Automated homogeneous immunoassay for gentamicin on the dimension clinical chemistry system.
BACKGROUND
Monitoring of the concentration of gentamicin in serum and plasma during therapy is widely recommended and practiced in hospitals. Our aim was to develop a homogeneous immunoassay based on particle-enhanced turbidimetric inhibition immunoassay technology to quantify gentamicin on the Dimension clinical chemistry system.


METHODS
Assay performance was assessed on each of the Dimension models in a 15-instrument interlaboratory comparison study. A split-sample comparison (n = 1171) was also performed between the gentamicin methods on the Dimension system and the Abbott TDx analyzer, using multiple reagent and calibrator lots on multiple instruments.


RESULTS
The Dimension method was linear to 25.1 micromol/L (12.0 microg/mL) with a detection limit of 0.63 micromol/L (0.3 microg/mL). Calibration was stable for 30 days. The within-run imprecision (CV) was <1.3%, and total imprecision ranged from 1.8% to 3.2% between 4.2 micromol/L (2.0 microg/mL) and 16.7 micromol/L (8.0 microg/mL) gentamicin. Linear regression analysis of the results on the Dimension method (DM) vs the Abbott TDx yielded the following equation: DM = 0.98TDx - 0.42; r = 0.987. Minimal interference was observed from structurally related compounds such as sagamicin, netilmicin, and sisomicin.


CONCLUSIONS
The monoclonal antibody used in this method has similar reactivities toward the individual gentamicin subspecies C1, C1a, and C2, thus providing analytical recovery not significantly dependent on relative subspecies concentrations.
Wei
T Q
TQ
Dade Behring Inc., Glasgow Business Community, Newark, DE 19714-6101, USA. weitq@dadebehring.com
Chu
V P
VP
Craig
A R
AR
Duffy
J E
JE
Obzansky
D M
DM
Kilgore
D
D
Masulli
I S
IS
Sanders
C M
CM
Thompson
J C
JC
D000900:Anti-Bacterial Agents / Q000097:blood* / Q000276:immunology; D000911:Antibodies, Monoclonal; D001322:Autoanalysis; D005839:Gentamicins / Q000097:blood* / Q000276:immunology; D006801:Humans; D007118:Immunoassay; D009391:Nephelometry and Turbidimetry; D011933:Reagent Kits, Diagnostic
D000900:Anti-Bacterial Agents; D000911:Antibodies, Monoclonal; D005839:Gentamicins; D011933:Reagent Kits, Diagnostic