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Staphylococcus aureus Membrane Vesicles and Its Potential Role in Bacterial Pathogenesis
이제철 대한미생물학회 2012 Journal of Bacteriology and Virology Vol.42 No.3
The production of extracellular vesicles is a ubiquitous process in both Gram-negative and Gram-positive bacteria. Gram-negative bacteria produce and secrete outer membrane vesicles during in vitro culture and in vivo infection and their contribution to bacterial pathogenesis has been well characterized. However, little is known about extracellular vesicles in Gram-positive bacteria. Until now, only few Gram-positive bacterial species, Staphylococcus aureus, Bacillus anthracis, B. cereus, and B. subtilis, have been found to produce membrane vesicles (MVs), but their contribution to bacterial pathogenesis has not been understood. Here, I discuss S. aureus MVs in terms of MV production, interaction of MVs with host cells, and immune response against MVs to understand its potential role in S. aureus pathogenesis.
Nalidixic Acid 내성균주의 Quinolone 제제에 대한 항균효과의 비교
이제철,강도원,김정민,김정완,이유철,설성용,조동택 慶北大學校 醫科大學 1992 慶北醫大誌 Vol.33 No.1
최소발육 억제농도(MIC)가 64㎍/㎖ 이상인 nalidixic acid(NA) 내성 장내세균, Shigella, E. coli, Proteus 및 Serratia를 대상으로 9종의 quinolone 제제에 대한 항균효과를 조사하였다. Quinolone 제제의 항균효과는 균종에 관계없이 MIC_90의 범위가 0.125-8㎍/㎖인 ciprofloxacin(Ci)이 가장 강력한 항균효과를 나타내었고 ofloxacin(Of), norfloxacin(Nf), Abott-56620(A0), Abott-56619(A9), pefloxacin(Pe), enoxacin(En)의 순이었으며, rosoxacin(Ro)과 oxolinic acid(Ox)는 가장 높은 MIC 분포를 보여 주었다. NA의 내성정도에 따라서 모든 quinolone 항균제의 MIC는 변화하였으며 NA의 MIC가 증가할수록 모든 quinolone 항균제의 MIC도 증가하는 것을 볼 수 있었다. NA의 MIC가 128㎍/㎖ 이하에서 fluoroquinolone 제제의 MIC는 2㎍/㎖ 이하로 낮았고 NA의 MIC가 512㎍/㎖이상에서는 NA는 2㎍/㎖ 이하로 낮았고 NA의 MIC가 512㎍/㎖ 이상에서는 NA의 MIC 증가폭보다 quinolone항균제의 MIC 증가폭이 커서 낮은 농도의 NA 내성을 가진 장내세균 감염에는 fluoroquinolone 제제의 사용 가능성을 볼 수 있었으며 NA의 내성정도에 따라 fluoroquinolone 제제의 항균제 감수성 정도도 간접적으로 알 수 있었다. 인위적으로 NA 내성 균주를 얻기 위한 실험에서 Shigella를 제외한 E. coli, Proteus 및 Serratia에서 NA 내성 변이주를 얻었으며 4균종 모두에서 NA의 MIC 증가와 함께 quinolone 항균제의 MIC가 증가하였으나 E. coli 변이주에서의 Ci와 Nf는 NA 내성이 증가하여도 MIC의 변화는 없었다. 인위적인 NA 내성 변이주들은 임상가검물에서 분리된 NA 내성주들 만큼 큰 폭으로 quinolone 제제의 MIC가 증가하지 않았다. Forty-six isolates of Enterobacteriaceae screened by the resistant to 50㎍/㎖ nalidixic acid(NA) were examined by minimal inhibitory concentration (MIC) for in vitro susceptibility to the quinolone derivatives, norfloxacin(Nf). enoxacin(En), Abott-56619(A9), Abott-56620(AO), ofloxacin(Of), ciprofloxa-cin(Ci), oxolinic acid(Ox), rosoxacin(Ro) and pefloxacin(Pe). Ci was the most active agents against all Enterobacteriaceae tested, followed by Nf, AO, A9, Pe, and En. The MICs required to inhibit at least 90% of the strains (MIC_90) ranged from 0.125 to 8㎍/㎖ for Ci and from 0.25 to 8㎍/㎖ for Of. Ci was about four times more active than Nf. Ox, old analog of NA, and Ro were lesser active than other fluoroquinolones. Cross resistance was observed between NA and Ox. The MICs of quinolone derivatives correlated with the MIC levels of NA. According to the MIC levels of NA, MICs of all quinolone derivatives were changed. The MICs of all quinolone derivatives were raised by stepwise increases of MIC of NA. Although stepwise increases in MIC of fluoroquino-lone were seen with Enterobacteriaceae tested, significant increases of MIC did not showed. Compared to the isolated strains, the selected variants strains with resistant to NA as a whole were more susceptible to all quinolone derivatives tested. The MICs of selected variants were raised by stepwise increases of MIC of NA. NA sensitive strains which were selected were at least two-fold more susceptible to En, AO, A9, Pe, Ro, Ox and Of than were the NA resistant strains.
