Prospective study of nosocomial infection in a medical ICU. A proposal for the generalized use of the National Nosocomial Infection Surveillance System rates

Objective. To know the more relevant nosocomial infection (NI) rates in our Intensive Care Unit (ICU), risk factors associated with NI and trends in the infective flora. Methods. During a three-month period, the cumulative incidence, density of overall incidence and device associated infection rates were determined in a total of 308 patients admitted to the medical ICU, following the recommendations of the National Nosocomial Infection Surveillance System (NNIS) in the USA. Results. The cumulative incidence was 8.4 infections per 100 admissions. The density of overall incidence was 12.9 nosocomial infections per 1,000 days of ICU stay. Device-associated infection rates were: 28.9 pneumonia per 1,000 mechanical ventilation days, 5.3 urinary tract infections per 1,000 days of catheter use and 0.4 bacteremia per 1,000 days of central venous catheter. Pneumonia was the more common NI, followed by urinary tract infection. Pseudomonas aeruginosa was the microorganism recovered most frequently. The most common used antibiotics were third generation cephalosporins, followed by quinolones and macrolides. Conclusions. The use of NNIS rates is advisable because its allows to know the impact of NI on our unit and to perform comparative studies with other units of similar characteristics.