Nosocomial bloodstream infections in ICU and non-ICU patients

Nosocomial bloodstream infections (BSI) create a serious health problem in hospitals all over the world. The objectives of our study were to explore putative disease markers and potential risk factors with nosocomial BSI in patients in intensive care units (ICU) and non-ICU patients and to determine risk factors associated with increased 28-day mortality rate in patients with nosocomial BSI acquired in combined medical-surgical ICU. However, the major purposes of this report were to identify epidemiologic differences between nosocomial BSI acquired in ICU and non-ICU, as well as analyses outcomes for patients with nosocomial BSI acquired in ICU.

A 1-year prospective cohort study was performed to determine the incidence of nosocomial BSI in hospitalized patients. Patient characteristics, risk factors related to health care, and source of infection of patients with BSI acquired in non-ICU were compared with those patient with BSI acquired in ICU. Also, nested case-control study of patients to nosocomial BSI acquired in ICU was performed to evaluate outcome. Patients were identified by active surveillance and positive blood culture during the study period.

The incidence of nosocomial BSI was 2.2 per 1000 admission in non-ICU patients and 17.4 per 1000 admission in ICU patients. The 28-day crude mortality rate was 69% in ICU patients. A multivariate model showed that nasogastric tube (RR, 25.1; 95% CI: 3.845-163.85; P=.001), mechanical ventilation (RR, 13.04; 95% CI: 1.974-96.136; P=.008), and H2 blockers (RR, 12.16; 95% CI: 1.748-84.623; P=.012) were more prevalent among patients with BSI acquired in ICU, and aggressive procedures (RR, 8.65; 95% CI: 1.70-44.00; P=.009) were more prevalent among patients with BSI acquired in non-ICU patients. Risk factors independently associated with increased 28-day mortality rate in ICU patients were mechanical ventilation (OR, 8.63; 95% CI: 1.5-49.8; P=.016) and SAPS II >40 (OR, 6.0; 95% CI: 1.0-35.7; P=.049). The most common isolated nosocomial BSI pathogens (in both groups of patients) were coagulase-negative staphylococci (21%), Staphylococcus aureus (14%), and Klebsiella species (13%). Klebsiella species was the only organism independently influencing the poor outcome of nosocomial BSI in ICU patients (OR, 4.3; 95% CI: 1.2-15.3; P=.022).

Our results show epidemiologic differences between non-ICU and ICU BSI. Also, this study suggests that severity of underlying host conditions, mechanical ventilation, and microbial agents (Klebsiella species) affect the outcome of NBI in patients in ICU.