 Data from all sites will be pooled and combined. Statistical analyses will be conducted with the use of SAS software, version 8.2 SAS Institute Inc., Cary, NC, USA. Data will also be presented as mean -SD for continuous variables and proportions for categories variables. The patient demographics and baseline characteristics will be tabulated. The distribution of comorbidities, disease severity, causative organisms, clinical condition and outcomes will be summarized and analyzed. To detect the significant differences between groups, Chi-square tests or Fisher exact test for categorical variables, and the two-tailed t test or Mann-Whitney test for continuous variables will be employed, when appropriate. Statistical significance will be established at alpha 0.05. Reported P values will be two-sided. 