ABSTRACT
We determined the optimal antimicrobial in the sodium mercaptoacetic acid double disk synergy test (SMA-DDST) for the detection of IMP-1-producing Pseudomonas aeruginosa isolates in Japan and evaluated the performance of the test. Fifty-four P. aeruginosa clinical isolates were tested, including 39 IMP-1 producers and 15 non-metallo-ß-lactamase (MBL)-producing carbapenem- and ceftazidime (CAZ)-resistant isolates. The SMA-DDST was performed with CAZ, cefepime (CFPM), imipenem (IPM), meropenem (MEPM), doripenem (DRPM), or biapenem (BIPM)-containing disks. The sensitivity of the SMA-DDST with CAZ, CFPM, IPM, MEPM, DRPM, and BIPM was 39/39 (100%), 36/39 (92%), 18/39 (46%), 8/39 (21%), 19/39 (49%), and 36/39 (92%), respectively. The specificity was 15/15 (100%) for all SMA-DDSTs. This suggests that the isolates may have a resistance mechanism other than MBL production for IPM, MEPM, or DRPM. Since the CAZ resistance mechanism in P. aeruginosa is the same as that of CFPM, but differs from that of carbapenems, we conclude that combining CAZ with BIPM SMA-DDSTs can prevent any failure in the detection of IMP-1-producing P. aeruginosa.
Subject(s)
Anti-Bacterial Agents/pharmacology , Ceftazidime/pharmacology , Pseudomonas aeruginosa/drug effects , Pseudomonas aeruginosa/isolation & purification , Thienamycins/pharmacology , Thioglycolates/pharmacology , beta-Lactamases/metabolism , Drug Resistance, Multiple, Bacterial/drug effects , Drug Synergism , Humans , Japan , Sensitivity and SpecificityABSTRACT
We developed and evaluated of multiplex real-time PCR assay for detection of vancomycin-resistant genes (vanA, vanB, vanC1 and vanC2/C3) using the new, fully automated BD MAX platform. Ct value analyses of real-time PCR simultaneous repeatability test have showed the usefulness; coefficient of variation: CV (%) were determined 2.09%, 1.72%, 1.41% and 1.52% with vanA, vanB, vanC1 and vanC2/C3, respectively. We also evaluated with 43 strains of enterococci were characterized by conventional PCR method; 4/4 for vanA-positive, 14/14 for vanB-positive, 1/1 for vanB plus vanC1-positive, 6/6 for vanC1-positive, 4/4 for vanC2/C3- positive and 14/14 for all-van gene-negative strains were identified correctly. This assay was automatically performing before and after PCR operations previously done manually by operator, such as DNA extraction, sample dispensing and gel electrophoresis or the ethidium bromide dyeing. As a result, work burden and the risk of the contamination were largely reduced and were shortened to about half for measurement time. We conclude that this assay could greatly contribute to efficient and rapid detection of vancomycin-resistant genes.
