• Natural Product Sciences
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• v.22 no.3
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• pp.216-219
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• 2016

The microbial transformation of anthranilic acid (1) by the marine-mudflat-derived fungus Thielavia sp. produced an antibacterial polycyclic quinazoline alkaloid, thielaviazoline (2). The stereostructure of the metabolite was assigned based on detailed spectroscopic data analyses including comparison of the NMR ($^1H$ and $^{13}C$) data with those of reported compound (2). Compound 2 displayed in vitro antimicrobial activity against methicillin-resistant and multidrug-resistant Staphylococcus aureus (MRSA and MDRSA), with minimum inhibitory concentrations (MICs) of 6.25 and $12.5{\mu}g/mL$, respectively. Compound 2 also showed potent radical-scavenging activity against 2,2-diphenyl-1-picrylhydrazyl (DPPH) with an $IC_{50}$ of $11{\mu}M$, which was more active than the positive control, L-ascorbic acid ($IC_{50}$, $20.0{\mu}M$).

• Journal of the Korean Chemical Society
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• v.54 no.1
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• pp.77-87
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• 2010

Hospital-acquired methicillin-resistant Staphylococcus aureus (MRSA) has been an increasing problem worldwide since the initial reports over 40 years ago. To examine new drug leads with potential antibacterial activities, Various N'-[(-3-substituted-4-oxo-1,3-thiazolidin-2-ylidene]-4-hydroxy benzohydrazide (4a-4.i) and N'-[-(3,4-disubstituted)-1,3-thiazolidin-2ylidene)]-4-hydroxybenzohydrazide from (5.a-5.i) to (10.a-10.i) were synthesized using appropriate synthetic route. The entire test compounds (4.a-4.i) and from (5.a-5.i) to (10.a-10.i) were assayed in vitro against s. aureus strain. The minimum inhibitory concentration (MIC) was determined for test compounds and for reference standards. The test compounds showed significant antibacterial activity against the strains used, when tested in vitro. In general, p-hydroxybenzohydrazide ring and substituted thiazoline ring are essential for antimicrobial activity. Among the compounds tested, compounds 6.f, 7.g, 9.f and 10.f, 10 i were found to be most potent. The test compounds were found nontoxic upto the dose level of 2000 ${\mu}g$/mL. The intact compounds were then subjected for 3D-QSAR studies. 3D-QSAR study based on the principal of alignment of pharmacophoric features by Schrodinger PHASE module. The 3D-QSAR study allowed us to confirm the preferential binding mode of p-hydroxybenzohydrazide inside the active site.

• Clinical and Experimental Pediatrics
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• v.46 no.1
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• pp.24-32
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• 2003

Purpose : Nosocomial infection with Staphylococcus aureus, especially methicillin resistant S. aureus, has become a serious concern in the neonatal intensive care unit. The aim of this study is to investigate the virulence factors, and the relationship between the antibiotic resistance and the associated genes of Staphylococcus aureus isolated from nasal cavity of neonates. Methods : Fifty one isolates of S. aureus were obtained from nasal swab taken in 28 neonates in the NICU and nursery of Pusan National University Hospital between February and May, 2001. They were tested in regard to antibiotic susceptibility, coagulase test and typing, plasmid DNA profile, as well as reactivity to enterotoxin A-E(sea, seb, sec, sed, see) genes and toxic shock syndrome toxin-1(tst) gene by polymerase chain reaction(PCR). Associated genes such as mecA, mecR1, mecI, and femA were also determined by PCR. The origin of MRSA strains was assessed using DNA fingerprinting by arbitrarily-primed polymerase chain reaction(AP-PCR). Results : Twenty three(45.1%) and six(11.8%) isolates were resistant to oxacillin and vancomycin respectively. Multidrug resistance to three or more of the antibiotics tested was observed in 51.0% of the isolates. Forty two isolates were coagulase positive and twenty two isolates had mecA gene. Sixteen isolates had both mecA and femA genes and had type I-III plasmids. 64.7% of isolates carried sec gene, and 80.4% carried tst gene. DNA fingerprinting by AP-PCR for 12 MRSA strains showed 10 distinct patterns, suggesting different origins. Conclusion : We confirmed that the prevalence of nasal carriage of S. aureus and the incidence of antimicrobial-resistant S. aureus, especially vancomycin resistance, is very high in neonates who were admitted in NICU and nursery. It is possible that these pathogens are responsible for serious nosocomial infections in neonates. The need for improved surveillance and continuous control of pathogens is emphasized.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1996.04a
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• pp.232-232
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• 1996

