• Restorative Dentistry and Endodontics
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• v.18 no.2
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• pp.341-356
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• 1993

In the prevention of root surface caries, antimicrobial therapy for the control of subgingival and supragingival plaque is seriously considered as a long term suppression of pathogenic microflora. Recently, varnishes containing antimicrobial agents have been developed to control the supragingival microflora. The purpose of this study was to determine the antimicrobial effects of 20% chlorhexidine varnish and 2.6% silane fluoride varnish with sealant. In clinical experiments, 12 subjects were selected from the periodontally treated patient and divided into 3 groups. After a dental prophylaxis, the subjects were treated with single application of placebo varnish (group I), 20% chlorhexidine varnish (group II), and 2.6% silane fluoride varnish (group III). Root surface plaque samples were taken before (baseline) and one, two, four, and 8 weeks after the treatments. Microbiological examinations of root surface plaque were performed with culture study and indirect immunoflorescence (I.I.F.) study, and immunological examination of gingival crevicular fluid antibody titers was performed with ELISA study. The results were as follows: 1. Pathogenic microflora on the root surface including S. mutans, S. sanguis, S. mitis, A. naeslundii, A. viscosus were 24 - 37% on I.I.F. study. 2. S. mutans, S. sanguis, S. mitis, A. naeslundii, A. viscosus of the root surface plaque was significantly reduced from 1 week to 8 weeks after antimicrobial varnish treatment, but showed generally increasing tendency in control group. 3. Gingival crevicular fluid antibody titers were significantly reduced from 1 or 2 weeks to 4 weeks after antimicrobial varnish treatment.

• Korean Journal of Agricultural and Forest Meteorology
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• v.8 no.2
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• pp.77-85
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• 2006

Entomopathogenic nematodes (EPNs) have been used as biological control agents for control of various agro-forest insect pests, and are especially effective against soil-dwelling insect pests. Effect of soil moisture on pathogenicity of commercial EPNs for white grub control was evaluated in laboratory, pots, and golf courses. Pathogenicity of EPNs in sand column was variable depending on depth, soil moisture, and EPN species or strain. All tested EPNs (Heterorhabditis sp. GSNUH1, Heterorhabditis sp. GSNUH2, Steinernema carpocapsae GSN1, and S. longicaudum Nonsan strain) showed similar pathogenicity against the bait insect, great wax moth (Galleria mellonella) larva at 2 cm deep at a given soil moisture. However, pathogenicity of the Heterorhabditis sp. GSNUH1 strain was decreased with increasing soil moisture. Pathogenicity of S. carpocapsae GSN1 strain was the lowest in 3% soil moisture (v/w) at 7 cm depth. However, there was no difference in pathogenicity between Heterorhabditis sp. GSNUH2 and S. longicaudum Nonsan strain. Although pathogenicity of Heterorhabditis sp. KCTC 0991BP strain showed no difference against the 2nd instar of Exomala orientalis, that of the S. carpocapsae GSN1 strain was decreased in the laboratory depending on soil moisture. Highly pathogenic strain EPN, Heterorhabditis sp. KCTC 0991BP strain, showed higher pathogenicity at 100 mm irrigation than non-irrigation or 10 mm irrigation. However, poor pathogenic strain EPN, S. carpocapsae GSN1 strain, was not different in pathogenicity from the 2nd instar of Exomala orientalis in creeping bentgrass (Agrostis palustris) depending on irrigation amount in the pot. Pathogenicity of EPNs in field experiment at the tee of Ulsan golf club showed a similar trend to that in the pot experiment.

• The Journal of the Korean Society for Microbiology
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• v.22 no.2
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• pp.155-162
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• 1987

To determine the prevalence of antibiotic resistance in fecal E. coli and to investigate possible associations between antibiotic resistance and other plasmid-mediated virulence properties, antibiotic disk susceptibility tests for nine antibiotics were done on 141 strains of E. coli isolated from diarrheal children and well controls. Eighty two percent of the test strains were resistant to one or more antibiotics. Antibiotics to which the test strains were most resistant in descending order were ampicillin (85%), trimethoprim/sulfamethoxazol (60%), and cephalothin (55%). Seventy nine percent of these resistant strains were resistant to two or more antibiotics. All 141 test strains were sorted into enterotoxigenic E. coli (ETEC), enteropathogenic E. coli (EPEC), enteroadherent E. coli (EAEC) and non-pathogenic E. coli and the percentages of strains resistant to multiple antibiotics were compared. Among ETEC regardless of its source, multiple drug resistance was more frequent in strains producing heatstable enterotoxin (ST) only than in strains producing only heat-labile enterotoxin (LT) or both. In EAEC, multiple resistance was more frequently associated with strains isolated from diarrheal patients than with those from well controls. The major antibiotic resistance patterns possessed by multiple resistant enteropathogenic strains were $SXT^R$ $AM^R$, $CR^R$, and $SXT^R$ $AM^R$ $CR^R$. Of 28 ST- producing $SXT^R$ ETEC, 26(96%) were also resistant to ampicillin and 17 (61%) were resistant to cephalothin. The similar pattern was observed in EAEC and EPEC as well. This study has important implications for the treatment of E. coli diarrhea with antibiotics because it is possible that dissemination of virulence could occur under the force of selective antibiotic pressure. In addition, this study suggests that the in vivo efficacy of SXT in treating diarrheal illness be reevaluated.

