Effect of delay in processing on lysis-centrifugation blood culture results from marrow transplant patients

Abstract

The effect of delay in processing on results of lysis-centrifugation (LC; Isolator) blood cultures was assessed in 4,577 paired blood specimens. Blood specimens were obtained at all hours from 384 febrile marrow transplant patients with indwelling venous catheters and were processed by the LC technique and by a conventional two-bottle method. Most patients (84%) were receiving broad-spectrum antibiotics at the time of blood culture. Specimens were delivered to the laboratory, where Isolator tubes were held at 35°C and processed in batches between 0700 and 1730 h daily. This procedure resulted in a delay beyond the manufacturer-suggested processing time of less than 8 h for 1,853 (42%) of the LC cultures. There was no overall difference in the recovery of organisms present in LC cultures processed after being held for 8 to 24 h compared with the conventional two-bottle method. LC methodology had shorter time to detection than the conventional method for detection of Candida spp. and Pseudomonas spp. (P < 0.05). However, time to detection for Streptococcus spp. and members of the family Enterobacteriaceae, responsible for 16.3% of total isolates, was prolonged significantly by delay in processing when compared with the conventional two-bottle method (P < 0.01). Results of this study support the recommendation of the manufacturer for processing of Isolator tubes within 8 h or less. Although one can safely delay processing beyond 8 h in terms of total recovery of organisms, such delays were associated with longer time to detection for certain important potentially pathogenic organisms which accounted for a sizeable proportion of blood culture isolates from marrow transplant patients.

Controlled comparison of the BACTEC high-blood-volume fungal medium, BACTEC Plus 26 aerobic blood culture bottle, and 10-milliliter isolator blood culture system for detection of fungemia and bacteremia

“…Blood culture processing. All blood culture sets were processed for purposes of patient care, but only those cultures received with at least two of the three bottles or tubes adequately filled and within 8 h of collection (10,27) were included in the study. HBV-FM and BP26 bottles were processed on BACTEC 660 blood culture instruments.…”

Review on evaluations of currently available blood-culture systems

“…The Isolator 10 tubes contain the following reagents in 0.7 mL of aqueous solution: saponin (cell‐lysing agent), propylene glycol (blocks the foaming tendency of saponin), and SPS (anticoagulant). At least 6 mL of blood should be inoculated into these tubes, which must be processed as soon as possible, or at most 8 h after the inoculation of blood [61].…”

Effect of delays in processing on the survival of Mycobacterium avium-M. intracellulare in the isolator blood culture system

“…Previous studies on the delayed processing of Isolator tubes either have not examined mycobacteria specifically or have used a design different from that of the present study. The studies of Hamilton et al (6) and Cashman et al (2) showed that rapidly growing bacteria were viable in the Isolator system after hold times of 8 to 24 h but that delayed processing led to an increase in the time needed to recover certain species (e.g., streptococci and members of the family Enterobacteriaceae) and decreased quantitative recovery rates for certain species (Streptococcus pneumoniae, Haemophilus influenzae). Only one mycobacterial strain (identified only as atypical mycobacterium) was studied.…”

“…when Isolator tubes are held for more than 8 h before processing (2,6). In one clinical study, delays of >9 h in processing Isolator tubes was associated with a fivefold reduction in the number of cultures positive for MAC (14).…”