Impact of single room design on the spread of multi-drug resistant bacteria in an intensive care unit

Abstract

Background: Cross-transmission of nosocomial pathogens occurs frequently in intensive care units (ICU). The aim of this study was to investigate whether the introduction of a single room policy resulted in a decrease in transmission of multidrug-resistant (MDR) bacteria in an ICU.

Methods: We performed a retrospective study covering two periods: between January 2002 and April 2009 (old-ICU) and between May 2009 and March 2013 (new-ICU, single-room). These periods were compared with respect to the occurrence of representative MDR Gram-negative bacteria. Routine microbiological screening, was performed on all patients on admission to the ICU and then twice a week. Multi-drug resistance was defined according to a national guideline. The first isolates per patient that met the MDR-criteria, detected during the ICU admission were included in the analysis. To investigate the clonality, isolates were genotyped by DiversiLab (bioMérieux, France) or Amplified Fragment Length Polymorphism (AFLP). To guarantee the comparability of the two periods, the 'before' and 'after' periods were chosen such that they were approximately identical with respect to the following factors: number of admissions, number of beds, bed occupancy rate, per year and month.

Results: Despite infection prevention efforts, high prevalence of MRD bacteria continue to occur in the original facility. A marked and sustained decrease in the prevalence of MDR-GN bacteria was observed after the migration to the new ICU, while there appear to be no significant changes in the other variables including bed occupancy and numbers of patient admissions.

Conclusion: Single room ICU design contributes significantly to the reduction of cross transmission of MRD-bacteria.

Fig. 1

Floor plan of the ICU before conversion: 1–6 and 10–15: beds situated in the open bay; 7–9 and 20–21: single rooms with controlled ventilation and with anteroom; 16/17 and 18/19: rooms without controlled ventilation an without anteroom

Fig. 2

Plan of the new ICU consisting of two identical floors with 9 patient rooms each. Single patient rooms with anteroom are indicated by dark green and light green, respectively

Fig. 3

Occurrence of MDR-resistant bacteria (each counted once per patient) between January 2002 and March 2013 with indication of the main infection control measures that were taken on the ICU. ICU closure I: during January–May 2003 for thorough cleaning and disinfection; ICU closure II: temporary closure for new admissions because of an outbreak with multi-drug resistant A. baumannii. After all beds became available through discharges the unit including equipment was decontaminated with vaporized hydrogen peroxide; new ICU opened with single-bed rooms

Fig. 4

Frequency distribution of the MDR Gram negative bacteria that were used for genotyping

Fig. 5

Data from typing of Enterobacter, Acinetobacter and ESBL-Kp isolates. Cross transmission of new microorganisms re-emerged and persisted after the old ICU was reopened in March 2008. The second closure ended the cross transmission of ESBL-Kp and MDR-Ab

Fig. 6

Plot diagram showing a decrease in the yearly numbers of MDR organisms isolated after the move to the new ICU. Data sets before and after the move consist of 88 and 47 months surveillance, respectively

Fig. 7

Pooled data from typing of Enterobacter, Acinetobacter, P. aeruginosa, C. freundii, E. coli and ESBL-Kp isolates. In the new ICU no transmission was observed