The clinical comparison of Oxoid Signal with Bactec blood culture systems for the detection of streptococcal and anaerobic bacteraemias.

Blood cultures were taken from 47 patients 1-2 min after dental extraction. These samples were tested by the radiometric Bactec 460 and Oxoid Signal systems for the detection of streptococcal and anaerobic bacteraemias. Streptococci were isolated from 19 (40%) patients and anaerobes from 15 (32%). In this study the Oxoid Signal system was significantly better for isolating oral anaerobes than the Bactec system; five isolates were obtained with the Bactec system and 14 with the Signal system. There was no significant difference in the isolation of streptococci between these two systems (Bactec 14, Oxoid Signal 10). The contamination rate was 4.1% for Bactec and 7.5% for the Oxoid Signal system.     

Clinical laboratory comparison of the 10-ml isolator blood culture system with BACTEC radiometric blood culture media.

The efficiency of the 10-ml Isolator (E. I. du Pont de Nemours & Co., Inc.) for recovery of pathogens from blood was compared with that of BACTEC 6B and 7C media (Johnston Laboratories) by using 4,195 cultures from 1,662 patients. During the first phase of the study, BACTEC bottles were inoculated with 3 ml of blood; in the second phase, bottles were inoculated with 5 ml. The objectives were to compare results with similar blood volumes used for the detection of anaerobes as well as similar overall volumes and to determine the relative sensitivity of BACTEC media inoculated with the minimum and maximum volumes suggested by the manufacturer. From 180 patients, 391 significant isolates were recovered, 354 (91%) with the Isolator and 304 (78%) with the bottles. Isolators recovered 31 (15%) and 19 (18%) more pathogens overall than did the two-bottle system inoculated with 3 and 5 ml of blood, respectively, including 30 (36%) and 10 (34%) more Enterobacteriaceae. Recovery of anaerobes was greater in the BACTEC anaerobic medium, but only when its inoculum was increased to 5 ml. No significant differences existed between the two systems in pathogen detection times or detection of polymicrobic bacteremia. The Isolator contamination rate (8.3%) was approximately 4 times that of the bottles. The number of CFU of pathogen per milliliter of blood, blood volume sampled, and number of Isolators collected were more important than antimicrobial agent pretreatment in contributing to patient bacteremia of fungemia undetected by the Isolator. The Isolator appeared to be a practical alternative for recovery of aerobic and facultatively anaerobic pathogens from the blood.     

Comparison of Sentinel and Bactec blood culture systems.

AIMS: To evaluate the Sentinel automated blood culture system and to compare its performance with that of Bactec. METHODS: The Sentinel blood culture system was evaluated in three centres. The performance of the system was assessed in comparison with the routine blood culture method used in these centres, the Bactec system. RESULTS: Blood culture sets (n = 2180) consisting of Sentinel aerobic and anaerobic, and Bactec aerobic and anaerobic bottles yielded 218 (10%) clinically important isolates. One hundred and fifty five (71%) of the isolates were detected by both systems; 35 (16%) were detected by Sentinel only; and 28 (13%) by Bactec only. For the duration of the evaluation, the Sentinel system was deliberately configured so that it was impossible to detect positive results during the first 12 hours. The times to positivity after the first 12 hours were similar. Data gathered during and subsequent to the evaluation have been used by the manufacturer to refine the algorithm so that positive results can be detected at a minimum of 2.25 hours. CONCLUSIONS: After a period of familiarization the Sentinel system was considered easy to use. Sentinel is a useful addition to the methods available for the detection of bacteria in blood cultures.     

Clinical comparison of a new automated infrared blood culture system with the BACTEC 460 system.

A new blood culture instrument, the BACTEC (Johnston Laboratories, Inc., Towson, Md.) NR-660, which utilizes infrared detection of carbon dioxide from microbial metabolism, was compared with the radiometric BACTEC 460 system. There were 1,554 isolates from 18,785 paired aerobic blood cultures. Of these isolates, 1,303 were isolated from the radiometric 6B medium, and 1,259 were isolated from the NR6A medium (P = 0.06). Analysis of the data indicated no significant differences in recovery when any individual species was considered. When organisms were considered as groups, there were no significant detection differences for gram-negative bacilli, yeasts, or anaerobes. For gram-positive cocci in aerobic medium, the BACTEC 460 detected 84.3% of the total isolates, and the BACTEC NR-660 detected 79.7% (P = 0.04). There were 891 isolates from 13,983 paired anaerobic blood cultures. Of these isolates, 725 were recovered from the radiometric 7D BACTEC medium, and 723 were recovered from the NR7A BACTEC medium (P greater than 0.9). In the anaerobic media there was no significant difference in detection of any organism group, including the gram-positive cocci. When the results of the aerobic and anaerobic media were combined, there was equivalence between the two systems for the detection of gram-positive cocci (P greater than 0.2) and other organism groups. When the ability to detect septic episodes was compared, there was no significant difference for any organism group (P = 0.12). For aerobic media, the mean times for detection were 30.5 and 29.5 h for the BACTEC 460 and NR-660, respectively. For anaerobic media, the mean times for detection were 39.8 and 41.6 h for the BACTEC 460 NR-660, respectively. Compared with the BACTEC 460, the BACTEC NR-660 system had a greater ease of operation, faster test cycle, computerized data base, and equally rapid detection of positive cultures.     

Clinical comparison of aerobic, hypertonic, and anaerobic culture media for the radiometric detection of bacteremia.

The BACTEC 225 was used to test 5,811 routine blood cultures over a 20-month period. Aerobic, anaerobic, and hypertonic media were employed. The BACTEC 225 detected 511 positive cultures; 407 of these were considered significant organisms, and 104 were presumed contaminants. Of the significant positive cultures, 15% were detected within the first 12 h of incubation, 52% within 24 h, 82% within 48 h and 92% within 72 h. Aerobic, anaerobic, and hypertonic media are recommended for each venipuncture since 56 cultures were isolated from the aerobic medium only, 110 from the anaerobic medium only, and 94 from the hypertonic medium only. There were 16 patients who had multiple venipunctures from which organisms were repeatedly isolated from only one medium: two from the aerobic medium, four from the anaerobic medium, and ten from the hypertonic medium only. Detection times were not significantly different for the aerobic and hypertonic media. However, there were five patients with multiple venipunctures in which growth was detected radiometrically at least 48 h earlier in the hypertonic than in the aerobic medium. False-positive growth index readings were noted in 1,085 (19%) of the aerobic vial, 11 (0.19%) of the anaerobic vials, microorganisms were isolated from at least one of the companion vials. Using 5% co2 to flush the aerobic vials. With some false-positive aerobic and hypertonic vials decreased the number of false positives to about 6% of the total.     

Clinical comparison of the Isolator 1.5 microbial tube and the BACTEC radiometric system for detection of bacteremia in children.

The Isolator 1.5 microbial tube (E. I. du Pont de Nemours & Co., Inc., Wilmington , Del.) was compared with the BACTEC radiometric detection system (Johnston Laboratories, Inc., Cockeysville, Md.) for the detection of bacteremia in children. The Isolator 1.5 is a blood culture system designed for small volumes of blood (0.5 to 1.5 ml). The method involves lysis of the cells of the patient and the direct plating of the entire blood lysate on agar media appropriate for the growth of fastidious microorganisms. Of 1,500 paired samples inoculated into the two systems, 68 were positive for 73 clinically significant organisms. The Isolator 1.5 recovered 81% of the positive cultures compared with 84% recovered by the BACTEC system. When paired blood samples with disproportionate volumes were excluded, the Isolator 1.5 detected 3% more positive cultures. More isolates of Streptococcus pneumoniae and Neisseria meningitidis were recovered by the Isolator 1.5, whereas Haemophilus influenzae was recovered most often in the BACTEC bottles (P greater than 0.1). The contamination rates were 8.7 and 3.1% for the Isolator 1.5 and the BACTEC system, respectively. In cultures positive by both systems, the mean time to detection was 4.1 h faster with the Isolator 1.5. The mean time to obtain isolated colonies was 26.6 h faster with the Isolator 1.5. These data indicate the potential value of the Isolator 1.5 microbial tube as a simple, rapid, and sensitive method for the detection of bacteremia in children.     

Clinical laboratory comparison of lysis-centrifugation and BACTEC radiometric blood culture techniques.

The lysis-centrifugation technique (ISOLATOR; E. I. du Pont de Nemours & Co., Wilmington, Del.) and the radiometric blood culture technique (BACTEC; Johnston Laboratories, Inc., Cockeysville, Md.) were compared on 1,000 blood cultures. A total of 16 ml of blood was distributed: 8 ml into an ISOLATOR 7.5 microbial tube and 4 ml each into BACTEC 7C and 8B bottles. The concentrate from the ISOLATOR tubes was inoculated under a laminar-flow hood onto two sheep blood agar plates (one incubated in CO2 and one incubated anaerobically), one chocolate agar plate, and one brain heart infusion agar plate. Of 91 blood specimens obtained that yielded clinically significant organisms, 52 were positive by both systems, 27 were positive by the ISOLATOR system only, and 12 were positive by the BACTEC system only. From the positive blood specimens, 97 clinically significant organisms were isolated: 57 by both systems, 27 by the ISOLATOR system only, and 13 by the BACTEC system only. Of the 57 organisms detected by both systems, 28 were detected simultaneously, 13 were detected earlier by the ISOLATOR system, and 16 were detected earlier by the BACTEC system. Isolated colonies were obtained earlier by the ISOLATOR system in 40 cases and by the BACTEC system in 5 cases. Organisms determined to be contaminants by thorough chart review were isolated from 138 ISOLATOR tubes. In 98 instances, these were represented by one colony of Staphylococcus epidermidis, alpha-hemolytic streptococci, or diphtheroids. The ability to determine CFU per milliliter with the ISOLATOR system did not help differentiate clinically significant organisms from contaminants.     

Clinical comparison of lysis-centrifugation and radiometric resin systems for blood culture.

The Isolator 10 lysis-centrifugation blood culture system (E. I. du Pont de Nemours & Co., Inc., Wilmington, Del.) and the BACTEC 16B-17D radiometric resin system (Johnston Laboratories, Inc., Towson, Md.) both remove antimicrobial agents from the blood for culture. We compared these two systems for recovery of aerobic bacteria, facultatively anaerobic bacteria, and yeasts. A total of 5,000 blood cultures yielded 467 clinically significant isolates. Both systems recovered 350 (75%) organisms, 56 (12%) were detected by Isolator only, and 61 (13%) were detected by BACTEC resin bottles only. No group of organisms was isolated significantly more often from either system.     

Clinical evaluation of the lysis-centrifugation blood culture system for the detection of fungemia and comparison with a conventional biphasic broth blood culture system.

In a comparative fungal blood culture study, a lysis-centrifugation system (Isolator; Du Pont Co., Wilmington, Del.) detected 89% of all episodes of fungemia; the lysis-centrifugation system detected fungemia exclusively or significantly earlier than did a biphasic brain heart infusion bottle system 83% of the time. The lysis-centrifugation system was particularly useful in the early detection of fungemia caused by Candida tropicalis and Candida glabrata. In 53% of the clinically significant episodes, the earlier detection was directly helpful in the management of patients with fungemia. High-magnitude candidemia (greater than 5 CFU/ml of blood) was significantly associated with the presence of an infected intravascular catheter and with Candida species other than Candida albicans. The lysis-centrifugation system was sensitive in the detection of fungemia during the monitoring of patients receiving antifungal agents or after removal of an infected intravascular catheter.     

