• YAKHAK HOEJI
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• v.52 no.4
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• pp.279-282
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• 2008

Plasmids were isolated from 15 tetracycline (Tc) resistant S. aureus. Two small tetracycline resistance plasmids, pKH16 and pKH17, have been isolated from Staphylococcus aureus JY10 and Staphylococcus aureus JY22, respectively and the complete nucleotide sequences of those plasmids have been determined. pKH16 consisted of 4,442 bp and showed high identity to pKH6 (99% matching percentage) isolated in 1989 from S. aureus SA2. pKH17 consisted of 4,441 bp and showed less identity to pKH6 (95% matching percentage) than pKH16. PCR analysis showed that tetK and tetM did not exist in ten large plasmids isolated from ten Tc resistant S. aureus. Twelve Tc resistant S. aureus showed reistance both to Tc and Mn and we might analogize that twelve Tc resistant S. aureus had tetM in their chromosome.

• Journal of Microbiology and Biotechnology
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• v.6 no.4
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• pp.292-294
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• 1996

To investigate the relationship between two tetracycline resistance ($Tc^r$) plasmids, the 24.82-kb pKHl and the 4.44-kb pKH6, of Staphylococcus aureus isolated in Korea, cloning of the 4570-bp HindIII fragment into pBluescript II $KS^+$ after partial digestion of the $Tc^r$ plasmid pKHl with HindIII and sequence determination of that fragment were carried out. Analysis of the sequences revealed that the 4570-bp HindIII fragment contained a 4011-bp fragment of the small $Tc^r$ plasmid pKH6 flanked by the partial sequences of IS431mec. It was concluded from the above result that the pKHl was produced by integration of the partial sequence of the pKH6 into another plasmid via IS431mec.

• Journal of Life Science
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• v.15 no.6 s.73
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• pp.863-870
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• 2005

One hundred and twenty three strains of Mycoplasma pneumoniae were isolated from patients with respiratory diseases from February 2002 to April 2005 in Busan, Korea. The MICs of tetracycline and erythromycin up to $90\%$ of the 123 M. pneumoniae isolates tested were $0.5\~1.0$, and $0.5\~512{\mu}/ml$, respectively. Plasmid DNA was not isolated from all of the M. pneumoniae isolates. Out of 323 strains of M. pneumoniae, 57 ($46.3\%$) stains contain tetM gene on their chromosomal DNA, and 60 ($48.8\%$) strains were mutated in domain V of 23S rRNA for erythromycin resistance. Out of 63 strains of M. pneumoniae which were not mutated in domain V of 235 rRNA for erythromycin resistance, 36 ($57.1\%$) strains contained tetM gene, and out of 60 strains of M. pneumoniae which were mutated in domain V of 23S rRNA for erythromycin resistance, 21 ($35.0\%$) strains contained tetM gene. These results suggest that the isolation rate of erythromycin and tetracycline resistant M. pneumoniae is higher than those of other countries, and erythromycin and tetracycline are not first choice drug for M. pneumoniae infection in Korea, and it need confirm by a nationwide surveilance of antimicrobial resistance.

• Korean Journal of Veterinary Research
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• v.59 no.4
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• pp.207-211
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• 2019

Mass mortality in commercially cultured Amur catfish (Silurus asotus), showing symptoms of dermal ulcerations, occurred on a private farm in Mar 2019 in Korea. β-hemolytic bacteria were isolated from the ulcers and kidneys of the fish and identified as Aeromonas veronii. The isolate was resistant to tetracycline and possessed cytotoxic heat-labile enterotoxin (aerolysin/hemolysin). We investigated the genetic determinants associated with tetracycline resistance, and the isolate has been confirmed to simultaneously possess tetA and tetE genes. This is the first report on the occurrence of tetracycline-resistant A. veronii infection related to mass mortality in commercially cultured Amur catfish in Korea.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.55 no.5
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• pp.505-513
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• 2022

In this study, 143 strains of Enterococcus spp. were isolated from inland pollution sources near shellfish farms on the west coast of South Korea. Not all isolated Enterococcus spp. strains possessed vancomycin resistance genes (VanA and VanB). However, since vancomycin-resistance Enterococcus (VRE) have been detected not only in the clinical field but also out in the world, it is possible that the VRE gene may be transferred to other bacterial strains commonly found in coastal waters where seafood is produced. It is important to monitor trends in the appearance of VRE. In addition, antimicrobial resistance patterns of isolates were examined in this study. Overall antimicrobial resistance rates were high: ciprofloxacin (32.2% of isolates resistant), chloramphenicol (30.8%), quinupristin/dalfopristin (19.6%), and tylosin (15.4%). Eight E. faecium strains (6.2%), out of the 129 strains assessed, showed multidrug resistance. All multidrug-resistant E. faecium showed resistance to erythromycin, quinupristin/dalfopristin, tetracycline, and tylosin, in all 14 strains. All multidrug-resistant E. faecalis showed resistance to erythromycin, quinupristin/dalfopristin, tetracycline, and tylosin. Both multidrug-resistant E. faecium and multidrug-resistant E. faecalis showed common resistance to erythromycin, quinupristin/dalfopristin, tetracycline, and tylosin.

