• 한국동물위생학회지
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• 제40권3호
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• pp.193-200
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• 2017

This study was carried out to investigate the antimicrobial resistance profiles and resistance genes in 62 Escherichia coli isolated from dogs and cats hospitalized at animal hospitals in Daegu. E. coli isolates showed high resistance to nalidixic acid (46.8%) and ampicillin (45.2%). Resistance to the other antimicrobial agents was less than 30%, and no resistant isolates were detected for imipenem and amikacin. Of the 28 ampicillin-resistant isolates, TEM and CTX-M genes were detected in 16 (57.1%) and 11 (39.3%), respectively. The aadA gene was found in 4 (26.7%) of 15 gentamicin-resistant isolates, and strA-strB gene was found in 10 (66.7%) isolates. The sul I and sul II genes were detected in 11 (61.1%) and 14 (77.8%) of 18 trimethoprim/sulfamethoxazole-resistant isolates, and tetB gene in 9 (81.8%) of 11 minocycline-resistant isolates, and cmlA gene in 2 (22.2%) of 8 chloramphenicol-resistant isolates. The qnrB and qnrS genes were found in 3 (10.3%) and 1 (3.4%) of 28 nalidixic acid-resistant isolates, respectively. Whereas, none of the SHV, CMY-2, tetA, dfr Ia and dfr VII, and qnrA genes were found. Our results show a wide variety of resistance genes in E. coli isolates from dogs and cats. This study also represents the first report of qnrB and qnrS gene producing E. coli isolates from dogs in republic of Korea.

• 상하수도학회지
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• 제30권1호
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• pp.1-8
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• 2016

Temperature correction trans-membrane pressure (TC-TMP) is frequently used as a fouling index in membrane water treatment plants. TC-TMP equation is derived based on an assumption that the total membrane resistance (i.e. the sum of the intrinsic membrane resistance and fouling resistance) is not affected by temperature. This work verified the validity of this assumption using microfiltration (MF) and ultrafiltration (UF) membranes with and without fouling. The foulants used in the work were kaolin (inorganic) and humic acid (organic). The intrinsic resistances of MF and UF membranes remains at constant values regardless of temperature change. When the same amount of foulants were accumulated on the membrane, inorganic fouling resistance with kaolin was constant regardless of temperature change while organic fouling resistance with humic acid decreased at higher temperatures, which means that TC-TMP cannot be used as a fouling index when organic fouling occurs in a real field application. Since TC-TMP underestimates the amount of fouling at higher temperatures, more attention should be necessary in the operation of membrane water treatment plant in a hotter season like summer.

• Journal of Microbiology and Biotechnology
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• 제20권12호
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• pp.1764-1768
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• 2010

In this study, the prevalence of antibiotic resistance was examined among 74 Staphylococcus pseudintermedius strains recently isolated from clinical cases of canine pyoderma and otitis externa at the veterinary teaching hospital at Konkuk University, Korea. Bacterial resistance to the nine commonly used antibiotics was evaluated by a standard disk diffusion technique based on the guidelines of the Clinical and Laboratory Standards Institute. The results demonstrated that most S. pseudintermedius isolates were resistant to penicillin (95.9%) or tetracycline (91.9%), but highly susceptible to amoxicillin/clavulanic acid (90.5%). Among the 74 isolates, 13 mecA-positive and methicillin-resistant S. pseudintermedius (MRSP) strains were identified, displaying a high level of resistance (84.6-100%) to each of the individual antibiotics evaluated, with the exception of amoxicillin/clavulanic acid (46.2% resistance). Notably, all of the MRSP isolates exhibited simultaneous resistance to four or more different antibiotics, indicating that they are multiple drug resistant (MDR) strains. Taken together, these results imply that more careful selection or prescription of antibiotics for canine pyoderma and otitis externa should be required for reducing the emergence and/or spread of MDR strains, especially MDR-MRSP isolates, in veterinary pet clinics in Korea.