Clinical comparison of the Roche Septi-Chek and Dupont Isolator blood culture systems

A study was conducted to compare the recovery of clinical isolates by the DuPont Isolator and Roche Septi-Chek blood culture systems. A total of 5,262 blood culture specimens were processed by the two systems. Of these, 358 cultures contained significant isolates: 219 were positive in both systems, 68 were recovered only by Isolator, 71 were recovered by Septi-Chek only (not statistically significant). Of the isolates recovered in both systems, 159 were positive the same day, 55 were recovered first by Isolator, and 5 were recovered first by Septi-Chek. In cases where Isolator recovered organisms first, the average difference in time was one to two days. Regarding particular groups of organisms, there was no difference between the systems in recovery of Enterobacteriaceae, anaerobes, yeast, and gram-positive bacteria, except for Streptococcus pneumoniae. Septi-Chek recovered S. pneumoniae significantly more often. These results suggest that these two systems are essentially comparable, except with S. pneumoniae, although the Isolator frequently provided results more rapidly.     

Comparison of the automated Bactec NR-660 with a conventional blood culture system

The Bactec NR-660 blood culturing system was compared with a conventional system using 347 consecutively obtained clinical blood samples tested simultaneously. Of 46 clinically relevant isolates, 12 were detected by the conventional system only, 5 by Bactec only and 29 by both methods (0.05相似文献   

Clinical comparison of the resin-containing BACTEC 26 Plus and the Isolator 10 blood culturing systems.

The new resin-containing BACTEC 26 Plus blood culturing system (Becton Dickinson Diagnostic Instrument Systems, Towson, Md.) was compared with the Isolator 10 system (Wampole Laboratories, Cranbury, N.J.). Blood samples were drawn by syringe, and equal 10-ml volumes were evaluated in each blood culture system by the recommended methods. Both systems were incubated aerobically with 5% CO2. Of 11,506 acceptable study specimens, 1,788 aerobic isolates were recovered. Overall, recoveries was similar for the two systems, with 626 bacteria or fungi recovered in the BACTEC 26 Plus system only, 499 recovered in the Isolator system only, and 663 recovered in both systems. Of 345 gram-negative rods, 62 grew in the BACTEC system only and 109 grew in the Isolator system only (P less than 0.001). Thirty-three of these Isolator-only gram-negative organisms were Acinetobacter spp. Of 209 yeasts, 38 grew in BACTEC only and 81 grew in Isolator only (P less than 0.001). Of 200 streptococci and enterococci, 98 were recovered in BACTEC only and 26 grew in Isolator only (P less than 0.001). Two hundred twenty-eight independent episodes of gram-negative rod bacteremia occurred. Isolator was the first system positive in 59 of 197 episodes, compared with 45 of 197 for BACTEC when Acinetobacter episodes were excluded. Times to detection were similar for the two systems. High colony counts correlated with repeat positive blood cultures. Isolator and BACTEC had similar overall recoveries, with individual merits and deficiencies for both systems. The additional quantitative information derived from Isolator had utility in our institution.     

Comparison between Bactec Nr. 660 and a conventional 12-tube blood culture system

The detection power of the automated blood culture system Bactec NR 660, based on infrared detection of carbon dioxide in an agitated aerobic medium and a non-agitated anaerobic medium, was compared with that of our conventional 12-tube blood culture system. Of 1685 paired blood cultures, 258 (15.3%) were positive in one or both systems. Clinically relevant isolates were found in 11.5%. The dominating species were Escherichia coli(41%), followed by Staphylococcus aureus(14%) and Klebsiella spp.(8%). The Bactec system detected 178 (10.6%) and the 12-tube system 157 (9.3%) clinically relevant microorganisms after seven days' incubation. Significantly more clinically relevant isolates were detected by the Bactec system alone as compared with the conventional system alone (40 versus 19, p less than 0.01). The detection time was significantly shorter in the Bactec system for all isolates and for E. coli and S. aureus separately (p less than 0.01). 1.8% of the isolates in the Bactec system and 2.1% in the 12-tube system were considered clinically non-relevant contaminants.     

Comparison of a radiometric and a broth-slide system for aerobic blood culture.

In a comparison of the radiometric BACTEC 460 (Johnston Laboratories) and the BCB broth slide system (Roche Diagnostics Division), the latter yielded a slightly greater number of clinically significant microorganisms, as well as contaminants, from aerobic blood cultures. These differences may reflect the larger volume of blood required for and the greater amount of manipulation associated with the BCB.     