DA-1131은 gram positive bacteria와 Pseudomonas aeruginosa를 포함한 gram negative bacteria에 대하여 광범위한 항균 spectrum과 우수한 항균력을 나타내었다. 각종 임상분리균주에 대한 항균력 시험 결과, gram positive bacteria 중 methicillin-resistant Staphylococcus aureus(MRSA)에 대하여는 DA-1131이 가장 우수한 항균력을 나타내었으며, methicillin-susceptible S. aureus(MSSA)에 대하여는 MEPM, CPR 및 CAZ보다 약 2-50배의 우수한 항균력을 나타내었으나 IPM/CS보다는 동등이하의 항균력을 나타내었다. Gram negative bacteria에 대하여는 IPM/CS, CAZ 및 CPR보다 우수한 항균력을 나타내어 0.2 $\mu\textrm{g}$/$m\ell$ 이하의 농도에서 91%의 Serratia marcescens, 89%의 Proteus mirabilis, 76%의 Morganella morganii 및 시험에 사용된 Enterobacteriaceae에 속하는 전균주의 생육이 억제되었다. P. aeruginosa 에 대하여 DA-1131은 1.56 $\mu\textrm{g}$/$m\ell$ 이하의 농도로 시험균주 전체의 생육을 저해하였으며, MEPM의 약 2배, IPM/CS의 약 4배의 강한 항균력을 나타내었다. CAZ에 내성인 Enterobacteriaceae 임상분리균주에 대한 DA-1131의 항균력은 CAZ 감수성균주에 대한 항균력과 동일한 것으로 나타났다.

• Annals of Clinical Microbiology
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• v.21 no.4
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• pp.80-85
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• 2018

Background: The aim of this study was to comparatively evaluate the bactericidal effects of copper, brass (copper 78%, tin 22%), and stainless steel against methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus faecium (VREFM), and multidrug-resistant Pseudomonas aeruginosa (MRPA). Methods: The isolates (MRSA, VREFM, MRPA) used in this study were mixed wild type 3 strains isolated from patients treated at Uijeongbu St. Mary's Hospital in 2017. These strains showed patterns of multidrug resistance. The lyophilized strains were inoculated into and incubated for 24 hr in tryptic soy broth at $35^{\circ}C$. The initial bacterial inoculum concentration was adjusted to $10^5CFU/mL$. A 100-mL bacterial suspension was incubated in containers made of brass (copper 78%, tin 22%), copper (above 99% purity), and stainless steel at $35^{\circ}C$. Viable counts of bacteria strains were measured for 9 days. Results: In this study, the bactericidal effects of copper and brass on MRSA, VREFM, and MRPA were verified. The bactericidal effect of stainless steel was much weaker than those of copper and brass. The bactericidal effect was stronger on MRPA than on MRSA or VREFM. Conclusion: To prevent cross infection of multidrug resistant bacteria in hospitals, further studies of longer duration are needed for testing of copper materials on objects such as door knobs, faucets, and bed rails.

• Journal of Microbiology and Biotechnology
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• v.31 no.1
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• pp.115-122
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• 2021

Phenol-soluble modulins (PSMs) are responsible for regulating biofilm formation, persister cell formation, pmtR expression, host cell lysis, and anti-bacterial effects. To determine the effect of psm deletion on methicillin-resistant Staphylococcus aureus, we investigated psm deletion mutants including Δpsmα, Δpsmβ, and Δpsmαβ. These mutants exhibited increased β-lactam antibiotic resistance to ampicillin and oxacillin that was shown to be caused by increased N-acetylmannosamine kinase (nanK) mRNA expression, which regulates persister cell formation, leading to changes in the pattern of phospholipid fatty acids resulting in increased anteiso-C15:0, and increased membrane hydrophobicity with the deletion of PSMs. When synthetic PSMs were applied to Δpsmα and Δpsmβ mutants, treatment of Δpsmα with PSMα1-4 and Δpsmβ with PSMβ1-2 restored the sensitivity to oxacillin and slightly reduced the biofilm formation. Addition of a single fragment showed that α1, α2, α3, and β2 had an inhibiting effect on biofilms in Δpsmα; however, β1 showed an enhancing effect on biofilms in Δpsmβ. This study demonstrates a possible reason for the increased antibiotic resistance in psm mutants and the effect of PSMs on biofilm formation.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.43 no.1
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• pp.33-38
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• 2010

