Biomedical subjects

S Mirrett

Publications and source records attributed to S Mirrett.

At least 19 recordsLinked to original sources

PubMed1995

Value of routine anaerobic blood cultures for pediatric patients.

OBJECTIVE: Anaerobic bacteremia rarely occurs in children. Therefore we assessed the usefulness of routinely obtaining anaerobic blood cultures in our pediatric patients. STUDY DESIGN: Records of 9360 paired aerobic anaerobic blood culture bottles (Bactec NR660 System) containing blood specimens from pediatric inpatients and outpatients at Duke University Medical Center, Durham, N.C., were reviewed retrospectively. Yield and speed of detection were calculated for each bottle and compared for statistical significance by the McNemar test. RESULTS: A total of 723 clinically important microorganisms were isolated; only 15 (2.1%) were strict anaerobes. Significantly more microorganisms (p < 0.001), especially staphylococci, nonfermenting gram-negative rods, enteric gram-negative rods, and yeasts, were detected by use of the aerobic bottle. The anaerobic bottle was important in identifying an anaerobic microorganism as the cause of sepsis in only five patients, all of whom were at increased risk of having anaerobic infection. CONCLUSIONS: Anaerobic blood cultures are rarely helpful in the majority of pediatric patients and usually show positive results only in clinical settings associated with anaerobic infection. Microorganisms that prefer an aerobic environment, such as Pseudomonas aeruginosa and yeasts, are now far more common than anaerobes in children; aerobic culturing of the entire volume of blood collected might increase the yield from pediatric blood cultures.

Adolescent↗

PubMed1995

Clinical impact of bacteria and fungi recovered only from broth cultures.

We prospectively evaluated 356 bacteria and fungi recovered from broth enrichment tubes from cultures with sterile direct plates to determine the clinical impact of isolates recovered only from broth cultures. These "broth only" isolates (BOI) were classified as contaminants or true on the basis of review of patient charts. True isolates were considered clinically relevant only if they altered or should have altered patient management. Of 356 BOI, 259 (73%) were considered contaminants (mostly coagulase-negative staphylococci and Propionibacterium spp.) and 97 (27%) were considered true. For individual microorganisms, 9 of 9 (100%) Staphylococcus aureus isolates, 13 of 13 (100%) members of the family Enterobacteriaceae, 10 of 12 (83%) fungi, 7 of 10 (70%) enterococci, 7 of 11 (64%) other gram-negative bacilli, 13 of 31 (45%) anaerobic bacteria, 10 of 24 (42%) streptococci, 22 of 140 (16%) coagulase-negative staphylococci, 6 of 92 (7%) Propionibacterium spp., and 0 of 14 (0%) diphtheroids and Bacillus spp. were classified as true. Eleven of 97 (11%) patients with true BOI had clinically relevant isolates. Fifty-nine of the 97 (61%) patients with true isolates already were on therapy, and no change was made because of the BOI. Six (6%) patients with contaminants received therapy for their BOI. We conclude that broth inoculated as an adjunct to direct plating seldom yields results that favorably alter patient management and could be omitted for most specimens without compromising patient care.

Adult↗

PubMed1995

Controlled evaluation of BacT/Alert standard aerobic and FAN aerobic blood culture bottles for detection of bacteremia and fungemia.

A new medium, FAN, designed to enhance the recovery of microorganisms, has been developed for the BacT/Alert blood culture system (Organon Teknika Corp., Durham, N.C.). We compared the yield and speed of detection of microorganisms in 6,847 adequately filled paired aerobic standard and FAN bottles at four university hospitals. Of 499 clinically significant microorganisms isolated from one or both bottles, significantly more Staphylococcus aureus isolates (P < 0.001), coagulase-negative staphylococci (P < 0.001), yeasts (P < 0.01), and all microorganisms combined (P < 0.001) were recovered from the FAN bottles. Overall, the speeds of detection of positive cultures did not differ between the two medium formulations; mean times to detection in the standard and FAN bottles were 16.1 and 16.0 h, respectively. When a subset of patients on antimicrobial therapy was evaluated, significantly enhanced yield from the FAN bottle was evident for staphylococci. Overall, the FAN bottle outperformed the standard aerobic BacT/Alert bottle.

