Quality of blood culture testing - a survey in intensive care units and microbiological laboratories across four European countries

Abstract

Introduction: Blood culture (BC) testing before initiation of antimicrobial therapy is recommended as a standard of care in international sepsis guidelines and has been shown to reduce intensive care unit (ICU) stay, antibiotic use, and costs in hospitalized patients. Whereas microbiological laboratory practice has been highly standardized, shortfalls in the preanalytic procedures in the ICU (that is indication, time-to-incubation, blood volume and numbers of BC sets) have a significant effect on the diagnostic yield. The objective of this study was to gain insights into current practices regarding BC testing in intensive care units.

Methods: Qualitative survey, data collection by 138 semi-structured telephone interviews in four European countries (Italy, UK, France and Germany) between September and November 2009 in 79 clinical microbiology laboratories (LABs) and 59 ICUs.

Results: Whereas BC testing is expected to remain the gold standard for sepsis diagnostics in all countries, there are substantial differences regarding preanalytic procedures. The decision to launch BC testing is carried out by physicians vs. ICU nurses in the UK in 92 vs. 8%, in France in 75 vs. 25%, in Italy in 88 vs. 12% and in Germany in 92 vs. 8%. Physicians vs. nurses collect BCs in the UK in 77 vs. 23%, in France in 0 vs. 100%, in Italy in 6 vs. 94% and in Germany in 54 vs. 46%. The mean time from blood collection to incubation in the UK is 2 h, in France 3 h, in Italy 4 h, but 20 h in German remote LABs (2 h in in-house LABs), due to the large number of remote nonresident microbiological laboratories in Germany. There were major differences between the perception of the quality of BC testing between ICUs and LABs. Among German ICU respondents, 62% reported that they have no problems with BC testing, 15% reported time constraints, 15% cost pressure, and only 8% too long time to incubation. However, the corresponding LABs of these German ICUs reported too many false positive results due to preanalytical contaminations (49%), insufficient numbers of incoming BC sets (47%), long transportation time (41%) or cost pressure (18%).

Conclusions: There are considerable differences in the quality of BC testing across European countries. In Germany, time to incubation is a considerable problem due to the increasing number of remote LABs. This is a major issue of concern to physicians aiming to implement sepsis guidelines in the ICUs.

Figure 1

BCs processed by 79 LABs from 59 ICUs in four European countries. Given are mean numbers of BC sets processed in the LABs per patient within 24 hours and the average number of BC sets taken per patient in the ICUs (below). BC, blood culture; LAB, microbiological laboratory.

Figure 2

Blood volumes collected per BC bottle in 59 ICUs in four European countries. Given are mean blood volumes filled into BC bottles and processed in the LABs. The mean volumes per bottle are given below. BC, blood culture; LAB, microbiological laboratory.

Figure 3

Number of BC sets processed and ID/AST tests performed per day (mean) in microbiological LABs in four European countries. The mean percentage of positive BC sets processed per day and LABs are given below. BC, blood culture; ID/AST, identification and antibiotic susceptibility testing; LAB, microbiological laboratory.