Evolution of micro-organisms isolated in nosocomial bloodstream infections in Belgian Intensive Care Units, 1992-1999

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Objectives

To compare the distribution of micro-organisms from nosocomial bloodstream infections (BSIs) in Belgian intensive care units (ICUs) during two surveillance periods: from October 1992 until June 1996 and from October 1998 until September 1999.

Methods

Since 1992, Belgian hospitals have been invited to participate on a voluntary basis in the national surveillance of nosocomial BSIs (NSIH). Surveillance data are transmitted by the hospitals to the IPH for analysis, national benchmarking and feedback. The surveillance was discontinued in July 1996 and started up again on 1 October 1998. We compared the distribution of pathogens isolated in BSIs occurring >48 h of hospital stay before and after the interruption of the surveillance.

Results

During the first period a total of 3563 isolates were reported from 104 hospitals, for the second period 925 isolates from 62 hospitals. Table 1 shows the distribution of the micro-organisms by type. The most frequently isolated micro-organisms were coagulase-negative staphylococci (1992–1996: 22.6% and 1998–1999: 22.8%), Staphylococcus aureus (13.1%;11.3%), enterococci (7.8%;9.8%), Escherichia spp (7.7%;8.6%), and Enterobacter spp (7.1%;9.4%). The proportion of Enterobacter spp. increased significantly from 7.1% in 1992-1996 to 9.4% in 1998-1999 (P=0.017). This increase was due to an increase of Enterobacter aerogenes isolates (from 3.2% to 4.7%, P=0.025). The proportion of Enterobacter cloacae isolates remained constant (3.1% to 3.6%). A significant decrease was observed for Citrobacter spp (0.9% to 0.2%, P<0.03) and Acinetobacter spp (2.2% to 1.2%, P=0.043).

Conclusions

Overall, the distribution of micro-organisms in BSIs in Belgian ICUs has remained quite stable since 1992. The earlier reported increasing trend in Enterobacter aerogenes BSIs was again confirmed.

Table 1 Distribution of micro-organisms isolated in nosocomial BSI's in Belgian ICUs, 92/96 and 98/99: