Gram-Negative Bacteria Blood Culture Nucleic Acid

Title:
Evaluation of Verigene (Nanosphere, Inc.) Gram-Negative Bacteria Blood Culture Nucleic Acid Test
(BC-GN) RUO
Speaker:
P. Ferrieri
Author(s):
P. Ferrieri1,2, K. Nelson2, S. Berger2, E. Thonen-Kerr2
1
Affiliation(s):
Dept of Lab. Med. and Pathology, Univ. of Minnesota Med Sch., Minneapolis, MN, 2Univ. of
Minnesota Med. Ctr., Fairview, Minneapolis, MN
®
The Verigene BC-GN is a qualitative multiplexed in vitro diagnostic assay for automated detection and identification of
nine gram-negative (GN) organisms and six antibiotic resistance gene markers: CTX-M, KPC, NDM, VIM, IMP, OXA. It
consists of two modules: the Verigene Processor SP and Verigene Reader. The processor utilizes single-use disposables,
including an extraction tray, utility tray and test cartridge; 700 ul of a gram-negative blood culture sample are
transferred into a loading well of the extraction tray. Hands-on time was approximately 5 minutes and time to result
after instrument loading was 1 hr 52 minutes. To date, 78 GN blood culture samples were tested and our results for
detection are: (1) 7 E. coli no resistance genes; 6 E coli CTX-M+, 1 E coli CTX-M and NDM+ and 1 E coli NDM+, all
concordant with routine ID; (2) 7/8 Klebsiella pneumoniae detected and one not detected - of these, 1 K
pneumoniae KPC+, 1 CTX-M+ and 1 NDM+ and also CTX-M+ and one un-evaluable; 2 reference strains K
pneumoniae KPC+ and K pneumoniae NDM+ (all in triplicate); (3) 3 Serratia marcescens; 1/3 modified Hodge test +, but
Verigene BC-GN negative for any gene markers (strain sent for sequencing; (4) 9 K oxytoca, of which 1 isolate was KPC+
and 1 isolate was CTX-M+; reference strain K oxytoca CTX-M+ (in triplicate); (5) 9/10 Enterobacter species were detected
correctly (no gene target on BC-GN for Enterobacter gergoviae); of these, 3/9 were KPC+ and 1/9 CTX-M+; (6)
3/4 Citrobacter species detected and 1 unresolved; also, one reference strain Citrobacter sp. was VIM positive (in
triplicate); (7) 4 Proteus sp. detected; (8) 5 Acinetobacter sp were detected and were resistance marker negative, and
one reference strain of Acinetobacter sp was OXA+ (in triplicate); (9) 7/8 Pseudomonas aeruginosa were detected; in
addition, one Pseudomonas aeruginosa reference strain was IMP + (in triplicate); (10) seven other miscellaneous gramnegative bacilli, not represented in targets on the BC-GN, were assayed and were not detected. Ongoing study of our
positive GN blood cultures will permit statistical analyses of the data. In summary, the Verigene® BC-GN assay was easy
to perform, efficient with relatively rapid TAT, and has the capability of detecting novel antibiotic resistance markers in
life threatening bacteremias that are gaining ascendancy world-wide.
Link: http://www.abstractsonline.com/Plan/ViewAbstract.aspx?sKey=656973f7-32f4-405b-8963efa9f1fc0921&cKey=d81aac81-ca71-4b62-afa8-0e90b69e292e&mKey=%7b673511F0-C86B-432F-A387058032B8500B%7d

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