Typing

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

Bacteriocin (Marcescin) typing of clinical isolates of Serratia marcescens.

Abstract: A simple, reproducible technique is described for bacteriocin typing of clinical isolates of Serratia marcescens. With 10 marcescin-producer strains, a total of 46 of 50 isolates (92%) of S. marcescens could be typed and categorized into 16 provisional types according to their sensitivity or tolerance to marcescins. The potential significance of this procedure with regard to delineation of outbreaks of nosocomial infection is discussed on the basis of preliminary epidemiological data.

Epidemiologic typing systems.

Abstract: Microbial strain typing is a useful adjunct to clinical epidemiology. Phenotypic typing systems examine expressed characteristics, whereas genotypic systems, including recent PCR-based systems, examine chromosomal or plasmid DNA. Typing systems have evaluated bacteria, fungi, and viruses successfully. The criteria used to assess the utility of each system include typeability, reproducibility, and discriminatory power.

Identification of the Major Spanish Clones of Penicillin-Resistant Pneumococci via the Internet Using Multilocus Sequence Typing

Abstract: Multilocus sequence typing was used to characterize isolates of the major Spanish clones of penicillin-resistant and multiple-antibiotic-resistant Streptococcus pneumoniae. Isolates of the multidrug-resistant Spanish serotype 23F clone and serotype variants of this clone either had identical allelic profiles or their allelic profiles differed from this typical allelic profile at only one of the seven housekeeping loci. Similarly, isolates of the Spanish serotype 6B and 14 clones and the penicillin-resistant serotype 9V clone (and serotype variants of this clone) each had the same allelic profiles or profiles that differed at a single locus. Multilocus sequence typing therefore allows resistant pneumococci to be assigned to the Spanish clones if they have the typical allelic profile of the clone or if their profiles differ from that profile at a single locus. A few resistant isolates that had allelic profiles typical of that of a Spanish clone or whose profiles differed from that of the typical profile at only a single locus possessed penicillin-binding protein pbp1a, pbp2b, or pbp2x genes that differed from those that are characteristic of the clone. In most cases these isolates could be assigned as variant members of the clone. Since almost all serotype 9V isolates have very similar genotypes, independently emerging penicillin-resistant clones of this serotype will inevitably appear to be similar by molecular typing procedures. Analysis of the pbp genes, in addition to multilocus sequence typing (or any other molecular typing procedure), is therefore required to assign isolates unambiguously to the penicillin-resistant Spanish serotype 9V clone.

Rapid molecular typing of methicillin-resistant Staphylococcus aureus by PCR-RFLP.

Abstract: Objective To establish a new, rapid, and reliable genotypic fingerprinting technique for methicillin-resistant Staphylococcus aureus (MRSA) typing in routine epidemiological surveillance. Design The method is based on polymerase chain reaction (PCR) restriction fragment-length polymorphism (RFLP) following HaeII digestion of simultaneously amplified parts of the protein A gene, the coagulase gene, and the hypervariable region adjacent to mecA. A total of 46 MRSA initial isolates were analyzed, including 14 isolates from five countries; the six German epidemic strains; 16 isolates from the Frankfurt metropolitan area, which were known to be heterogeneous by pulsed-field gel electrophoresis (PFGE); and 10 isolates obtained during three epidemics, all of which displayed an identical genotype. Results Restriction analysis by PCR-RFLP permitted discrimination of 10 of 14 international isolates, all six German epidemic strains, and 15 of 16 national isolates. It also confirmed the homogeneous character of the 10 outbreak isolates. Conclusions This new and rapid PCR-RFLP typing method is an attractive tool in routine epidemiological surveillance. Its impressive characteristics are ease of performance and interpretation, while at the same time guaranteeing good discriminatory power, reproducibility, and typeability.