Is it Always Necessary to Take Blood Cultures before Starting Antibiotics in the Emergency Department? A Review of Usefulness of Blood Cultures in Community-Acquired Pneumonia, Cellulitis, Urinary Tract Infection and Pyelonephritis

Routine blood cultures are commonly taken in patients who present to the Emergency Department (ED) with suspicion of infection. This is also in conjunction with treatment guidelines for severe community-acquired pneumonia, acute meningitis and bacteraemia, etc. The above practice has become a major area of resource utilisation, despite many studies showing poor yield of these cultures. The poor yield of blood cultures is financially costly for patients, and even more so for hospitals. Hidden costs such as wastage of resources, additional working hours for healthcare staff and increased needle stick injuries are a huge burden to hospitals. In addition, contamination (or false-positive blood culture results) has been shown to lead to increased length of stay and total hospital charges. This review questions the efficacy of routine blood cultures taken in the emergency department, in the context of community-acquired pneumonia, cellulitis, urinary tract infection and pyelonephritis. The results of the review showed that blood cultures for community acquired pneumonia, simple and complicated cellulitis as well as simple acute urinary tract infections are not recommended as they do not hold much significant clinical impact on the antibiotic regimen and there is no need for them to be taken prior to the administration of antibiotics. Blood cultures should be taken in patients with severe signs of systemic infection, hospital-acquired pneumonia, complicated cellulitis and pyelonephritis because it is possible for blood cultures to have a bearing on the clinical management. ISSN: 2474-3674 DOI: 10.23937/2474-3674/1510062 • Page 2 of 5 • Jun et al. Int J Crit Care Emerg Med 2019, 5:062 patients with severe illness as there is a higher chance that pathogens not covered by empiric therapy will be found and hence influence antibiotic regimens [1]. A study by Makam, et al. looked at the trend of blood cultures collected in patients with CAP and found a relative increase of 73.4% in 2002 and 2010, whereas cultures obtained for urinary tract infection remained relatively stable [8]. One reason provided for the increase follows from the mandate by JCAHO and The Centres for Medicare and Medicaid guidelines on quality measures that emphasized performing blood cultures before administering antibiotics in the ED [10,11]. This prompted doctors to reflexively order cultures for patients with CAP for whom antibiotics are expected. Makam, et al. concluded that appropriate blood cultures use should be reserved only for the sickest patients when the results could reduce harm, limit hospital stay and lower costs [8]. Other literature suggest that blood cultures rarely altered the management of CAP. Ramanujam, et al. in 2006 revealed positive blood cultures for bacteraemia in 4.5% of the patients with 1.3% warranting a change in antibiotic regimen because of deterioration of clinical status and not due to blood culture results [9]. This is similar to another article in 2007 where a true positive rate of 3.4% was found and for the 0.7% that required a change in antibiotic therapy, none of them had antibiotics coverage broadened due to a resistant organism [10]. These authors recommend eliminating blood cultures for CAP, but still obtaining blood cultures for patients at risk of hospital-acquired pneumonia, since the blood cultures taken rarely altered therapy for patients presenting to the ED with pneumonia [9,10]. Another 2005 study by Kennedy, et al. found 7.0% true positives of which 11 patients had antibiotic coverage narrowed and 4 had theirs broadened due to resistance to empirical therapy [13]. Abe, et al. in 2009 showed that 3.7% of the study population had been found positive for bacteraemia, out of whom 2 had their coverage narrowed and 1 had theirs broadened [14]. The blood cultures taken could only identify microbes in a small percentage of people with pneumonia and since few patients altered therapy, it may not be necessary to obtain blood cultures for most patients. Significant healthcare cost was incurred for this practice of taking blood cultures which could possibly have been reduced with proper decision on blood cultures usage. From the above literature, blood cultures appear to be of low value and are not recommended for use with community-acquired pneumonia prior to antibiotics management [8,9,13-15].