• Tuberculosis and Respiratory Diseases
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• 제60권5호
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• pp.571-575
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• 2006

최근 비결핵성 마이코박테리아 폐질환에 대한 관심이 증가되고 있으며 이에 대한 다양한 보고가 이뤄지고 있다. 외국 문헌에서는 M. avium 감염의 대표적인 임상상인 상엽 공동형과 결절성 기관지 확장증 형과는 다른 형태의 M. avium 기관지 질환이 후천성 면역 결핍증 환자뿐만 아니라 면역 적격자인 건강한 성인에서도 드물게 보고 되고 있으나, 국내에서는 지금까지 이에 대한 보고가 없었다. 본 저자들은 이전 폐질환이 없는 건강한 면역 적격자에서 M. avium 감염에 의한 기관지 질환을 경험하고 이 환자의 임상적인 소견과 경과를 문헌 고찰과 함께 보고하는 바이다.

• Journal of Microbiology and Biotechnology
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• 제32권10호
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• pp.1234-1244
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• 2022

Oral streptococci are considered as an opportunistic pathogen associated with initiation and progression of various oral diseases. However, since the currently-available treatments often accompany adverse effects, alternative strategy is demanded to control streptococci. In the current study, we investigated whether short-chain fatty acids (SCFAs), including sodium acetate (NaA), sodium propionate (NaP), and sodium butyrate (NaB), can inhibit the growth of oral streptococci. Among the tested SCFAs, NaP most potently inhibited the growth of laboratory and clinically isolated strains of Streptococcus gordonii under anaerobic culture conditions. However, the growth inhibitory effect of NaP on six different species of other oral streptococci was different depending on their culture conditions. Metabolic changes such as alteration of methionine biosynthesis can affect bacterial growth. Indeed, NaP enhanced intracellular methionine levels of oral streptococci as well as the mRNA expression level of methionine biosynthesis-related genes. Collectively, these results suggest that NaP has an inhibitory effect on the growth of oral streptococci, which might be due to alteration of methionine biosynthesis. Thus, NaP can be used an effective bacteriostatic agent for the prevention of oral infectious diseases caused by oral streptococci.

• 대한약침학회지
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• 제27권2호
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• pp.91-100
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• 2024

Objectives: Candida albicans is an opportunistic pathogen that occurs as harmless commensals in the intestine, urogenital tract, and skin. It has been influenced by a variety of host conditions and has now evolved as a resistant strain. The aim of this study was thus detect the fluconazole resistant C. albicans from the root caries specimens and to computationally evaluate the interactions of an opaque-phase ABC transporter protein with the Psidium guajava bio-active compounds. Methods: 20 carious scrapings were collected from patients with root caries and processed for the isolation of C. albicans and was screened for fluconazole resistance. Genomic DNA was extracted and molecular characterization of Cdrp1 and Cdrp2 was done by PCR amplification. P. guajava methanolic extract was checked for the antifungal efficacy against the resistant strain of C. albicans. Further in-silico docking involves retrieval of ABC transporter protein and ligand optimization, molinspiration assessment on drug likeness, docking simulations and visualizations. Results: 65% of the samples showed the presence of C.albicans and 2 strains were fluconazole resistant. Crude methanolic extract of P. guajava was found to be promising against the fluconazole resistant strains of C. albicans. In-silico docking analysis showed that Myricetin was a promising candidate with a high docking score and other drug ligand interaction scores. Conclusion: The current study emphasizes that bioactive compounds from Psidium guajava to be a promising candidate for treating candidiasis in fluconazole resistant strains of C. albicans However, further in-vivo studies have to be implemented for the experimental validation of the same in improving the oral health and hygiene.

• ALGAE
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• 제29권4호
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• pp.249-265
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• 2014