Large-scale clinical comparison of the lysis-centrifugation and radiometric systems for blood culture.

A reverse hemagglutination assay was used to study adherence to human erythrocytes by Escherichia coli H10407, which possesses colonization factor antigen I. Pretreatment of erythrocytes with trypsin, chymotrypsin, papain, protease, and neuraminidase completely abolished attachment reactivity. In addition, the hemagglutination reaction was prevented by the presence of urea and guanidine. In contrast, the lipases, nucleotide hydrolases, exoglycosidases, and reagents affecting disulfide or sulfhydryl moieties did not alter receptor reactivity. Glycoconjugates containing sialic acid inhibited the hemagglutination reaction. Furthermore, a sialoglycoprotein isolated from the erythrocyte membrane inhibited the hemagglutination reaction. Collectively, these data indicate that the erythrocyte receptor responsible for attachment by E. coli possessing colonization factor antigen I is a sialoglycoconjugate.     

Clinical laboratory comparison of a slide blood culture system with a conventional broth system

The recovery of bacteria and fungi from blood cultures was compared in conventional tryptic soy broth (TSB) bottles and in TSB bottles with an agarcoated slide attachment. A total of 2,662 sets of blood cultures, including 413 that were positive (15.5%), were evaluated. Significantly more gram-positive and gram-negative bacteria were recovered in the slide culture bottles than in conventional bottles (299 versus 253 isolates). Growth of gram-positive organisms and fungi was detected in the slide culture bottles 24 to 48 h earlier than in the TSB bottles. In addition, 76% of the isolates in the slide culture system were detected on the agar slide. In comparison, only 40% of the isolates in the TSB bottles were detected initially by blind subculturing. The incidences of contamination were 2.7% (71 cultures) for the slide culture system and 1.5% (39 cultures) for the TSB bottles.     

Anomalous results using countercurrent immunoelectrophoresis for the detection of pneumococcal antigen in Bactec blood culture media.

On examination of Bactec blood cultures for pneumococcal antigen by countercurrent immunoelectrophoresis the consistent presence of a non-specific protein band caused problems with the interpretation of results, even in laboratories experienced in performing countercurrent immunoelectrophoresis. When the Bactec blood culture system is used, countercurrent immunoelectrophoresis should not be relied on for the detection of pneumococcal antigen.     

Evaluation of the use of Bactec anaerobic blood cultures in the detection of bacteraemia and fungaemia in children

In an attempt to reduce costs, the role of Bactec anaerobic blood culture in the detection of bacteraemia and fungaemia in children was evaluated. Results from 3167 sets of aerobic and anaerobic blood cultures from children admitted to the University Hospital, Kuala Lumpur during a one year period, were analysed. Four hundred and eight (12.9%) sets of blood cultures were positive, of which 348 sets (11.0%) from 201 patients were clinically significant. Of the 348 significant positive sets, organisms were isolated on 177 (50.9%) occasions from both aerobic and anaerobic bottles, on 136 (39.1%) occasions from the aerobic bottle only and 35 (10.0%) occasions from the anaerobic bottle only. No strict anaerobes were isolated, but clinically significant isolates recovered from the anaerobic bottle only included Klebsiella pneumoniae, Salmonella species, Enterobacter cloacae, Staphylococcus aureus, coagulase negative staphylococci, Streptococcus pneumoniae and Group B streptococcus. Patients with bacteraemia diagnosed solely by anaerobic culture were distributed evenly across the various paediatric subspecialities. When results from the anaerobic bottles were excluded, the overall isolation rate was reduced from 11% to 9.9%. Potential financial savings resulting from omission of anaerobic cultures must be balanced against the small number of bacteraemic episodes that could be missed. Undiagnosed bacteraemia may result in increased morbidity and mortality with its own attendant financial implications.     

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.

