• Korean Journal of Microbiology
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• v.30 no.6
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• pp.438-443
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• 1992

Thirteen strains of Bacillus thuringiensis were isolated from soil in Korea and characterized. The all strains produced parasporal crystals and spores in their cells. Two strains had bipyramidal crystals, seven strains contianed round ones and four strains had unregular ones. Only minor biochemical characteristics of the thirteen isolates were different and distinctive, however general characteristics were similar to the known serotypes of B. thuringiensis. Two strains were resistant to ampicilin. Three strains were resistant to bacitracin, six strains were resistant to cephalothin, two strains were resistant to colistin, HL-68 strain was resistant to gentamycin, HL-67 strain was resistant to kanamycin and HL-71 was resistant to tetracycline. Two strains were resistant to penicillin G. Four strains were toxic to Bombyx mori larvae and eleven strains were toxic to Culex pipiens larvae.

• The Journal of the Korean Society for Microbiology
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• v.6 no.1
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• pp.21-27
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• 1971

Recent reports confirm that R factors is widespread in Korea among Enterobacteriaceae isolated from humans. However, no reports have been made concerning the incidence of transferable drug resistance in domestic animals in this country. A total of 211 isolates of Escherichia coli, including 94 strains from dogs, 76 strains from pigs, 30 strains from chickens, and 21 strains from cow milk, were examined for drug resistance and distribution of R factors. And, respective two strains of Salmonella E group and Salmonella cholerasuis which were isolated from dogs and pigs, respectively were also examined for the same purposes. Of 211 strains of E. coli isolated, 66.8% were found to be resistant to 8 antibacterial agents such as streptomycin(SM), tetracycline(TC), chloramphenicol(CP), ampicillin sodium(AP), nalidixic acid(NA), gentamicin(GM), and polymyxin B(PX). Among the isolates, 86.2% of the strains from dogs, 70% of the strains from chickens, 43.4% of the strains from pigs, and 28.6% of the strains from milk, respectively, were found to be resistant to the drugs. The following percentage of resistance of E. coli to each individual drugs was encountered: of 94 strains from dogs, AP, 64.9%; SM, 20.2%; NA, 12.8%, CP and PX, 8.5% each; GM, 2.1% each; GM, 2.1%. Among 76 strains from pigs, 42.2% and 2.6% each were resistant to TC, AP and PX, respectively. Among 30 strains from chickens, 43.3% were resistant to SM, TC, AP, respectively, and no strains were resistant to the other drugs. No strains of the isolated from milk were resistant to the drugs, except that 28.6% were resistant to SM and AP, respectively. Of the strains from dogs, multiply resistant strains(56.8%) were more than singly resistant one(43.2%) and sixteen different drug resistant patterns were observed. The most frequently encountered patterns were AP TC AP and SM CP AP NA. Of the isolates from other sources, the most frequently encountered resistant patterns were as follows: TC among the strains from pigs; SM TC AP from chickens; SM AP from milk. Of the resistant strains from dogs, 32% carried R factors and the most common resistance patterns of R factors were AP TC AP and SM TC CP, whereas 35.2% of the resistant strains from pigs carried R factors of which the most common encountered pattern was TC. Of the resistant strains from chickens, 46.9% carried R factors of which the most common patterns were SM TC TC AP and AP, whereas 50% of the resistant strains from milk carried R factors of which the most common pattern was SM. Of 4 strains of Salmonella isolated, no strains were resistant to the drugs, except that only one strain of Salmonella E group isolated from a dog was resistant to AP. The strain did not harbor R factor.

