Comparative evaluation of the oxoid signal and Roche Septi-Chek blood culture systems

Abstract

The Oxoid Signal blood culture system (Oxoid USA, Inc., Columbia, Md.) was compared with the Roche Septi-Chek system (Roche Diagnostics, Div. Hoffmann-La Roche Inc., Nutley, N.J.), with the latter consisting of a tryptic soy broth (R-TSB) bottle with an attached agar slide unit and a Columbia broth bottle. A total of 5,034 cultures with equal volumes of blood in each bottle were processed. Overall, more organisms were recovered in the R-TSB bottle than in the Signal bottle, with significantly more aerobic organisms (Pseudomonas spp., Acinetobacter spp., and yeasts) recovered in the R-TSB bottles and anaerobes and viridans group streptococci recovered in Signal bottles. Approximately equivalent numbers of organisms were recovered in the Signal and Columbia broth bottles. The times of detection were essentially identical with the three blood culture broth systems. During the study, 30.6% of the Signal bottles had a positive indicator of growth, of which 1,103 (71.7%) were false-positive cultures. Additionally, nonviable organisms resembling streptococci were observed in 13.7% of the Signal bottles that were Gram stained and in unioculated blood culture bottles. With appropriate modifications of the preparation of the media, the latter problem can be eliminated.

Comparative evaluation of nonradiometric BACTEC and improved oxoid signal blood culture systems in a clinical laboratory

“…7expressed concern over the isolation of N. meningitidis and anaerobic organisms by the Oxoid Signal system. Modifications made to the Oxoid formulation did improve the yield of anaerobic organisms (3,5,8,9), but problems still remained with the detection of Haemophilus species, Neisseria species, yeasts, and the nonfermentative gram-negative bacilli. Further modifications to the Oxoid medium to improve performance and the recent development of the nonradiometric BACTEC system provided an opportunity to compare the two improved systems for yield and mean detection time of clinically significant isolates.…”

Evaluation and comparison of different blood culture techniques for bacteriological isolation of Salmonella typhi and Brucella abortus

“…At the moment of use, the frozen aliquots were diluted 1:10 in a 0.85% saline solution. This dilution was read with a spectrophotometer at 640 nm, and this reading became the basis for reproducing the inoculum later (16). Serial dilutions of the 1:10 inoculum were made up to 1:10 Ϫ8 , and the number of CFU per milliliter of dilution was determined on a nutrient agar (BBL Microbiology Systems); this procedure was carried out each time the inoculum was prepared (18).…”

“…Recent advances in faster detection methods for bacteremia have included the development of commercial systems such as the BACTEC system (Johnson Laboratories, Inc., Towson, Md.) (16,32), Oxoid Signal (Oxoid, U.S.A., Inc., Columbia, Md.) (16), the Roche Septi-Chek system (Roche Diagnostics, Division of Hoffman-La Roche Inc., Nutley, N.J.) (8,20), Isolator (E. I. du Pont de Nemours and Co., Inc., Wilmington, Del.)…”

“…(16,32), Oxoid Signal (Oxoid, U.S.A., Inc., Columbia, Md.) (16), the Roche Septi-Chek system (Roche Diagnostics, Division of Hoffman-La Roche Inc., Nutley, N.J.) (8,20), Isolator (E. I. du Pont de Nemours and Co., Inc., Wilmington, Del.) (9), and the Septi-Chek Release culture bottle (Roche Diagnostics) (12).…”

Comparison of Signal and Bactec NR‐660 blood culture systems

“…The performance of the Signal manometric blood culture system (Unipath) has already been compared with a variety of conventional and automated methods (Murray et al 1988;Weinstein et al 1988Weinstein et al , 1989Wilson et al 1988;Rohner and Auckenthaler 1989). Three comparisons of the Signal with the Bactec non-radiometric NR-660 system (Becton Dickinson) have been reported (Rimmer and Cabot 1988;Daley et al 1990;Schwabe et al 1990).…”