• The Journal of the Korean Society for Microbiology
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• v.16 no.1
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• pp.1-5
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• 1981

Shigella is one of the most prevalent pathogens for the diarrhoeal diseases in the developing countries. One hundered and six strains of shigella were isolated from January 1980 to August 1981 at the dept. of clinical pathology, Han Yang Medical Center. Subgroups of these strains were identified as one strain of S. dysenteriae, 98 strains of S. flexneri and 7 strains of S. sonnei. None of S. boydii was observed. Sex ratio, male to female was 48 to 58. Age distribution disclosed 6 cases under one year, 11 cases one to under 2 years and 21 cases(19.8%) two to under 3 years. Subtotal of 0 to 9 years showed 64 cases(60.4%). Susceptibility for antibiotics of these strains revealed dibekacin 100%, sisomicin 100%, amikacin 98.1%, cefazolin 97.2%, tobramycin 97.1%, gentamicin 95.2%, colistin 93.0%, minocycline 89.6%, kanamycin 83.0%, carbenicillin 18.9%, streptomycin 18.9%, tmp-smz 8.6%, ampicillin 2.8% and chloramphenicol 1.9%. Patterns of resistance to sulfa, streptomycin, chloramphenical and tetracycline have already started at the early part of 1960 decade. Although ampicillin was highly sensitive to shigella at the end of 1960 to the early part of 1970 decade, this study has disclosed high resistance to the strains. New antibiotics such as amikacin, cefazolin, dibekacin, gentamicin, and tobramycin have revealed highly sensitive to these strains, however, multiresistance for those antibiotics will be shown to be prevalent in this country within several years, where it is probably related to the unrestricted sale and use of antibiotics in man.

• Korean Journal of Clinical Laboratory Science
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• v.38 no.3
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• pp.166-172
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• 2006

Metallo-${\beta}$-lactamase (MBL) can hydrolyze all ${\beta}$-lactams except monobactams and frequently coexists with various antibiotic resistance genes such as aminoglycoside resistance, sulfonamide resistance gene, etc. Therefore, the effective antibiotics against infections by these bacteria are markedly limited or can't even be found. We tried to search in-vitro antimicrobial combinations with synergistic effects for a VIM-2 type MBL producing Pseudomonas aeruginosa, isolated from clinical specimen. On the selection of antibiotic combinations with synergistic effects, we performed a one disk synergy test, modified Pestel's method, in agar without aztreonam (AZT). The bacteriostatic synergistic effects of this tests were scored as $S_1$ (by susceptibility pattern in agar without antibiotics), $S_2$ (by the change of susceptibility in agar with or without antibiotics) and $S_3$ ($S_1$ + $S_2$) and was classified into weak (1 point), moderate (2 points) and strong (3 points) by $S_3$ score. Subsequently, we carried out the time-killing curve for the antibiotic combinations with the strong synergistic bacteriostatic effect. One VIM-2 type MBL producing P. aeruginosa confirmed by the PCR showed all resistance against all ${\beta}$-lactams except AZT, aminoglycoside and ciprofloxacin. In the one disk synergy test, this isolate showed a strong bacteriostatic synergistic effect for the antibiotic combination of AZT and piperacillin-tazobactam (PIP-TZP) or AZT and amikacin (AN). On the time-killing curve after six hours of incubation, the colony forming units (CFUs/mL) of this bacteria in the medium broth with both combination antibiotics were decreased to 1/18.7, 1/17.1 of the least CFUs of each single antibiotics. The triple antibiotic combination therapy including AZT, PIP-TZP and AN was shown to be significantly synergistic after 8 hrs of exposure. In a VIM-2 MBL producing P. aeruginosa with susceptibility for AZT, the triple antibiotic combination therapy including AZT, PIP-TZP and AN may be considered as an alternative antibiotics modality against the infection by some MBL type. But the antimicrobial combination therapy for many more MBL producing isolates is essential to know as soon as possible for the selection of effective treatment against the infection by this bacteria.

• Korean Journal of Veterinary Service
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• v.42 no.4
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• pp.301-304
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• 2019

The objective of this study was to determine the in vitro intracellular and extracellular minimum inhibitory concentrations (MICs) of 13 antimicrobials against one recently isolate Lawsonia intracellularis, the etiological agent of proliferative enteropathy (PE). The final MICs were assessed by counting the number of heavily infected cells (HICs;>30 bacteria per cell) using an immunoperoxidase monolayer assay. Enrofloxacin (InMIC; 1~2 ㎍/mL and ExMIC; 16 ㎍/mL) still presented the most notable antimicrobial susceptibility, and marbofloxacin (2 ㎍/mL and 8 ㎍/mL) was followed. Colistin (0.25 ㎍/mL and 2 ㎍/mL) presented a susceptibility followed by tylvalosin (1 ㎍/mL and 2 ㎍/mL). Florfenicol and lincomycin had the weakest susceptibility and amoxicillin, penicillin G, chlortetracycline, oxytetracycline, tiamulin, tilmicosin, and tylosin displayed weak susceptibility. Although some antibiotics showed decreased susceptibility patterns, they showed similar patterns to recent antibiotic susceptibility patterns in Korea. In addition, these results could be one of contributions in clinical fields.

