• Journal of Microbiology and Biotechnology
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• v.20 no.12
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• pp.1672-1676
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• 2010

The Actinomycete strain KH29 is antagonistic to the multidrug-resistant Acinetobacter baumannii. Based on the diaminopimelic acid (DAP) type, and the morphological and physiological characteristics observed through the use of scanning electron microscopy (SEM), KH29 was confirmed as belonging to the genus Streptomyces. By way of its noted 16S rDNA nucleotide sequences, KH29 was found to have a relationship with Streptomyces cinnamonensis. The production of an antibiotic from this strain was found to be most favorable when cultured with glucose, polypeptone, and yeast extract (PY) medium for 6 days at $27^{\circ}C$. The antibiotic produced was identified, through comparisons with reported spectral data including MS and NMR as a cyclo(L-tryptophanyl-L-tryptophanyl). Cyclo(L-Trp-L-Trp), from the PY cultures of KH29, was seen to be highly effective against 41 of 49 multidrug-resistant Acinetobacter baumannii. Furthermore, cyclo(L-Trp-L-Trp) had antimicrobial activity against Bacillus subtilis, Micrococcus luteus, Staphylococcus aureus, Saccharomyces cerevisiae, Aspergillus niger, and Candida albicans, However, it was ineffective against Streptomyces murinus.

• Journal of Microbiology and Biotechnology
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• v.10 no.5
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• pp.595-598
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• 2000

Aeromonas hydrophila is a pathogen to fish as well as human. It is a food-borne disease, and causes severe mortality in fish, and sometimes severe septicemia in human. In this study, a rapid detection method using latex agglutination has been developed for A. hydrophila. Polyclonal antibodies were raised against membrane and whole cells of three isolates from rainbow trout. Among these, latex particles coated with antibodies raised against whole cells of isolate No. 2 showed the best sensitivity. With latex particles coated with this antibody, we could detect $5{\times}10^4$ CFU of A. hydrophila in 5 min. The cross-reactivity with bacteria constituting the normal intestinal microflora and other pathogens for rainbow trout was insignificant. This latex agglutination assay method produced positive reaction with all clinical isolates of A. hydrophila which were identified by species-specific PCR for 16S rRNA in A. hydrophila.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.45 no.6
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• pp.324-331
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• 2019

Objectives: This study investigated the types and antibiotic sensitivity of bacteria in odontogenic abscesses. Materials and Methods: Pus specimens from 1,772 patients were collected from affected areas during incision and drainage, and bacterial cultures and antibiotic sensitivity tests were performed. The number of antibiotic-resistant bacteria was analyzed relative to the total number of bacteria that were tested for antibiotic susceptibility. Results: Bacterial cultures from 1,772 patients showed a total of 2,489 bacterial species, 2,101 gram-positive and 388 gram-negative. For penicillin G susceptibility tests, 2 out of 31 Staphylococcus aureus strains tested showed sensitivity and 29 showed resistance. For ampicillin susceptibility tests, all 11 S. aureus strains tested showed resistance. In ampicillin susceptibility tests, 46 out of 50 Klebsiella pneumoniae subsp. pneumoniae strains tested showed resistance. Conclusion: When treating odontogenic maxillofacial abscesses, it is appropriate to use antibiotics other than penicillin G and ampicillin as the first-line treatment.

• Biomedical Science Letters
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• v.11 no.4
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• pp.525-531
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• 2005

Staphylococcus aureus is a major cause of nosocomial infections and is one of the most commonly isolated bacterial species in the hospital and continues to be an important pathogen in both community and hospital-acquired infection. Methicillin resistant S. aureus (MRSA), which is associated with hospitals is now being isolated in the community. The purpose of this study is to investigate the carrier rate of S. aureus in the community, antibiotic resistance patterns of the organism, detection of MRSA and mecA gene in MRSA. Ninety strains $(46.4\%)$ of S. aureus were isolated from the nasal specimens of 194 elementary school students. Eighty-nine strains $(98.9\%)$ of 90 S. aureus were resistant to penicilin, 36 strains $(40.0\%)$ to erythromycin, 14 strains $(15.6\%)$ to fusidic acid, 11 strains $(12.2\%)$ to gentamycin, 9 strains $(10.0\%)$ to tobramycin, 5 strains $(5.6\%)$ to oxacillin, 4 strains $(4.4\%)$ to clindamycin, 2 strains $(2.2\%)$ to tetracycline, 1 strains $(1.1\%)$ to fosfomycin. None of $90(0\%)$ S. aureus isolates was resistant to ciprpfloxacin, trimethoprim/sulfamethoxazole, levofloxacin, linezolid, moxifloxacin, nitrofurantoin, norfloxacin, rifampicin, quinupristin/dalfopristin, teicoplanin, and vancomycin. Five strains $(5.6\%)$ of 90 S. aureus isolates were MRSA. The mecA gene was detected from five MRSA strains by PCR.

• Journal of Microbiology and Biotechnology
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• v.19 no.2
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• pp.204-207
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• 2009

We investigated novel antibacterial and synergistic activities of isocryptomerin isolated from Selaginella tamariscina. Isocryptomerin showed potent antibacterial activity against Gram-positive and Gram-negative bacterial strains including clinical isolates of antibiotic-resistant species such as methicillin-resistant Staphylococcus aureus(MRSA). Additionally, we further investigated the synergistic activity of isocryptomerin with a conventional antibiotic against MRSA. The result indicated that isocryptomerin had considerable synergistic activity in combination with cefotaxime. In summary, the present study suggests that isocryptomerin may have potential as a novel therapeutic agent for treatment of infectious diseases by not only human pathogenic bacteria but also multidrug-resistant bacteria.

