• 약학회지
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• 제50권3호
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• pp.199-203
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• 2006

A new type of macrolides, lincosamides and streptogramin B antibiotics (MLS) resistance, showing the characteristic phenotype growing within the inhibition zone area around the clindamycin disk, was identified among clinically isolated Staphylococcus aureus. We named the phenotype as MLS resistance with foggy-D shape (fMLS). The average frequency of MLS isolates was 9%. All of fMLS isolates have only erm(A) for the resistance determinant. The growth pattern of the challenged MLS isolate looks intermediate phase between the patterns of inducible MLS resistance and constitutive MLS resistance.

• 약학회지
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• 제35권1호
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• pp.22-29
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• 1991

pMB4 is a 2.4-kilobase plasmid of Staphylococcus aureus TR-1 that confers inducible resistance to the macrolide-lincosamide-streptogramin B(MLS) antibiotics. By subcloning studies, it was found that the MLS resistance determinant was located at 1.0Kb fragment between Sau3AI and TaqI sites. DNA sequence of the MLS resistant determinant, named ermC-4 was determined, and found to be highly homologous with that of ermC. Because the leader peptide sequence of ermC-4 was identical with that of ermC, the expression of the resistance gene is thought to be controlled by posttranscriptional attenuation in S. aureus TR-1.

• Biomolecules & Therapeutics
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• 제1권2호
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• pp.177-182
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• 1993

From 84 clinical isolates of Staphylococcus species, ten strains showing inducible resistance to MLS antibiotics were selected by disk agar diffusion method. Colony hybridization was executed using two MLS inducible resistance genes, ermA and ermC, previously identified from S. aureus as probes. S. hemolyticus 401 and S. epidermidis 542 whose genes were not homologous to those probes were finally selected. It was determined that the resistance genes of S. hemolyticus 401 and S. epidermidis 542 were not homologous to ermA, ermC and ermAM by Southern hybridization. S. epidermidis 542 had a plasmid DNA. To know if the plasmid may have genes related to inducible resistance, it was attempted to transform B. subtilis BR151 and S. aureus RN4220 with the plasmid prepared from S. epidermidis 542. It was shown that the gene related to inducible resistance to MLS antibiotics did not exist in this plasmid. These results indicate that two clinical isolates of S. hemolyticus 401 and S. epidermidis 542 had novel genes which were not homologous to MLS resistance genes identified previously. It was assumed that these genes may exist in chromosomal DNA.

• 약학회지
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• 제38권3호
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• pp.293-299
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• 1994

Forty nine clinical isolates of S. aureus showing resistance to erythromycin(EM) were selected from 83 strains isolated recently in Korea. Fourteen strains of S. aureus showing inducible resistance to MLS antibiotics were selected by disc agar diffusion method. Colony hydridization was executed using two MLS inducible resistance genes, ermA and ermC, identified previously from S. aureus as probes. S. aureus 375 and S. aureus 507 whose genes were not homologous to those probes were finally selected. It was confirmed that the resistance genes of S. aureus 375 and S. aureus 507 had no homology with those probes in southern hybridization test using ermA, ermC and ermAM as probes. It was determined that S. aureus 375 had a plasmid whose size was about 35 kb. To know if the plasmid may have the genes related to inducible resistance to MLS antibiotics, it was attempted to transform Bacillus subtillis BR151 and S. aureus RN4220 with the plasmid isolated from S. aureus 375. It was shown that the gene related to inducible resistance to MLS antibiotics did not exist in this plasmid. These results indicate that two clinical isolates of S. aureus showing inducible resistance to MLS antibiotics have novel genes that have no homology with MLS resistance genes identified so far. It is assumed that these genes may exist in chromosomal DNA.

• 미생물학회지
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• 제23권4호
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• pp.282-290
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• 1985

Small size antibiotic resistance plasmids having molecular weights less than 10 Mdal were isolated and characterized from ten clinically isolated multiple resistant Staphylococcus aureus. Agarose gel electrophoresis profiles and antibiotic resistance patterns divided these strains into four groups. Strain 2-23-6, the representative strain of a group of five strains conferred two plasmids of molecular weights $1.6{\times}10^6\;dal\;and\;2.0{\times}10^6$ dal. The small plasmid (pSBK 112) specified macrolides, lincosamides and streptogramin type B (MLS) resistance gene which are expressed constitutively. Lage plasmid (pSBK 125) specified chloramphenicol resistance gene which is inducible. Strain 10-5 conferred a $3.0{\times}10^6$ dal plasmid (pSBK 141) which carry an inducible ampicillin resistance gene and strain P-H-2 conferred and $1.6{\times}10^6$ dal plasmid (pSBK 190) which carry a constitutive MLS resistance gene. Strain D-H-1 conferred four plasmids of molecular weights $0.8{\times}10^6$ dal (pSBK 201), $1.6{\times}10^6$ dal (pSBK 202), $2.5{\times}10^6$ dal (pSBK 203), and $1.2{\times}10^7$ dal (pDBK 204), respectively. Among those four plasmids, only pSBK 203 specified chloramphenicol resistance gene. Curing of constitutive MLS resistance using acriding orange or ethidium bromide in 2-23-6 and P-H-2 strains produced 'inducible' MLS resistance strains which are less resistant to MLS than the wild type strains, suggesting that there are two resistance genes in both strains; one is constitutive and the other is inducible.

