Validation of a nosocomial infections surveillance program

Objective. To validate the nosocomial infections surveillance system, estab lish its impact in morbi-mortality. Material and methods. Surveillance of e very single patient admited during a one month period was done by one of us (DMG). Each posibile case was discussed with two other hospital epidemiolo gists (SPLR, MSRF). This intensive surveillance was compared against the ro utinely surveillance performed by the nurses. We included all hospitalized patients between 11(th) July and 12(th) of August according to CDC (Atlanta , GA) nosocomial infections definitions. Patients were followed everyday an d information about age, gender, underlying diagnosis, microorganisms respo nsible for nosocomial infections, hospital length of stay and mortality. Re sults. During the study period 429 were admitted, 45 developed a nosocomial infection (cases) and 384 did not (controls). The incidence of nosocomial infections was 10.48 casesl 100 discharges. The sensitivity and specificity of the surveillance system was 95.3 and 98.7%, respectively. Mortality in infected was 11.11% and in non infected was 2.4%. The average length of sta y was 20 and 11 days for cases and non infected respectively (p<0.01). Urin ary tract infections were the most common NI (42%), secondary bacteremia (1 4 less than or equal to%), pneumonia (11.11%) and deep surgical site infect ion (9.25%). The surgical wound infection rates were: 1.3%, 1.9% and 1.9% f or clean, clean-contaminated and contaminated wounds. Patients with rapidly fatal diseases had an increased frequency of infections. The microorganism s most commonly isolated were Escherichia coil (28%), Staphylococcus aureus (11.11%),and Pseudomonas aeruginosa (8.6%). The level of antibiotic resista nce was in average of 43% for those antibiotics tested. Conclusions. The se nsitivity and specificity of the surveillance system was excelent. patients with nosocomial infections had an increased length of stay and a higher mo rtality compared to those without NI. The validation of the surveillance sy stem allows the production of trustable conclusions about nosocomial infect ions.