Aerobiosis↗

PubMed1995

Rapid bacterial antigen detection is not clinically useful.

Latex agglutination (LA) of capsular polysaccharide bacterial antigen is a frequently performed laboratory procedure, but its use is controversial. To assess the clinical utility of this test, we reviewed all LA tests performed over a 10-month period at two sites, a major university-based referral center and a private specialty pediatric hospital. Samples were assayed either individually or as a panel for the group B streptococcus, Streptococcus pneumoniae, Haemophilus influenzae, and three sets of Neisseria meningitidis serogroups (A and Y, C and W135, and B and Escherichia coli K1). Of 5,169 assays performed on 1,268 clinical samples (786 urine and 478 cerebrospinal fluid, 3 pleural fluid, and 1 synovial fluid sample), 57 (1.1%) were positive, including 1.7% of urine and 0.3% of cerebrospinal fluid samples. All LA true-positive cerebrospinal fluid samples showed the causative microorganisms by Gram stain. Detailed chart review of these 57 positive samples showed that the LA result was false-positive in 31 (54%), true-positive in 22 (38%), and indeterminate in 4 (7%) samples. Therapy was not altered on the basis of any of the true-positive LA results. The 31 false-positive results led to additional cost, prolonged hospitalization, and some clinical complications. Total patient charges were $175,000 ($7,954 per true-positive), with no detectable clinical benefit. Our retrospective study does not support the current use of LA for rapid antigen detection. What, if any, specific indications exist for this test remain to be elucidated.

Adolescent↗

PubMed1995

Controlled evaluation of BacT/alert standard anaerobic and FAN anaerobic blood culture bottles for the detection of bacteremia and fungemia.

FAN medium was formulated to improve microbial recovery, particularly for fastidious microorganisms and for microorganisms causing sepsis in patients receiving antimicrobial therapy. In a controlled clinical evaluation performed at four university-affiliated hospitals, FAN anaerobic bottles were compared with standard anaerobic bottles for yield, speed of detection of microbial growth, and detection of septic episodes. A total of 10,431 blood culture sets were received; both anaerobic bottles of 7,694 blood culture sets were adequately filled with blood. Altogether, 925 isolates were recovered: 557 that were the cause of sepsis, 99 that were indeterminate as the cause of sepsis, and 269 contaminants. More Staphylococcus aureus (P < 0.001), coagulase-negative staphylococci (P < 0.001), Escherichia coli (P < 0.02), and all microorganisms combined (P < 0.005) were recovered from FAN bottles; more nonfermentative gram-negative bacilli (P < 0.05), Torulopsis glabrata (P < 0.001), and other yeasts (P < 0.01) were recovered from standard bottles. Growth of S. aureus (P < 0.001), coagulase-negative staphylococci (P < 0.001), Enterococcus faecalis (P < 0.025), streptococci other than Streptococcus pneumoniae (P < 0.01), and all microorganisms combined (P < 0.001) was detected earlier in standard bottles; growth of more isolates of E. coli (P < 0.05) and anaerobic bacteria (P < 0.01) was detected earlier in FAN bottles. The mean times to detection were 14.2 and 16.1 h for standard and FAN bottles, respectively. More septic episodes caused by S. aureus (P < 0.001), coagulase-negative staphylococci (P < 0.005), members of the family Enterobacteriaceae (P < 0.02), and all microorganisms combined (P < 0.02) were detected in FAN bottles; more septic episodes caused by nonfermentative gram-negative bacilli (P < 0.025) and yeasts (P < 0.005) were detected in standard bottles. In summary, more isolates (except for strict aerobes) were recovered from FAN bottles than from standard anaerobic bottles. Similarly, significant more septic episodes (except for those caused by strict aerobes) were detected with FAN bottles than with standard anaerobic bottles. With the exception of E. coli and anaerobic bacteria, growth of more isolates was detected earlier in standard anaerobic bottles.

