• Journal of Microbiology
• /
• v.43 no.2
• /
• pp.172-178
• /
• 2005

To determine the prevalence and genotypes of $\beta$-lactamases among clones of a metagenomic library from the cold-seep sediments of Edison seamount (10,000 years old), we performed pulse-field gel electrophoresis, antibiotic susceptibility testing, pI determination, and DNA sequencing analysis. Among the 8,823 clones of the library, thirty clones produced $\beta$-lactamases and had high levels of genetic diversity. Consistent with minimum inhibitory concentration patterns, we found that five ($167\%$) of thirty clones produced an extended-spectrum $\beta$-lactamase. 837- and 259-bp fragments specific to bla$_{TEM}$ genes were amplified, as determined by banding patterns of PCR amplification with designed primers. TEM­1 was the most prevalent $\beta$-lactamase and conferred resistance to ampicillin, piperacillin, and cephalothin. TEM-116 had a spectrum that was extended to ceftazidime, cefotaxime, and aztreonam. The resistance levels conferred by the pre-antibiotic era alleles of TEM-type $\beta$-lactamases were essentially the same as the resistance levels conferred by the TEM-type alleles which had been isolated from clinically resistant strains of bacteria of the antibiotic era. Our first report on TEM-type $\beta$-lactamases of the pre-antibiotic era indicates that TEM-type $\beta$-lactamases paint a picture in which most of the diversity of the enzymes may not be the result of recent evolution, but that of ancient evolution.

• International Journal of Oral Biology
• /
• v.39 no.2
• /
• pp.87-95
• /
• 2014

The purpose of this study was to isolate and identify bacteria from the 4 patients with non-odontogenic infectious lesions (mucormycosis, chronic inflammation from wound infection, and two actinomycosis) and determine their antimicrobial susceptibility against eight antibiotics. Bacterial culture was performed under three culture conditions (anaerobic, $CO_2$, and aerobic incubator). The bacterial strains were identified by 16S rRNA gene (16S rDNA) sequence comparison analysis method. For investigating the antimicrobial susceptibility of the bacteria against eight antibiotics, penicillin G, amoxicillin, tetracycline, cefuroxime, erythromycin, clindamycin, vancomycin, and Augmentin$^{(R)}$ (amoxicillin + clavulanic acid), minimum inhibitory concentration (MIC) measurement was performed using broth microdilution assay. Nosocomial pathogens such as Enterococcus faecalis, Klebsiella pneumoniae, Bacillus subtilis, and Neisseria flavescens were isolated from mucormycosis. Veillonella parvula, Enterobacter hormaechei, and Acinetobacter calcoaceticus were isolated from chronic inflammatory lesion. Actinomyces massiliensis was isolated from actinomycosis in parotid gland. Capnocytophaga ochracea was isolated from actinomycosis in buccal region in anaerobic condition. There was no susceptible antibiotic to all bacteria in mucormycosis. Tetracycline was susceptible to all bacteria in chronic inflammation. C. ochracea was resistant to vancomycin and penicillin G; and other antibiotics showed susceptibility to all bacteria in actinomycosis. The results indicated that the combined treatment of two or more antibiotics is better than single antibiotic treatment in mucormycosis, and penicillin is the first recommended antibiotic to treat actinomycosis.

• Journal of fish pathology
• /
• v.37 no.1
• /
• pp.133-138
• /
• 2024

This study is a report on combinational effects between four sesquiterpene lactones (SLs) from bay laurel (Laurus nobilis) leaves, and oxytetracycline (OTC) or amoxicillin (AMX) against four fish pathogenic bacteria such as Vibrio anguillarum, V. harveyi, Edwardsiella tarda, and Streptococcus iniae. Individually, four SLs exerted little antibacterial activity against fish pathogenic bacteria. However, when combined with OTC or AMX, they showed synergistic interaction against pathogenic bacteria. Especailly, zaluzanin C (1) reduced the MIC of OTC (or AMX) eight-fold. Our results showed that combinations of SLs with antibiotics (ABTs) are more effective than ABTs alone to control pathogenic bacteria. The highest synergistic effect was observed when zaluzanin C (1) was combined with OTC or AMX against V. harvey or S. iniae, displaying significant reductions of MICs up to 8-fold (0.125 to 0.015 ㎍/mL and 0.0078 to 0.0009 ㎍/mL). In addition, zaluzanin C (1) improved the antibiotic potency of OTC against OTC resistant V. harveyi (250 ㎍/mL to 62.5 ㎍/mL). Synergism between ABTs and phytochemical such as SLs could be a therapeutically helpful concept to improve the efficacy of ABTs and prevent antibiotic resistance. These results suggest that SLs can be used as an alternative to reduce antibiotic resistance in aquaculture.

