JCM Accepts, published online ahead of print on February 0 J. Clin. Microbiol. doi:./jcm.01- Copyright 0, American Society for Microbiology and/or the Listed Authors/Institutions. All Rights Reserved. 1 Comparison of BD BACTEC Plus Blood Culture Media versus VersaTREK REDOX Blood Culture Media for Detection of Bacterial Pathogens in Simulated Adult Blood Cultures Containing Therapeutic Concentrations Of Antibiotics 1 1 1 1 Nancy S. Miller 1,*, Dagmar Rogan 1, Beverley L. Orr 1, Dana Whitney Department of Pathology and Laboratory Medicine 1 and Department of Pharmacy, Boston Medical Center, and Boston University School of Medicine, Boston, MA 0 Keywords: Blood culture media, blood culture systems, antibiotic inactivation Running head: Antibiotic inactivation in simulated blood cultures: BACTEC vs. VersaTREK Contact information for corresponding author: Nancy S. Miller, M.D. Division of Laboratory Medicine, Boston Medical Center East Newton Street, H00, Boston, MA 0 nancy.miller@bmc.org Downloaded from http://jcm.asm.org/ on September 1, 01 by guest 1 Phone: (1) -0, Fax: (1) - 1
Abstract 1 1 1 1 1 1 1 1 0 1 Antibiotic neutralization in blood culture media from two automated systems was evaluated by measuring recovery of organisms and time to detection in simulated cultures. Overall, BD BACTEC Plus Media (BACTEC FX system) outperformed TREK 0 ml REDOX media (VersaTREK system), although results suggest a relative rather than an absolute increased recovery for BACTEC. Blood samples taken from patients on antibiotic therapy can delay or prevent the detection of bacteremia in automated blood culture systems. BD BACTEC TM Plus Media on the new BACTEC TM FX and the incumbent 000 series blood culture systems (BD Diagnostics, Sparks, MD) utilize cationic exchange and nonionic adsorbent resins to remove antibiotics from blood samples. In contrast, 0 ml REDOX media on the VersaTREK blood culture system (TREK Diagnostics, Cleveland, OH) relies on an optimal 1: blood:broth dilution to neutralize antibiotic effects. Few recent studies (1,,) have compared VersaTREK media to BACTEC media for antibiotic inactivation. This in vitro study compared the ability of each system and media to neutralize various antibiotics at trough (T), mid (M), and peak (P) simulated therapeutic serum concentrations when tested against susceptible bacterial challenge organisms. BACTEC Plus /F (0 ml) media (BACTEC) and TREK 0A aerobic REDOX 1 (0 ml) media (TREK) were used for all challenge organisms. BACTEC Plus Anaerobic/F ( ml) media and TREK 0N anaerobic REDOX media (0 ml) were also used for Streptococcus oralis and Streptococcus pneumoniae. Stock solutions of each antibiotic (0.1 Downloaded from http://jcm.asm.org/ on September 1, 01 by guest
1 1 1 1 1 1 1 1 0 1 ml) were potency-adjusted to simulate T, M, and P serum concentrations based on ml of blood per media bottle. Antibiotics were chosen for clinical relevance and serum concentrations were based on current dosing recommendations. Final antibiotic concentrations (T, M, and P levels in µg/ml) were as follows: ampicillin (, 1, ), cefepime (, 1, 1), ceftriaxone (1,, 0), levofloxacin (1.,., 1), piperacillin/tazobactam (1./0., 1/, /), and vancomycin (,, 0). These were tested against ATCC challenge strains as indicated in Tables 1 and. Concentrations for each antibiotic were per manufacturer or calculated from antibiotic half-life and based on recommended doses for the treatment of severe infections in an average weight adult with normal renal function. A susceptible minimal inhibitory concentration (MIC) for each antibiotic was confirmed by replicate testing using Etest agar gradient method (biomérieux SA) for each relevant bacterial species tested against that drug. Media bottles were inoculated with ml banked whole blood (Interstate Blood Bank, Inc., Memphis, Tennessee) not more than days old, 0.1 ml potency-adjusted antibiotic (or saline for controls) and 0.1 ml challenge organism suspended in 0.