Aerobiosis↗

PubMed1994

Subcultures of BACTEC-positive but gram or acridine orange stain-negative NR 6A and 7A blood culture bottles are unnecessary.

A prospective study was done to assess the comparative use of acridine orange and Gram stains for detecting false-positive BACTEC blood culture bottles, thereby eliminating unnecessary subcultures. A total of 1049 NR 6A and 7A bottles that were instrument-positive in the BACTEC 660 nonradiometric system, but were Gram stain-negative, had aerobic and anaerobic subcultures as well as an acridine orange stain performed. Only five of 1049 (0.5%) instrument-positive, Gram stain-negative bottles grew microorganisms on subculture. Of these five microorganisms, acridine orange stain detected two. All five microorganisms were assessed not to be clinically significant based on review of the patients' charts. Our data showed that the Gram stain and the acridine orange stain are comparable for detecting false-positive NR 6A and 7A bottles. We conclude that subculture of BACTEC-positive, Gram stain-negative NR 6A and 7A bottles is not necessary.

Acridine Orange↗

PubMed1994

Controlled evaluation of 5 versus 10 milliliters of blood cultured in aerobic BacT/Alert blood culture bottles.

Bottles developed for use in the BacT/Alert automated blood culture system (Organon Teknika Corp., Durham, N.C.) can accept up to 10 ml of blood without falling below a 1:5 ratio of blood to broth. We compared the yield and speed of detection of microorganisms in 13,128 adequately filled, paired, aerobic bottles inoculated with 5 versus 10 ml of blood at three university hospitals. A total of 798 microorganisms causing sepsis grew in one or both bottles. The overall recovery of microorganisms from 10-ml samples exceeded that from 5-ml samples (P < 0.001); the increased yield attributed to the additional 5 ml in the samples was 7.2%. The increased yield from 10-ml inocula was most marked for Escherichia coli (P < 0.01) and other members of the family Enterobacteriaceae (P < 0.001). Ten-milliliter samples did not yield more gram-positive bacteria, nonfermentative gram-negative rods, or yeasts. When both bottles were positive, the bottles inoculated with 10 ml of blood showed growth sooner (P < 0.001). Earlier detection with 10-ml inocula was especially notable for coagulase-negative staphylococci (P < 0.001), streptococci (P < 0.001), E. coli (P < 0.025), and other members of the family Enterobacteriaceae (P < 0.025). We conclude that an increase in the volume of blood inoculated into BacT/Alert aerobic blood culture bottles from 5 to 10 ml will increase the overall yield and the speed of detection of clinically important blood pathogens.

Aerobiosis↗

PubMed1994

Recovery of select rare and fastidious microorganisms from blood cultures.

Most, if not all, rare or fastidious microbial pathogens can be recovered from standard blood culture bottles and media using routine laboratory methods. Because they are only rarely recovered from blood cultures, relatively few data exist concerning the ability of different blood culture systems to recover these microorganisms. Thus, clinical microbiologists should take a conservative approach when processing blood cultures that may contain one of the microorganisms reviewed in this article, including the use of additional media, media supplements, blind and terminal subcultures, or prolonged incubation and testing.

Bacteremia↗

PubMed1994

Antimicrobial susceptibility testing and blood cultures.