• Journal of Microbiology and Biotechnology
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• v.29 no.9
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• pp.1401-1411
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• 2019

Mycobacterial cell walls comprise thick and diverse lipids and glycolipids that act as a permeability barrier to antibiotics or other chemical agents. The use of OH radicals from a non-thermal plasma jet (NTPJ) for the inactivation of mycobacteria in aqueous solution was adopted as a novel approach. Addition of water vapor in a nitrogen plasma jet generated OH radicals, which converted to hydrogen peroxide ($H_2O_2$) that inactivated non-pathogenic Mycobacterium smegmatis and pathogenic Mycobacterium tuberculosis H37Rv. A stable plasma plume was obtained from a nitrogen plasma jet with 1.91 W of power, killing Escherichia coli and mycobacteria effectively, whereas addition of catalase decreased the effects of the former. Mycobacteria were more resistant than E. coli to NTPJ treatment. Plasma treatment enhanced intracellular ROS production and upregulation of genes related to ROS stress responses (thiolrelated oxidoreductases, such as SseA and DoxX, and ferric uptake regulator furA). Morphological changes of M. smegmatis and M. tuberculosis H37Rv were observed after 5 min treatment with $N_2+H_2O$ plasma, but not of pre-incubated sample with catalase. This finding indicates that the bactericidal efficacy of NTPJ is related to the toxicity of OH and $H_2O_2$ radicals in cells. Therefore, our study suggests that NTPJ treatment may effectively control pulmonary infections caused by M. tuberculosis and nontuberculous mycobacteria (NTM) such as M. avium or M. abscessus in water.

• Parasites, Hosts and Diseases
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• v.61 no.4
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• pp.449-454
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• 2023

Free-living amoebae (FLA) rarely cause human infections but can invoke fatal infections in the central nervous system (CNS). No consensus treatment has been established for FLA infections of the CNS, emphasizing the urgent need to discover or develop safe and effective drugs. Flavonoids, natural compounds from plants and plant-derived products, are known to have antiprotozoan activities against several pathogenic protozoa parasites. The anti-FLA activity of flavonoids has also been proposed, while their antiamoebic activity for FLA needs to be emperically determined. We herein evaluated the antiamoebic activities of 18 flavonoids against Naegleria fowleri and Acanthamoeba species which included A. castellanii and A. polyphaga. These flavonoids showed different profiles of antiamoebic activity against N. fowleri and Acanthamoeba species. Demethoxycurcumin, kaempferol, resveratrol, and silybin (A+B) showed in vitro antiamoebic activity against both N. fowleri and Acanthamoeba species. Apigenin, costunolide, (-)-epicatechin, (-)-epigallocatechin, rosmarinic acid, and (-)-trans-caryophyllene showed selective antiamoebic activity for Acanthamoeba species. Luteolin was more effective for N. fowleri. However, afzelin, berberine, (±)-catechin, chelerythrine, genistein, (+)-pinostrobin, and quercetin did not exhibit antiamoebic activity against the amoeba species. They neither showed selective antiamoebic activity with significant cytotoxicity to C6 glial cells. Our results provide a basis for the anti-FLA activity of flavonoids, which can be applied to develope alternative or supplemental therapeutic agents for FLA infections of the CNS.

