• Journal of Microbiology
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• 제44권6호
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• pp.632-640
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• 2006

In this study, the biodegradative activities of monocyclic aromatic compounds were determined from the multi-drug resistant (MDR) Acinetobacter baumannii, which were studied in the form of clinical isolates from a hospital in Korea. These bacteria were capable of biodegrading monocyclic aromatic compounds, such as benzoate and p-hydroxybenzoate. In order to determine which pathways are available for biodegradation in these stains, we conducted proteome analyses of benzoate, and p-hydroxybenzoate-cultured A. baumannii DU202, using 2-DE/MS analysis. As genome DB of A. baumannii was not yet available, MS/MS analysis or de novo sequencing methods were employed in the identification of induced proteins. Benzoate branch enzymes [catechol 1,2-dioxygenase (CatA) and benzoate dioxygenase $\alpha$ subunit (BenA)] of the $\beta$-ketoadipate pathway were identified under benzoate culture condition and p-hydroxybenzoate branch enzymes [protocatechuate 3,4-dioxygenas $\alpha$ subunit (PcaG) and 3-carboxy-cis,cis-muconate cycloisomerase (PcaR)] of the $\beta$-ketoadipate pathway were identified under p-hydroxybenzoate culture condition, respectively, thereby suggesting that strain DU202 utilized the $\beta$-ketoadipate pathway for the biodegradation of monocyclic aromatic compounds. The sequence analysis of two purified dioxygenases (CatA and PcaGH) indicated that CatA is closely associated with the CatA of Acinetobacter radiresistance, but PcaGH is only moderately associated with the PcaGH of Acinetobacter sp. ADPI. Interestingly, the fused form of PcaD and PcaC, carboxymuconolactone decarboxylase (PcaCD), was detected on benzoate-cultured A. baumannii DU202. These results indicate that A. baumannii DU202 exploits a different $\beta$-ketoadipate pathway from other Acinetobacter species.

• 대한미생물학회지
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• 제35권1호
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• pp.69-76
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• 2000

Members of the genus Acinetobacter are recognized as newer pathogens of the nosocomial infection with an increasing frequency in recent years. Strains that belonged to A. calcoaceticus A. baumannii complex (genomic species 1, 2, 3, and 13TU) were major groups associated with nosocomial infection. Phenotypic identification was unreliable and laborious method to classify Acinetobacter strains into 19 genomic species. Rapid and reliable identification of clinical isolates is essential to diagnosis and epidemiology of Acinetobacter. We investigated the suitability of amplified ribosomal DNA restriction analysis (ARDRA) to identify genomic species of 131 Acinetobacter isolates. The 16S rRNA genes (ribosomal DNA) were enzymatically amplified and the amplified PCR products were restricted independently with the enzymes, AluI, CfoI, and MboI. Genomic species of Acinetobacter was classified by the combinations of restriction patterns. The analysis was showed that restriction profiles were characteristic for each genomic species. One hundred fourteen isolates were identified as A. baumannii, twelve were identified as genomic species 13TU, and one was identified as genomic species 3. Four isolates were found to be unknown organisms. All of the isolates which were identified to A. baumannii by phenotypic tests were completely discriminated into A. baumannii and genomic species 13TU by ARDRA. This study demonstrates that ARDRA is a rapid and simple techniques for the identification of Acinetobacter species according to the genomic species.

• Journal of Microbiology and Biotechnology
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• 제26권8호
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• pp.1481-1489
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• 2016

