Showing papers on "Typing published in 1973"

A simplified method for immunological typing of trachoma-inclusion conjunctivitis-lymphogranuloma venereum organisms.

Abstract: Responding to the pressure of large numbers of trachoma-inclusion conjunctivitis (TRIC)-lymphogranuloma venereum (LGV) isolates from field studies requiring serotyping, we have developed a simplified, less-precise method that utilizes cell culture-grown organisms to produce mouse antisera which is tested agaist prototype TRIC-LGV antigens in the micro-immunofluorescence test. Cell cultures with as few as 5 to 15% of cells showing inclusions produced adequate antibody in mice 4 days after single injection. Knowledge of the reaction of prototype antisera with the antigens has allowed typing of most isolates tested from the pattern of cross-reaction of their antiserum.

Phage typing of coagulase-negative staphylococci and micrococci

Abstract: A total of 3217 strains of coagulase-negative staphylococci and micrococci were tested for susceptibility to a collection of phages isolated from coagulase-negative cocci; it was concluded that a useful typing scheme could be developed. Of the strains of Baird-Parker's biotype 1, 72% were lysed by one or more phages, although rather a large proportion of strains are lysed by many phages to give a complex typing pattern.Normal persons commonly yield 10 or more distinguishable strains of coagulase-negative cocci in cultures from the nose and the skin.

Nursery outbreak of Pseudomonas aeruginosa: epidemiological conclusions from five different typing methods.

Abstract: In April 1971, nine cases of Pseudomonas aeruginosa septicemia occurred in a high-risk nursery. The epidemiology of the outbreak was studied by pyocin production, pyocin sensitivity, serological typing, antibiotic susceptibility, and phenotypic properties such as colonial morphology, pigment, and hemolysis. Ten isolates of P. aeruginosa were recovered from 9 newborn infants and from 13 environmental sources. Twenty-one of the 23 isolates had identical pyocin production patterns against 60 different indicator strains and were of the same serotype. These 21 isolates were designated as the „outbreak strain”; the other 2 isolates had no epidemiological significance. The results of pyocin sensitivity, antibiotic susceptibility tests, and phenotypic properties were dissimilar. They would yield incorrect epidemiological conclusions if used alone. The outbreak strain dissociated in vitro and these phenotypic changes accounted for the variable results by the latter three typing methods. Although the precise mode of introduction of the organism into the nursery could not be determined in retrospect, the epidemiological data strongly suggested that one infant contracted a P. aeruginosa infection, and this strain spread throughout the nursery by means of contaminated resuscitation equipment.

Quantitative differentiation of Yersinia pestis strains by their murine toxin and fraction I contents

Abstract: Until now the serological typing of Yersinia pestis into subgroups has not proved possible because all the antigenic components are present in each isolate. Using acrylamide disk electrophoresis it was observed that differences exist in the protein distribution patterns of aqueous extracts from various Y. pestis isolates. One component that was especially plentiful in some Javanese and South American isolates was identified as the murine toxin. The amount of murine toxin varies significantly from isolate to isolate, and so permits them to be roughly grouped. In 28°C cultures the variation in the murine toxin content is independent of the variation in the F-I content. A new method of typing based on this 2-trait variation in quantities, in contrast to classical typing based on qualitative differences, might prove to be a means of differentiating Y. pestis isolates.

Re s is to ty p i n g 0 f shig ell a so nnei

Abstract: RE s I s T o T Y P I N G is based on the selective toxicity of randomly chosen chemicals. By the use of a suitable range of selective substances, at critical concentrations, a pattern of resistance can be obtained that is characteristic of a strain. This approach was first described by Elek and Higney (1970) and illustrated by its application to Escherichia coli in relation to serology. The general principle can, however, be applied to any commonly occurring pathogenic bacterium for which a system of typing is required for epidemiological purposes. Shigella sonnei is a single species, and cannot be subdivided by serology. It is also the commonest and only endemic dysentery bacillus at present in England. Small- or medium-sized outbreaks occur fairly frequently and colicine typing, considered together with the antibiogram, provides at present the only tool for the tracing of this organism within a community. Eleven substances were chosen as the basis of a resistogram system for S. sonnei. The results of typing were compared with the colicine types and antibiograms, and were examined in the light of the known epidemiological background of the isolates.