Contamination of Blood Cultures From Indwelling Arterial Catheters in Critically Ill Patients

FOR RELATED ARTICLE, SEE PAGE 90Blood cultures are some of the most important tests for detecting life-threatening bacteremia, which is associated with high mortality rates. Accurate diagnosis from cultured blood samples plays a crucial role in providing appropriate treatment. Contaminated blood cultures thus can result in inappropriate antibiotic use, unnecessarily long hospital stays, increased health care costs, and increased risks of antimicrobial resistance.1Dempsey C. Skoglund E. Muldrew K.L. Garey K.W. Economic health care costs of blood culture contamination: a systematic review.Am J Infect Control. 2019; 47: 963-967Abstract Full Text Full Text PDF PubMed Scopus (0) Google Scholar Several strategies have been proposed to reduce blood culture contamination. A meta-analysis reported two key methods for achieving this: sampling from a separate venipuncture site or collection by a well-trained phlebotomy team.2Snyder S.R. Favoretto A.M. Baetz R.A. et al.Effectiveness of practices to reduce blood culture contamination: a Laboratory Medicine Best Practices systematic review and meta-analysis.Clin Biochem. 2012; 45: 999-1011Crossref PubMed Scopus (94) Google Scholar In seriously ill patients, an indwelling arterial catheter is an attractive option for blood culture collection because it allows reliable blood sampling without frequent invasive punctures, accurate microbiological diagnosis with prompt initiation of antimicrobial therapy, and reduced burdens on health care practitioners. FOR RELATED ARTICLE, SEE PAGE 90 In this issue of CHEST, Nakayama et al3Nakayama I. Izawa J. Gibo K. et al.Contamination of blood cultures from arterial catheters and peripheral venipuncture in critically ill patients: a prospective multicenter diagnostic study.Chest. 2023; 164: 90-100Google Scholar describe a multicenter self-controlled prospective non-inferiority trial comparing blood culture contamination proportions between cultures collected from an indwelling arterial catheter and those collected from a peripheral vein.3Nakayama I. Izawa J. Gibo K. et al.Contamination of blood cultures from arterial catheters and peripheral venipuncture in critically ill patients: a prospective multicenter diagnostic study.Chest. 2023; 164: 90-100Google Scholar The results of this study suggest that obtaining cultures from an indwelling arterial catheter is an acceptable alternative to peripheral venipuncture among adult patients in the ICU with suspected bloodstream infection. Blood cultures drawn from arterial catheters and venipunctures have shown comparable contamination proportions,4Martinez J.A. DesJardin J.A. Aronoff M. Supran S. Nasraway S.A. Snydman D.R. Clinical utility of blood cultures drawn from central venous or arterial catheters in critically ill surgical patients.Crit Care Med. 2002; 30: 7-13Crossref PubMed Google Scholar,5McBryde E.S. Tilse M. McCormack J. Comparison of contamination rates of catheter-drawn and peripheral blood cultures.J Hosp Infect. 2005; 60: 118-121Abstract Full Text Full Text PDF PubMed Scopus (0) Google Scholar but no previous studies have formally examined a non-inferiority hypothesis. Nakayama et al3Nakayama I. Izawa J. Gibo K. et al.Contamination of blood cultures from arterial catheters and peripheral venipuncture in critically ill patients: a prospective multicenter diagnostic study.Chest. 2023; 164: 90-100Google Scholar used arterial catheters with a closed sampling system, which might have contributed to a much lower contamination proportion than previously reported in studies that investigated blood cultures from arterial catheters.4Martinez J.A. DesJardin J.A. Aronoff M. Supran S. Nasraway S.A. Snydman D.R. Clinical utility of blood cultures drawn from central venous or arterial catheters in critically ill surgical patients.Crit Care Med. 2002; 30: 7-13Crossref PubMed Google Scholar,5McBryde E.S. Tilse M. McCormack J. Comparison of contamination rates of catheter-drawn and peripheral blood cultures.J Hosp Infect. 