The influence of the composition of the nursing staff on primary bloodstream infection rates in a surgical intensive care unit

OBJECTIVES: To determine the risk factors for acquisition of nosocomial pri mary bloodstream infections (BSIs), including the effect of nursing-staff l evels, in surgical intensive care unit (SICU) patients. DESIGN: A nested case-control study. SETTING: A 20-bed SICU in a 1,000-bed inner-city public hospital. PATIENTS: 28 patients with BSI (case-patients) were compared to 99 randomly selected patients (controls) hospitalized greater than or equal to 3 days in the same unit. RESULTS: Case- and control-patients were similar in age, severity of illnes s, and type of central venous catheter (CVC) used. Case-patients were signi ficantly more likely than controls to be hospitalized during a 5-month peri od that had lower regular-nurse-to-patient and higher pool-nurse-to-patient ratios than during an 8-month reference period; to be in the SICU for a lo nger period of time; to be mechanically ventilated longer; to receive more antimicrobials and total parenteral nutrition; to have more CVC days; or to die. Case-patients had significantly lower regular-nurse-to-patient and hi gher pool-nurse-to-patient ratios for the 3 days before BSI than controls. In multivariate analyses, admission during a period of higher pool-nurse-to -patient ratio (odds ratio [OR] =3.8), total parenteral nutrition (OR=1.3), and CVC days (OR=1.1) remained independent BSI risk factors. CONCLUSIONS: Our data suggest that, in addition to other factors, nurse sta ffing composition (ie, pool-nurse-to-patient ratio) may be related to prima ry BSI risk. Patterns in intensive care unit nurse staffing should be monit ored to assess their impact on nosocomial infection rates. This may be part icularly important in an era of cost containment and healthcare reform (Inf ect Control Hosp Epidemiol 2000;21:12-17).