• Journal of Periodontal and Implant Science
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• v.26 no.3
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• pp.625-639
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• 1996

The purpose of this study was to an in estimate the antibiotic susceptibility of P. gingivalis and P. interrnedia isolate from the subgingival plaque to adult periodontitis. Six P. gingivalis and five P. intermedia bacterial strains were tested for their susceptibility to 10 antimicrobial agents under disc diffusion method and broth dilution method. Ten patients with deep pocket(6mm) were selected for this study. They had not taken antibiotics for 6 months and no history of dental treatment for 6 months before this study. The result were as follow : 1. For antibiotic disc diffusion method, six P. gingivalis and five P. interrnedia were tested with 10 antimicrobial agents which comprised penicillin, gentamycin, clindamycin, lincomycin, ampicillin, erythromycin, tetracycline, amikacin, chloramphenicol, vancomycin. The sensitive antibiotics were tetracycline, penicillin, ampicillin, vancomycin, chloramphenicol and resisitent antibiotics were lincomycin. The other antimicrobial agents were less active. 2. From the study of determination on the minimal inhibitory concentration(MIC) by broth dilution method, the MIC of tetracycline to P. gingivalis and P. intermedia were $0.5-1.0{\mu}g/ml$, $0.5{\mu}g/ml$, that of ampicillin were $1-8{\mu}g/ml$, that of clindamycin were $1-32{\mu]g/ml$, $8-16{\mu}g/ml$, that of lincomycin were $16-32{\mu}g/ml$, $2-32{\mu}g/ml$. These data suggest that tetracycline and ampicillin may be valuable drug in the elemination of P. gingivalis and P. interrnedia from the patients with adult periodontitis.

• Biomolecules & Therapeutics
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• v.31 no.2
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• pp.141-147
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• 2023

Antibiotic resistance has emerged as a global threat to modern healthcare systems and has nullified many commonly used antibiotics. β-Lactam antibiotics are among the most successful and occupy approximately two-thirds of the prescription antibiotic market. They inhibit the synthesis of the peptidoglycan layer in the bacterial cell wall by mimicking the D-Ala-D-Ala in the pentapeptide crosslinking neighboring glycan chains. To date, various β-lactam antibiotics have been developed to increase the spectrum of activity and evade drug resistance. This review emphasizes the three-dimensional structural characteristics of β-lactam antibiotics regarding the overall scaffold, working mechanism, chemical diversity, and hydrolysis mechanism by β-lactamases. The structural insight into various β-lactams will provide an in-depth understanding of the antibacterial efficacy and susceptibility to drug resistance in multidrug-resistant bacteria and help to develop better β-lactam antibiotics and inhibitors.

• Journal of Microbiology and Biotechnology
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• v.24 no.1
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• pp.8-12
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• 2014

Biofilm formation and antibiotic resistance are important determinants for bacterial pathogenicity. Ribonucleases control RNA degradation and there is increasing evidence that they have an important role in virulence mechanisms. In this report, we show that ribonucleases affect susceptibility against ribosome-targeting antibiotics and biofilm formation in Salmonella.

• Proceedings of the PSK Conference
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• 2003.04a
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• pp.127.1-127.1
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• 2003

The purpose of this study is to investigate the prevalence of resistance to macrolide, lincosamide, streptogramin and ketolide antibiotics in Korea. The antibiotic susceptibility test was performed to the macrolide erythromycin, clarithromycin, azithromycin, josamycin, the lincosamide clindamycin, the streptogramin synercid and the ketolide ABT -773 against 337 clinical Staphylococcus aureus(SAU). Coagulase-negative Staphylococci (CNS) and Enterococci isolates exhibited an average percentage of 64％, 56％, and 81 ％ of resistance to erythromycin, respectively.

• The Journal of Korean Medicine
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• v.22 no.3
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• pp.179-188
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• 2001

Diarrhea is the frequent passage of loose, watery stool (frequency: ${\geq}4/day$, weight: ${\geq}250g/day$) Most antibiotics can cause inflammatory change of the colon or Pseudomembranous colitis (PMC). Typical presentations of PMC are watery diarrhea, abdominal pain, fever, leukocytosis ($12,000~20,000/\textrm{mm}^3$), hypoalbuminemia, hypovolemia and recent or concurrent use of antibiotics. Diagnostic methods of PMC are stool assay, sigmoid scopy, abdominal CT, abdominal US, etc. The age-related susceptibility noted with PMC is impressive but unexplained. Two stroke patients had diarrhea, abdominal pain, fever hypoalbuminemia and a history of recent or concurrent use of antibiotics. By use of Shirhyung- Tang, we could improve clinical symptoms (diarrhea, abdominal pain, fever hypoalbuminemia, etc.) and so report clinical course of two stroke patients with antibiotics-associated PMC.

• 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.

• Archives of Pharmacal Research
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• v.5 no.2
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• pp.87-91
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• 1982

In order to develop an analytical method for amikacin and butirosin in presence of their parent antibiotics, kanamycin A and ribostamycin, high-performance liquid chromatographic technique and microbioassay method were evaluated and compared. Using high performance liquid chromatography, two acylated antibiotics, amikacin and butirosin was partially separated from their parent antibiotics, to provide a qualitative analytical method. In microbioassay using Pseudomonas aeruginosa TI-13, a producer of aminoglycoside-3-phosphotransferase I, only acylated antibiotics were selectively analyzed when paper disc-susceptibility assay was used. The standard curve showed a good correlation between the response and odse in semilogarithmic plat with correlation coefficients above 0.96, and analytical deviation from expected dose was within 10%.