• Korean Journal of Veterinary Service
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• v.38 no.4
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• pp.241-248
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• 2015

This study was aimed to investigate factors that affected the status of wearing personal protective equipment (PPE) for handling poultry carcasses with potential exposure to virulent avian infectious agents. A large outbreak of high pathogenic avian influenza (HPAI) occurred in South Korea in 2014. Many public officers participated for euthanizing and handling livestock carcass. However, several safety issues with using PPE were revealed. Therefore, a questionnaire survey was conducted for 340 people who participated euthanasia and carcass disposal in the place where HPAI mainly occurred in 2014. It was found that 31.8% of the respondents had ever taken off their protective equipment during operations because of its inconvenience. The most inconvenient PPE was goggles (54.6%), followed by mask (20.2%), latex gloves (11.6%), shoe covers (5.9%) and protective clothing (5.3%). The main complaints about this individual PPE was unclear sight, damp emitted toward eye, sweating, tearing easily and sweating, respectively. Considering such problems of PPE, new possible directions for improvement of gloves and goggles were suggested. With newly developed rubber coating fabric gloves and conventionally using latex and fabric gloves, H3N2 influenza virus transmission experiment was conducted. Rubber coating fabric gloves showed similar efficiency for blocking virus transmission with latex laboratory gloves and were not easily torn by sharp claws of chicken. In addition, air flow control safety eyewear was suggested to minimize moisture formation. The air flow control system efficiently suppressed moisture formation inside the goggles. Therefore our study will provide more specific directions about new PPE development for safety protection of actual wearers.

• Journal of Ginseng Research
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• v.40 no.4
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• pp.315-324
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• 2016

Background: Biocontrol agents are regarded as promising and environmental friendly approaches as agrochemicals for phytodiseases that cause serious environmental and health problems. Trichoderma species have been widely used in suppression of soil-borne pathogens. In this study, an endophytic fungus, Trichoderma gamsii YIM PH30019, from healthy Panax notoginseng root was investigated for its biocontrol potential. Methods: In vitro detached healthy roots, and pot and field experiments were used to investigate the pathogenicity and biocontrol efficacy of T. gamsii YIM PH30019 to the host plant. The antagonistic mechanisms against test phytopathogens were analyzed using dual culture, scanning electron microscopy, and volatile organic compounds (VOCs). Tolerance to chemical fertilizers was also tested in a series of concentrations. Results: The results indicated that T. gamsii YIM PH30019 was nonpathogenic to the host, presented appreciable biocontrol efficacy, and could tolerate chemical fertilizer concentrations of up to 20%. T. gamsii YIM PH30019 displayed antagonistic activities against the pathogenic fungi of P. notoginseng via production of VOCs. On the basis of gas chromatography-mass spectrometry, VOCs were identified as dimethyl disulfide, dibenzofuran, methanethiol, ketones, etc., which are effective ingredients for antagonistic activity. T. gamsii YIM PH30019 was able to improve the seedlings' emergence and protect P. notoginseng plants from soil-borne disease in the continuous cropping field tests. Conclusion: The results suggest that the endophytic fungus T. gamsii YIM PH30019 may have a good potential as a biological control agent against notoginseng phytodiseases and can provide a clue to further illuminate the interactions between Trichoderma and phytopathogens.

• Journal of Life Science
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• v.27 no.4
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• pp.430-434
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• 2017

Essential oils are fragrant oils extracted from the leaves, stems, peels, petals and roots of aromatic plants cultivated by natural means or using organic agricultural techniques. Essential oils have commonly been used as antibacterial and antifungal agents. In the present study, essential oil was extracted from lisianthus (Eustoma grandiflorum [Raf.] Shinn.) and tested for antifungal activities against three eumycetes (Penicillium pinophilum, Chaetomium glogosum and Aspergillus niger). Lisianthus essential oil showed high antifungal activities against three eumycetes, especially against Aspergillus niger, for which the resulting minimum inhibitory concentration (MIC) was 0.005 mg/ml. In addition, the extracted essential oil was shown to have antimicrobial activity against ten intestinal pathogenic bacteria (Escherichia coli, Salmonella typhimurium, Klebsiella pneumonia, Staphylococcus aureus, Bacillus cereus, Listeria monocytogenes, Pseudomonas aeruginosa, Bacillus subtilis, Enterococcus faecalis and Vibrio parahaemolyticus) according to the disc diffusion method and was also shown to exhibit strong antibacterial activity against an additional three pathogenic bacteria (Bacillus subtilis, Listeria monocytogenes and Vibrio parahaemolyticus). These results indicate that lisianthus essential oil could be used as an antibiotic against harmful bacteria that produce intestinal illnesses. From the present study, we suggest that lisianthus extracts can be utilized as potential antifungal and antibacterial agents and for the development of pharmaceutical and cosmetic products.