• Korean Journal of Veterinary Service
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• v.15 no.2
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• pp.134-143
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• 1992

The present study was conducted to investigate the biochemical characteristics and anti-biotic resistance of Escherichia coli(E. coli) isolated from piglets with diarrhea in Kyongbuk province during the Period from February to November 1991. 368 E. coli strains were isolated from 382 piglets with diarrhea and the biochemical and cultural reaction were compared with the classification criteria of Edwards and Ewing. Tetracycline and sulfadimethoxine were found to be highly ineffective at in vitro inhibition of the E. coli of piglets origin. The majority of E. coli were susceptible to amikacin, chloramphenicol and gentamicine. 89 (89.0%) of 100 strains of E. coil were resistant to one or more drugs. The organisms resistant to 20 or 3 drugs were 54(60.6%) of 89 strains, whereas 16(17.9%) strains were found to be resistant to one drug. 55(61.8%) out of 89 drug resistance strains carried R factors($R^+$) which were transfer-able to the recipients by conjugation.

• Journal of Korean Biological Nursing Science
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• v.8 no.1
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• pp.5-14
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• 2006

Staphyloccus aureus is one of the most important pathogens in clinical settings. It is also one of the leading causes of nosocomial infections and the dissemination of multiple drug-resistant strains, mainly methicillin resistant Staphyloccus aureus, and the recent emergence of a vancomycin resistant MRSA is the concern to hospital worldwide. MRSA strains have acquired multiple resistance to a wide range of antibiotics, including aminoglycosides and macrolides. $\beta$-Lactam resistance of methicillin-resistnat Staphyococcus aureus is determined by the function of penicillin binding protein 2'(PBP2') encoded by the methicillin resistance gene mec A. MRSA strains carry methicillin resistance gene mecA, encoded by a mobile genetic element designated staphylococoal cassette chromosome mec(SCCmec). MRSA clones are defined by the type of SCCmec element and the genotype of the methicilline-susceptible Staphyococcus aureus chromosome in which the SCCmec element is integrated.

• Genomics & Informatics
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• v.20 no.4
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• pp.47.1-47.13
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• 2022

Klebsiella pneumoniae is a gram-negative bacterium that is known for causing infection in nosocomial settings. As reported by the World Health Organization, carbapenem-resistant Enterobacteriaceae, a category that includes K. pneumoniae, are classified as an urgent threat, and the greatest concern is that these bacterial pathogens may acquire genetic traits that make them resistant towards antibiotics. The last class of antibiotics, carbapenems, are not able to combat these bacterial pathogens, allowing them to clonally expand antibiotic-resistant strains. Most antibiotics target essential pathways of bacterial cells; however, these targets are no longer susceptible to antibiotics. Hence, in our study, we focused on a hypothetical protein in K. pneumoniae that contains a DNA methylation protein domain, suggesting a new potential site as a drug target. DNA methylation regulates the attenuation of bacterial virulence. We integrated computational-aided drug design by using a bioinformatics approach to perform subtractive genomics, virtual screening, and fingerprint similarity search. We identified a new potential drug, koenimbine, which could be a novel antibiotic.

• 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.

• Journal of Food Hygiene and Safety
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• v.17 no.2
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• pp.61-70
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• 2002

In order to investigate the classification and antibiotic resistance of Salmonella species,718 isolates were isolated from patient in Seoul from 1996 to 2001. The two hundred and ninety eight isolates (41.5%) were identified as Sal. Enteritidis, followed by Sal. Typhi 218 isolates (30.4%), and Sal. Typhimurium 87 isolates (12.1%). The identified Salmonella species were most resistant to tetracycline (32.7%), followed by streptomycin (28.0%), ticarcillin (18.1%) and ampicillin (12.4%). Among isolates,34.7% of Sal. Enteritidis were resistant to tetracycline, 32.3% to streptomycin,23.2% to ticarcillin,13.5% to ampicillin, respectively. 13.8% of Sal. Typhi were resistant to streptomycin,10.6% to tetracycline, respectively.66.7% of Sal. Typhimurium were resistant to tetracycline, 42.5% to streptomycin, 28.7% to ticarcillin, 26.4% to ampicillin and 17.2% to chloramphenicol, respectively. Of 718 isolates, 324 isolates (45.1%) were resistant to 1 or more drugs and 64 isolates (19.8%) were resistant to 1 drug, 132 isolates (40.7%) were resistant to 2 drugs,50 isolates (15.4%) were resistant to 3 drugs, 27 isolates (8.3%) to 4 drugs,27 isolates (8.3%) to 5 drugs,22 Isolates (6.8%) to 6 drugs. The most prevalent multiple resistant pattern was tetracycline-kanamycin (35.5%), followed by tetracycline-kanamycin-ticarcillin (8.3%), and tetracycline-kanamycin-ticarcillin-ampicillin (7.4%) . Antibiotic resistant rate of Sal. Typhimurium was 73.6%,1311owe4 by Sal. Enteritidis 53.7% and Sal. Typhi 19.3%. Most Sal. Enteritidis was resistant to 1 drug o.2 drugs, whereas Sal. Typhi. and Sal.. Typhunurium were more .resistant to 5 (16.7%) or 6 drugs (26.6%). The old generation antibiotics such as ampicillin, tetracycline, and streptomycin were annually more resistant than the new generation antibiotics such as ceftriaxone, ciprofloxacin or cefoxitin.