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Typing

About: Typing is a research topic. Over the lifetime, 5010 publications have been published within this topic receiving 146539 citations.


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TL;DR: In this article, the nucleotide sequences of the 18S, 5.8S, and 26S rRNA genes of Pneumocystis carinii were determined and were found to be identical to each other.
Abstract: Small portions of the 18S and the 26S rRNA genes, the entire 5.8S rRNA gene, and internal transcribed spacers ITS1 and ITS2 (located between the 18S and 5.8S rRNA genes and between the 5.8S and 26S rRNA genes, respectively) of Pneumocystis carinii that infect humans were cloned and sequenced. The nucleotide sequences of the 18S, 5.8S, and 26S rRNA genes determined in the study were approximately 90% homologous to those of P. carinii that infect rats, while the sequences of ITS1 and ITS2 of P. carinii from the two different hosts were only 60% homologous. The 18S, 5.8S, and 26S rRNA gene sequences of P. carinii from 15 patient specimens were determined and were found to be identical to each other, whereas the ITS sequences were found to be variable. With the observed sequence variation, it was possible to classify the ITS1 sequences into two types and the ITS2 sequences into three types. P. carinii strains that had the same type of ITS1 sequence could have a different type of ITS2 sequence. On the basis of the sequence types of the two ITS regions, P. carinii from the 15 patients were classified into four groups. P. carinii from three patient specimens were found to contain two different ITS sequence patterns. More surprisingly, one additional specimen was found to have one ITS sequence typical of P. carinii isolates that infect humans and another typical of P. carinii isolates that infect rats. The studies indicate that it is possible to type P. carinii strains on the basis from one patient, suggesting that coinfection with more than one strain of P. carinii may occur in the same patient.

104 citations

Journal ArticleDOI
TL;DR: Legionellae are environmental bacteria that can be frequently isolated from technical water supply systems and the most prevalent species is Legionella pneumophila, especially serogroup 1.
Abstract: Legionellae are environmental bacteria that can be frequently isolated from technical water supply systems. The most prevalent species is Legionella pneumophila, especially serogroup 1. In the environment, legionellae multiply in amoebae. Since Legionella pneumonias cannot be distinguished from pneumonias caused by other microbial pathogens, special microbiological tests, e.g., urinary antigen assays, are essential to detect Legionella infections. All water supply systems to which the patient is exposed during the incubation time of 2 to 10 days might be the source of the infection. This can be confirmed or excluded by molecular typing of isolates from patients and the environment. The most commonly used techniques are monoclonal antibody typing and sequence-based typing (SBT). Some sequence types (ST) are frequently found among clinical strains but are seldom isolated from the environment, e.g., ST 23, 42, 47, 62, and 146. It is safe to assume that such strains are highly virulent. Conversely, it does not seem to be justified to dedicate the same awareness to all environmental Legionella strains.

104 citations

Journal ArticleDOI
TL;DR: The newly developed spa typing method appeared to be a promising tool for easy and rapid typing of MRSP, either alone or in combination with SCCmec and mecA typing for fine-structure epidemiological analysis.

104 citations

Journal ArticleDOI
TL;DR: In this paper, the repeated units encoding hypervariable regions of the Staphylococcus aureus coagulase gene were amplified by the PCR technique; this was followed by AluI restriction enzyme digestion and analysis of restriction fragment length polymorphism (RFLP) patterns.
Abstract: To perform coagulase gene typing, the repeated units encoding hypervariable regions of the Staphylococcus aureus coagulase gene were amplified by the PCR technique; this was followed by AluI restriction enzyme digestion and analysis of restriction fragment length polymorphism (RFLP) patterns. In order to assess the discriminatory power of this typing method, 30 epidemiologically unrelated S. aureus strains which differed by their pulsed-field gel electrophoresis patterns were examined. Although 18 of the 30 strains had unique and unshared AluI RFLP patterns, there were only four observed patterns in the remaining 12 strains. This finding indicated that unrelated strains may share identical AluI RFLP patterns. To elucidate the degree of genetic variation in the C-terminus-encoding loci within the coagulase genes, the PCR products of these 12 strains were subjected to Taq polymerase-mediated sequencing. Sequence analysis confirmed the AluI recognition sites in each of the four RFLP groups and demonstrated that AluI appears to yield the highest RFLP in restriction enzyme analysis. By their DNA sequences the majority of strains sharing common AluI groups could be clearly differentiated from each other and revealed between 93.2 and 98.5% homology. When we determined the nucleotide sequences of two strains after six subcultivations no significant alterations were observed. Because the discriminatory power of the current coagulase gene typing method is not great enough to be used as the sole method to type S. aureus, additional techniques are necessary. Sequence analysis of the repeated unit-encoding region for the typing of S. aureus may be potentially useful as an alternative to other current molecular typing techniques. Images

103 citations

Journal ArticleDOI
14 Nov 1991-Nature

103 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023329
2022690
2021145
2020126
2019136
2018147