% saline containing between 0 colony forming units (inocula confirmed by colony count plating). Inoculated bottles were incubated per -day protocol on their respective instruments. Each organism/antibiotic concentration was run concurrently in triplicate for a total of two trial replications on two separate days. Antibiotic neutralization was measured as the percent recovery of organisms and time to detection (TTD) in seeded, antibiotic-containing blood culture bottles. Data are reported as aggregate results from all trials and were analyzed using SAS (SAS Institute, Cary, NC). Comparison of organism recovery was performed using Fisher s exact test with a P-value < 0.0 to indicate statistical significance. Downloaded from http://jcm.asm.org/ on September 1, 01 by guest
1 1 1 1 1 1 1 1 0 1 Overall recovery of organisms by BACTEC was.% (1/) and 1.% (/) for TREK. This difference was statistically significant (p<0.0001). Results were further stratified by media type and antibiotic concentrations (Table 1). Differences were statistically significant in favor of BACTEC. There were no instances for which both systems performed equally well at recovering challenge organisms for all concentrations of a specific antibiotic (Table ). Significant differences between the two systems were observed for specific concentrations of agents. For all concentrations of vancomycin, organism recovery by BACTEC was significantly different since no challenge organisms, including S. aureus, were recovered by TREK. For all concentrations of ceftriaxone both systems failed to recover any S. pneumoniae or S. oralis despite acceptable growth in control bottles. Results are further tabulated in Table. Results showed BACTEC Plus media to be significantly more efficient at recovery of challenge organisms in the presence of antibiotics as compared to TREK REDOX media. For both systems when percent organism recovery was not 0% it decreased with increasing amounts of antibiotic, consistent with expectations (,, ). (Two outliers to this are evident in Table for TREK media: for ampicillin there was recovery of E. faecalis at trough and peak but none at mid concentration; for vancomycin there was recovery of E. faecalis only at peak concentration of vancomycin. For each of these apparent paradoxes a clerical error or variation in bottle inoculation (pipetting) cannot be excluded). The current study design intentionally mirrored one used by Flayhart et al. () for their comparison of BACTEC to BacT/Alert media. But we used the BACTEC FX instrument and the 0 ml Plus /F bottle (instead of the 0 cabinet and ml Plus /F bottle); slightly different T, M, and P serum concentrations of antibiotics were based on our clinical Downloaded from http://jcm.asm.org/ on September 1, 01 by guest
