Abstract:

Objective To evaluate the reliabilities of VITEK 2-Compact GN13 and MicroScan WalkAway 96 Plus NM38 to determine the drug susceptibility of carbapenems against Klebsiella pneumoniae. Methods GN13,NM38 and broth micro-dilution method were used to determine the drug susceptibility of carbapenems to 168 isolates of Klebsiella pneumoniae which were isolated from Huangshan People's Hospital from January 2016 to August 2017. The determination results of GN13 and NM38 were judged by broth micro-dilution method as gold standard. A modified carbapenem inactivation method （mCIM） was used to determine carbapenems and to analyze their reliabilities of advanced expert system（AES） as a predictor or early warning indicator for carbapenem production. Results Using broth micro-dilution method as gold standard,GN13 and NM38 classification categorical agreement （CA） was >90%. Minor errors （MIE） and major errors （ME） for imipenem were reduced by 0.6%,and MIE for ertapenem was increased by 0.6% without very major errors （VME） after AES modification. The MIE,ME and VME determined by NM38 for imipenem accounted for 1.19%,1.19% and 2.97%,and MIE,ME and VME for ertapenem accounted for 3.6%,0.0% and 0.6%. The mCIM phenotype determination showed that the positive rate of carbapenems was 27.4% （46/168）,and the positive rates of carbapenems after GN13 AES modification and NM38 prediction were 31.0% and 30.4%,respectively. Compared with mCIM,there was no statistical significance （P>0.05）. Conclusions The results of GN13 and NM38 are reliable in determining the drug susceptibility of carbapenems against Klebsiella pneumoniae. However,attention should be paid to the modification or early warning of AES.

Key words: Klebsiella pneumoniae, Carbapenems, Drug susceptibility, GN13, NM38