2005; 60: 118-121Abstract Full Text Full Text PDF PubMed Scopus (0) Google Scholar The proportion of arterial catheters in the femoral artery was small (1.9%; 11/590), and the proportion of those placed in the ED was not high (20%; 120/590), both of which would have contributed to the low contamination rate in this study. Femoral sites are colonized more often than other sites6Gowardman J.R. Robertson I.K. Parkes S. Rickard C.M. Influence of insertion site on central venous catheter colonization and bloodstream infection rates.Intensive Care Med. 2008; 34: 1038-1045Crossref Scopus (74) Google Scholar and are thus associated with catheter-related bloodstream infection.7Lorente L. Jiménez A. Iribarren J.L. Jiménez J.J. Martín M.M. Mora M.L. The micro-organism responsible for central venous catheter related bloodstream infection depends on catheter site.Intensive Care Med. 2006; 32: 1449-1450Crossref Scopus (22) Google Scholar Previous studies have revealed that selection of the femoral artery for blood collection was significantly associated with contamination of blood cultures in the ED.8Ota K. Oba K. Fukui K. et al.Sites of blood collection and topical antiseptics associated with contaminated cultures: prospective observational study.Sci Rep. 2021; 11: 1-6Crossref Scopus (5) Google Scholar,9Ota K. Nishioka D. Ito Y. et al.Regression discontinuity of blood culture contamination rate after changing of disinfectants: retrospective observational study.Sci Rep. 2021; 11: 1-7Crossref Scopus (0) Google Scholar A distinguishing feature of the study by Nakayama et al3Nakayama I. Izawa J. Gibo K. et al.Contamination of blood cultures from arterial catheters and peripheral venipuncture in critically ill patients: a prospective multicenter diagnostic study.Chest. 2023; 164: 90-100Google Scholar is the use of arterial catheters with a closed sampling system, and standard intravascular catheter care and strict aseptic techniques for blood culture collection in the ICU.3Nakayama I. Izawa J. Gibo K. et al.Contamination of blood cultures from arterial catheters and peripheral venipuncture in critically ill patients: a prospective multicenter diagnostic study.Chest. 2023; 164: 90-100Google Scholar Could the difference in results be attributable to differences in the setting (ED or ICU, with or without closed sampling system, usual aseptic techniques or strict aseptic techniques, child or adult patients) of blood collection? The answers to these questions remain unclear. Several reports have described associations between blood samples collected from newly inserted peripheral venous catheters and blood culture contamination.10Norberg A. Christopher N.C. Ramundo M.L. Bower J.R. Berman S.A. Contamination rates of blood cultures obtained by dedicated phlebotomy vs intravenous catheter.J Am Med Assoc. 2003; 289: 726-729Crossref PubMed Scopus (0) Google Scholar,11Self W.H. Speroff T. McNaughton C.D. et al.Blood culture collection through peripheral intravenous catheters increases the risk of specimen contamination among adult emergency department patients.Infect Control Hosp Epidemiol. 2012; 33: 524-526Crossref PubMed Scopus (0) Google Scholar According to those reports, collecting blood culture specimens through a newly inserted peripheral venous catheter increases the risk of contamination compared with venipuncture.10Norberg A. Christopher N.C. Ramundo M.L. Bower J.R. Berman S.A. Contamination rates of blood cultures obtained by dedicated phlebotomy vs intravenous catheter.J Am Med Assoc. 2003; 289: 726-729Crossref PubMed Scopus (0) Google Scholar,11Self W.H. Speroff T. McNaughton C.D. et al.Blood culture collection through peripheral intravenous catheters increases the risk of specimen contamination among adult emergency department patients.Infect Control Hosp Epidemiol. 2012; 33: 524-526Crossref PubMed Scopus (0) Google Scholar Previous results, however, have suggested that obtaining a blood culture sample from a newly inserted peripheral venous catheter using a sterile technique protocol might still represent a valid alternative method of blood culture sampling to prevent blood culture contamination in the ED,9Ota K. Nishioka D. Ito Y. et al.Regression discontinuity of blood culture contamination rate after changing of disinfectants: retrospective observational study.Sci Rep. 2021; 11: 1-7Crossref Scopus (0) Google Scholar and a review article also emphasized the need to balance the practical advantages of this method against the risk of increased contamination.12Ombelet S. Barbé B. Affolabi D. et al.Best practices of blood cultures in low- and middle-income countries.Front Med. 2019; 6: 131Crossref Scopus (46) Google Scholar The most common sites for placement of arterial catheters were the upper limb in the study by Nakayama et al,3Nakayama I. Izawa J. Gibo K. et al.Contamination of blood cultures from arterial catheters and peripheral venipuncture in critically ill patients: a prospective multicenter diagnostic study.Chest. 