1 1 1 1 1 1 1 1 0 1 pharmacist s calculations. Our results are similar to those reported by Flayhart et al. However, our BACTEC s overall recovery of organisms (.%) and recovery of organisms from test bottles (.%) differs from Flayhart et al. (.1% and.%, respectively) and is likely attributable to differences in MIC, or the number of organisms or antibiotics used. Where calculated serum concentrations were the same and results could be equitably compared both our study and Flayhart et al. showed equivalent or enhanced recovery of organisms for BACTEC versus the comparator system (). Notable variations in BACTEC performance between the two studies include S. pneumoniae in the presence of ampicillin, S. aureus (MSSA) in the presence of vancomycin, and E. coli and P. aeruginosa in the presence of cefepime. In each instance, BACTEC recovered a higher percentage of organisms in Flayhart et al. than in the present study. However, in our study BACTEC recovered more S. pneumoniae in the presence of vancomycin than it did in Flayhart et al. We used lower calculated mid-level antibiotic concentrations than did Flayhart et al., but our recovery rates for BACTEC were lower. These differences are possibly due to variations in inoculum at extremes of the allowed range or differences in antibiotic MIC (data unable to be compared). In the present study BACTEC also provided an advantage over TREK regarding overall TTD (Table 1). Delay in detection time was generally dependent on increased concentration of antibiotic, consistent with other studies (, ). Divergent results seem due to a majority of isolates not growing within five days at the higher drug concentration. LaBombardi et al. () also noted discrepancies between their own incomplete resinadsorption results and other reports citing apparent resin-binding and successful organism recovery including those cited by Flayhart et al. Results for simulated studies (,,) are not always concordant with controlled clinical trials (,, 1). But two seeded studies (1, ) and one Downloaded from http://jcm.asm.org/ on September 1, 01 by guest
limited prospective study () have favored BACTEC media versus TREK media in their respective scenarios of antibiotic or other antimicrobial neutralization. 1 1 1 1 1 1 Simulated trials do not account for any advantages that might be conferred to TREK by patient serum-related antibiotic neutralizing factors in the context of broth dilution; to date this has not been thoroughly evaluated by controlled clinical studies. Our findings suggest a relative rather than absolute advantage for the BACTEC system as compared to TREK, within the limitations of a simulated study. Time of draw for blood cultures should remain an important clinical consideration, to ensure that samples are taken at the lowest possible serum levels of antibiotics in order to facilitate optimal recovery of bloodstream pathogens. We acknowledge Christopher Amantia and his colleagues in the BMC Clinical Microbiology Laboratory for their technical help in conducting this study. We thank Dr. Gheorghe Doros (Boston University Department of Biostatistics) for his analysis of the study data. Material support for this study was provided by BD Diagnostics, Sparks, MD. Authors Disclosure Statement The authors report no conflict of interest in relation to this manuscript. References Downloaded from http://jcm.asm.org/ on September 1, 01 by guest 1 1 0 1. Dam, L.M., S.W. Eisinger, P.D. Stamper, N. Epie, K.C. Carroll, and S. Riedel. 0. Comparison of the BACTEC Plus blood culture media to the VersaTREK REDOX blood culture media for detection of yeast in seeded blood culture specimens containing therapeutic levels of