• Korean Journal of Veterinary Research
• /
• v.48 no.1
• /
• pp.75-81
• /
• 2008

The rapid evolution of antibiotic resistance in Staphylococcus (S.) aureus is of considerable concern. Methicillin-resistant S. aureus (MRSA) strains are especially one of the greatest public concerns since the treatment of infections is more difficult when encountering resistance. In this study, we conducted a nationwide survey on the antimicrobial resistance of S. aureus isolated from raw meat samples collected from 16 countries, including Korea, and investigated the prevalence of MRSA as a possible source of human infection. Of 1,984 meat samples, S. aureus was isolated from 218 (11.0%) samples consisting of 23 (12.1%) from domestic meat and 195 (10.9%) from imported meat. The isolation rates of poultry meat, pork and beef were 12.8%, 7.0% and 10.0%, respectively. With regard to imported meat, the incidence varied from 4.8% to 16.6% from 13 countries, with the exception of Austria and Poland. In a resistance test to 20 antimicrobial agents, one hundred and eighty-four isolates (84.4%) were resistant to one or more antimicrobial agents tested. Especially, 17 (7.8%), 124 (56.9%) and 28 (12.8%) isolates showed a resistance to 3, 2 and 1 drugs, respectively. One isolate originating from domestic beef was resistant to 7 drugs. Another isolate originating from imported poultry meat showed resistance to oxacillin and methicillin by the disk diffusion test and minimal inhibition concentration methods, but showed negative for detection of the mecA gene.

• Journal of Microbiology
• /
• v.40 no.1
• /
• pp.63-69
• /
• 2002

A total of twenty-five norfloxacin resistant Escherichia coli were isolated from Joongrang-chun stream, a branch of the Han River in Seoul, Korea from May to July in 2000 and their norfloxacin resistance mechanism was characterized for target site mutation, permeability, and efflux pump. Fourteen iso- lates contained the same three mutations, Ser83→Leu and Asp87→Asn in GyrA and Ser90→ lle in ParC. Six isolates had Ser83→Leu and Asp87→Tyr in GyrA and Ser87→lle in ParC while one isolate had Ser83→Leu and Va1103→Ala in GyrA and Ser80→lle in ParC. Two isolates had mutation(s) in GyrA without any mutation in ParC. Two isolates had Ser80→Arg in ParC instead of the commonly found Ser80→lle. Every norfloxacin resistant isolate had an efflux system but the correlation between the efflux activity and MIC was not observed. The amount of OmpF for norfloxacin permeability decreased in resistant isolates compared to the susceptible strains. When amplified polymorphic DNA (RAPD) and pulse field gel electrophoresis (PFGE) were performed, these isolates showed no similarity to each other or clinical isolates.

• KSBB Journal
• /
• v.26 no.6
• /
• pp.543-551
• /
• 2011

Bacterial antibiotic resistance is a real and growing problem for both Gram positive and Gram negative bacterial pathogens in the hospital setting. Among Gram negative bacteria, the ubiquitous bacterium Pseudomonas aeruginosa is a particular concern in immunocompromised and burn patients. The present study evaluated antibacterial activity and efficacy of a Korean herbal medicine against eight multi-drug resistant clinical isolates of P. aeruginosa (0225, 0254, 0347, 0826, 1113, 1378, 1731, and 2492) isolated at Daegu Catholic University Hospital. Methanol extracts of Galla rhois (5 and 10 mg/mL) displayed inhibition diameters for isolate 2492 of 10 and 12 mm, respectively, in a conventional disc diffusion assay. In seven kinds of Korean herbal medicines, increased inhibitory power of Lonicera japonica, Gardenia jasminoides, Galla rhois, and Scultellaria baicalensis was evident with the fermentation of six kinds of lactic acid bacteria. Three lactic acid bacteria (Lactobacillus plantarum subsp. plantarum KCTC 3108, L. casei KCTC 3109, and L. fermentum KCTC 3112) were identified as excellent strains for the production of antibacterial materials. In the six Korean herbal medicine extracts, strong inhibitory activity of fermented Forsythia suspensa, Glycyrrhizae radix, Lycium chinense, Platycodon grum, and Schizandra chinensis with five kinds of lactic acid bacteria was evident for seven multi-drug resistant P. aeruginosa isolates.

