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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: Phage typing was helpful in interpreting PFGE data and could have been used as a simple, rapid screen to eliminate the need for performing PFGE on unrelated isolates, and appeared to be a more sensitive method than bacteriophage typing for distinguishing outbreak and non-outbreak-related strains.
Abstract: Two hundred thirty-three isolates of Escherichia coli O157:H7 were analyzed by both pulsed-field gel electrophoresis (PFGE) and bacteriophage typing All 26 isolates from persons whose illness was associated with a recent multistate outbreak of E coli O157:H7 infections linked to the consumption of undercooked hamburgers and all 27 isolates from incriminated lots of hamburger meat had the same phage type and the same PFGE pattern Twenty-five of 74 E coli O157:H7 isolates from Washington State and 10 of 27 isolates from other states obtained during the 6 months before the outbreak had the same phage type as the outbreak strain, but only 1 isolate had the same PFGE pattern PFGE thus appeared to be a more sensitive method than bacteriophage typing for distinguishing outbreak and non-outbreak-related strains The PFGE patterns of seven preoutbreak sporadic isolates and five sporadic isolates from the outbreak period differed from that of the outbreak strain by a single band, making it difficult to identify these isolates as outbreak or non-outbreak related Phage typing and PFGE with additional enzymes were helpful in resolving this problem While not as sensitive as PFGE, phage typing was helpful in interpreting PFGE data and could have been used as a simple, rapid screen to eliminate the need for performing PFGE on unrelated isolates

362 citations

Journal ArticleDOI
TL;DR: All techniques appear to be capable of detecting outbreak strains, but only REA and MLVA showed sufficient discrimination to distinguish strains from different outbreaks.
Abstract: Using 42 isolates contributed by laboratories in Canada, The Netherlands, the United Kingdom, and the United States, we compared the results of analyses done with seven Clostridium difficile typing techniques: multilocus variable-number tandem-repeat analysis (MLVA), amplified fragment length polymorphism (AFLP), surface layer protein A gene sequence typing (slpAST), PCR-ribotyping, restriction endonuclease analysis (REA), multilocus sequence typing (MLST), and pulsed-field gel electrophoresis (PFGE). We assessed the discriminating ability and typeability of each technique as well as the agreement among techniques in grouping isolates by allele profile A (AP-A) through AP-F, which are defined by toxinotype, the presence of the binary toxin gene, and deletion in the tcdC gene. We found that all isolates were typeable by all techniques and that discrimination index scores for the techniques tested ranged from 0.964 to 0.631 in the following order: MLVA, REA, PFGE, slpAST, PCR-ribotyping, MLST, and AFLP. All the techniques were able to distinguish the current epidemic strain of C. difficile (BI/027/NAP1) from other strains. All of the techniques showed multiple types for AP-A (toxinotype 0, binary toxin negative, and no tcdC gene deletion). REA, slpAST, MLST, and PCR-ribotyping all included AP-B (toxinotype III, binary toxin positive, and an 18-bp deletion in tcdC) in a single group that excluded other APs. PFGE, AFLP, and MLVA grouped two, one, and two different non-AP-B isolates, respectively, with their AP-B isolates. All techniques appear to be capable of detecting outbreak strains, but only REA and MLVA showed sufficient discrimination to distinguish strains from different outbreaks.

349 citations

Journal ArticleDOI
TL;DR: A typing enzyme immunoassay (TYPE-EIA) was used to determine the antigenic types of 64 astrovirus-positive specimens from nine collections from seven countries, finding most strains of the same type were identical.
Abstract: A typing enzyme immunoassay (TYPE-EIA) was used to determine the antigenic types of 64 astrovirus-positive specimens from nine collections from seven countries. Six of the seven known astrovirus types were detected in the collections, with HAstV-1 predominating in all collections for one from the United Kingdom. Selected specimens were analyzed further by reverse transcriptase PCR and nucleotide sequencing of 348 bp within the capsid protein precursor region of the genome. The phylogenetic groupings (genotypes) determined from the sequences were entirely consistent with the antigenic groupings (serotypes) of isolates obtained by using the TYPE-EIA. The genetic variation within genotypes was small compared with the variation between genotypes, allowing unambiguous categorization of all specimens. Although some strains from widely separated geographic areas had identical sequences, in general, within a region most strains of the same type were identical. The TYPE-EIA may help further our understanding of the epidemiology of astrovirus and the possible role of serotype-specific immunity, while further knowledge of sequences could facilitate the development of simpler molecular methods of typing astrovirus strains.

349 citations

Journal ArticleDOI
TL;DR: Over a 2-month period, 12 new MRSA cases caused by isolates carrying mecA(LGA251) were identified, emphasizing the clinical importance of testing for these new MR SA isolates.

348 citations

Journal ArticleDOI
TL;DR: A previously described sequence-based epidemiological typing method for clinical and environmental isolates of Legionella pneumophila serogroup 1 was extended by the investigation of three additional gene targets and modification of one of the previous targets as mentioned in this paper.
Abstract: A previously described sequence-based epidemiological typing method for clinical and environmental isolates of Legionella pneumophila serogroup 1 was extended by the investigation of three additional gene targets and modification of one of the previous targets. Excellent typeability, reproducibility, and epidemiological concordance were determined for isolates belonging to both serogroup 1 and the other serogroups investigated. Gene fragments were amplified from genomic DNA, and PCR amplicons were sequenced by using forward and reverse primers. Consensus sequences are entered into an online database, which allows the assignment of individual allele numbers. The resulting sequence-based type or allelic profile comprises a string of the individual allele numbers separated by commas, e.g., 1,4,3,1,1,1, in a predetermined order, i.e., flaA, pilE, asd, mip, mompS, and proA. The index of discrimination (D) obtained with these six loci was calculated following analysis of a panel of 79 unrelated clinical isolates. A D value of >0.94 was obtained, and this value appears to be sufficient for use in the epidemiological investigation of outbreaks caused by L. pneumophila. The D value rose to 0.98 when the results of the analysis were combined with those of monoclonal antibody subgrouping. Sequence-based typing of L. pneumophila is epidemiologically concordant and discriminatory, and the data are easily transportable. This consensus method will assist in the epidemiological investigation of L. pneumophila infections, especially travel-associated cases, by which it will allow a rapid comparison of isolates obtained in more than one country.

337 citations


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