antifungal agents, abstr. C-0, Abstr.1th Gen. Meet. Am. Soc. Microbiol. American Society for Microbiology, San Diego, CA. 1 1 1 1 1 1 1 1 0. DiPersio, J. and H. Bonilla. 0. Comparison of BACTEC Plus /F and VersaTREK REDOX 1 Blood Culture Media for the Recovery of S. aureus from Patients with Suspected Persistent Bacteremia, abstr. C-, Abstr.1th Gen. Meet. Am. Soc. Microbiol. American Society for Microbiology, San Diego, CA.. DiPersio, J., L. DiPersio, and J. Beach. 00. Recovery of Staphylococcus aureus from BACTEC PLUS and VersaTrek REDOX 1 blood culture media with increasing concentrations of vancomycin, daptomycin, or linezolid, abstr. D-0, Abstr. th Ann. Intersci. Conf. Antimicrob. Agents Chemother. / th Ann. Infect. Dis. Soc. Amer., Washington, D.C.. Flayhart, D., A.P. Borek, T. Wakefield, J. Dick, and K.C. Carroll. 00. Comparison of BACTEC PLUS blood culture media to BacT/Alert FA blood culture media for detection of bacterial pathogens in samples containing therapeutic levels of antibiotics. :1 1.. Jorgensen, J. H., S. Mirrett, L. C. McDonald, P. R. Murray, M. P. Weinstein, J. Fune, C. W. Trippy, M. Masterson, and L. B. Reller. 1. Controlled clinical laboratory comparison of BACTEC Plus aerobic/f resin medium with BacT/Alert aerobic FAN medium for detection of bacteremia and fungemia. J. Clin. Microbiol. :.. LaBombardi, V., J. Sotos, S. Allen, and N. Sullivan. 00. Resins do not adsorb all antibiotics at peak serum concentrations, especially the newer beta-lactam antibiotics. American Society for Microbiology. th ASM General Meeting, May 1-1, Philadelphia, PA. Abstract C-0. Downloaded from http://jcm.asm.org/ on September 1, 01 by guest
. Pohlman, J. K., B. A. Kirkley, K. A. Easley, B. A. Basille, and J. A. Washington. 1. Controlled clinical evaluation of BACTEC Plus /F and BacT/Alert FAN bottles for detection of bloodstream infections. J. Clin. Microbiol. :. 1 1 1 1 1 1. Spaargaren, J., C. P. A. van Boren, and G. P. Voorn. 1. Effectiveness of resins in neutralizing antibiotic activities in BACTEC Plus /F culture medium. J. Clin. Microbiol. :1.. Vigano, E.F., E. Vasconi, C. Agrappi, P. Clerici. 00. Use of simulated blood cultures for time to detection comparison between BacT/ALERT and BACTEC 0 blood culture systems. Diagn. Microbiol. Infect. Dis. : 0.. Vigano, E. F., E. Vasconi, C. Agrappi, P. Clerici, and P. Melloni. 00. Use of simulated blood cultures for antibiotic effect on time to detection of the two blood culture systems BacT/Alert and BACTEC 0. New Microbiol. :.. Washington, J. A., II, and D. M. Ilstrup. 1. Blood cultures: issues and controversies. Rev. Infect. Dis. : 0. 1. Ziegler, R., I. Johnscher, P. Martus, D. Lenhardt, and H.-M. Just. 1. Controlled clinical laboratory comparison of two supplemented aerobic and anaerobic media used in automated blood culture systems to detect bloodstream infections. J. Clin. Microbiol. :-1. Downloaded from http://jcm.asm.org/ on September 1, 01 by guest
Table 1. Overall Organism recovery and average time-to-detection (TTD) by media type and antibiotic concentrations BACTEC TREK p value score Media Drug (T; M; P) 1 Statistic Total Control (%) Trough (%) Mid (%) Peak (%) Control (%) Trough (%) Mid (%) Peak (%) C T M P Anaerobic Anaerobic Ampicillin (;1;) Cefepime (;1;1) Recovered (0) (.) 0 (.) (.) (0) (1.) (.) (.) 1.000 <0.001 <0.001 <0.001 AVG TTD 1. 1 0. 1. 0.1. 1. Combined 1/ (.) /() (1.) Recovered 0 0 (0) 1 (.) 1 (.) 1 (0) (.) (0) (1.) 0 (0) 1.000 <0.001 0.00 <0.001 AVG TTD. 1 0 1. 1.. NA Combined Overall (0) 0/0 (.) 1/ (.) (.1) /0 (1.) / (1.) Recovered (0) (0) (.) (.) (0) (.) 0 (0) 1 (.1) 1.000 0.0 0.00 0. AVG TTD. 1. 0. 1...1 NA 0. Recovered (0) (.) 