• The Journal of the Korean Society for Microbiology
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• v.19 no.1
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• pp.11-24
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• 1984

Shigella remains to be an important enteric pathogen in this country for the present. Moreover, most of the isolates have become multiple resistant to various antibiotics which used to be drugs of choice for shigellosis. This study was made as an attempt to assess the present stage of antibiotic resistance and the incidence and transferability of R factors of Shigella. A total of one hundred and seventeen strains of Shigella isolated from patients in Seoul and provincial area between 1982 and 1983 were tested for their resistant to antimicrobial agents and transmission of R-plasmid. Antibiotic susceptibilities were determined by an agar dilution method. Muller hinton agar were used for the assay of drug resistance and tryptic soy broth were used for propagating medium for conjugation. Shigella isolated found to be one or more antibiotics were considered potential donor of R-plasmid. The following results were obtained. 1. Among 117 strains of Shigella isolated, 111 strains(94.9%) were found to be resistant to one or more drugs tested and 97.3% of these resistant strains were multiply resistant, indicating the multiply resistant strains were more than the single resistant strains. Only six strains were susceptible to all drugs tested. 2. Among 117 strains of Shigella isolated, 107 strains(91.5%) were resistant to Tetracyclin(Tc), 106 strains(90.6%) to Chloramphenicol(Cp) and Streptomycin(Sm), 97 strains(82.9%) to Ampicillin(Ap), 68 strains(58.1%) to Cephaloridine(Cr), 10 strains(8.5%) to Nalidixic acid(Na), 5 strains(4.3%) to Kanamycin(Km) and 2 strains(1.7%) to Rifampicin. No strain was resisfant to Amikacin(Ak) and Gentamicin(Gm). 3. All drug-resistant Shigella strains, except three, were multiply resistant to two or more drugs. Fifty eight strains were resistant to five drugs, followed by 26 strains resistant to dour drugs, 12 strains resistant to three drugs and 11 strains resistant to six drugs. 4. The 73% of multiply drug-resistant Shigella transferred their resistance to E. coli by conjugation and the resistance was considered to be mediated by R-plasmid. Resistance to Nalidixic acid and Rifampicin were not transferred by conjugation to recipient. As for the transferability of resistance to each seperate drug, Ap resistance was transferred with 73.2% frequence and Cm and Tc resistance were transferred with approximately 50-60% frequence whereas Sm and Cr resistance were transferred in 19.1-21.4% The other four drugs resistant failed to transfer their resistance to recipient. 5. As for the incidence and transferability of resistance to each seperate drug, the strains resistant to Tc and Cm were encountered most frequently with the rate of 91-92%, whereas transfer of Tc and Cm were low, 51-52%. The incidence of Sm resistance was very high(90.6%) but transferability of drugs resistance was much lower(25.4%). Though the incidence of Km reristance was much lower(4.3%) transferability of Km resistance was considerably higher(60%). 6. The greater the multiplicity of resistance, the greater was the likelihood that part of all of the resistance markers would be transferable.

• Mycobiology
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• v.36 no.4
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• pp.270-273
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• 2008

Trichoderma spp. cause large crop losses of the cultivated shiitake mushroom, Lentinula edodes. We bred several shiitake strains that are resistant to Trichoderma spp. using di-mon mating to establish a useful method for controlling the greenmold disease. We examined the competitive ability of L. edodes against Trichoderma spp. using a dual culture system to select resistant strains. By screening Trichoderma-resistant strains, we found that among 11 parental strains, 4 strains, including KFRI 36, were confirmed resistant strains. They showed especially strong resistance to T. harzianum, which formed deadlock after mycelial contact and then invaded into the territory of T. harzianum. KFRI 171 also showed resistance to T. atroviride strains. Among 13 strains, which were made by hybridization of shiitake strains, 5 were confirmed to be resistant to Trichoderma, including KFRI 58-1. Their resistance was not correlated to the resistant activity of their parents’ strains. Two strains lose resistance and two strains acquire resistance compared to their parents’ strains. In SEM observation, the mycelium of L. edodes at the interaction zone of Lentinula-Trichoderma was rugged and swollen by T. harzianum.