As with land crops, cultivated algae are affected by various diseases ranging from large outbreaks of a disease to chronic epiphytes, which may downgrade the value of the final product. The recent development of intensive and dense mariculture practices has enabled some new diseases to spread much faster than before. A new disease is reported almost every year, and the impact of diseases is expected to increase with environmental change, such as global warming. We observed the incidence of diseases in two Pyropia sea farms in Korea from 2011 to 2014, and estimated the economic loss caused by each disease. Serious damage is caused by the oomycete pathogens, Pythium porphyrae and Olpidiopsis spp., which decreased the productivity of the Pyropia sea farms. In Seocheon sea farms, an outbreak of Olpidiopsis spp. disease resulted in approximately US $1.6 million in loss, representing approximately 24.5% of total sales during the 2012-2013 season. The damage caused by green-spot disease was almost as serious as oomycete diseases. An outbreak of green-spot disease in the Seocheon sea farms resulted in approximately US $1.1 million in loss, representing 10.7% of total sales in the 2013-2014 season in this area. However, the causative agent of green-spot disease is still not confirmed. "Diatom felt" is regarded as a minor nuisance that does not cause serious damage in Pyropia; however, our case study showed that the economic loss caused by "diatom felt" might be as serious as that of oomycete diseases. Bacteria and cyanobacteria are indigenous members of epiphytic microbial community on Pyropia blades, but can become opportunistic pathogens under suitable environmental conditions, especially when Pyropia suffers from other diseases. A regular acid wash of the Pyropia cultivation nets is the most common treatment for all of the above mentioned diseases, and represents approximately 30% of the total cost in Pyropia sea farming. However, the acid wash is ineffective for some diseases, especially for Olpidiopsis and bacterial diseases.

• Journal of Microbiology and Biotechnology
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• 제15권6호
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• pp.1197-1206
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• 2005

Vibrio vulnificus is an opportunistic pathogen that causes a septicemia and expresses numerous virulence factors, in which luxS and smcR are genes encoding for components responsible for quorum-sensing regulation. In the present study, null mutants were constructed with lesions in each or both of these two genes from the V. vulnificus Vv$\Delta$Z strain, which is a lacZ$^{-}$ and chloramphenicol/streptomycin-resistant derivative of the wild-type ATCC29307 strain, and their phenotypes related to virulence were compared with those of the parental cells. $LD_{50}$ and histopathological findings of luxS-, smcR-, or luxS- smcR- deficient mutant were not different from those of the parent strain, a lacZ-deficient streptomycin-resistant strain in mice. However, time of death in mice was delayed, and numbers of bacteria survived in bloodstream after intraperitoneal injection in mice were decreased by mutation, especially luxS and smcR double mutant (VvSR$\Delta$ZSR). These phenomena were supported by increased serum sensitivity and delayed bacterial proliferation in both murine blood and iron-restricted medium. These results suggest that the luxS and luxR homologous genes in V. vulnificus could playa role in bacterial survival in host by enhancing proliferation and adjusting to changed environment.

• Molecules and Cells
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• 제42권12호
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• pp.850-857
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• 2019

The Gram-negative opportunistic pathogen, Pseudomonas aeruginosa, has multiple multidrug efflux pumps. MexT, a LysR-type transcriptional regulator, functions as a transcriptional activator of the MexEF-OprN efflux system. MexT consists of an N-terminal DNA-binding domain and a C-terminal regulatory domain (RD). Little is known regarding MexT ligands and its mechanism of activation. We elucidated the crystal structure of the MexT RD at 2.0 Å resolution. The structure comprised two protomer chains in a dimeric arrangement. MexT possessed an arginine-rich region and a hydrophobic patch lined by a variable loop, both of which are putative ligand-binding sites. The three-dimensional structure of MexT provided clues to the interacting ligand structure. A DNase I footprinting assay of full-length MexT identified two MexT-binding sequence in the mexEF-oprN promoter. Our findings enhance the understanding of the regulation of MexT-dependent activation of efflux pumps.

• Journal of Microbiology and Biotechnology
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• 제17권2호
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• pp.234-243
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• 2007

Vibrio vulnificus is an opportunistic pathogen that causes septicemia in humans. To identify the genes associated with its pathogenicity, in vivo expression technology (IVET) was used to select genes specifically expressed in a host, yet not significantly in vitro. Random lacZ-fusions in the genome of V vulnificus strain MO6-24/O were constructed using an IVET vector, pSG3, which is a suicide vector containing promoterless-aph and -lacZ as reporter genes. A total of ${\sim}18,000$ resulting library clones were then intraperitoneally injected into BALB/c mice using a colony forming unit (CFU) of $1.6{\times}10^6$. Two hours after infection, kanamycin was administered at $200{mu}g$ per gram of mouse weight. After two selection cycles, 11 genes were eventually isolated, which were expressed only in the host. Among these genes, VV20781 and VV21007 exhibiting a homology to a hemagglutinin gene and tolC, respectively, were selected based on having the highest frequency. When compared to wild-type cells, mutants with lesions in these genes showed no difference in the rate of growth rate, yet a significant decrease in cytotoxicity and the capability to form a biofilm.