1 (1.) 0 (0) (.) 0 (0) 0 (0) 0 (0) 1.000 0.01 1.000 1.000 AVG TTD. 1.1. NA 1. NA NA NA Recovered 1 1 (0) (0) () 0 (0) 1 (0) (0) 0 (0) 0 (0) 1.000 1.000 0.1 1.000 AVG TTD 1. 0. NA 1.. NA NA Recovered (0) 0 (0) 0 (0) 0 (0) (0) 0 (0) 0 (0) 0 (0) Ceftriaxone AVG TTD 1.1 NA NA NA 1. NA NA NA Anaerobic (1;;0) Recovered (0) 0 (0) 0 (0) 0 (0) (0) 0 (0) 0 (0) 0 (0) AVG TTD 1. NA NA NA 1. NA NA NA Recovered 1 1 (0) 1 (.) (.) (.) (0) 1 (.) (.) 0 (0) 1.000 1.000 0.0 0.00 Levofloxacin AVG TTD 1. 1. 1 1. 1. 1.. NA Anaerobic (1.;.;1) Recovered (0) (0) (0) (0) (0) (0) (.) 0 (0) 1.000 1.000 1.000 0.00 AVG TTD... 1.1 1.. NA Piperacillin/ Tazobactam Recovered (1./0.; 1/; 1 1 (0) 1 (0) () (.) 1 (0) 1 (0) (1.) 0 (0) 1.000 1.000 0.01 0.0 /) AVG TTD 1. 1. 1. 1. 1. 1.. Recovered (0) (0) (1.) 1 (.) (0) 0 (0) 0 (0) 1 (.) 1.000 <0.001 <0.001 <0.001 Vancomycin AVG TTD. 1.... NA NA. Anaerobic (;;0) Recovered (0) (0) (0) (0) (0) 0 (0) 0 (0) 0 (0) AVG TTD. 1... 1. NA NA NA 1 Antimicrobial concentration (ug/ml) for Trough. Mid, and Peak levels C=Control; T=Trough' M=Mid; P=Peak. in hours; values rounded to the nearest decimal. Downloaded from http://jcm.asm.org/ on September 1, 01 by guest
1 Table 1: Overall organism recovery and average-time-to-detection (TTD) by media type and antibiotic concentrations 1 Antibiotic concentration (ug/ml) for Trough, Mid, and Peak levels C = Control; T = Trough; M = Mid; P = Peak TTD in hours, values rounded to the nearest decimal Table : Microorganism specific recovery by antibiotic concentration 1 Microoganism ATCC catalog numbers: Streptococcus pneumoniae ATCC 1; Streptococcus oralis ATCC ; Enterococcus faecalis ATCC ; Staphylococcus aureus ATCC (MSSA); Staphylococcus aureus ATCC 00 (MRSA); Escherichia coli ATCC ; Pseudomonas aeruginosa ATCC. Downloaded from http://jcm.asm.org/ on September 1, 01 by guest
Table : Microorganism specific recovery by antibiotic concentration Trough (%) Mid (%) Peak (%) Trough (%) Mid (%) Peak (%) Drug Microorganism 1 * 1* * * 1* * Ampicillin Cefepime Ceftriaxone Streptococcus pneumoniae (0) 1 (1.) 0 (0) 0 (0) 0 (0) 0 (0) Streptococcus oralis (.) (0) 1 (1.) 1 (1.) 0 (0) 0 (0) Enterococcus faecalis (0) (0) (.) (0) 0 (0) 1 (.) Escherichia coli Total BACTEC Antimicrobial concentration (ug/ml)* * 1* 1* * 1* 1* 1 (1.) 0 (0) 0 (0) 1 (1.) 0 (0) 0 (0) Pseudomonas aeruginosa (.) (0) 0 (0) (.) 0 (0) 0 (0) 1* * 0* 1* * 0* Streptococcus pneumoniae 0 (0) 0 (0) 0 (0) 0 (0) 0 (0) 0 (0) Streptococcus oralis 1 0 (0) 0 (0) 0 (0) 0 (0) 0 (0) 0 (0) 1.*.* 1* 1.*.* 1* Streptococcus pneumoniae 1 1 (0) 1 (0) 1 (0) 1 (0) (1.) 0 (0) Levofloxacin Escherichia coli (.) 0 (0) 0 (0) 1 (1.) 0 (0) 0 (0) Pseudomonas aeruginosa (0) (.) 1 (1.) (0) (.) 0 (0) 1./0.* 1/* /* 1./0.* 1/* /* Piperacillin/ Escherichia coli (0) (.) (0) (0) (.) 0 (0) Tazobactam Pseudomonas aeruginosa (0) (.) 1 (1.) (0) 0 (0) 0 (0) * * 0* * * 0* Staphylococcus aureus MSSA (0) (.) 1 (1.) 0 (0) 0 (0) 0 (0) Staphylococcus aureus MRSA (0) (0) (0) 0 (0) 0 (0) 0 (0) Vancomycin Streptococcus pneumoniae (0) (0) (0) 0 (0) 0 (0) 0 (0) Streptococcus oralis 1 1 (0) 1 (0) 1 (0) 0 (0) 0 (0) 0 (0) Enterococcus faecalis (0) (0) (0) 0 (0) 0 (0) 1 (.) 1 Microoganism ATCC catalog numbers: Streptococcus pneumoniae ATCC 1; Streptococcus oralis ATCC ; Enterococcus faecalis ATCC ; Staphylococcus aureus ATCC (MSSA); Staphylococcus aureus ATCC 00 (MRSA); Escherichia coli ATCC ; Pseudomonas aeruginosa ATCC. TREK Antimicrobial concentration (ug/ml)* Downloaded from http://jcm.asm.org/ on September 1, 01 by guest