The emergence and dissemination of carbapenemase-producing Acinetobacter baumannii isolates have been reported worldwide, and A. baumannii isolates harboring bla_OXA-23 are often resistant to various antimicrobial agents. Antimicrobial resistance can be particularly strong for biofilm-forming A. baumannii isolates. We investigated the genetic basis for carbapenem resistance and biofilm-forming ability of multidrug-resistant (MDR) clinical isolates. Ninety-two MDR A. baumannii isolates were collected from one university hospital located in the Chungcheong area of Korea over a 5-year period. Multiplex PCR and DNA sequencing were performed to characterize carbapenemase and bap genes. Clonal characteristics were analyzed using REP-PCR. In addition, imaging and quantification of biofilms were performed using a crystal violet assay. All 92 MDR A. baumannii isolates involved in our study contained the bla_OXA-23 and bap genes. The average absorbance of biomass in Bap-producing strains was much greater than that in non-Bap-producing strains. In our study, only three REP-PCR types were found, and the isolates showing type A or type B were found more than 60 times among unique patients during the 5 years of surveillance. These results suggest that the isolates have persisted and colonized for 5 years, and biofilm formation ability has been responsible for their persistence and colonization.

• Genomics & Informatics
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• 제13권1호
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• pp.2-6
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• 2015

Pathogenic bacteria survive in iron-limited host environments by using several iron acquisition mechanisms. Acinetobacter baumannii, causing serious infections in compromised patients, produces an iron-chelating molecule, called acinetobactin, which is composed of equimolar quantities of 2,3-dihydroxybenzoic acid (DHBA), L-threonine, and N-hydroxyhistamine, to compete with host cells for iron. Genes that are involved in the production and transport of acinetobactin are clustered within the genome of A. baumannii. A recent study showed that entA, located outside of the acinetobactin gene cluster, plays important roles in the biosynthesis of the acinetobactin precursor DHBA and in bacterial pathogenesis. Therefore, understanding the genes that are associated with the biosynthesis and transport of acinetobactin in the bacterial genome is required. This review is intended to provide a general overview of the genes in the genome of A. baumannii that are required for acinetobactin biosynthesis and transport.

• Tuberculosis and Respiratory Diseases
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• 제61권1호
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• pp.13-19
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• 2006

연구 배경: A. baumannii는 전 세계적으로 중요한 병원 내 병원균으로 부각되고 있고 이들 균에 의한 감염 또한 빠르게 증가하고 있다. 이들 감염에 연관된 사망률(균혈증:52%, 폐렴:23-73%)은 매우 높고 다제 내성은 비교적 흔하게 발생하고 있는 실정이다. 그러므로 다제 내성 A. baumannii 감염에 대한 효과적인 치료를 위해서 이들의 임상 특징과 결과를 분석하고 이해하는 것이 필요하다. 이에 본 연구는 A. baumannii 병원내 폐렴 중 다제 내성군과 약제 감수성군 간의 임상적 특징, 사망률, 이환율을 비교하였다. 방 법: 2002년 1월 1일부터 2004년 11월 1일까지 춘천성심병원에 입원했던 환자 중 Acinetobacter 병원 내 폐렴으로 판단되는 47명의 환자를 연구 대상으로 하였고 이들의 의무기록을 후향적으로 분석하였다. 본 연구에서는 다제 내성 A. baumannii를 실험 환경에서 A. baumannii에 효과적이며 상업적으로 이용할 수 있는 모든 항생제에 내성을 보이는 것으로 정의하였다. 결 과: 47명의 A. baumannii 병원내 폐렴 환자 중 17명이 다제 내성군, 30명이 약제 감수성군으로 분류되었다. 이들의 평균 연령은 다제 내성군은 $69{\pm}11$세, 약제 감수성군 $70{\pm}13$세이었고 APACHE II 점수, 중환자실 입원기간, 사망률에 있어서 두 군간에 유의한 차이는 없었다($16.1{\pm}5.4$ vs $14.9{\pm}4.8$, P=0.43, $25.1{\pm}13.6$ vs $39.1{\pm}31.0$, P=0.2, 58.8% vs 40%, P=0.21). 결 론: Acinetobacter baumannii 다제 내성군과 약제 감수성군 간의 사망률과 임상적 특징 사이에서 유의한 차이는 보이지 않았다. 그러나 양군 모두 사망률과 이환율은 높게 나타나 A. baumannii 감염의 효과적인 감시 및 조절이 지속적으로 필요하겠다.