Emerging of antibiotic resistance of pathogenic bacteria is now a very serious problem in the clinics to treat the diseases, which have been easy to cure by antibiotic treatments before. Unfortunately, antibiotics developed till now are not effective any more against the resistant bacteria. Lots of efforts to discover new antibiotics having novel and unique structures and functions are really urgent and undergoing in the whole world. In this study, we tried to screen and isolate Same unique bacterial strains producing antibacterial substances from the sea water, which is the poor environment for bacteria 10 make their growing. Three bacterial strains among 916 strains isolated showed inhibition clear zone on the marine agar plate growing pathogenic bacteria including Acinetobacter baumannii, Edwardsiella tarda, Pseudomonas aeruginosa, Staphylococcus aureus, Salmonella enterica. One of them, which was identified as Bacillus sp. DH-9 from 16S rRNA gene analysis, showed especially considerable antibacterial activity against S. aureus which is notorious for methicillin resistant S. aureus (MRSA). The growth of S. aureus was totally inhibited when the supernatant of Bacillus sp. DH-9 culture was treated on.

• Natural Product Sciences
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• v.20 no.1
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• pp.39-43
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• 2014

Papenfussiella kuromo (PK) is a marine plant and an abundant ecological resource for the future; it is found in almost 80% of the terrestrial biosphere. The aim of this study was to investigate the antibacterial activity of PK against methicillin-resistant Staphylococcus aureus (MRSA), multidrug-resistant pathogen. The minimum inhibitory concentrations (MICs) of PK hexane fraction (PKH) against 7 strains of MRSA ranged from 1.0 to 2.0 mg/mL. In the checkerboard dilution method, a synergistic effect of the PKH and the antibiotics (oxacillin and norfloxacin) was seen. PKH markedly reduced the MIC of each of the 4 antibiotics against MRSA. The time-kill assay showed that the synergistic activity of PKH and an antibiotic reduced the bacterial counts below the lowest detectable limit after 24 h. These findings suggest that PKH has antibacterial activity, and may be important baseline data in future extensive studies of living marine resources as a source of compounds active against MRSA.

• Journal of Microbiology and Biotechnology
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• v.29 no.11
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• pp.1841-1851
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• 2019

Garcinol, a well-known medicinal phytochemical, was extracted and isolated from the dried fruit rinds of Garcinia quaesita Pierre. In this study, garcinol has successfully used to reduce silver ions to silver in order to synthesize garcinol-capped silver nanoparticles (G-AgNPs). The formation and the structure of G-AgNPs were confirmed by UV-visible spectroscopy, transmission electron microscopy and Fourier transform infrared spectroscopy. The antimicrobial activity of garcinol and G-AgNPs were investigated by well diffusion assays, broth micro-dilution assays and time-kill kinetics studies against five microbial species, including Staphylococcus aureus (ATCC 25923), Pseudomonas aeruginosa (ATCC 27853), Escherichia coli (ATCC 25922), Candida albicans (ATCC 10231) and clinically isolated methicillin-resistant Staphylococcus aureus (MRSA). The formation of G-AgNPs is a promising novel approach to enhancing the biological activeness of silver nanoparticles, and to increase the water solubility of garcinol which creates a broad range of therapeutic applications.

• Korean Journal of Veterinary Service
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• v.35 no.2
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• pp.99-104
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• 2012

Otitis externa (OE) is a frequent disease in the ear canals of dogs. To identify the pathogens causing OE in dogs and to determine their antimicrobial resistances, specimens were collected from animal hospitals in Daejeon. The isolates were examined by morphological and biochemical tests, 16S rRNA analysis and antimicrobial susceptibility tests. We analyzed correlation between the isolated pathogens and external factors of dogs such as breed, age, gender, ear mite, hair in ears and experience with antibiotic therapy. Thirty three strains of bacteria were isolated from 26 of the 68 heads of dogs with OE. The most isolated bacteria were Enterococcus faecalis (E. faecalis) followed by Staphylococcus aureus (Sta. aureus), Sta. pseudointermedius, E. faecium, E. avium and Streptococcus canis (Strep. canis) in order of frequency of occurrence. Isolation frequency of Enterococcus spp. and Staphylococcus spp. were 51.5% and 45.5%, respectively. E. faecalis and E. faecium isolates showed VanB phenotype, which is resistant to vancomycin but sensitive to teicoplanin were 58% and 25%, respectively. Nine isolates among total twelve isolates of E. faecalis were isolated from the dogs treated with antibiotics. There was no methicillin-resistant Sta. aureus (MRSA), but were MR-Sta. pseudointermedius (MRSP) (57.1%) and vancomycin-resistant (VR)-Sta. pseudointermedius (14.3%) (VRSP) showing VanB phenotype. However, vanA, vanB and vanC genes were not detected in VR isolates from the dogs. Taken together, VR-Enterococcus spp. (VRE) is one of the major pathogens in domestic animals, as well as community-and hospital-acquired infection.