisture levels(30%, 60%, and 90% of saturated soil moisture) to investigate the effects of both on SOM decomposition and its temperature sensitivity at different elevations. The results showed that incubation temperature(F = 1 425.10, P < 0.001), soil moisture(F = 1 327.65, P < 0.001), and elevation(F = 1 937.54, P < 0.001) all had significant influences on the decomposition rate of SOM. The significant effect of the interaction of incubation temperature and soil moisture on the SOM decomposition rate was observed at all the 5 sampling elevations(P < 0.001). A two-factor model that used temperature and moisture as variables fitted the SOM decomposition rate well(P < 0.001) and could explain 80%–93% of the variation of SOM decomposition rate at the 5 elevations. Temperature sensitivity of SOM decomposition, expressed as the change of SOM decomposition rate in response to a 10?C increase in temperature(Q_(10)), was significantly different among the different elevations(P < 0.01), but no apparent trend with elevation was discernible. In addition, soil moisture and incubation temperature both had great impacts on the Q_(10) value(P < 0.01), which increased significantly with increasing soil moisture or incubation temperature. Furthermore, the SOM decomposition rate was significantly related to soil total Gram-positive bacteria(R^2= 0.33, P < 0.01) and total Gram-negative bacteria(R^2= 0.58, P < 0.001). These findings highlight the importance of soil moisture to SOM decomposition and its Q_(10) value,which needs to be emphasized under warming climate scenarios.