Controlled evaluation of supplemented peptone and Bactec blood culture broths for the detection of bacteremia and fungemia

Publisher Website
Google Scholar
Abstract
Comparisons of conventional blood culture media with newer formulations of Bactec media for radiometric detection are lacking. Therefore, the yield and speed of detection of clinically important microorganisms with supplemented peptone broth (SPB) and Bactec aerobic (6B) and anaerobic (7C or 7D) broths were compared in 7627 blood samples from adult patients. Acridine orange stains from SPB, radiometric readings from Bactec, and routine subcultures from all bottles were done at the same time intervals. Bactec grew more facultative gram-positive bacteria (P < 0.02), Bacteroides spp. (P < 0.001) and gram-negative anaerobes (P < 0.001). The 2-bottle Bactec system required less time to detect Staphylococcus aureus (P < 0.001), facultative gram-positive bacteria (P < 0.001), Escherichia coli (P < 0.02), facultative gram-negative bacteria (P < 0.001) and fungi (P < 0.001). Bactec yielded 11% more microorganisms and detected bacteremia sooner in 18% of samples than did SPB. This advantage was not because of radiometric monitoring, since most positive Bactec bottles were detected macroscopically. SPB offered no advantage for any group of microorganisms. Evidently, Bactec 6B and 7C or 7D broths used as a unit are superior to a single bottle of SPB with an equal vol of blood for the detection of bacteremia and fungemia, and Bactec''s superiority is not due to the method of detection.