• The Journal of the Korean Society for Microbiology
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• v.5 no.1
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• pp.1-8
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• 1970

This report is to observe the rate of multiple resistance to various antibiotics among staphylococcus aureus and E. coli which were isolated with high frequency at our department during 1969. 1. One hundred fifty two strains(20.6%) resistant to four antibiotics multiple resistant was the highest incidence among 739 strains of Staphylococcus aureus. 2. Regarding the multiple antibiotic resistant of Staphylococcus aureus, 75strains(10.1%) to SA. PC. TC the three antibiotics resistant, have been observed, with the highest incidence, and next to this, 69 strains(9.3%) to SA. PC. SM. TC the four autibiotics resistant, and 68 strains(9.2%) to SA. PC. SM. CM. TC. SM. the six antibiotics resistant, have been observed in descending order. 3. The case of one hundred twenty seven strains(28.0%) of the six antibiotic multiple resistant among 454 strains of Escherchia coli was the highest incidence. 4. Concerning the multiple antibiotic resistant of Escherichia coli, 70 strains(l5.4%) to SA. SM. CM. TC. EM. FD. the six antibiotics resistant, have been observed, with the highest incidence, and next to this, 59 strains(l3.0%) to SA. SM. CM. TC. EM. FD. AC the seven antibiotics resistant, and 42 strains(9.3%) to SA. SM. CM. TC. EM. FD. KM. AC the eight antibiotics resistant have been observed in descending order.

• Korean Journal of Veterinary Research
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• v.21 no.1
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• pp.25-31
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• 1981

A total of 250 enteric bacteria (148 Escherichia coli, 41 Klebsiella pneumoniae, 46 Enterobacter spp. and 15 Proteus spp.) isolated from bovine udder infections in 1979 through 1980 were examined for drug resistance and prevalence of R. plasmids. The drug tested were streptomycin (SM), kanamycin (KM), ampicillin (AP), chloramphenicol (CP), tetracycline (TC), gentamicin (GM), oxolinic acid (OA) and nalidixic acid (NA). The detection of R. plasmids was performed with Escherichia coli ML 1410 NAr as the recipient. Of the 148 Escherichia coli isolated, 68(45.9%) were found to be resistant to one or more drugs tested, and about 50% of the resistant strains were multiply resistant. of the 68 drugresistant strains, 13(19.1%) were found to carry R. plasmids which were capable of performing a conjugal transfer. CP resistance was transfered together with the other resistance. Of 41 strains of Klebsiella pneumoniae isolated, 90.2% were resistant to the drugs, alone or in combination thereof. Strains resistant to AP and TC were 63.4%, and 48.8%, respectively. R. plasmids were detected in 78.4% of the drug-resistant strains, and these strains transfered all or a part of their drug resistance pattern. AP and CP resistance were transfered in 100% of AP and CP-resistant strains. Eleven (37.9%) of 29 R. plasmids showed a thermosensitive transfer. Of the 46 strains of Enterobacter spp. isolated, 37(80.4%) were resistant to the drugs tested. A high percentage of resistance was noted for AP(65.2%). All strains resistant to four or more drugs transferred their resistances to Escherichia coli ML 1410, but strains resistant to three or fewer drugs did not transfer the resistances. All of the 15 Proteus strains isolated were resistant to more than two drugs. of them, 6 were quadruple resistance to SM, KM, CP and TC, and 9 were double one to AP and TC. Three (20.0%) of the drug-resistant isolates had R.plasmids conferring AP and TC resistance. GM, OA and NA of the drugs tested were very active to all of 250 Gram-negative enteric bacteria isolated from bovine udder infections.

• Journal of Microbiology and Biotechnology
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• v.28 no.12
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• pp.2064-2070
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• 2018

Pseudomonas tolaasii 6264 is a representative strain that causes bacterial blotch disease on the cultivated oyster mushroom, Pleurotus ostreatus. Bacteriophages are able to sterilize the pathogenic P. tolaasii strains, and therefore, they can be applied in creating disease-free mushroom cultivation farms, through a method known as "phage therapy". For successful phage therapy, the characterization of phage-resistant strains is necessary, since they are frequently induced from the original pathogenic bacteria in the presence of phages. When 10 different phages were incubated with P. tolaasii 6264, their corresponding phage-resistant strains were obtained. In this study, changes in pathogenic, genetic, and biochemical characteristics as well as the acquired phage resistance of these strains were investigated. In the phylogenetic analyses, all phage-resistant strains were identical to the original parent strain based on the sequence comparison of 16S rRNA genes. When various phage-resistant strains were examined by three different methods, pitting test, white line test, and hemolytic activity, they were divided into three groups: strains showing all positive results in three tests, two positive in the first two tests, and all negative. Nevertheless, all phage-resistant strains showed that their pathogenic activities were reduced or completely lost.

