Nosocomial infection caused by P. aeruginosa is frequently found among patient with low immunity or long term hospital patients. The infected patients had a high mortality rate, especially due to septicemia. The aim of this study was to investigate the factors associated with P. aeruginosa bloodstream infection among patients at Roi Et hospital. The methods was a casecontrol study (control: cases = 1:1). All data were collected from medical records and blood culture tests from the microbiology laboratory of admitted patients in Roi Et hospital, Roi Et Province between January 1, 2014 to December 31, 2015. The variables which were interestincluded general information, invasive medical procedures and treatment history. The statistical analyses employed descriptive statistics, univariate analysis and multivariate analysis by multiple logistic regressions. In term of the results, there were eighty nine cases most of them were male(55.10%) with mean age 57.62 + 16.18 years and eighty nine controls, the majority were female (51.70%) with mean age 56.55 + 16.89 years. The risk factors for P. aeruginosa bloodstream infection were statistically significant with factors included being for admitted more than seven days (OR Adjusted = 2.40; 95% CI: 1.33-4.52), complications (OR Adjusted = 2.50 ; 95% CI: 1.39-4.64), ventilators (OR Adjusted = 2.20; 95% CI: 1.17-4.31), endotracheal tubes (OR Adjusted = 2.20 ; 95% CI: 1.16-4.22. In conclusion, hospitalized patients who has experienced complications and undergonesome type of invasive medical procedure were at risk for the P. aeruginosa bloodstream infection.All patients in risk group should be provided with special guidelines and special care from medical staff for the prevention and control of the P. aeruginosa blood stream infection