• The Plant Pathology Journal
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• 제38권6호
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• pp.629-636
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• 2022

Colletotrichum species is known as the major causal pathogen of red pepper anthracnose in Korea and various groups of fungicides are registered for the management of the disease. However, the consistent use of fungicides has resulted in the development of resistance in many red pepper-growing areas of Korea. Effective management of the occurrence of fungicide resistance depends on constant monitoring and early detection. Thus, in this study, various methods such as agar dilution method (ADM), gene sequencing, allele-specific polymerase chain reaction (PCR), and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) were applied for the detection of benzimidazole resistance among 24 isolates of Colletotrichum acutatum s. lat. and Colletotrichum gloeosporioides s. lat. The result of the ADM showed that C. gloeosporioides s. lat. was classified into sensitive and resistant isolates to benomyl while C. acutatum s. lat. was insensitive at ≥1 ㎍/ml of benomyl. The sequence analysis of the β-tubulin gene showed the presence of a single nucleotide mutation at the 198th amino acid position of five isolates (16CACY14, 16CAYY19, 15HN5, 15KJ1, and 16CAYY7) of C. gloeosporioides s. lat. Allele-specific PCR and PCR-RFLP were used to detect point mutation at 198th amino acid position and this was done within a day unlike ADM which usually takes more than one week and thus saving time and resources that are essential in the fungicide resistance management in the field. Therefore, the molecular techniques established in this study can warrant early detection of benzimidazole fungicide resistance for the adoption of management strategies that can prevent yield losses among farmers.

• Bulletin of the Korean Chemical Society
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• 제11권5호
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• pp.403-406
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• 1990

Two types of new silica catalysts modified with benzenesulfonic acid derivatives were prepared by esterification or phenylation followed by sulfonation. Both catalysts thus prepared were tested as acid catalysts for 2-propanol dehydration and cumene dealkylation reactions. B catalyst () were more active than A catalyst (). Highter catalytic activity for B catalyst may be accounted for by higher resistance to water, higher acid strength, more acidity, and better thermal stability as compared with A catalyst.

• Structural Engineering and Mechanics
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• 제64권2호
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• pp.243-257
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• 2017

Investigating the properties and durability of high-strength concrete exposed to sulfuric acid attack for the purpose of its application in structures exposed to this acid is of outmost importance. In this research, the resistance and durability of high-strength concrete containing macro-polymeric or steel fibers together with the pozzolans of silica fume or nano-silica against sulfuric acid attack are explored. To accomplish this goal, in total, 108 high-strength concrete specimens were made with 9 different mix designs containing macro-polymeric and steel fibers at the volume fractions of 0.5, 0.75, and 1.0%, as well as the pozzolans of silica fume and nano-silica with the replacement levels of 10 and 2%, respectively. After placing the specimens inside a 5% sulfuric acid solution in the periods of 7, 21, and 63 days of immersion, the effect of adding the fibers and pozzolans on the compressive properties, ultrasonic pulse velocity (UPV), and weight loss of high-strength concrete was investigated and the respective results were compared with those of the reference specimens. The obtained results suggest the dependency of the resistance and durability loss of high-strength concrete against sulfuric acid attack to the properties of fibers as well as their fraction in concrete volume. Moreover, compared with using nano-silica, using silica fume in the fibrous concrete mix leads to more durable specimens against sulfuric acid attack. Finally, an optimum solution for the design parameters where the crushing load of high-strength fibrous concrete is maximized was found using response surface method (RSM).

• Journal of Applied Biological Chemistry
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• 제44권3호
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• pp.105-112
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• 2001

Insect pests can be controlled through direct application of insecticides. Insect control by residual protectants is relatively inexpensive and has an advantage of destroying all stages of infestations. The efficacy of control is largely determined by the concentration of insecticides to which the pest species is exposed. A reduction in the period of control in the field afforded by a specific level of a protectant indicates that resistance has developed. An increase in the level of protectant is required to maintain control, and the efficacy of currently used insecticides has been severely reduced by insecticide resistance in pest species. Development of resistance to particular insecticide varies with species because insecticide resistance is often correlated with increased levels of certain enzymes, which are cytochrome P450-dependent monooxygenases, glutathione S-transferases and esterases. Some sections of insecticide molecules can be modified by one or more of these primary enzymes. A reduction in the sensitivity of the action site of a xenobiotic also constitutes a mechanism of resistance. Acetylcholinesterase is a major target site for insecticide action, as are axonal sodium ion channels and ${\gamma}$-aminobutyric acid receptors. Development of reduced sensitivity of these target sites to insecticides usually occurs. This review not only may contribute to a better understanding of insecticide resistance, but also illustrates the gaps still present for a full biochemical understanding of the resistance.