• 한국임상약학회지
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• 제22권2호
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• pp.181-186
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• 2012

Objective: To report a fatal case of Multidrug-resistant Acinetobacter baumannii (MDR-AB) in a patient with interstitial lung disease (ILD) on high-dose glucocorticoids. Case Summary: A 66-year-old man with a history of coniosis was transferred to the hospital with progressive cough and sputum production. This patient has been diagnosed with pneumonia and ILD on admission, requires antimicrobial therapy and systemic immunosuppressants. He received high dose of methylprednisolone and cyclophosphamide for ILD as well as ceftriaxone and azithromycin for pneumonia. On day 7 in the intensive care units (ICUs), patient had fever and leukocytosis, thus antimicrobials were switched to piperacillin. After 13 days in the ICU, Acinetobacter baumannii and methicillin-resistant Staphylococcus aureus (MRSA) were isolated on transtracheal aspirate (TTA) and meropenem was initiated. However, it was revealed a multidrug-resistant Acinetobacter baumannii (MDR-AB) species, resistant to carbapenem. Patient was administered colistin but expired due to septic shock on day 84. Discussion: Systemic immunosuppressive therapy can result in infections that may compromise patient's survival. MDR-AB has emerged as a serious cause of nosocomial infections in immunocompromised patients. MDR-AB is resistant to most standard antimicrobials and therapeutic options are limited. Conclusion: We report our recent experience with a fatal MDR-AB pneumonia in a patient with ILD, who had to be treated with high dose glucocorticoids and immunosuppressnts.

• Journal of Microbiology and Biotechnology
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• 제34권8호
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• pp.1718-1726
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• 2024

Development of novel antibacterial agents is imperative due to the increasing threat of antibiotic-resistant pathogens. This study aimed to develop the enhanced antibacterial activity and in-vivo efficacy of a novel truncated endolysin, CHAP^SAP26-161, derived from the endolysin Lys^SAP26, against multidrug-resistant bacteria. CHAP^SAP26-161 exhibited higher protein purification efficiency in E. coli and antibacterial activity than Lys^SAP26. Moreover, CHAP^SAP26-161 showed the higher lytic activity against A. baumannii with minimal bactericidal concentrations (MBCs) of 5-10 ㎍/ml, followed by Staphylococcus aureus with MBCs of 10-25 ㎍/ml. Interestingly, CHAP^SAP26-161 could lyse anaerobic bacteria, such as Clostridioides difficile, with MBCs of 25-50 ㎍/ml. At pH 4-8 and temperatures of 4℃-45℃, CHAP^SAP26-161 maintained antibacterial activity without remarkable difference. The lytic activity of CHAP^SAP26-161 was increased with Zn²⁺. In vivo tests demonstrated the therapeutic effects of CHAP^SAP26-161 in murine systemic A. baumannii infection model. In conclusion, CHAP^SAP26-161, a truncated endolysin that retains only the CHAP domain from Lys^SAP26, demonstrated enhanced protein purification efficiency and antibacterial activity compared to Lys^SAP26. It further displayed broad-spectrum antibacterial effects against S. aureus, A. baumannii, and C. difficile. Our in vitro and in-vivo results of CHAP^SAP26-161 highlights its promise as an innovative therapeutic option against those bacteria with multiple antibiotic resistance.

• 한국미생물·생명공학회지
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• 제49권2호
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• pp.239-248
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• 2021