Susceptibility testing of microorganisms isolated from blood cultures should follow the guidelines of the NCCLS in the selection of antimicrobial agents and the method for testing. Standardized testing can be performed on isolated colonies from pure subcultures of the blood/broth mixture. Direct susceptibility testing can provide results up to 24 hours sooner, but the techniques for testing have not been standardized. The disk diffusion and agar dilution techniques do not utilize automated testing techniques and seem to provide reliable results. Limited studies of direct susceptibility testing using automated procedures have been published, but the results are not conclusive. The number of discrepancies with direct automated procedures in comparison with standardized techniques is low, and most investigators agree that direct testing is appropriate given the rapidity with which the results are available. New resistance patterns for microorganisms are appearing regularly, and the technology for automated procedures is changing rapidly. New clinical evaluations of direct susceptibility testing with larger numbers of microorganisms that include some of the recently described resistant microorganisms would help to clarify the accuracy and reliability of current procedures. Standardized direct susceptibility testing guidelines should be established so that reliability and accuracy can be improved. There is general consensus that repeat testing by standardized techniques is advisable, although the decision as to whether to repeat the test using a standardized method rests with the individual laboratory director based on his or her expertise and experience with the procedures. Each laboratory director should compare the advantages and limitations of direct antimicrobial susceptibility testing with the methodology currently in use and determine the need for repeat testing by standardized techniques.

Autoanalysis↗

PubMed1993

Recovery of clinically important microorganisms from the BacT/Alert blood culture system does not require testing for seven days.

Recently, we published a comparison of the BacT/Alert blood culture system with the BACTEC 660/730 nonradiometric blood culture system using blood inocula of 5 ml per bottle. By reanalyzing data collected during that study, we found that, for true-positive isolates causing bacteremia or fungemia, 363 (97.6%) of 376 and 341 (97.7%) of 349 isolates were recovered by the end of day 5 of testing, and 364 (97.9%) of 376 and 343 (98.3%) of 349 isolates were recovered by the end of day 6 of testing for aerobic and anaerobic bottles, respectively. Most isolates recovered on days 6 (24 of 27) and 7 (20 of 25) of testing were either contaminants or indeterminate as a cause of sepsis. When used as recommended by the manufacturer, only six (1.3%) of 464 clinically important isolates recovered on test days 6-7 would have gone undetected had testing been limited to 5 days and four (0.9%) of 464 had testing been limited to 6 days. We conclude that BacT/Alert bottles can be tested for as few as 5 days and then discarded with minimal loss of true-positive isolates and maximal reduction of contaminants.

Bacteremia↗

PubMed1993

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.

Aerobiosis↗

PubMed1993

Rationale for selective use of anaerobic blood cultures.

Because of the declining frequency of anaerobic bacteremia, routinely using half the collected blood volume for anaerobic culture has been challenged. There is no data indicating whether more clinically relevant isolates would be recovered if all or most of the given blood sample were cultured aerobically. In this two-part study, we reviewed cases of anaerobic bacteremia to determine what proportion occurred in situations when anaerobes would be expected and then estimated the yield of different culture approaches by reanalyzing the data from a large prospective clinical blood culture study. The records of 61 patients who had an anaerobic isolate (excluding Propionibacterium species) recovered only from an anaerobic bottle were examined to define clinical settings in which such isolates occur. Fifty-six (92%) patients had clinically important isolates, and the source of infection was obvious at the time of culture in 47 of the 56 (84%). Of 56 patients, 36 (64%) had abdominal signs and symptoms, including 12 with recent abdominal surgery. Of nine patients without an obvious source of infection, six were on high-dose steroids. Relative yields were compared for (i) one aerobic bottle and one anaerobic bottle (5 ml to each) for all blood cultures, (ii) two aerobic bottles (5 ml to each), or (iii) two aerobic bottles plus an extra anaerobic bottle (only for clinically suspected anaerobic sepsis) (5 ml to each). The third approach had the highest yield (475 isolates), because the routine use of two aerobic bottles recovered more Candida spp., members of the family Enterobacteriaceae, and nonfermenters than did the first approach (448 isolates) (P < 0.02), and clinically directed culturing for anaerobes would recover anaerobes missed with the second approach (458 isolates). Our data suggest that the use of two aerobic bottles with selective culturing for anaerobes could increase the number of clinically relevant isolates by at least 6% compared with the current practice of inoculating an aerobic bottle and an anaerobic bottle with equal volumes of blood.