• 한국식품영양학회지
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• 제26권1호
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• pp.132-136
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• 2013

Antimicrobial resistance and multi-drug resistance patterns have been carried out on total of 210 isolated of Salmonella spp. and pathogenic E. coli isolated from food poisoning patients on January through December 2012 in Incheon, Korea. The highest percentage of antibiotics resistance was found to the following antimicrobial agents: tetracycline 43.8%, ampicillin 34.8%, nalidixic acid 23.8%, sulfamethoxazole/trimethoprim and chloramphenicol 12.4%, and ampicillin/sulbactam 11.4%. The highest percentage of resistance was 37.5% to ampicillin for Salmonella spp. and 59.0% to tetracycline for pathogenic E. coli. Overall the multidrug resistance rates of 1 drug was 26.2%, 2 drugs 9.0%, 3 drugs 9.5%, 4 drugs 7.1%, and 5 or more drugs 12.46%. The multi-drug (MDR) strains to four or more antimicrobial agents among the resistant organisms were quite high: 15.9% and 22.1% for Salmonella spp. and pathogenic E. coli, respectively. The study implies that limitation of unnecessary medication use is pertinent in order to maintaining the efficacy of drugs.

• 한국동물위생학회지
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• 제32권1호
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• pp.93-102
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• 2009

In this study, antimicrobial resistance of E. coli isolated from domestic beef on sale in Busan and Gyeongnam province was investigated from March to October 2008. A total of 400 beef samples were collected for the monitoring of antimicrobial resistance, and 39 (9.8%) strains of E. coli were isolated. Antimicrobial resistance test was carried out by agar disc diffusion method with 17 antimicrobials. In general, E. coli isolates showed the highest antimicrobial resistance to tetracycline (85.3%), followed by doxycycline (76.5%), streptomycin (61.8%) and sulfamethoxazole/trimethoprim (61.8%). Then they showed higher resistance to several antimicrobials like kanamycin and neomycin (55.9%). However, They had low antimicrobial resistance to amikacin (8.8%), amoxicillin/clavulanic acid (2.9%). Of 39 isolates, 31 (79.5%) were resistant to more than 2 antimicrobials. Among 17 antimicrobials examined, tetracyclines were the most resistant, followed by aminoglycosides, sulfonamides. The resistance was seemed to be correlated to amounts of antimicrobial use. In the result of this study, we suggest that there be need to regulate the abuse of antimicrobial on food-producing animals in Korea because the concern on antimicrobial resistant is gradually increased worldwide.

• 한국미생물·생명공학회지
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• 제23권5호
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• pp.556-558
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• 1995

A strain which showed cephalosporin C resistance and 7-aminocephalosporanic acid sensitivity was isolated from nature. Among the isolates, SS5 was sensitive to cephalosporin C, penicillin G, ampicillin, 7-aminocephalosporanic acid, 6-aminopenicillanic acid, and 7-aminodeacetoxy cephatosporanic acid at concentrations of 1,000 $\mu $g/ml, 2,000 $\mu $g/ml, 3,000 $\mu $g/ml, 30 $\mu $g/ml 100 $\mu $g/ml and 100 $\mu $g/ml, respectively. But SS5 was sensitive at very low concentration of chloramphenicol, kanamycin, neomycin, streptomycin and tetracycline. Since SS5 was sensitive to 7-ACA (30 $\mu $g/ml) and didn't have $\beta $-lactamase activity on the cephalosporin C, SS5 could be useful as an indicator strain for the production of 7-ACA, which is an important precursor for the synthesis of many semisynthetic cephalosporins.