대전지역 소재 대학병원에 blaOXA-23 유전자를 가지고 있는 다제내성 Acinetobacter baumannii의 확산 = Clonal Dissemination of Multidrug Resistant Acinetobacter baumannii Isolates Harboring blaOXA-23 at One University Hospital in Daejeon, Korea

국문 초록 (Abstract)

Acinetobacter species는 중요한 기회감염균으로 빈번하게 원내감염을 일으킨다. 뿐만 아니라 다제내성을 보이는 경우가 많아 치료를 위한 항균제 선택이 매우 제한적이다. 본 연구에서는 Acinetobacter species 68균주를 대상으로 하여 다양한 carbapenemase 유전자를 조사했다. 디스크확산법으로 항균제 감수성 양상을 조사했으며 다중 중합효소연쇄반응을 통해 carbapenemase 유전자를 포함하고 있는 균주를 선별하였고 PCR과 염기서열분석을 통해 최종적으로 carbapenemase 유전형을 확인했다. 한편 REP-PCR 방법으로 균주간의 clonality를 분석했다. 본 연구에서 A. baumannii 균주는 분석된 모든 항균제에 대해 높은 내성을 나타냈으나 non- A. baumannii 균주는 분석된 항균제 중aztreonam과 cefotaxime을 제외한 항균제에 모두 감수성을 보였다. A. baumannii 51 균주는 blaOXA-51 유전자를 가지고 있었으며 그 중 37(72.5%)균주는 blaOXA-23 유전자도 동시에 가지고 있었다. 본 연구에서 39 균주의 다제내성 A. baumannii 가 분리되었는데 그 중 37균주가 blaOXA-23 유전자를 가지고 있었다. blaOXA-23 유전자를 포함하고 있는 균주들은 I (n=22) 형 또는 II (n=15) 형의 REP-PCR band 패턴을 보였는데 이는 대전에 위치한 일개의 대학병원에 blaOXA-23 유전자를 포함하고 있는 다제내성 균주들이 수평확산 되어 있음을 의미한다. 다제내성 A. baumannii 균주에 의한 감염 및 집락화를 막기 위해서는 지속적으로 내성을 유발하는 인자를 조사하고 MDR균주의 출현 및 확산을 감시할 필요가 있을 것으로 사료된다.

다국어 초록 (Multilingual Abstract)

Acinetobacter species isolates are important opportunistic pathogens and commonly implicated in nosocomial infections. The therapeutic options for treatment of the bacterial infections are limited because the bacteria isolates are usually multidrug resistant (MDR). In the current study, we investigated various carbapenemase genes in 68 Acinetobacter species isolates. Antimicrobial susceptibilities were tested using the disk diffusion method. Screening of carbapenemase genes was performed via multiplex PCR. In addition, PCR and DNA sequencing were used to identify the carbapenemase genes. Repetitive extragenic palindromic-PCR (REP-PCR) was also performed to assess the clonality of isolates. In our study, A. baumannii isolates were highly resistant to all agents tested while all non- A. baumannii isolates were susceptible to all agents tested, with the exception of aztreonam and cefotaxime. All 51 A. baumannii isolates contained the blaOXA-51 gene and 37 (72.5%) isolates also harbored the blaOXA-23 gene. In addition, 39 MDR A. baumannii isolates were identified in our study and 37 isolates contained the blaOXA-23 gene. The 37 MDR strains harboring blaOXA-23 showed type I (n=22) or type II (n=15) banding patterns on their REP-PCR profiles. Our results suggest clonal relation and horizontal spreading of MDR A. baumannii isolates containing the blaOXA-23 gene at the hospital located in Daejeon. Continuous investigation of antimicrobial resistant determinants and monitoring emergence and dissemination of MDR isolates is required to prevent and control infection and colonization of MDR A. baumannii isolates.

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