The BACTEC high-blood-volume fungal medium (HBV-FM) (Becton Dickinson Diagnostic Instrument Systems, Sparks, Md.) was compared with the Isolator (IS) tube and the BACTEC Plus 26 (BP26) blood culture bottle for the ability to recover fungi from the blood of adult patients suspected of having fungemia. A total of 6,836 blood culture sets that fulfilled criteria for inclusion in the study were received. Three separate comparisons were performed: 4,907 HBV-FM versus IS, 4,886 BP26 versus HBV-FM, and 4,949 BP26 versus IS. For the HBV-FM versus IS comparison, 218 isolates were recovered: 125 (57.3%) were bacteria and 93 (42.7%) were fungi. HBV-FM was comparable to IS for recovery of yeasts, but IS was superior for recovery of Histoplasma capsulatum (25 versus 0 isolates recovered [P < 0.001]). Growth of Torulopsis glabrata was detected earlier (P < 0.05) in HBV-FM bottles. For the BP26 versus HBV-FM comparison, 229 isolates were recovered: 161 (70.3%) were bacteria, and 68 (29.7%) were fungi. HBV-FM was superior for recovery of T. glabrata (P < 0.025) and all fungi combined (P < 0.025). There were no statistically significant differences in the speed of detection of microbial growth. For the BP26 versus IS comparison, 251 isolates were recovered: 165 (65.7%) were bacteria, and 86 (34.2%) were fungi. IS was superior for recovery of H. capsulatum (P < 0.001), T. glabrata (P < 0.05), and fungi other than H. capsulatum (P < 0.025). BP26 was superior for recovery of all bacteria combined (P < 0.001) and viridans group streptococci (P < 0.01). Growth of T. glabrata (P < 0.05) was detected earlier in IS tubes. Growth of Staphylococcus aureus (P < 0.01), viridans group streptococci (P < 0.01), Pseudomonas aeruginosa (P < 0.05), and all microorganisms combined (P < 0.05) was detected earlier in BP26 bottles. For yeast, 57 of 59 (96.6%), 79 of 80 (98.7%), and 64 of 67(95.5%) were recovered from BP26 bottles, HBV-FM bottles, and IS tubes, respectively, by day 14; for H. capsulatum, 14 of 36 (38%) isolates were recovered from IS tubes by day 14. Mean times of recovery were similar for BACTEC bottles and IS. We conclude that (i) for recovery of fungi from blood cultures, HBV-FM is equivalent to IS (with the exception of H. capsulatum); (ii) for recovery of bacteria, BP26 is superior to IS; (iii) BP26 bottles are inferior to both HBV-FM bottles and IS tubes for recovery of T. glabrata; and (iv) HBV-FM bottles must be paired with another blood culture bottle or system to optimize detection of bacteremia.     

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

The 1-min leukocyte esterase (LE)-nitrite test (Chemstrip 9; Biodynamics, Division of Boehringer Mannheim Biochemicals, Indianapolis, Ind.) and a bioluminescence assay (Monolight centrifugation method; Analytical Luminescence Laboratory, Inc., San Diego, Calif.) were tested for their efficacy as urine screens among 453 patients at a tertiary-care teaching hospital. Both methods had the capacity to exclude significant bacteriuria (greater than or equal to 10(5) CFU/ml) when compared with the results of conventional culture methods, with predictive values of 99 and 93%, respectively, for a negative test. Bioluminescence was the more accurate nonculture method used. Sensitivity and specificity values were 97 and 71%, respectively, for bioluminescence, 82 and 60%, respectively, for LE with nitrite, and 72 and 64%, respectively, for LE without nitrite. At reduced levels of bacteriuria less than 10(5) CFU/ml), the sensitivities of LE-nitrite and bioluminescence were decreased but comparable. The addition of protein and blood test results in the Chemstrip 9, along with LE-nitrite as bacteriuria indicators, were unsatisfactory because of the large numbers of false-positive results attributed to protein and blood determinations. LE activity as detected by the LE test was a poor predictor of significant bacteriuria in both male and female patients. The sensitivity (71%) and specificity (57%) of the LE test in male patients were significantly lower than those previously reported and varied with the patient population studied.