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M Toucas

Publications and source records attributed to M Toucas.

15 recordsLinked to original sources
PubMed1980

[Correlation between the loss of plasmid DNA and the transition from virulent phase I to avirulent phase II in Shigella sonnei].

Transition from virulent phase I to non virulent phase II in five strains of Shigella sonnei was studied by immunofluorescence and plasmid electrophoresis. High frequency loss of phase I specific antigens was observed by use of fluorescent phase specific antibodies. Agarose gel electrophoresis of bacterial lysates showed that transition from phase I to phase II is associated with the loss of extrachromosomal DNA.

Animals↗
PubMed1979

A code for reporting and comparing results in phage typing.

This code, like the others proposed, involves the definition of a characteristic reaction for each system. Each reaction must be positive or negative. As regards the interpretation of results, it is worth noting that if the bacteriophage typing system uses not less than 5 phages, there is no problem for interpreting the results of small series of 10 to 20 strains, whatever the code used. But should the system use more than 5 phages, the advantage offered by the octal code becomes obvious because, without computer, the manual coding for comparing the results of various series is always possible. Beyond 6 phages, the binary pattern reporting, unintelligible without correction, is possible with an octal number not exceeding 7 digits for a pattern corresponding to a 21-phage set. When very large series of strains are considered, the coding can be completely done and printed out by any computer through a very simple program. This proposed code is not only rational but also a useful method even if the number of phages used is larger than 20 or 30, but after a computer becomes necessary however the coding system used.

Bacteriophage Typing↗
PubMed1978

[Phage-typing modifications induced by "in vitro" transfer of R plasmids. I.--Phage typing of Salmonella typhi (author's transl)].

The phage-typing modifications induced by transfer of antibiotic-resistance plasmids wre studied in two S. typhi Vi+ strains: n 2411 (phage-type A) and Ty2 (phage-type E1a). Forty-one R plasmids belonging to twenty-two incompatibility groups were investigated. Twenty-two plasmids were unable to produce any phage typing modifications. Among the groups of plasmids with phage-typing restriction capacity,four (I1, 10.B.O., N and W) groups were found heterogeneous with regard to this property and one (F1 group) caused significant modifications of the phage-types defined by the Vi phage-typing international system.

Anti-Bacterial Agents↗
PubMedDate not supplied

[Phage-typing modifications induced by in vitro transfer of R plasmids. II. -- Phage-typing of Shigella sonnei (author's transl)].

Forty-two antibiotic resistance plasmids and twelve metabolic plasmids have been transferred to a strain of Shigella sonnei. The phage-typing modifications have been investigated after transfer of the different above described plasmids. Eleven of the R plasmids and five of the metabolic plasmids affect phage sensitivity. These modifications are not specific for any compatibility group.

Anti-Bacterial Agents↗
PubMedDate not supplied

[Interest of gamma-glutamyltransferase in "Enterobacteriaceae" (author's transl)].

Gamma-Glutamyltransferase (gammaGT) could be detected in 86,6% of 3,027 strains of Enterobacteriaceae, by the use of gamma-L-glutamin-p-nitranilide acid for substrate. The following species produced gamma GT: Citrobacter freundii, Levinea malonatica, L. amalonatica, Klebsiella pneumoniae, K. oxytoca, K. ozaenae, Enterobacter aerogenes, E. cloacae, E. agglomerans, E. gergoviae, K. ozaenae, Enterobacter aerogenes, E. cloacae, E. agglomerans, E. gergoviae, Hafnia alvei, Erwinia carotovora, Serratia marcescens, S. liquefaciens, S. plymuthica, S. marinorubra, S. odorifera, S. ficaria, Proteus vulgaris, P. mirabilis, P. morganii, P. rettgeri, Providencia alcalifaciens, P. stuartii, Yersinia enterocolitica and Y. pseudotuberculosis. Most strains of Escherichia coli and Alkalescens Dispar group are gamma GT+. The following species did not produce gammaGT: Shigella sonnei, Edwardsiella tarda, Klebsiella rhinoscleromatis and Yersinia pestis. Within the Salmonella, most strains of subgenus I, II and IV, and diphasic strains of subgenus III (S. arizonae) produced gamma GT, whereas monophasic strains of subgenus III did not produce gammaGT. Salmonella enteritidis (gammaGT+) and S. dublin (gammaGT-) can readily be distinguished. This test (gammaGT) could also serve as a biochemical marker for S. typhi-murium strains. Shigella dysenteriae serotypes 3 to 9 were gammaGT+ whereas other serotypes were gammaGT-. Within S. flexneri serotype 6, varieties Boyd 88 and Newcastle were found gammaGT+; and varieties Sussex and Manchester were gammaGT-. The use of gammaGT test as an epidemiological marker for other Shigella serotypes is suggested.

Enterobacteriaceae↗
PubMedDate not supplied

Plasmid-mediated invasiveness of "Shigella-like" Escherichia coli.

Invasive Escherichia coli is a "Shigella-like" microorganism which causes a dysenteric syndrome through invasion of the human colonic epithelium. Representative strains of different serotypes were studied in order to determine whether plasmids are involved in their virulence. All invasive E. coli strains, irrespective of serotype, were found to harbour a large plasmid of approximately 140 Mdal. Spontaneous variants of serotypes O143 and O124 had lost this plasmid and had become avirulent, i.e. could neither penetrate into HeLa cells nor produce a keratoconjunctivitis in guinea-pigs. pWR110, a Tn5-labelled virulence plasmid of Shigella flexneri, was transferred into these avirulent variants, thus restoring their virulence and demonstrating that S. flexneri and invasive E. coli share a common extrachromosomal control of their ability to penetrate into cells.

Dysentery↗
PubMedDate not supplied

Taxonomic value of a chromogenic test for the detection of aminopeptidases in the genus Shigella.

In addition to the conventional methods for the identification of Enterobacteriaceae, enzymatic tests using chromogenic substrates have been proposed [1, 2, 5, 7, 8, 9, 10]. Many chromogenic and fluorogenic substrates are now available, and some of these have been employed for the determination of enzymatic profiles of Neisseria [3] and Enterobacteriaceae [7]. In this article, we report the activity of bacterial cultures of the genus Shigella on a new chromogenic substrate: chromozym PL.

Aminopeptidases↗
PubMedDate not supplied

[Fermentation of galacturonate by "Shigella" (author's transl)].

The ability of 300 Shigella strains to produce acid from galacturonate (galacturonate test) was examined. With respect to this galacturonate test, all S. flexnerii serotypes (except serotype 6) were positive, and all S. dysenteriae serotypes (except serotypes 8 and 10) negative. In S. boydii, serotypes 5, 7 and 11-13 were positive, and 1-4, 6, 8-10, 14 and 15 negative. In S. dysenteriae (except serotype 8), S. flexnerii and S. boydii, strains of a same serotype gave always identical reactions in the galacturonate test. S. sonnei biotypes d and e and ornithine decarboxylase (ODC) negative strains of biotype a gave a positive galacturonate test. S. sonnei biotypes a (ODC positive strains), g and f were negative in this test.

Fermentation↗