• Pediatric Infection and Vaccine
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• 제29권3호
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• pp.173-178
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• 2022

Streptococcus intermedius는 입안, 상부 호흡기, 위장관 등에 정상 상재균 중 하나로 존재하는 그람 양성 산소내성 혐기성 알균이다. 면역저하나 심장질환자에서 외상 또는 침습적 치료 후에 발생하는 기회 감염의 원인이 될 수 있다. 저자들은 최근 침습적 치료나 외상 등 특이 과거력이 없이 건강했던 7세 소아에서 S. intermedius에 의해 발생한 엉덩관절 화농 관절염을 경험하였기에 보고하고자 한다. 환자는 내원 3주전부터 왼쪽 엉덩관절 통증이 있었으며, 본원 내원 당일부터 발열이 발생하였다. 엉덩관절 자기공명영상에서 왼쪽 엉덩관절의 급성 화농 관절염으로 진단한 후 수술적 배농을 시행하였고, 혈액과 흡인 관절액에서 S. intermedius가 배양되었다. 수술 후 2주간의 ceftriaxone 정맥주사 후 3주간의 amoxicillin 경구 항생제로 치료한 후 재발없이 안정된 상태를 보이고 있다.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• 제27권2호
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• pp.95-103
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• 2024

Purpose: Diarrhea is one of the leading causes of mortality in children living in developing countries. The etiology of acute diarrhea in each healthcare center varies depending on place, time, and population. This study aimed to identify pathogen patterns in human immunodeficiency virus (HIV)-infected and non-HIV children suffering from acute diarrhea, using multiplex real time reverse transcriptase polymerase chain reaction (RT-PCR), in an Indonesian tertiary hospital. Methods: This cross-sectional study was conducted at Dr. Cipto Mangunkusumo National Hospital from March 2019 to April 2020. Results: The study showed that multiplex RT-PCR results were positive in 58.9% of the specimens, with more positive results in HIV-infected children than in non-HIV-infected children (70% vs. 54.7%). Altogether 72 enteropathogens were detected from all specimens. Enteropathogens in non-HIV children with acute diarrhea consisted of bacteria (70.6%) and viruses (29.4%) with a predominance of enteroaggregative Escherichia coli (25.4%), followed by Campylobacter spp. (11.8%), enteropathogenic E. coli (9.8%), Norovirus GII (7.8%), and Clostridium difficile (7.8%). Enteropathogens in HIV-infected children consisted of viruses (57.1%), bacteria (28.6%), and parasites (14.3%) comprising Norovirus GII (24%), Cryptosporidium spp. (14.3%), Campylobacter spp. (14.3%), Norovirus GI (14.3%), and Astrovirus (14.3%). Cryptosporidium spp. was the only parasite found in this study and was found only in HIV-infected children. In non-HIV children with acute diarrhea, most pathogens were invasive bacteria, while in HIV-infected children, more viral and parasite infections occurred, primarily caused by opportunistic pathogens. Conclusion: The pattern of enteropathogens can help clinicians determine further examinations and appropriate empirical antimicrobial therapy for the patient.

• Parasites, Hosts and Diseases
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• 제54권2호
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• pp.155-161
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• 2016

Toxoplasma gondii is an important opportunistic pathogen that causes toxoplasmosis, which has very few therapeutic treatment options. The most effective therapy is a combination of pyrimethamine and sulfadiazine; however, their utility is limited because of drug toxicity and serious side effects. For these reasons, new drugs with lower toxicity are urgently needed. In this study, the compound, (Z)-1-[(5-nitrofuran-2-yl)methyleneamino]-imidazolidine-2,4-dione (nitrofurantoin), showed anti-T. gondii effects in vitro and in vivo. In HeLa cells, the selectivity of nitrofurantoin was 2.3, which was greater than that of pyrimethamine (0.9). In T. gondii-infected female ICR mice, the inhibition rate of T. gondii growth in the peritoneal cavity was 44.7% compared to the negative control group after 4-day treatment with 100 mg/kg of nitrofurantoin. In addition, hematology indicators showed that T. gondii infection-induced serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels, biochemical parameters involved in liver injury, were reduced by nitrofurantoin significantly. Moreover, nitrofurantoin exerted significant effects on the index of antioxidant status, i.e., malondialdehyde (MDA) and glutathione (GSH). The nitrofurantoin-treated group inhibited the T. gondii-induced MDA levels while alleviating the decrease in GSH levels. Thus, nitrofurantoin is a potential anti-T. gondii candidate for clinical application.