Typing

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

Investigation of an outbreak of Campylobacter upsaliensis in day care centers in Brussels : analysis of relationships among isolates by phenotypic and genotypic typing methods

Abstract: An outbreak of Campylobacter upsaliensis in four Brussels day care centers (A, B-1, B-2, and C) affected 44 children. Diarrhea was the major symptom. From January 1991 to June 1992, the outbreak strain was isolated from 3, 1, and 21 (of 68) children in centers A, B-1, and B-2, respectively, and from 19 of 22 children in center C. IgG, IgM, and IgA antibodies were detected by Western blotting of serum specimens of 9 of 10 and 13 of 16 children in centers B-2 and C, respectively. Strains were typed by biotyping, DNA restriction-based and antibiotic susceptibility typing, whole cell protein and plasmid analysis, restriction fragment length polymorphism (RFLP), and polymerase chain reaction (PCR). On the basis of RFLP and PCR typing, the strains could be divided into two strongly related clonal variants : One was isolated only from the children of center A and the second only from children in the other day care centers.

BOX-PCR is an adequate tool for typing Aeromonas spp.

Abstract: PCR-based methods of fingerprinting take advantage of the presence of repetitive sequences that are interspersed throughout the genome of diverse bacterial species. They include the repetitive extragenic palindromic (REP) sequence, the enterobacterial repetitive intergenic consensus sequence (ERIC) and the 154-bp BOX element. The combination of the three methods is used for fine discrimination of strains and is designated as rep-polymerase chain reaction (PCR). REP-PCR and ERIC-PCR have been shown to be useful for typing Aeromonas strains. To our knowledge, rep-PCR fingerprinting method using the BOXA1R primer has never been tested on aeromonads. In this study, the BOX-PCR fingerprinting technique was evaluated for the discrimination of strains of some Aeromonas species. All strains were typeable and the majority showed unique banding patterns. Four strains from culture collections were used to investigate the reproducibility of the method. According to our results, BOX-PCR fingerprinting is applicable for typing of Aeromonas strains and can be considered as a useful complementary tool for epidemiological studies of members of this genus.

Coagulase gene typing of Staphylococcus aureus isolated from cows with mastitis in southeastern Brazil

Abstract: A typing procedure based on polymorphism of the coagulase gene (coa) was used to discriminate Staphylococcus aureus isolated from Minas Gerais dairy cows with mastitis. Amplification of the gene from the 64 S. aureus isolates produced 27 different polymerase chain reaction (PCR) products; 60 isolates showed only 1 amplicon, and 4 showed 2 amplicons. The isolates were grouped into 49 types by analyzing the restriction fragment length polymorphism (RFLP) of the coa gene; the 10 most common types accounted for 39% of the isolates. The results demonstrate that many variants of the coa gene are present in the studied region, although only a few predominate.

Typing of human rotavirus VP4 by an enzyme immunoassay using monoclonal antibodies.

Abstract: Two different neutralization specificities exist on the outer capsid of group A rotaviruses. At least seven VP7 (G) antigenic types are distinguishable among human rotaviruses. Four distinct antigenic (P) types of human rotavirus VP4 corresponding to separate rotavirus gene 4 groups have been described. The aim of this study was to identify P types in clinical specimens by developing an enzyme immunoassay, using P-type-specific neutralizing monoclonal antibodies (N-MAbs). Three N-MAbs primarily or solely recognizing each of P types 4, 6, and 8 and binding to VP4 or its subunit VP5* were derived. These N-MAbs served as detector antibodies in an enzyme immunoassay P-typing system similar to that in use for G typing. P-type specificity was highest when the G-type specificity of the capture antiserum was matched to the G type of the rotavirus in the test sample. The method correctly identified the P types of 13 well-characterized, cell culture-adapted human rotaviruses and was used to classify a further six strains. P typing of 118 rotavirus-positive stools gave results consistent with the P type inferred from the G type for 98 (83%) samples. Twelve (10%) of the stools showed no reaction with any N-MAb and eight (7%) samples were untypeable because of cross-reactivity between N-MAbs or high background readings. This P-typing enzyme immunoassay system is economical and amenable to large-scale use in epidemiological studies. Its use will facilitate assessment of the distribution of P types worldwide and of the role of VP4 in eliciting protective immune responses.