• 약학회지
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• 제51권2호
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• pp.108-114
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• 2007

The predominant Macrolides-Lincosamide-Streptogramin B (MLS$_B$) antibiotics resistance genes in staphylococci are erm(A) and erm(C). There is the phenomenon that the ratio of constitutively MLS$_B$ antibiotics resistance (cMLS) in erm(A) is much higher than in erm(C). Thus, we confirmed that the difference of the mutation ratio between erm(A) and erm(C) makes the phenomenon. We examined 8 staphylococci carrying inducibly expressed (iMLS) erm(A) or erm(C) genes. After overnight incubation in the presence of the non-inducer MLS$_B$ antibiotics, spontaneous mutants constitutively expressed MLS$_B$ resistance were selected. Against our expectation, the mutation ratio of erm(A) was lower than erm(C). Therefore, possibilities of other factors determining the ratio of cMLS phenotype might be concerned. All the mutants showed sequence alterations in translational attenuator and all the alterations seemed to give rise to change the second structure of mRNA to express constitutively. For erm(A), 4 different types of sequence deletions ranging from 72 bp to 122 bp and 3 different types of duplications ranging 24 bp to 93 bp were detected. Also, there were 9 different types of duplications ranging 15bp to 154bp in erm(C).

• 미생물학회지
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• 제28권1호
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• pp.27-34
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• 1990

지속성 및 유발성 발한의 두 macrolide-lincosamide-streptogramin B 저항성 인자가 한 Staphylococcus aureus DHI 균주의 염색체 DNA 및 plasmid pDE1(7.4kb)로부터 각각 분리되었다. pDE1상의 유발성 Em 저항성 인자의 염기서열은 이미 보고 된 바 있는 pE194상의 ermC와 동일하였으며 지속성 Em 저항성 인자의 경우는 그 제한효소 인식부위의 mapping 결과로 보아 ermCdb전자에서 유발성 기구에 관여하는 leader peptide 부위가 결여된 인자인 것으로 밝혀졌다.

• 약학회지
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• 제32권4호
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• pp.213-221
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• 1988

Inducible MLS resistance gene of Bacillus licheniformis specified by erm K was subcloned in Bacillus subtilis and the DNA sequence corresponding to its control region was determined. The determinant erm K was in Pvu II=Hind III fragment, which was 1.3 kb. The leader region is capable of forming a complex series of inverted complementary repeat sequences (ICRS) centering on at least six axes of symmetry, some of them mutually exclusive, in a way that resulted ultimately in post-transcriptional unmasking of the ribosome loading site for methylase synthesis.

• Archives of Pharmacal Research
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• 제12권3호
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• pp.176-180
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• 1989

Four bacterial strains having inducible resistance to erythromycin were isolated from soil samples in Korea and characterized. MLS inducibility was checked in each strain. Cloning of inducible resistance gene(s) has been tried. Four isolates were identified as B. anthracis, Micrococcus luteus, Streptococcus faecium and B. licheniformis, in which erythromycin, oleandomycin, cirramycin and carbomycin acted as resistance inducers respectively. The resistance gene cloned from B, licheniformis 597 strain using pBS 42 vector was found to have a 3.2 kb insert.

• 약학회지
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• 제34권2호
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• pp.139-146
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• 1990

Streptococcus sp. TR-1 which has inducible resistance to MLS antibiotics was isolated from soil samples in Korea. Streptococcus sp. TR-1 was cultured in Lysis broth, then a plasmid was isolated by modified Elliker method. Bacillus subtilis UOTO277 was transformed with that plasmid. This result showed that the plasmid has the gene relating with inducible resistance to MLS antibiotics. It was named pMB4 and its size was determined about 2.4 Kb by results of digestion with various restriction enzymes. Restriction endonuclease cleavage site map of pMB4 plasmid was made by double digestion of the plasmid. pMB4 plasmid has different restriction endonuclease site map from the other plasmids that have been discovered in Streptococcus sp. so far. And it could be identified that pMB4 plasmid does not have homology with ermK of Bacillus licheniformis EMR but has homology with ermC of Staphylococcus aureus from the results of Southern hybridization.