• Korean Journal of Veterinary Research
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• v.44 no.1
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• pp.89-98
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• 2004

This study was carried out to investigate the serotype, and antimicrobial susceptibility and analyze the plasmid profile for the 145 isolates of L. monocytogenes isolated from livestock products and these product processing plants in Gyeongnam, Korea. All of L. monocytogenes strains belonged to serotype 1/2b (57.9%), 1/2a (20.0%), 4b (11.4%), 1/2c, 3b, 4c (each 2.9%) and 4d (0.7%). Serotype 1/2b, 1/2a, 4b from each source were found predominantly. Serotype 1/2b was predominantly higher than other serotype, and there was no significant difference between serotypes isolated from livestock products and product processing plants. 4b was major serotype isolated from raw milk and pork, and serotypes isolated from beef, chickens and slaughterhouse were 1/2b and 1/2a. The susceptibility of 145 strains of L. monocytogenes to 14 antibiotics commonly used in veterinary and human therapy was determined by disk diffusion method. All of L. monocytogenes strains were susceptible to amikacin, ampicillin, cephalothin, chloramphenicol, gentamicin, kanamycin, neomycin and penicillin. L. monocytogenes strains had the highest resistance with colistin (100%), oxytetracycline (44.8%), tetracycline (43.4%) followed by erythromycin (2.8%), spectinomycin (1.4%) and streptomycin (0.7%). Tetracycline resistance, and serotype distribution of the isolates from sample sources were significantly different. Resistance to at least one antibiotic was observed in all of them and 7 different resistant profiles were recorded. The most common resistance pattern were CL-OTC-TC (colistin-oxytetracycline-tetracycline) (42.8%). Among all tested isolates, two different plasmid profiles were observed. Of the 97 examined strains, 14 (14.4%) contained either the 8 and 11 kb plasmid or the 11 kb.

• Journal of fish pathology
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• v.36 no.2
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• pp.287-292
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• 2023

This study investigated the genetic determinants of plasmid-mediated antibiotic resistance (PMAR) to quinolones and tetracycline in 106 Aeromonas strains isolated from eel (Anguilla japonica, 70 strains) and ornamental fish (36 strains) in Korea. Quinolones and tetracycline resistance phenotypes were found to be widely distributed throughout the both fish groups. However, the prevalence of qnr and tet genes was higher in ornamental fish strains than in eel strains (42.9% vs. 86.1% for qnr and 51.4% vs. 69.4% for tet). In addition, the profiling of the present genetic determinants revealed the dominance of qnrS, tetA, tetE and tetE+qnrS genes for eel strains but of tetA+qnrS qnrS and tetE+qnrS genes for ornamental fish strains. These results indicate that aquaculture and related industries could be a major threat to public health due to the possible spread of PMAR.

• Microbiology and Biotechnology Letters
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• v.24 no.4
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• pp.423-426
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• 1996

The complete nucleotide sequence of pKH6, a tetracycline-resistance (Tc$^{r}$) plasmid isolated from multi-drug resistant Staphylococcus aureus SA2, has been determined and compared with that of the staphylococcal Tc$^{r}$ plasmid pTl8l. The nucleotide sequences of the two plasmids are in agreement except for 7 nucleotides. All differences are caused by base pair substitutions. Among 6 substitutions, 3 occurred in coding regions. However, only two base substitutions in coding regions resulted in changes of amino acid sequences in two different ORFs of repC and Pre proteins.

• Microbiology and Biotechnology Letters
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• v.15 no.5
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• pp.319-327
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• 1987

In order to develop useful plasmid vectors for Zymomonas cells, attempts were made to isolate natural plasmids from Z. mobilis ATCC10988. Among a few plasmids isolated, a small plasmid of 3.9 Kb size was chosen and designated as pZM3. By introducing the replication origin of pZM3 into pBR325, a hybrid plasmid vector of 8.4 Kb size, pHZ22, was constructed. This vector contained chloramphenicol resistant gene as a selectable marker and proved to be conjugally transmissible and stably maintained in Z. mobilis. Tetracycline resistant gene was isolated from RP4 and introduced into pHZ22 to make a new vector called pHZT224 of 10.7 Kb size. Through n series of experiments, it was evident that these plasmid vectors containing selectable markers of chloramphenicol and tetracycline resistance were shuttle vectors functional in Z. mobilis as well as E. coli.

