An incidence study on nosocomial infections in critically ill infectious disease patients was carried out in the intensive care unit (ICU) of a university hospital for infectious diseases over a 7-year period (1 January 1990 to 31 December 1996). A total of 660 patients who stayed in the ICU for over 48 h were prospectively observed. The patients were divided into two groups: one with central nervous system infections (442 patients) and the other with other severe infections (218 patients). The risk of nosocomial sepsis and pneumonia was significantly higher in patients suffering from severe central nervous system infections. The incidence of sepsis was 24.2% vs 11.4% (relative risk 1.95; 95% confidence interval 1.32-2.89); the incidence of pneumonia was 30.5% vs 14.7% (relative risk 2.09; 95% confidence interval 1.47-2.96). The incidence of urinary tract infection was 14.3% vs 13.3% (relative risk 1.07; 95% confidence interval 0.71-1.61). Density rates of nosocomial septic episodes were 21.1 +/- 37.1 vs 11.7 +/- 32.4 episodes/100 central venous-line days (P < 0.006). Nosocomial pneumonia occurred only in mechanically ventilated patients (36.9 +/- 61.2 vs 28.5 +/- 65.8 episodes per 1000 ventilatory days, P = 0.012). Nosocomial urinary tract infection occurred only in patients with urinary catheters (11.6 +/- 60.7 episodes/1000 urinary catheter days vs 18.7 +/- 90.1, P = 0.886). Multivariate regression analysis identified age, diagnosis of CNS infection, duration of urinary tract catheterization, the use of central venous lines and mechanical ventilation as independent risk factors of nosocomial sepsis. Duration of mechanical ventilation, use of steroids and diagnosis of CNS infection were independent risk factors of nosocomial pneumonia. A subanalysis identified tetanus patients to be at particular risk of nosocomial infections.