2023; 164: 90-100Google Scholar and this practice is comparable to blood culture sampling from a newly inserted peripheral venous catheter. Thus, newly inserted arterial catheters using a sterile technique protocol might represent a valid alternative for blood culture sampling not only in the ICU, but also in the ED. Internal jugular sites were mostly chosen for central venous (CV) catheter insertion in the ED. This site has been confirmed to carry a higher risk of contamination, even though blood is drawn from a newly inserted CV catheter.6Gowardman J.R. Robertson I.K. Parkes S. Rickard C.M. Influence of insertion site on central venous catheter colonization and bloodstream infection rates.Intensive Care Med. 2008; 34: 1038-1045Crossref Scopus (74) Google Scholar, 7Lorente L. Jiménez A. Iribarren J.L. Jiménez J.J. Martín M.M. Mora M.L. The micro-organism responsible for central venous catheter related bloodstream infection depends on catheter site.Intensive Care Med. 2006; 32: 1449-1450Crossref Scopus (22) Google Scholar, 8Ota K. Oba K. Fukui K. et al.Sites of blood collection and topical antiseptics associated with contaminated cultures: prospective observational study.Sci Rep. 2021; 11: 1-6Crossref Scopus (5) Google Scholar, 9Ota K. Nishioka D. Ito Y. et al.Regression discontinuity of blood culture contamination rate after changing of disinfectants: retrospective observational study.Sci Rep. 2021; 11: 1-7Crossref Scopus (0) Google Scholar A CV catheter is unsuitable as a route for blood culture sampling when compared with arterial catheters or direct peripheral venipuncture.4Martinez J.A. DesJardin J.A. Aronoff M. Supran S. Nasraway S.A. Snydman D.R. Clinical utility of blood cultures drawn from central venous or arterial catheters in critically ill surgical patients.Crit Care Med. 2002; 30: 7-13Crossref PubMed Google Scholar,5McBryde E.S. Tilse M. McCormack J. Comparison of contamination rates of catheter-drawn and peripheral blood cultures.J Hosp Infect. 2005; 60: 118-121Abstract Full Text Full Text PDF PubMed Scopus (0) Google Scholar Handling and disinfection of access points, such as catheter hubs, needleless connectors, and antiseptic barrier caps, are complicated with CV catheters. The number of manipulations per blood collection through a CV catheter is thus higher than that with arterial catheters. As mentioned by the authors, considering that only approximately one-half of screened cultures were considered eligible for inclusion, some degree of selection bias could not be excluded. As such, an analysis of the excluded cultures, including demographics, reasons for exclusion, and microbiologic results, would add to the ability to generalize from these results to a general ICU population. However, the study brings up other important concerns. Notably, the authors suggested using arterial catheter collection when venipuncture was not feasible. However, their study was not limited to patients with unfeasible venipuncture. Indeed, given the study design, such patients were likely to be excluded. As such, interpretations of the study should focus on those critically ill patients for whom venipuncture was possible, with secondary interpretation of those for whom venipuncture was difficult or nearly impossible. The findings from this study indicate that usual practice for blood culture sampling might need to be reconsidered to include the option of obtaining cultures from an indwelling arterial catheter in critically ill adult patients with suspected bloodstream infection in the ICU.3Nakayama I. Izawa J. Gibo K. et al.Contamination of blood cultures from arterial catheters and peripheral venipuncture in critically ill patients: a prospective multicenter diagnostic study.Chest. 2023; 164: 90-100Google Scholar More studies are required, and consideration should be given to designing studies involving the general ICUs of other institutions using the usual sterile technique protocol; patients in EDs; blood cultures drawn from newly inserted arterial catheters with or without a closed sampling system rather than from indwelling arterial catheters; children; and comparison of blood cultures from arterial catheters and directly from CV catheters, using current antiseptic techniques as a primary outcome. None declared. Contamination of Blood Cultures From Arterial Catheters and Peripheral Venipuncture in Critically Ill Patients: A Prospective Multicenter Diagnostic StudyCHESTVol. 164Issue 1PreviewObtaining blood cultures from arterial catheters is an acceptable alternative to venipuncture in critically ill patients. Full-Text PDF