Imipenemase (IMP)-6-producing Pseudomonas aeruginosa sequence type (ST) 235 is a dominant clone of carbapenemase-producing P. aeruginosa (CPPAE) in Korea. As part of the Antimicrobial Resistance Surveillance System in Korea, we found an increase in the carbapenem resistance rate of P. aeruginosa isolates from blood cultures and a shift in the molecular epidemiology of CPPAE. A total of 212 non-duplicated P. aeruginosa blood isolates were obtained from nine general hospitals and two nursing homes. Twenty-four isolates were identified as CPPAE. We observed the emergence of the NDM-1 P. aeruginosa ST 773 clone (N = 10), mostly from Gyeongsang Province. The IMP-6 ST 235 clone (N = 11) was detected in all provinces. CPPAE isolates showed very high resistance rates to amikacin, and all NDM-1 P. aeruginosa strains carried rmtB. This is the first nationwide surveillance of the recently emerged NDM-1-producing P. aeruginosa ST773 clone in Korea. Continuous surveillance is necessary to prevent the infection and transmission of carbapenem-and amikacin-resistant P. aeruginosa in Korea.

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Background:The purpose of this study was to evaluate the reliability of identification with the strains of Acinetobacter baumannii and non-baumanni Acinetobacter spp, determined with matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), compared to the molecular genetic method. Methods: A total of 225 blood isolates of A. baumannii and non-baumanni Acinetobacter spp. were included in this study. Species identification was performed using MALDI-TOF MS, blaOXA-51 polymerase chain reaction (PCR), and RNA polymerase β-subunit (rpoB) PCR-sequencing. Results:The MALDI-TOF MS results showed 100% category agreement with that of blaOXA-51 PCR, which clearly distinguished A. baumannii from nonbaumanni Acinetobacter spp. The species-concordance rate of non-baumanni Acinetobacter spp. was 73.7% (14/19) on the basis of rpoB sequence results. Conclusions: MALDI-TOF MS is very useful in distinguishing between A. baumannii and non-baumanni Acinetobacter spp. accurately, which is useful information on the choice of therapeutic agents. However, there was a limitation in correctly identifying non-baumanni Acinetobacter spp.