• Korean Journal of Microbiology
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• v.38 no.4
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• pp.299-305
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• 2002

Clinically isolated Salmonella Enteritidis strain has a multi drug resistance plasmid, which confers ampicillin, chloramphe-nicol, sulfonamide, streptomycin and tetracycline, named pCAST2. We cloned a 7 kb Sacl fragment of pCAST2 which has sulfonamide, streptomycin and tetracycline resistance genes. The 7 kb SacI fragment showed the organization of sulII-strA-strB-tetR-tetA gene cluster which is different from the other clusters reported previously. In this study, we presented the method to detect this cluster by PCR analysis and showed that this cluster was found in Salmonella strains occurred sporadically at Kyungpook province in 2002.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.35 no.2
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• pp.115-121
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• 2002

To develop a new method of conjugation and to determine the distribution of R plasimds, we isolated multi-drug resistant strains from fish pathogenic bacteria in the farms of south and east seacoasts of Korea. Out of the 134 isolates examined, 10 showed resistance to chloramphenicol, tetracycline, streptomycin, ampicillin, colistin, nalidixic acid, oxolinic acid and kanamycin. One out of 10 multi-drug resistance bacteria, Vibfio damsela JE1 (V. damsela JE1), contained transferable R plasmid of chlorarnphenicol- tetracycline resistance genes and other nucleic acids encoding ampicillin and kanamycin resistance. The presence of the R plasmid was confirmed by conjugation using the chromocult medium (CC) as a selective and differential medium for transconiugants with identification based on the growth or colors of the colonies. The frequency of R plasmid transfer with filter mating method was come out much higher than that of broth mating method and appeared to be dependent upon the mating time and temperature. The optimum conditions for filter mating method were found to be 30$^{\circ}C$ and 24hrs as mating temperature and period, respectively, Moreover, donor cells with R plasmid, both isolate and standard bacteria, were shown to have an ability to transfer the plasmid against Escherichia coli K-12 HB101 (E. coli HB101) and Edwardsiella tarda (E. tarda) RE14 at fairly high frequencies, finally, we isolated 3 isolates of Sphingomonas sp., carrying R plasmid from 12 multi-drug resistant bacteria in normal microflora of the flounder (Paralichthys olivaceus) group used for the isolation of V emsela JE1 four months before. The same size and gene transfer chayateristics of R plasimds with those of V damsela JE1 confirmed that normal microflora have the reservoir activity for R plasmid in natural aquatic environment.

• Korean Journal of Veterinary Research
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• v.35 no.3
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• pp.537-542
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• 1995

In this study, we aim to find the presence of virulence-related plasmid in Salmonella isolates from poultry, and the difference between S pullorum and S gallinarum on the plasmid profile and antibiotics resistance. We used seventeen isolates of Salmonella spp that were isolated from poultry. Thirteen isolates, S typhimurium(ST), S pullorum(SP) and S gallinarum(SG), contained virulence-related plasmids. These are 95Kd plasmid in ST and 85Kd plasmid in SP and SG. Three(1/4 of ST, 1/1 of SE, and 1/9 of SP) isolates have no detectable plasmids. The isolates of ST have relatively variable plasmid profile but the isolates of S pullorum except No 12(additional 3.0Kb plasmid) have common 85K6, 8.1Kb, 4.0Kb and 2.3Kb plasmid and two of three isolates of S gallinarum have common 85Kb, 4.0Kb and 2.3Kb plasmid but the rest has only 85Kb plasmid. Interestingly, all of the isolates of SP have 8.1Kb plasmid, and same size of plasmid is also found in one of ST isolates. All of the isolates have the resistance to penicillin, chloramphenicol, rifampicin, streptomycin, sulfamethazine and some isolates show the resistance to ampicillin and tetracycline. There is no relatedness between plasmid profile and antibiotics resistance and no differences between SP and SG in antibiotics resistance. Therefore further differentiation of each isolates by restriction enzyme assay and, if possible, charaterization of each plasmid, especially, 8.1Kb plasmid in SP and ST, may be necessary.

