• Title, Summary, Keyword: Antimicrobials

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In vitro combination effects of natural substances and antimicrobials against Edwardsiella tarda and Streptococcus iniae (In vitro에서 Edwardsiella tarda와 Streptococcus iniae에 대한 항균제와 천연 유래 항균물질의 병용효과)

  • Bak, Su-Jin;Kang, Bong-Jo;Park, Kwan Ha
    • Journal of fish pathology
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    • v.28 no.1
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    • pp.17-26
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    • 2015
  • The purpose of this study is to explore the possibility of essential oils and flavonoids improving the performance of antibiotics, proving a higher efficacy in the presence of natural substances against Edwardsiella tarda and Streptococcus iniae. Increased efficacy was observed in several cases: both essential oils and flavonoids increased antibacterial efficacy of oxytetracycline and flumequine against E. tarda by 2-fold; essential oils and flavonoids increased antibacterial efficacy of nalidixic acid against E. tarda by 4-fold; flavonoids increased antibacterial efficacy of josamycin against S. iniae by 4-fold. The results obtained in this study suggest that essential oils and flavonoids might be especially useful in increasing the antimicrobial activity of nalidixic acid and josamycin against E. tarda and S. iniae in fish. Natural compounds examined in this study could also be useful to help decrease the overuse of antibiotics in fish.

Antimicrobial Resistance and Virulence Genes Presence in Escherichia coli Strains Isolated from Gomso Bay, Korea

  • Park, Kwon-Sam
    • Fisheries and aquatic sciences
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    • v.16 no.4
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    • pp.221-227
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    • 2013
  • In total, 131 Escherichia coli isolates from surface seawater of the Gomso Bay, of Korea, were analyzed for their susceptibility to 22 different antimicrobials and for genes associated with antimicrobial resistance and virulence. According to the disk diffusion susceptibility test, the resistance to tetracycline was most prevalent (33.6%), followed by that to ampicillin (22.1%), ticarcillin (22.1%), and trimethoprim (16.8%). More than 46.6% of the isolates were resistant to at least one antimicrobial, and 22.9% were resistant to three or more classes of antimicrobials; these were consequently defined as multidrug resistant. We further found that 29 ampicillin-resistant isolates possessed genes encoding TEM-type (93.1%) and SHV-type (6.9%) ${\beta}$-lactamases. Among the 44 tetracycline-resistant isolates, tetA and tetC were found in 35 (79.5%) and 19 (43.2%), respectively, whereas tetB was detected in only three isolates (6.8%). With regard to virulence genes, merely 0.8% (n = 1) and 2.3% (n = 3) of the isolates were positive for the enteroaggregative E. coli-associated plasmid (pCVD432) gene and the enteropathogenic E. coli-specific attaching and effacing (eae) gene, respectively. Overall, these results not only provide novel insight into the necessity for seawater sanitation in Gomso Bay, but they help reduce the risk of contamination of antimicrobial-resistant bacteria.

Methicillin-resistant or susceptible Staphylococcus pseudintermedius isolates from dogs and cats (개와 고양이에서 분리한 methicillin 내성 및 감수성 Staphylococcus pseudintermedius)

  • Cho, Jae-Keun;Lee, Mi-Ree;Kim, Jeong-Mi;Kim, Hwan-Deuk
    • Korean Journal of Veterinary Service
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    • v.39 no.3
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    • pp.175-181
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    • 2016
  • Staphylococcus pseudintermedius is an important opportunistic pathogen of dog and cats. Since 2006 there has been a significant emergence of methicillin-resistant S. pseudintermedius (MRSP) mainly due to clonal spread. The aim of this study was to investigated the prevalence of antibiotic resistance and presence of mecA and femA gene in 91 S. pseudintermedius isolates isolated from dogs and cats associated with various clinic infections. Methicillin resistance was confirmed by oxacillin disc diffusion method. MRSP isolate was detected 19 isolates (20.9%). MRSP and methicillin-resistant S. pseudintermedius (MSSP) isolates were highly resistant to penicillin, kanamycin, tetracycline, erythromycin, trimethoprim-sulfamethoxazole, clindamycin, ciprofloxacin, enrofloxacin and choloramphenicol (100~47.3% and 90.3~33.3%, respectively). About 90% of MRSP isolates were multi-drug resistance (resistance to at least five or more antimicrobials), and MSSP isolates was ca 74%. Among the 91 isolates, mecA gene was detected in 25 isolates (27.5%, 19 in MRSP isolates and 6 in MSSP isolates), but none carried the femA gene. Our results indicated MRSA isolates show a strong resistance to antimicrobials commonly used in veterinary medicine. A continuous surveillance and monitoring should be called for to prevent the contamination and spread of MRSP in dogs and cats.