• YAKHAK HOEJI
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• v.34 no.1
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• pp.54-63
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• 1990

These studies were made to assess the present stage of resistance of Shigella species to antibiotics and to find characteristics of R-plasmid of these bacteria. From 1986 to 1988, 125 strains of Shigella species were isolated from patients specimens collected in Chung Cheong-do Hospital, Kyunghee Medical Center, city an provincial health & environmental institutes. These specimens were tested for resistance to 12 kinds of antimicrobial agents by agar dilution method. Using Muller-Hinton agar for the assay of drug resistance and Trypticane Soy Broth as propagating medium for conjugation. All the strains (100%) were resistant to one or more antibiotics. Drug resistance patterns of isolated strains were found as the highest resistance to ampicillin (98%) in 1986, to tetracycline (98%) in 1987, to tetracycline (100%) in 1988, all strains were sensitive to gentamicin, amikacin, tobramycin. Chronologically, resistance decreased gradually as it was shown in relation to kanamycin, rifampicin in 1986, 1987 and 1988, (4%, 2%) (4%, 2%) (0%, 0%) respectively. But, resistance was increased year by year as it was shown in relation to tetracycline, nalidixic acid, streptomycin in 1986, 1987, 1988 (89%, 19%, 45%) (98%, 46%, 71%) and (100%, 58%, 88%). The resistance in correlation to more than 5 drugs, which was 13 strains among 47 strains in 1986, 38 strains among 87 strains in 1987, 23 strains among 26 strains in 1988, was increased gradually. In the transfer test of drug resistance by conjugation methods, the rate which was 3 strains (50%) in 1986, 8 strains (62%) in 1987, 3 strains (100%) in 1988, was increased gradually. When the donor strains were conjugated with the recipient strains, the conjugation rate was high in the multiple resistant strains. The relationships of transferring patterns of drug resistance and molecular weight of R-plasmid were variable. However, only a plasmid which has more than 35 Mgd was transferred.

• Korean Journal of Microbiology
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• v.42 no.4
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• pp.252-256
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• 2006

We monitored antibiotic resistance of Escherichia coli isolates from healthy volunteers of community and hospital patients from February to July in 2006. From disc diffusion test on 4915 E. coli isolates from healthy volunteers of the community, the resistance rates were as follows; tetracycline resistant, 46.6%; ampicillin resistant, 41.1%; ticarcillin resistant,37.9%. From disc diffusion test on 120 E. coli isolates from hospital patients, the resistance rates were as follows: ampicillin resistant, 66.9%; ticarcillin resistant, 63.8%; tetracycline resistant, 47.2%. Extended spectrum $\beta$-lactamase producing E. coli were isolated 0.6% and 4.1% from healthy volunteers and hospital patients.

• Korean Journal of Food Science and Technology
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• v.38 no.2
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• pp.313-316
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• 2006

To obtain antibiotic resistant profiles of Bifidobacterium, minimum inhibitory concentrations (MIC) of 14 antibiotics for 93 Bifidobacterium isolates from Korean intestine origin were determined. All strains tested were sensitive to chloramphenicol, rifampicin, and amoxicillin, whereas resistant to aminoglycoside family, nalidixic acid, and vancomycin. Among vancomycin-resistant strains, 34% were resistant at more than $100\;{\mu}g/mL$, and showed variant resistances toward tetracycline, erythromycin, and penicillin. Their resistances against penicillin, cephalothin, and tetracycline were higher than ten years ago. MIC of ten isolates from commercial yoghurt products were very similar to those of strains from Korean intestine origin, and 20% strains showed resistance at higher than $100\;{\mu}g/mL$ vancomycin. These results indicated patterns of antibiotic resistance against Bifidobacterium from Korean intestine origin and commercial yoghurts were very similar,and prevalence of vancomycin resistance for Bifidobacterium was 20%. To develop new probiotic, antibiotic resistance of vancomycin and risks involved should be evaluated.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.56 no.4
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• pp.388-400
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• 2023

Aeromonas spp. and Pseudomonas spp. are opportunistic pathogens widely distributed in the aquatic environment. To test the antibiotic susceptibility, the MIC of the 18 antibiotics mainly used in aquaculture were measured. Aeromonas spp. and Pseudomonas spp. straoms had different resistance patterns against most antibiotics. The MIC of tetracycline for four Aeromonas spp. strains (10.5%) was < 0.25 ㎍/mL. However, 0.5-4 ㎍/mL tetracycline inhibited most Pseudomonas spp. strains. The tet resistance performance of 14 genes including tet(B), tet(E), and tet(M) were investigated. Investigating, the tetracycline resistance gene of 38 Aeromonas spp. strains detected tet(A) in 21 strains (55.3%). Two Pseudomonas spp. strains showed high MIC values and no inhibition zone. tet gene analysis detected tet(D) in only one strain (5%).

• YAKHAK HOEJI
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• v.30 no.1
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• pp.51-54
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• 1986

Fecal samples from Kim-Hae farm animals were examined for the frequency of gram-negative enteric organisms resistant to tetracycline, streptomycin, or penicillin. The propertions of antibiotic resistant to total organisms in fecal specimens of poultry, swine and cow were as follows: 95%, 92%, 70% for tetracycline, 100%, 27%, 9% for streptomycin, 18%, 1%, 1% for penicillin, respectively. The bacteria had multiresistance to antibiotics. These strains had more than one plasmid. From the transformation study, it was concluded that the resistance to streptomycin was attributed to one of these plasmids.