• Korean Journal of Environmental Biology
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• v.29 no.4
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• pp.286-295
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• 2011

Bacteria resistant to various antibiotics have recently become an issue of the utmost importance. Resistant strains are not uncommon, even in municipal drinking water sources. The health threat posed by resistant, pathogenic bacteria has serious ramifications for both public health and agriculture. In this study, we isolated antibiotic resistant bacteria from water samples from the Han River, Korea, which is contaminated by the wastewater from many industrial complexes, hospitals, agricultural and animal husbandry estates, and from wastewater treatment facilities. We determined the degrees of resistance to various antibiotics exhibited by the isolated strains. The similarities between the isolated $E.$ $coli$ strains were examined, using the pulsed field gel electrophoresis and multilocus sequence typing, in order to trace their origins and to explore the syntechnic adaptations and pathogenicity of the various strains and relate these to their genetic sequence. A total of 25 $E.$ $coli$ strains were isolated from six stations along the Han River. All the 25 strains exhibited resistance to ampicillin. We also investigated resistance to amoxicillin, clavulanic acid, cefazolin, cofoxitin, cefotaxime, cefpodoxime, ceftriaxone, cefepime, nalidixic acid, aztreonam, ciprofloxacin, streptomycin, gentamicin, chloramphenicol and imipenem. Based on the ESBL detection, 14 strains belonged to the ESBL producing strains. The number of the clonal complex producing strains was 5 among the 14 isolated strains. The 5 strains were included in the 168, 23, 38, 469, 156 clonal complex, respectively. The rest 9 strains were not included in the clonal complex, but showed independent STs.

• Korean Journal of Veterinary Research
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• v.17 no.1
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• pp.5-8
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• 1977

One hundred and fifty seven Escherichia coli strains isolated from 18 cattle (9 dairy cattle received penicillin, streptomycin (SM) or sulfadimethoxine for treatment of diseases and 9 Korean native cattle not received antibiotics) were studied for the drug resistance and distribution of R factors. Of 88 E. coli strains isolated from cattle not received antibiotics, only 1 strain was resistant to SM, but about 46 per cent of 69 E. coli strains isolated from cattle received antibiotics were resistant to SM, tetracycline (TC), ampicillin (AP), kanamycin (KM), chloramphenicol (CM), and sulfisomidine (Su), alone or in combination thereof. Of resistant strains, about 72% were resistant to three or more antibiotics, but 28% were found to singly resistant. The most frequent resistant pattern was triple resistance to AP, KM and Su (37.6%), and quadruple one to SM, TC, CM and Su (12.5%). About 28% of resistant strains carried R factors which were transferable to E. coli ML 1410 $NA^r$ by conjugation.

• Journal of Microbiology and Biotechnology
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• v.26 no.12
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• pp.2043-2050
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• 2016

Exploring novel antibiotics is necessary for multidrug-resistant pathogenic bacteria. Because the probiotics in soybean food have antimicrobial activities, we investigated their effects on multidrug-resistant Acinetobacter baumannii. Nineteen multidrug-resistant A. baumannii strains were clinically isolated as an experimental group and 11 multidrug-sensitive strains as controls. The growth rates of all bacteria were determined by using the analysis for xCELLigence Real-Time Cell. The combination of antibiotics showed synergistic effects on the strains in the control group but no effect on the strains in the experimental group. Efflux pump gene adeS was absent in all the strains from the control group, whereas it exists in all the strains from the experimental group. Furthermore, all the strains lost multidrug resistance when an adeS inhibitor was used. One strain of probiotics isolated from soybean food showed high antimicrobial activity for multidrug-resistant A. baumannii. The isolated strain belongs to Bacillus subtilis according to 16S RNA analysis. Furthermore, E. coli showed multidrug resistance when it was transformed with the adeS gene from A. baumannii whereas the resistant bacteria could be inhibited completely by isolated Bacillus subtilis. Thus, probiotics from soybean food provide potential antibiotics against multidrug-resistant pathogenic bacteria.