Prevalence of enterovirulent Escherichia coli from diarrhea of cattles in Jeonbuk, Korea (전북지역 소 설사유래 병원성대장균 감염실태 조사)

  • Jeong, Hansol;Baek, Kui-Jeong;Koh, Won-Seok;Lee, Jeong-Won;Jeong, Jae-Kyo
    • Korean Journal of Veterinary Service
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    • v.43 no.2
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    • pp.53-58
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    • 2020
  • Enterovirulent Escherichia coli are among the most important causes of diarrhea in cattles. Between January and December, 2017, a total of 150 stool specimens from cattles were investigated for enterohaemorrhagic E. coli (EHEC), enteropathogenic E. coli (EPEC), enteroaggregative E. coli (EAEC), enterotoxigenic E. coli (ETEC) and enteroinvasive E. coli (EIEC) using real-time PCR. 131 E. coli were isolated from feces. The most frequently isolated pathotype in feces was EHEC (37 isolates). EPEC, ETEC and EAEC were detected in feces with 14, 7 and 3 respectively. EIEC was not detected. Antimicrobial resistance test was performed by agar disc diffusion method with 14 antimicrobials. Enterovirulent E. coli isolates showed the highest antimicrobial resistance to ampicillin 61.3%, followed by tetracycline 54.5% and streptomycin 45.5%. They had low resistance to amikacin 11.4%. Of 44 isolates, 37 (84.1%) were resistant to more than 2 antimicrobials. futher study a highest antimicrobial susceptibility to trimethoprim/sulfamethoxazole 50.0% and florofenicol 47.7%.

Generation of Hybrid Polyketides through Combinatorial Biosynthesis of Polyketide Synthase (PKS) and Modification of Post-PKS Tailoring Steps

  • Yoon, Yeo-Joon
    • Proceedings of the PSK Conference
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    • pp.75-78
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    • 2003
  • Polyketides are a class of structurally diverse natural products which possess a wide range of biological activities. These compounds are used throughout medicine and agriculture as antimicrobials, immunosuppressants, antiparasitics, and anticancer agents. While structurally diverse, polyketides are assembled by a common mechanism of decarboxylative condensations of simple malonate derivatives by polyketide synthases (PKSs) in a manner very similar to fatty acid biosynthesis (Fig 1). (omitted)

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Occurrence and antibiotic resistance of Enterococcus spp. from retail fresh-cut products in Korea (국내 신선 편이식품으로부터 분리한 Enterococcus의 항생제 저항성)

  • Kim, Hyun Jung;Kim, Seung Min
    • Korean Journal of Food Science and Technology
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    • v.50 no.6
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    • pp.581-586
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    • 2018
  • Enterococcus spp. have been considered major indicator organisms for antibiotic resistance due to their ability to easily acquire and to harbor antibiotic resistance. In this study, Enterococcus spp. were isolated from 174 retail fresh-cut products (fresh vegetable salads, microgreens, and sprouts) in Korea. Among the 20 Enterococcus isolates obtained, 18 (90.0%) were Enterococcus faecalis and 2 (10.0%) were Enterococcus faecium. The patterns of antibiotic resistance against nine antimicrobials were analyzed. Most of the isolates (85.0%) were resistant to quinupristin/dalfopristin, 40.0% and 50.0% of the isolates showed intermediate resistance to two critically important antimicrobials for human medicine, ciprofloxacin and erythromycin, respectively. Vancomycin-resistant enterococci were not detected in this study. Given the importance of antimicrobial resistance of enterococci in food safety as well as in public health, our results regarding the occurrence (level of contamination) and antimicrobial resistance of Enterococcus spp. could provide useful information that aids the risk analysis of antibiotic resistance.