Adult↗

PubMed1992

Controlled evaluation of BACTEC PLUS 27 and Roche Septi-Chek anaerobic blood culture bottles.

Becton Dickinson Diagnostic Instrument Systems (Sparks, Md.) recently introduced BACTEC high-volume aerobic and anaerobic bottles that accept up to 10 ml of blood for use on their nonradiometric blood culture instruments. Both bottles contain 25 ml of tryptic soy broth, 0.05% sodium polyanetholesulfonate, and mixed resins. We compared the anaerobic bottle, designated BACTEC PLUS 27 (BP27), with the Roche Septi-Chek (RSC) Columbia broth anaerobic bottle in a collaborative evaluation at three university hospitals. A total of 5,152 adequately filled blood cultures were obtained from adult patients with suspected bacteremia or fungemia. Staphylococcus aureus was recovered significantly more often (P less than 0.03) from BP27 bottles alone; there were no other significant differences in yield. When microorganisms were recovered from both anaerobic bottles, growth was detected earlier in BP27 than it was in RSC (P less than 0.001), especially for S. aureus (P less than 0.001) and Staphylococcus epidermidis (P less than 0.02). We conclude that the yield from BP27 bottles is equivalent to or better (S. aureus) than that from RSC anaerobic bottles with Columbia broth and that speed of detection is superior with BP27 bottles.

Adult↗

PubMed1992

Controlled comparison of the BacT/Alert and BACTEC 660/730 nonradiometric blood culture systems.

In a collaborative study at three university hospitals, the recovery of microorganisms and the speed of detection of microbial growth by the BacT/Alert (Organon Teknika Corporation, Durham, N.C.) and BACTEC 660/730 (Becton-Dickinson Diagnostic Instrument Systems, Sparks, Md.) nonradiometric blood culture systems were compared. A total of 5,918 comparisons were made between BacT/Alert aerobic and BACTEC NR 6A bottles and 5,992 comparisons were made between BacT/Alert anaerobic and BACTEC NR 7A bottles. Each bottle was inoculated with 5 ml of blood. The overall recoveries of microorganisms from the two aerobic bottles were comparable; members of the family Enterobacteriaceae were recovered more often from BacT/Alert aerobic bottles alone (P less than 0.001). The overall recoveries of microorganisms from the anaerobic bottles were not significantly different. Growth of Staphylococcus aureus (P less than 0.001), coagulase-negative staphylococci (P less than 0.01), streptococci (P less than 0.001), Escherichia coli (P less than 0.01), other members of the family Enterobacteriaceae (P less than 0.02), and Pseudomonas aeruginosa (P less than 0.05) was detected earlier in BacT/Alert aerobic bottles. Growth of S. aureus (P less than 0.001), coagulase-negative staphylococci (P less than 0.05), enterococci (P less than 0.01), Streptococcus pneumoniae (P less than 0.02), viridans group streptococci (P less than 0.05), E. coli (P less than 0.001), Klebsiella pneumoniae (P less than 0.01), and other members of the family Enterobacteriaceae (P less than 0.001) was detected earlier in BacT/Alert anaerobic bottles. In a system-versus-system comparison, more gram-positive cocci were recovered from the BACTEC system alone (P < 0.05), and more members or the family Enterobacteriaceae were recovered from the BacT/Alert system alone (P < 0.001). As a system, the BacT/Alert system detected growth of S. aureus (P < 0.001), coagulase-negative staphylococci (P < 0.01), streptococci (P < 0.001), E. coli (P < 0.001), other members of the familyEnterobacteriaceae (P < 0.001), and P. aeruginosa (P < 0.05) earlier than the BACTEC system did. Significantly fewer (40 versus 1,183) false-positive results occurred with the BacT/Alert system. We conclude that the BacT/Alert and BACTEC 660/730 nonradiometric systems are comparable for recovering clinically significant microorganisms form adult patients with bacteremia or fungemia, but that the BacT/Alert system detects microbial growth earlier than the BACTEC system does, with significantly fewer false-positive results.

