Topic
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: A new DNA-based typing approach that is rapid, fully automated, and therefore suitable for routine typing, and easily applicable to other gene systems is developed.
89 citations
TL;DR: The high rate of exclusion reported here combined with the ability of PCR to type old evidence samples suggests the relevance of this genetic test for postconviction review; two cases in which the convicted suspect was excluded are discussed.
Abstract: The polymerase chain reaction (PCR) method of specific gene amplification was used in casework to synthesize millions of copies of the polymorphic second exon of the human leukocyte antigen (HLA)-DQ alpha (or DQA1) locus from a variety of evidence samples The HLA-DQ alpha allelic variants in the amplified deoxyribonucleic acid (DNA) were determined in a rapid non-radioactive test by hybridization to sequence-specific oligonucleotide probes in both the dot-blot and reverse dot-blot formats This genetic typing system has been subjected to blind proficiency testing; the performance of this test in the analysis of experimentally mixed samples was also evaluated As of August 1990, over 250 cases have been tested and more than 2000 individual evidence (bloodstains, semen stains, individual hairs, bone fragments, and tissue sections) and reference samples have been analyzed The first 198 of these cases are summarized in this paper; in 65% of the cases with conclusive results a suspect was included, and in 35%, all suspects were excluded Individual cases as well as some of the general issues relating to forensic science analysis and this genetic typing system are discussed The high rate of exclusion reported here combined with the ability of PCR to type old evidence samples suggests the relevance of this genetic test for postconviction review; two cases in which the convicted suspect was excluded are discussed
89 citations
TL;DR: The findings suggest that food animals could represent an important reservoir of PMQR in this region of Africa, and that the spread of these resistance determinants in this country could be particularly relevant.
Abstract: Methods: One hundred and sixty-two ampicillin-resistant E. coli were obtained from healthy chickens and pigs at slaughter in Ibadan, Nigeria. Strains were tested for antimicrobial susceptibility by disc diffusion assay. MICs of ciprofloxacin were determined by Etest. Resistance genes were screened by PCR and DNA sequencing. Clonal relatedness of the isolates was determined by enterobacterial repetitive intergenic consensus –PCR. Plasmids were transferred by conjugation and transformation and characterized by PCR-based replicon typing and plasmid multilocus sequence typing. Results: PMQR genes were detected in 18 E. coli strains; 11 of them showed reduced susceptibility to ciprofloxacin. Twelve strains carried qnrS1, three strains carried qnrB19, one strain carried qnrB10 and three strains carried qepA; one strain carried both qepA and qnrB10. All strains carried the blaTEM gene; one strain was positive for the CTX-M-15 extended-spectrum b-lactamase. Conclusions: Our findings suggest that food animals could represent an important reservoir of PMQR in this region of Africa. Previous studies reported high prevalence of qnr genes in clinical isolates from humans in Nigeria, suggesting that the spread of these resistance determinants in this country could be particularly relevant.
89 citations
TL;DR: A protocol is described that enables sequencing of the spa gene fragment directly from a multiplex PCR targeting the clinically relevant mecA, pvl and spa genes, resulting in high-throughput characterisation of S. aureus.
89 citations
TL;DR: Application of this typing method to C. trachomatis strains isolated from clinical material gave the same results as the immunotyping method for 14 of 17 strains, and restriction endonuclease analysis detected differences within a serovar.
Abstract: A procedure was developed for characterization of Chlamydia trachomatis strains by using restriction endonuclease analysis of amplified genes of the major outer membrane protein (MOMP) Reference strains of the 15 serovars (A through K and L1 through L3) and clinical isolates were tested The nucleotide sequences of the MOMP genes of each of the 15 serovars were arbitrarily constructed by using the sequences of the four variable domains known for each serovar and the constant domains of serovar L1 Computer analysis of these sequences indicated that two restriction digestions performed in parallel, one with AluI and the other with IIpaII, followed by HinfI and EcoRI, would allow the theoretical differentiation of 13 serovars Serovars Ba and L1 presented the same theoretical restriction profile Our typing method consisted of polymerase chain reaction amplification of a fragment of about 1,200 bp of the MOMP gene, followed by restriction endonuclease digestion with the aforementioned enzymes From the 15 serovars, we obtained 14 different patterns; 13 profiles were serovar specific, while serovars B and Ba presented the same pattern Application of this typing method to C trachomatis strains isolated from clinical material gave the same results as the immunotyping method for 14 of 17 strains Furthermore, restriction endonuclease analysis detected differences within a serovar This method seems to be promising for epidemiological studies
89 citations