Inducible spy Transcription Acts as a Sensor for Envelope Stress of Salmonella typhimurium

  • Jeong, Seon Mi;Lee, Hwa Jeong;Park, Yoon Mee;Kim, Jin Seok;Lee, Sang Dae;Bang, Iel Soo
    • Food Science of Animal Resources
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    • v.37 no.1
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    • pp.134-138
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    • 2017
  • Salmonella enterica infects a broad range of host animals, and zoonostic infection threatens both public health and the livestock and meat processing industries. Many antimicrobials have been developed to target Salmonella envelope that performs essential bacterial functions; however, there are very few analytical methods that can be used to validate the efficacy of these antimicrobials. In this study, to develop a potential biosensor for Salmonella envelope stress, we examined the transcription of the S. enterica serovar typhimurium spy gene, the ortholog of which in Escherichia coli encodes Spy (${\underline{s}}pheroplast$ ${\underline{p}}rotein$ ${\underline{y}}$). Spy is a chaperone protein expressed and localized in the periplasm of E. coli during spheroplast formation, or by exposure to protein denaturing conditions. spy expression in S. typhimurium was examined by constructing a spy-gfp transcriptional fusion. S. typhimurium spy transcription was strongly induced during spheroplast formation, and also when exposed to membrane-disrupting agents, including ethanol and the antimicrobial peptide polymyxin B. Moreover, spy induction required the activity of regulator proteins BaeR and CpxR, which are part of the major envelope stress response systems BaeS/BaeR and CpxA/CpxR, respectively. Results suggest that monitoring spy transcription may be useful to determine whether a molecule particularly cause envelope stress in Salmonella.

Assessment of Bacterial Contamination and Antibiotic Resistance Patterns in Ready-To-Eat Side Dishes in Seoul Area, 2007 (2007년 서울 지역에서 판매되고 있는 반찬류의 세균 오염과 항생제 내성실태)

  • Kim, Mi-Jin;Lee, Do-Kyung;Jang, Seok;Yang, Hwan-Jin;An, Hyang-Mi;Baek, Eun-Hye;Ha, Nam-Joo
    • YAKHAK HOEJI
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    • v.52 no.6
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    • pp.434-440
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    • 2008
  • The purpose of this research was to investigate the microbiological quality and antimicrobial susceptibilities of the ready-to-eat side dishes, which are were collected from the grocery stores, big markets, and department stores in Seoul throughout November, 2007. Of total 124 samples, presence of staphylococci and enteric bacilli was observed in 38 samples (31%) and 53 samples (43%), respectively. And 30 samples (24%) were shown to be of unsatisfactory quality for total bacterial count (>$10^5$). Antimicrobial susceptibilities of the staphylococci isolated from the side dishes were tested for six different antimicrobial agents, which are in widespread clinical use in Korea, as well as four new antimicrobials, daptomycin, linezolid, quinupristin/dalfopristin and tigecycline. As a result, the staphylococcal isolates were found to be resistant to oxacillin (${MIC}_{90}$, >128 ${\mu}g$/ml), teicoplanin (${MIC}_{90}$, >128 ${\mu}g$/ml), mupirocin (${MIC}_{90}$, >128 ${\mu}g$/ml), linezolid (${MIC}_{90}$, 128 ${\mu}g$/ ml) and quinupristin/dalfopristin (${MIC}_{90}$, 32 ${\mu}g$/ml). Especially, some of the staphylococcal isolates exhibited high level and multi-drug resistance. Moreover, these bacteria were also resistant to new antimicrobials, except tigecycline.