Adult↗

PubMed1991

Controlled evaluation of BACTEC Plus 26 and Roche Septi-Chek aerobic blood culture bottles.

Blood culture bottles that accept up to 10 ml of blood have recently been introduced for the BACTEC nonradiometric blood culture system. The new formulation, designated BACTEC Plus, contains 25 ml of tryptic soy broth, 0.05% sodium polyanetholesulfonate, and mixed resins. In a collaborative study conducted at three university hospitals, we evaluated the BACTEC Plus 26 (BP26) aerobic bottle and the Roche Septi-Chek aerobic bottle with its agar slide paddle in 5,293 paired blood cultures. Significantly more microorganisms (P less than 0.001), especially Staphylococcus aureus (P less than 0.001), Staphylococcus epidermidis (P less than 0.01), enterococci (P less than 0.005), and members of the family Enterobacteriaceae (P less than 0.005), were detected by the BP26 bottle. When both bottles detected growth, BP26 did so earlier (P less than 0.001). In particular, S. epidermidis (P less than 0.001), streptococci (P less than 0.005), enterococci (P less than 0.05), and members of the family Enterobacteriaceae (P less than 0.001) were detected earlier by the BP26 bottle. We conclude that the BP26 bottle provides a yield and speed of detection of microorganisms superior to those of the Roche Septi-Chek aerobic blood culture bottle.

Adult↗

PubMed1990

Effect of altered headspace atmosphere on yield and speed of detection of the Oxoid Signal blood culture system versus the BACTEC radiometric system.

The one-bottle Oxoid Signal blood culture system altered to provide a more aerobic bottle headspace was reassessed in a comparative study versus the two-bottle BACTEC radiometric system in 5,426 blood cultures. The BACTEC system detected more microorganisms (P less than 0.02), particularly anaerobes (P less than 0.05) and fungi (P less than 0.05).

Bacteria↗

PubMed1990

BacT/Alert: an automated colorimetric microbial detection system.

BacT/Alert (Organon Teknika Corp., Durham, N.C.) is an automated microbial detection system based on the colorimetric detection of CO2 produced by growing microorganisms. Results of an evaluation of the media, sensor, detection system, and detection algorithm indicate that the system reliably grows and detects a wide variety of bacteria and fungi. Results of a limited pilot clinical trial with a prototype research instrument indicate that the system is comparable to the radiometric BACTEC 460 system in its ability to grow and detect microorganisms in blood. On the basis of these initial findings, large-scale clinical trials comparing BacT/Alert with other commercial microbial detection systems appear warranted.

Bacteria↗

PubMed1989

Comparative evaluation of radiometric tryptic soy broth versus radiometric tryptic soy broth with 10% sucrose for detection of bacteremia and fungemia in pediatric patients.

We compared BACTEC radiometric blood culture media with (8B) and without (6B) 10% sucrose for the detection of bacteremia and fungemia in pediatric patients at four university teaching hospitals that used identical methods for obtaining and processing specimens. Overall, the yields of microorganisms from 5,714 blood culture sets were no different in the two media, although a trend was noted favoring 6B for the detection of pneumococci. Speed of detection of positive results was faster in the 6B than in the 8B medium (P less than 0.05), largely due to the faster detection of Staphylococcus aureus in the 6B medium. We conclude that, overall, with pediatric patients the hypertonic 8B radiometric medium has no advantage and that it possibly has a modest disadvantage, compared with isotonic 6B radiometric medium.

Bacteria↗