이제철,김동선,Dong Chan Moon,Jung-Hwa Lee,Mi Jin Kim,Su Man Lee,이용석,Se-Won Kang,Eun Jung Lee,강상순,Eunpyo Lee,현성희 한국미생물학회 2009 The journal of microbiology Vol.47 No.5
Nuclear targeting of bacterial proteins is an emerging pathogenic mechanism whereby bacterial proteins can interact with nuclear molecules and alter the physiology of host cells. The fully sequenced bacterial genome can predict proteins that target the nuclei of host cells based on the presence of nuclear localization signal (NLS). In the present study, we predicted bacterial proteins with the NLS sequences from Klebsiella pneumoniae by bioinformatic analysis, and 13 proteins were identified as carrying putative NLS sequences. Among them, HsdM, a subunit of KpnAI that is a type I restriction-modification system found in K. pneumoniae, was selected for the experimental proof of nuclear targeting in host cells. HsdM carried the NLS sequences, 7KKAKAKK13, in the N-terminus. A transient expression of HsdM-EGFP in COS-1 cells exhibited exclusively a nuclear localization of the fusion proteins, whereas the fusion proteins of HsdM with substitutions in residues lysine to alanine in the NLS sequences, 7AAAKAAA13, were localized in the cytoplasm. HsdM was co-localized with importin α in the nuclei of host cells. Recombinant HsdM alone methylated the eukaryotic DNA in vitro assay. Although HsdM tested in this study has not been considered to be a virulence factor, the prediction of NLS motifs from the full sequenced genome of bacteria extends our knowledge of functional genomics to understand subcellular targeting of bacterial proteins.
이제철,Hee-Young Kang,오재영,Jae-Ho Jeong,김정민,Sung-Yong Seol,조동택,이유철 대한미생물학회 2006 Journal of Bacteriology and Virology Vol.36 No.3
The emergence and spread of antimicrobial resistance among the pathogenic and commensal Enterobacteriaceae are of great concern worldwide. We characterized the antimicrobial resistance and integrons found in commensal Escherichia coli from healthy humans in the community. Class 1 integrase (intl1) and class 2 integrase (intl2) genes were identified in 22 (13.3%) and 2 (1.2%) of 165 E. coli isolates, respectively. dfrA17-aadA5 and dfrA1-aadA2 were the most common class 1 integrons. The prevalence of each type of class 1 integron among commensal E. coli isolates during 2001~2003 was similar to that of clinical E. coli isolates from hospital-acquired infections during 1994~1999. The resistant rates of commensal E. coli isolates carrying intl1 to ampicillin, streptomycin, gentamicin, sulfamethoxazole, trimethoprim, chloramphenicol, and tetracycline were significantly higher than those of intl1-negative E. coli isolates (p<0.05). Integrons were directly associated with multidrug resistance in commensal E. coli isolates. It is hypothesized that multidrug-resistant Enterobacteriaceae from hospital-acquired infections are a potential reservoir for integrons associated with resistance genes found in commensal E. coli isolates in the community
Epidemiology of Shigellosis in Korea
이제철,Young-Sook Jeong,오재영,Hee-Young Kang,Kwang-Hoon Kim,김정민,Yoo-Chul Lee,조동택,설성용 대한미생물학회 2006 Journal of Bacteriology and Virology Vol.36 No.2
Shigellosis is an acute diarrheal disease caused by bacteria of the genus Shigella. Following the occurrence of a large outbreak of shigellosis as well as sporadic cases since 1998, shigellosis has been a major health problem in Korea. There have been major changes in epidemiology during the last five decades concerning shigellosis in terms of total incidence of shigellosis, prevalence of certain serogroups, selection of specific clones, and introduction of new Shigella clones. S. dysenteriae was the most prevalent species until the early twentieth century, S. flexneri was the most prevalent until the late 1980s, and S. sonnei has been the most prevalent since 1990. Diverse serotypes of S. dysenteriae (4 serotypes), S. flexneri (8 serotypes), and S. boydii (4 serotypes) were found during the Korean War and many of these Korean endemic Shigella strains circulated in the community until the late 1970s. However, the endemic strains of S. dysenteriae, S. boydii, and S. sonnei disappeared in the late 1980s. A new clone of S. sonnei that was introduced between the late 1980s and the early 1990s was responsible for a large proportion of shigellosis in recent years. S. flexneri serotype 4a was the most frequently found during the Korean War and then the incidence of S. flexneri 2a gradually increased with time. S. flexneri isolates detected from 1991 to 1997 were all serotype 2a. However, the diverse clones of S. flexneri reemerged in Korea since 1999. It has not been determined whether the S. flexneri strains from the 2000s were the descendants of the Korean endemic strains or imported new strains, but the PFGE patterns were different between S. flexneri strains from the 1980s and 2000s. The widespread of new S. sonnei strains and the persistence of S. flexneri strains are responsible for the endemicity of shigellosis in Korea.