Antimicrobial Activity of Mupirocin, Daptomycin, Linezolid, Quinupristin/Dalfopristin and Tigecycline against Vancomycin-Resistant Enterococci (VRE) from Clinical Isolates in Korea (1998 and 2005)

  • Lee, Do-Kyung;Kim, Yu-Na;Park, Kun-Sup;Yang, Jae-Wook;Kim, Kyung-Jae;Ha, Nam-Joo
    • BMB Reports
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    • v.40 no.6
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    • pp.881-887
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    • 2007
  • It is a hot clinical issue whether newly approved antimicrobial agents such as daptomycin, linezolid, quinupristin/dalfopristin (synercid) and tigecycline are active enough to be used for infections caused by vancomycin resistant bacteria. We performed susceptibility tests for mupirocin, which is in widespread clinical use in Korea, and four new antimicrobials, daptomycin, linezolid, quinupristin/dalfopristin and tigecycline, against vancomycin-resistant Enterococcus faecalis and Enterococcus faecium isolated from Korean patients in 1998 and 2005 to evaluate and compare the in vitro activity of these antimicrobials. Among these agents, quinupristin/dalfopristin, which is rarely used in hospitals in Korea, showed relatively high resistance to several vancomycin-resistant enterococci (VRE) isolated in 2005. Likewise, daptomycin, linezolid and tigecycline have not yet been in clinical use in Korea. However, our results showed that most of the 2005 VRE isolates were already resistant to linezolid and daptomycin (highest minimum inhibitory concentration (MIC) value >$100{\mu}g$/ml). Compared with the other four antimicrobial agents tested in this study, tigecycline generally showed the greatest activity against VRE. However, four strains of 2005 isolates exhibited resistance against tigecycline (MIC >$12.5{\mu}g$/ml). Almost all VRE were resistant to mupirocin, whereas all E. faecium isolated in 1998 were inhibited at concentrations between $0.8\sim1.6{\mu}g$/ml. In conclusion, resistances to these new antimicrobial agents were exhibited in most of VRE strains even though these new antibiotics have been rarely used in Korean hospitals.

Antimicrobial resistance and distribution of resistance gene in Enterobacteriaceae and Pseudomonas aeruginosa isolated from dogs and cats (개와 고양이에서 분리된 Enterobacteriaceae와 Pseudomonas aeruginosa의 항균제 내성 및 내성 유전자의 분포)

  • Cho, Jae-Keun;Kim, Jin-Hyun;Kim, Jeong-Mi;Park, Choi-Kyu;Kim, Ki-Seuk
    • Korean Journal of Veterinary Service
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    • v.36 no.3
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    • pp.171-180
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    • 2013
  • This study was carried out to investigate the antimicrobial resistance pattern and distribution of resistance gene in 44 Enterobacteriaceae and 21 Pseudomonas (P) aeruginosa isolated from hospitalized dogs and cats in animal hospital from 2010 to 2011 in Daegu. Among Enterobacteriaceae, Escherichia (E) coli was highly resistant to ampicillin (56.7%), followed by tetracycline (53.3%), cephalothin, streptomycine, sulfamethoxazole/trimethoprim, gentamicin and norfloxacin (40.0~43.3%). The remaining isolates of Enterobacteriaceae had high resistance to ampicillin (64.3%) and streptomycin (42.9%). Whereas, P. aeruginosa was low resistant to all antimicrobials tested (less than 15%). int I 1 gene was detected in 20 (57.1%) of 35 antimicrobial resistant Enterobacteriaceae and 2 (9.5%) of 21 P. aeruginosa., but int I 2 gene was not detected in all isolates. The eight resistance genes were found either alone or combination with other gene (s): $bla_{TEM}$, aadA, strA-strB, clmA, tetA, tetB, sul I and sul II. About 78% of integron-positive isolates were resistance to more than four antimicrobial agents. The findings suggest that class I integrons are widely distributed in E. coli among Enterobacteriaceae from dogs and cats and multi-drug resistance related to the presence of class I integrons. The prudent use of antimicrobials and continuous monitoring for companion animals are required.