The emergence of multidrug-resistant Acinetobacter baumannii has partly increased treatment failure and patient mortality. Class D β-lactamases is an important mechanism of resistance to beta-lactam antibiotics in this species. This study aimed to investigate the relationship between the presence oxacillinase gene and genetic fingerprints of A. baumannii isolates from the intensive care unit of an Egyptian tertiary care hospital. One hundred and twenty A. baumannii clinical isolates were collected. Multiplex PCR was performed to detect genes encoding oxacillinases (OXA-23, OXA-24, OXA-51, OXA-58 and OXA-143). Molecular typing of all collected isolates was performed using random amplified polymorphic DNA (RAPD)-PCR assay. Out of 120 examined isolates, 92, 88 and 84% were resistant to ertapenem, imipenem and meropenem, respectively. The species-specific, commonly present OXA-51 gene was found in all isolates while OXA-23 showed a high prevalence of 88% of isolates. OXA-24 and OXA-143 genes were detected in 3% and 1% of isolates, respectively. No OXA-58 gene was detected. Five clusters consisting of 19 genotypes were detected using RAPD-PCR. Genotype A was the most prevalent, it was observed in 62% of the isolates followed by genotype B (12%). These results revealed that genotypes A and B are common in the hospital. Results also demonstrate that RAPD-PCR is a rapid and reliable method for studying the clonal similarity among A. baumannii isolated from different clinical specimens.

• Tuberculosis and Respiratory Diseases
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• 제64권2호
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• pp.102-108
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• 2008

연구배경: 최근 다제내성 A. baumannii에 의한 폐렴이 중환자실 환자에서 매우 빈번하게 발생하고 있으며, 이탈 지연, 중환자실 재원기간 및 사망률의 증가가 초래되기도 한다. 수 년 전부터 colistin이 치료제로 다시 주목받고 있으나 병원획득폐렴에 대한 치료 경험은 많지 않으며, 분무치료의 효과에 대해서는 근거가 매우 부족하다. 이에 저자들은 한 대학병원 중환자실에서 발생한 다제내성 A. baumannii에 의한 병원획득폐렴에서 colistin 분무치료의 적용 가능성을 평가해보고자 하였다. 방법: 다제내성 A. baumannii에 의한 병원획득폐렴의 발생이 확인되어 colistin 분무치료를 시행한 환자 10명을 대상으로 후향적 분석을 시행하였다. 결과: Colistin 분무치료 기간은 평균 $12.7{\pm}2.4$일이었다. 10명의 대상환자 중 9명(90.0%)의 환자에서 효과적인 치료 반응을 나타내었다. 치료 종료 후 추적한 객담 배양 검사에서 다제내성 A. baumannii는 단 한 명도 분리되지 않았다. 1명의 환자에서 기관지연축이 발생하였으나 기관지확장제 치료 후 호전되었다. 결론: 다제내성 A. baumannii에 의한 병원획득폐렴에서 colistin 분무치료는 매우 효과적일 가능성이 있으며, 향후 전향적인 연구를 진행할 가치가 있을 것으로 판단된다.

• 미생물학회지
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• 제46권3호
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• pp.303-307
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• 2010

임상분리 균주인 A. baumannii 1625는 imipenem (carbapenem 계열)을 포함한 대부분의 ${\beta}$-lactam계열의 항생제들과 kanamycin, gentamicin, tobramycin 및 제 3세대와 4세대 cephalosporin 계열의 항생제들에 광범위한 내성을 나타내었고, 한국에서는 드문 IMP-1형 metallo-${\beta}$-lactamase (MBL)를 생성하는 균주임이 확인되었다. A. baumannii 1625는 약 2.5 kb 크기의 class 1 integron을 갖고 있었으며, 이 integron내에 aminoglycoside계열 내성 유전자인 accA4, carbapenem 계열 내성 유전자인 $bla_{IMP-1}$, 광범위한 ${\beta}$-lactam 내성 유전자인 $bla_{OXA-2}$ 유전자 cassette들이 차례대로 위치해 있음을 확인하였는데, 이것은 IMP-1형과 OXA-2형 ${\beta}$-lactamase의 유전자를 같은 integron내에 동시에 갖는 새로운 배열 및 구조로서 이전에 국내에서 보고된 바 없는 것이다. 이 2.5 kb 크기의 integron을 항생제 내성이 없는 E. coli에 형질전환 시켰을 때, imipenem, ampicillin, piperacillin, cefazolin, cefoperazone, aztreonam 등의 항생제들에 대하여 8배 이상 증가된 내성정도를 보였다. 이는 A. baumannii 1625의 integron이 다제내성을 부여하는 기능을 하고 있음을 보여준다.