Journal of Microbiology

Research Support, Non-U.S. Gov'ts

Characterization of Antibiotic Resistance Determinants in Oral Biofilms: Seon-Mi Kim , Hyeong C. Kim , Seok-Woo S. Lee; J. Microbiol. 2011;49(4):595-602. Published online September 2, 2011; DOI: https://doi.org/10.1007/s12275-011-0519-1

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Abstract: Oral biofilms contain numerous antibiotic resistance determinants that can be transferred within or outside of the oral cavity. The aim of this study was to evaluate the prevalence and the relative level of antibiotic resistance determinants from oral biofilms. Oral biofilm samples that were collected from healthy subjects and periodontitis patients were subjected to qualitative and quantitative analyses for selected antibiotic resistance determinants using PCR. The prevalence of tet(Q), tet(M), cfxA, and blaTEM was very high both in the patient and the healthy subject group, with a tendency toward higher values in the patient group, with the exception of erm(F), which was more prevalent in the healthy group. The two extended spectrum β-lactam (ESBL) resistance determinants blaSHV and blaTEM showed a dramatic difference, as blaTEM was present in all of the samples and blaSHV was not found at all. The aacA-aphD, vanA, and mecA genes were rarely detected, suggesting that they are not common in oral bacteria. A quantitative PCR analysis showed that the relative amount of resistance determinants present in oral biofilms of the patient group was much greater than that of the healthy group, exhibiting 17-, 13-, 145-, and 3-fold increases for tet(Q), tet(M), erm(F), and cfxA, respectively. The results of this study suggest that the oral antibiotic resistome is more diverse and abundant in periodontitis patients than in healthy subjects, suggesting that there is a difference in the diversity and distribution of antibiotic resistance in oral biofilms associated with health and disease.

Prevalence of Tetracycline Resistance Genes in Greek Seawater Habitats: Theodora L. Nikolakopoulou , Eleni P. Giannoutsou , Adamandia A. Karabatsou , Amalia D. Karagouni; J. Microbiol. 2008;46(6):633-640. Published online December 24, 2008; DOI: https://doi.org/10.1007/s12275-008-0080-8

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Abstract: The presence of selected tetracycline resistance (TcR) genes was studied in different Greek seawater habitats, originated from wastewater treatment facilities, fishfarm, and coastal environments. The methods employed included assessment of the presence of twelve gene clusters by PCR, followed by hybridization with specific probes, in habitat extracted DNA, TcR bacteria, and exogenous isolated plasmids conferring TcR. The direct DNA-based analysis showed that tet(Α) and tet(K) genes were detected in all habitats, whilst tet(C) and tet(E) were present in fishfarm and wastewater effluent samples and tet(M) was detected in fishfarm and coastal samples. Resistance genes tet(A), tet(C), tet(K), and tet(M) were detected in 60 of the 89 isolates screened. These isolates were identified by fatty acid methyl ester analysis (FAME) as Stenotrophomonas, Acinetobacter, Pseudomonas, Bacillus, and Staphylococcus strains. The presence of the TcR genes in 15% of the bacterial isolates coincided with the presence of IncP plasmids. A habitat-specific dissemination of IncP alpha plasmids in wastewater effluent isolates and of IncP beta plasmids in fishfarm isolates was observed. Exogenous isolation demonstrated the presence of plasmids harbouring TcR genes in all the habitats tested. Plasmids were shown to carry tet(A), tet(C), tet(E), and tet(K) genes. It is concluded that TcR genes are widespread in the seawater habitats studied and often occur on broad host range plasmids that seem to be well disseminated in the bacterial communities.

Arg243, Invariably Critical for the Transcriptional Activation of Yeast Gcn4p: Cho, Gyu Chull , Lee, Jae Yung , Kim, Joon; J. Microbiol. 1999;37(3):154-158.

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Abstract: The arginine residue at position 243 (Arg 243) of the yeast transcription factor, Gcn4p, is invariably conserved among bZIP transcription factors. Using site-directed oligonucleotide saturation mutagenesis involving two-step polymerase chain reaction (PCR) amplification, random mutations were successfully introduced at the codon of 243 in the basic domain of Gcn4p. This mutant library was transformed ito Gcn4p defective yeast strain and selected for the transcriptionally active colonies. All colonies which were transcriptionally active had arginines in the codon 243. In this study, the strand preference by Taq polymerase during mutagenesis was also tested. Oligonucleotides were specially designed to test whether or not the polymerase was preferred using the strand as a template. A population of randomly mutated products were cloned into an appropriate vector and characterized by DNA sequencing analysis. Saturation mutagenesis which was performed efficiently by this method revealed a strong bias in terms of strand preference of Taq polymerase by an approximate ratio of 3 to 1 in this study.

Detection of Lymphotropic Herpesviruses by Multiplex Polymerase Chain Reaction: Sang-Tae Park , Seung-Han Kim , Dong-Gun Lee , Jung-Hyun Choi , Wan-Shik Shin , Tai - Gyu Ki m , Soon-Young Paik , Chun-Choo Kim; J. Microbiol. 2001;39(3):226-228.

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Abstract: Human lymphotropic herpesvirus is known to be a major pathogen associated with various diseases in bone marrow transplantation (BMT) recipients. A multiplex nested-polymerase chain reaction (PCR) method was developed for the simultaneous detection of human lymphotropic herpesviruses, including Ebstein-Barr virus (EBV), cytomegalovirus (CMV), and human herpesvirus 6 variants A and B (HHV6-A, HHV6-B). To demonstrate the usefulness of multiplex PCR for the analysis of clinical samples, peripheral blood mononuclear cells and serum from BMT recipients were analysed. The results showed that a clear detection could be made between EBV, HCMV and HHV-6. This multiplex PCR assay is an efficient and cost-effective approach to the analysis of large numbers of samples to determine the epidemiological importance of EBV, HCMV and HHV-6.

Determination of Enteric Bacteria at Microbiologically Risky Points by Multiplex Polymerase Chain Reaction: Mahir Gulec , Bilal Bakir , Recai Ogur , Omer Faruk Tekbas; J. Microbiol. 2002;40(4):327-330.

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Abstract: The purpose of this research was to test multiplex polymerase chain reaction in investigating the microbiological quality of the risky surfaces in social living places of a military base where over 15 thousand people live together. In 22 samples of 99, there were no bacteria. Only four of the samples contained Shigella, and one of them contained Salmonella, but 77 of the samples contained thermotolerant coliform organisms. There was no statistically significant difference among the microbiological quality of different sites and different equipment surfaces (p>0.05).

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