• The Journal of the Korean Society for Microbiology
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• v.21 no.1
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• pp.33-45
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• 1986

On hundred and forty stains of shigella cultures isolated from the twelve hygiene laboratories of cities and provincial general hospital laboratories in 1983 were tested for their resistance to thirteen antimicrobial drugs and their R-plasmid transfer. Antimicrobial drugs were used amikacin, ampicillin, cephalothin, chloramphenicol, gentamicin, kanamycin, nalidixic acid, rifampicin, streptamycin, tetracycline, tobramycin, cefoperazone and piperacillin. All strains were resistant to one or more of thirteen antimicrobial drugs but 94.3% were susceptible to amikacin, gentamicin and tobramycin of total isolated. The most strains commonly found resistance was to chloramphenicol (94%) followed by streptamycin (93%), tetracyline (92%) piperacillin (90%) ampicillin (83%), cefoperazone (42%), nalidixic acid (14%), cephalothin (17%), rifampicin (22%) and kanamycin (6%), sixty percent of strains among 140 were resistance to ampicillin, chloramphenicol, streptomycin, tetracycline at the same time. The transfer of drug resistance by conjugation was tested and ninety four strains (94.3%) were resistant to one or more drugs were found to transfer their drug resistance of E. coli. percentage of transfer frequency by conjugation was one strains (54%), the transfer frequency of drug resistance varied by donor strains and recipients, but not by selecting drugs. Resistance to nalidixic acid was not transferred by conjugation to recipients. Percentage of plasmid curing after the treatment of acriflavine, acridine orange was about 8%. Among strains cured two strains were tested compare original strains with them in biochemical properties in arginine dihydrolase and arabinose fermentation reaction. It was found to growth curves of No.2 shigella flexneri, serotype 1b, and its derivatives cured with acriflavine in $M{\ddot{u}}ller$ Hinton broth medium (pH 7.4, $38^{\circ}C$) by temperature Gradient Biophoto Recorder TN-1120 (Tokyo, Japan).

• 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.

• Journal of Microbiology and Biotechnology
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• v.11 no.1
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• pp.1-6
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• 2001

Ten strains of plasmid-harboring Bifidobacterium sp. were isolated from the feces of adults and children, and named as Bifidobacterium sp. GE1-GE8, ST, and SH5. These plasmids were categorized into three homologous groups (pKJ50-homologous, pKJ36-homologous, and non-homologous groups) according to Southern hybridization patterns using the formerly characterized bifidobacterial plasmids, pKJ50 and pKJ36, as probes. nine strains harboring the plasmids were shown to accumulate single-stranded DNA as a replication intermediate, based on the S1 nuclease treatment and Southern hybridization. These results suggest that the strains replicate by a rolling circle mechanism. Minimal inhibitory concentrations (MIC) of the isolated bifidobacteria against several antibiotics were determined. Two strains, GE2 and GE3, showed relatively high MiC values against tetracycline ($793.6{\mu}g/ml$) and erythromycin ($153.6{\mu}g/ml$), respectively. The tetracycline resistance of GE2 disappeared when the resident plasmid of GE2 was cured by ethidium bromide. These results show that pKJ36-homologous and pKJ50-homologous plasmids are prevalent among various Bifidobacterium strains and some Bifidobacterium plasmids appear to code for antibiotic resistance.