OBJECTIVES. The objectives of this study were to determine the incidence density and the occurrence of horizontal spread of highly resistant gram-negative rods (HR-GNRs) in Dutch hospitals. The factors that influence these outcome measures were also investigated. METHODS. All patients with HR-GNRs, as determined by sample testing, who were hospitalized in 1 of 18 hospitals during a 6-month period (April through October 2007) were included in this study. For all available isolates, the species was identified, susceptibility was determined (including the presence of extended-spectrum β-lactamases [ESBLs]), and molecular typing was performed. On the basis of a combination of species identification, molecular typing, and epidemiological data, the occurrence of nosocomial transmission was determined. RESULTS. The mean incidence density of patients with HR-GNRs was 55 per 100,000 patient-days (cumulative incidence, 39 per 10,000 patients admitted). A facility being a university hospital was a statistically significant (Pp.03) independent determinant of a higher incidence of patients with HR-GNRs. The majority of HR-GNR isolates were ESBL producers. The adjusted transmission index - the ratio between secondary and primary cases - in the participating hospitals ranged from 0.0 to 0.2. The overall adjusted transmission index of HR-GNRs was 0.07. No determinants for a higher transmission index were identified. DISCUSSION. The nosocomial transmission rate of HR-GNRs was relatively low in all hospitals where well-established transmission-based precautions were used. The incidence density of patients with HR-GNRs was higher in university hospitals, probably due to the patient population and the complexity of the care provided.

doi.org/10.1086/658941, hdl.handle.net/1765/72267
Infection Control & Hospital Epidemiology
Erasmus MC: University Medical Center Rotterdam

Willemsen, I., Elberts, S., Verhulst, C., Rijnsburger, M., Filius, M., Savelkoul, P., … Vandenbroucke-Grauls, C. (2011). Highly resistant gram-negative microorganisms: Incidence density and occurrence of nosocomial transmission (TRIANGLe Study). Infection Control & Hospital Epidemiology, 32(4), 333–341. doi:10.1086/658941