Evaluation of dipicolinic acid-based Mueller Hinton agar biplate for detection of IMP-1 and VIM-2 type metallo-beta-lactamase in imipenem non-susceptible gram negative bacilli.
BACKGROUND
Since metallo-beta-lactamase (MBL)-producing isolates can hydrolyze carbapenem and also easily transfer the resistance genes to other bacteria, a rapid and accurate detection of MBL has become very important. We evaluated the utility of Mueller Hinton agar (MHA) biplate containing dipicolinic acid (DPA) as a screening method to detect IMP-1 and VIM-2 type MBL-producing isolates.


METHODS
Based on our preliminary tests using various concentrations of DPA, 200 and 300 microg/mL concentration of DPA were chosen for further study. Bacterial lawns were grown on MHA biplate, one half of which contained DPA while the other did not. The inhibition zone around the imipenem (IPM) disk on both sides of this plate was compared. The stability of DPA in the stored DPA-MHA biplate was also evaluated during three months using two MBL- and one non-MBL-producing isolates.


RESULTS
When the criterion of a > or =7 mm increase of inhibition zone around the IPM disk on the MHA containing DPA compared to MHA without DPA was used, the sensitivities and specificities were 94.7% and 97.6% for 200 microg/mL DPA-MHA biplate, and 98.2% and 97.6% for 300 microg/mL DPA-MHA biplate, respectively. The activity of the DPA in this biplate was stable for three months.


CONCLUSIONS
Assays using DPA 300-MHA biplate were highly sensitive and specific for the detection of IMP-1 and VIM-2 type MBL-producing bacteria. In addition, it is easy to perform; so, it may be useful to apply this method for detection of IMP-1 and VIM-2 type MBL in clinical laboratories.
Shin
Kyeong Seob
KS
Department of Laboratory Medicine, College of Medicine, Chungbuk National University, Heungdeok-Gu, Cheongju, Korea. ksshin@chungbuk.ac.kr
Son
Bo Ra
BR
Koo
Sun Hoe
SH
Lee
Sang Hwa
SH
Ahn
Jun Bae
JB
Park
Seock Hwan
SH
Hwang
Seock Yeon
SY
D000362:Agar; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001431:Bacteriological Techniques; D002614:Chelating Agents / Q000737:chemistry / Q000494:pharmacology*; D024881:Drug Resistance, Bacterial; D006090:Gram-Negative Bacteria / Q000187:drug effects / Q000201:enzymology / Q000302:isolation & purification*; D015378:Imipenem / Q000494:pharmacology*; D010848:Picolinic Acids / Q000737:chemistry / Q000494:pharmacology*; D011933:Reagent Kits, Diagnostic; D012680:Sensitivity and Specificity; D001618:beta-Lactamases / Q000032:analysis* / Q000096:biosynthesis
D000900:Anti-Bacterial Agents; D002614:Chelating Agents; D010848:Picolinic Acids; D011933:Reagent Kits, Diagnostic; D015378:Imipenem; D000362:Agar; C409201:beta-lactamase IMP-1; C425108:beta-lactamase bla(vim-2); D001618:beta-Lactamases; C004860:dipicolinic acid