Annales de microbiologie最新文献

Guinea-pigs were experimentally infected with Legionella pneumophila. L. pneumophila antigen was detected in urine samples by a double antibody sandwich ELISA. Urinary antigen was present from the beginning of the acute phase of the disease. In two out of five cases, this antigen was found with no antibody detectable in sera by indirect immunofluorescence staining.

Ingestion of Bacillus thuringiensis var. israelensis crystals by Aedes aegypti larvae is followed by midgut epithelium disruption. Earliest ultrastructural changes consist of an enlargement of intra- and intercellular spaces in the basal region of the cell. Endoplasmic reticula disintegrate by forming spherical structures which increase in size during intoxication. Mitochondria are transformed at first into a condensed form, then become swollen with the disappearance of internal cristae. In the cardia cells, which secrete the peritrophic membrane, the Golgi apparatus may produce electron-dense secretion vesicles; in this event, the peritrophic membrane assumes an abnormal configuration. Before complete breakdown, a cellular hypertrophy is observed: few cells become balloon-like. At the same time, the microvilli decrease in size, widen and then disappear after a few hours exposure to crystal delta-endotoxin.

Sulbactam and clavulanic acid, both beta-lactamase inhibitors, were studied alone or associated on 85 isolates of Acinetobacter calcoaceticus. When sulbactam was tested alone the minimal inhibitory concentration (MIC) was less than 2 micrograms/ml with the carbenicillin-sensitive strains of A. Calcoaceticus and between 8 to 16 micrograms/ml with the carbenicillin-resistant strains. In the presence of clavulanic acid (5 or 10 micrograms/ml) the MIC of sulbactam on all the carbenicillin-resistant strains decreased to less than 4 micrograms/ml.

The activity of new cyclopentanoic and cyclohexanoic analogues of ethambutol on various strains of mycobacteria was determined. Three compounds were effective mainly on tuberculous strains; only one was like ethambutol, being effective on both tuberculous and saprophytic strains.

Fast-growing Rhizobium and Agrobacterium strans were studied for their behaviour towards two carbohydrates (glucose and fructose) according to the following criteria: acidification and soluble exopolysaccharide production by resting cells. R. meliloti and Agrobacterium spp. showed a similar behaviour: in glucose-containing medium, acidification occurred and few exopolysaccharides were produced, whereas in medium supplemented with fructose, a neutral pH was maintained and large amounts of exopolysaccharides were synthesized. Other fast-growing Rhizobium spp. did not acidify these media and produced variable amounts of exopolysacchrides.

N-formimidoyl-thienamycin (MK-0787) is not subject to beta-lactamase hydrolysis. Nevertheless, this compound does show some affinity for the TEM-type penicillinases, cephalosporinases and a few other beta-lactamases. Surprisingly no affinity was found for the penicillinases of the CARB-type. The results thus obtained for affinity constants Ki and Km were submitted to a statistical analysis treatment, i.e. correspondence analysis and hierarchic ascendent classification. This confirms the fact that MK-0787 presents an unusual behaviour towards beta-lactamases.

The antibiotic resistance of 12 strains of Shigella sonnei isolated in Sicily was studied. All the strains were proved to carry autotransferable R plasmids belonging to 4 incompatibility groups: Inc I1, FI, FII and B-10-0. The variety of R plasmids identified gives evidence of the frequency of exchange of S. sonnei with other enterobacteria.

CAMP-tests with Staphylococcus aureus and Rhodococcus equi and acid production from D-xylose allowed to separate the five DNA relatedness groups described for Listeria monocytogenes sensu lato; acid production from L-rhamnose and alpha-methyl-D-mannoside are secondary markers.

Analysis of the lipids of seven species of Micromonospora showed the constant presence of five phospholipids and three glycolipids. The phospholipids were identified as cardiolipids, phosphatidylethanolamine, phosphatidyl-inositol, mannosides of phosphatidyl-inositol, and possibly lysocardiolipids. The glycolipids were monoglucosyl-diglycerides, diglucosyl-diglycerides (with a small amount of galactosyl-glucosyl-diglycerides) and esters of fatty acids and trehalose. The simultaneous presence of glucosyl-diglycerides and trehalose esters might be specific of the genus Micromonospora. In the seven species studied, a large amount of the total fatty acids (obtained by direct saponification of the cells) consisted of iso and anteiso fatty acids. Three groups could be distinguished, having respectively iso-C15, iso-C16 and n-C17 fatty acids as the main members. A monounsaturated C17 acid has been identified as heptadec-9,10-enoic acid.

The extracellular endo-beta-1.4-glucanase activity of Bacteroides succinogenes S85, grown on filter paper, was poorly stimulated by cysteine, slightly inhibited by cellobiose, but strongly inhibited by ethylthiomercuribenzoate. Active fractions against hydroxy-ethylcellulose and milled filter paper were eluted from a polyacrylamide gel filtration column with an apparent molecular weight of 60,000 daltons.