• 한국균학회소식:학술대회논문집
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• 2016.05a
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• pp.13-13
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• 2016

Insects constitute the largest and most diverse group of animals in the world. They also serve as the hosts or nutrient sources for an immense assemblage of pathogens, parasites, and predators. More than 700 fungal species from 100 genera have adopted an entomopathogenic lifestyle. Although entomopathogenic fungi were studied as only biocontrol agents against a variety of pests in various countries, it has been recently focused their additional roles in nature. They are antagonists to/against plant pathogens, endophytes, and possibly even plant growth promoting agents. The potential antimicrobial effect against fungal plant pathogens by an isolate of entomopathogenic fungi including Beauveria bassiana, Lecanicillium spp., and Isaria fumosorosea have been reported since late 1990s, but wasn't reported pathogenicity of the isolate against pests. Later, a Canadian Lecanicillium sp. isolate and L. longisporium isolated from Vertalec$^{(R)}$ showed simultaneous control effect against both aphid and cucumber powder mildew. Therefore, the antimicrobial activities of 342 fungi isolates collected from various regions and conditions in Korea were evaluated against plant pathogenic fungus Botrytis cinerea using dual culture technique on agar plate. As a result, 186 isolates (54.4%) shown the antifungal activity against B. cinerea. The culture filtrates of selected fungi completely suppressed the growth of the microorganisms, indicating that suppression was due to the presence of antimicrobial substances in the culture filtrate. Mode of action of these fungi against insect involves the attachment of conidia to the insect cuticle, followed by germination, cuticle penetration, and internal dissemination throughout the insect. During infection process, secreted enzymes, proteinous toxins, and/or secondary metabolites secreted by entomopathogenic fungi can be used to overcome the host immune system, modify host behavior, and defend host resources. Recently, secondary metabolites isolated from entomopathogenic fungi have been reported as potential bioactive substances. Generally, most of bioactive substances produced by entomopathogenic fungi have reported low molecular weight (lower than 1,000 g/mol) as peptide and, in contrast the high molecular weight fungal bioactive substances are rare. Most substances based on entomopathogenic fungi were shown antimicrobial activity with narrow control ranges. In our study we analyzed the antimicrobial substances having antagonistic effects to B. cinerea. Antimicrobial substances in our fungal culture filtrates showed high thermostability, high stability to proteolytic enzymes, and hydrophilicity and their molecular weights were differed from substance. In conclusion, entomopathogenic fungi showed pathogenicity against insect pests and culture filtrate of the fungi also shown to antimicrobial activity. In the future, we can use the entomopathogenic fungi and its secondary metabolites to control both insect pest control and plant pathogenic fungi simultaneously.

• Korean Journal of Veterinary Research
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• v.22 no.2
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• pp.121-138
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• 1982

The present study was conducted in order to investigate the role of yeast-like fungi in bovine mastitis. Attempts were made to isolate and identify yeast-like fungi from the milk from normal udders and those with clinical or subclinical mastitis and from feces. Also incuded in the study were trials for the pathogenicity of the isolates for laboratory animals and efficacy of an anti-fungal drug for the treatment of mastitis. A total of 133 isolates of yeast-like fungi was made from milk and feces and they were identified as Candida (C.) albicans (5 isolates), C. krusei (63 isolates), C. tropicalis (27 isolates), Torulopsis (T.) glabrata (10 isolates), Rhodotourla sp. (6 isolates), Hansenula sp. (6 isolates) and Pichia sp. (1 isolate). Sixty seven strains of yeast-like fungi were isolated from the milk of 64 quarters (4.3% of quarters examined) of 55 cows (14.3% of cows examined). C. krusei, C. tropicalis, C. pseudotropicalis, C. parapsilosis and T. glabrata were isolated as the causative agents from 20 quarters (1.3% of quarters examined) with clinical mastitis. C. krusei, C. tropicalis, C. albicans, C. pseudotropicalis, T. glabrata, Rhodotorula sp. and Hansenula sp. were isolated as the causative agents from 22 quarters (1.5% quarters examined) with subclinical mastitis. C. tropicalis, C. krusei, T. glabrata and Rhodotorula sp. were isolated as the contaminants from 22 normal quarters (1.5% of quarters examined). C. krusei, C albicans, C. tropicalis, C. pseudotropicalis, C. parapsilosis, T. glabrata, Hansenula sp., Rhodotorula sp. and Pichia sp. were isolated as the contaminants from feces and all of the species except Pichia sp. were isolated from milk of the same cows at the some time. Intramammary infusion of nystatin was effective for the treatment of mastitis caused by C. albicans, C. krusei, C. tropicalis, C. pseudotoropicalis, C. parapsilosis, T. glabrata and Rhodotorula sp. C. albicans, C. krusei, C. tropicalis, C. pseudotropicalis, T. glabrata, Hamsenula sp. and Pichia sp. were pathogenic for rat but C. parapsilosis and Rhodotorula sp. were not.