• Clinical and Experimental Pediatrics
• /
• v.59 no.2
• /
• pp.96-99
• /
• 2016

Survival rates of preterm infants have improved in the past few decades, and central venous catheters play an important role in the intensive medical treatment of these neonates. Unfortunately, these indwelling catheters increase the risk of intracardiac thrombosis, and they provide a nidus for microorganisms during the course of septicemia. Herein, we report a case of persistent bacteremia due to methicillin-resistant Staphylococcus aureus in an extremely low birth weight (ELBW) infant, along with vegetation observed on an echocardiogram, the findings which are compatible with a diagnosis of endocarditis. The endocarditis was successfully treated with antibiotic therapy, and the patient recovered without major complications. We suggest a surveillance echocardiogram for ELBW infants within a few days of birth, with regular follow-up studies when clinical signs of sepsis are observed.

• Microbiology and Biotechnology Letters
• /
• v.13 no.2
• /
• pp.103-107
• /
• 1985

A variety of plasmid curing agents such as sodium dodecyl sulfate, acriflavine, ethidium bromide, and mitomycin-C were used to cure Bacillus subtilis cells of streptomycin resistant factor. The drug susceptibility was increased by 0.1％ sodim dodecyl sulfate at stationary growth phase. The curing frequency was obtained highly at 4 $\mu\textrm{g}$/$m\ell$ of acriflavine, 10 $\mu\textrm{g}$/$m\ell$ of ethidium bromide, and 200 $\mu\textrm{g}$/$m\ell$ of mitomycin-C. respectively. Curing action occurred competitively for the streptomycin and terramycin resistant factors in B. subtilis.

• International Journal of Oral Biology
• /
• v.38 no.2
• /
• pp.61-65
• /
• 2013

Erythromycin is a macrolide antibiotic and inhibits bacterial protein synthesis by stimulating the dissociation of the peptidyl-tRNA molecule from the ribosomes during elongation. The use of macrolides has increased dramatically over the last few years and has led to an increase in bacterial resistance to these antibiotics. Bacterial resistance to erythromycin is generally conferred by the ribosome methylation and/or transport (efflux) protein genes. Among the identified erythromycin-resistant genes, erm(B) (erythromycin methylation) and mef(A) (macrolide efflux) are generally detectable in erythromycin-resistant streptococcal species. The distribution of these genes in oral streptococcal isolates has been reported in studies from other countries but has not been previously examined in a Korean study. We here examined by PCR the presence of erm(B) and mef(A) in oral streptococci isolated from Korean dental plaques. Among the 57 erythromycin-resistant strains tested, 64.9% harbored erm(B) whereas 40.4% were positive for mef(A). Eleven isolates had both the erm(B) and mef(A) genes. Twenty six isolates had only erm(B) and 12 isolates had only mef(A). Eight of the 57 strains examined were negative for both genes.

• Microbiology and Biotechnology Letters
• /
• v.42 no.2
• /
• pp.152-161
• /
• 2014

The in vitro antimicrobial potential of the unexplored Moringa oleifera seed coat (SC) was evaluated against some Gram-positive and Gram-negative bacteria and yeast pathogens. Antimicrobial studies with various solvent extracts indicated ethyl acetate to be the best extractant, which was used for the rest of the antimicrobial studies as it tested neither toxic nor mutagenic. Gram-positive bacteria including a methicillin resistant Staphylococcus aureus (MRSA) strain were more susceptible with a minimum inhibitory concentration (MIC) range of 0.03-0.04 mg/ml. The antimicrobial pharmacodynamics of the extract exhibited both concentration-dependent and time-dependent killing. Most of the test organisms exhibited a short post antibiotic effect (PAE) except Enterococcus faecalis, Staphylococcus aureus, and Klebsiella pneumoniae 1, which exhibited longer PAEs. Amongst the major phytoconstituents established, flavonoids, diterpenes, triterpenes and cardiac glycosides exhibited inhibitory properties against most of the test organisms. The identified active phytochemicals of the M. oleifera seed coat exhibited antimicrobial potential against a wide range of medically important pathogens including the multidrug-resistant bugs. Hence, the M. oleifera seed coat, which is usually regarded as an agri-residue, could be a source of potential candidates for the development of drugs or drug leads of broad spectrum that includes multidrug-resistant bugs, which are one of the greatest concerns of the $21^{st}$ century.