Annales de microbiologie最新文献

Holoxenic Hairless mice were used in an experimental model to study the in vivo bactericidal activity of several antiseptics. In these experiments skin was sampled by biopsy; after contact between antiseptic and skin, bactericidal activity was neutralized. The results obtained with several products (polyvinylpyrrolidone iodine, alcoholic iodine, ethanol, chlorhexidin, benzalkonium chloride, mercurothiolic acid, trichlorocarbanilid and hexachlorophen) were quite similar to those obtained on human skin. The differences must be related to the composition of the Hairless mouse skin flora which contains Staphylococcus xylosus, Micrococcus sp. and Streptococcus faecalis, but does not contain Corynebacterium sp. or Propionibacterium sp.

The C14 to C18 fatty acid content of spongious bone was measured by gas-liquid chromatography. Palmitic acid (C16:0), oleic acid (C18:1) and linoleic acid (C18:2) represented 20 to 40% of the total free fatty acid concentration (30 mM/l). Linoleic acid was found to have the greatest bacteriostatic activity against Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa strains. The effect of linoleic acid-gentamicin combination was synergistic against S. aureus. In contrast, both gentamicin and colistin activities were highly antagonized by linoleic and oleic acids against E. coli and P. aeruginosa strains. These different effects of free fatty acids on antibiotic activity could be explained, in part, by a change in permeability of bacterial cells. The clinical implications of these results in bone infections are discussed.

With the aim of knowing more exactly what species and biotypes are responsible for brucellosis in France, 2,058 strains have been examined since 1972. Of these, 1,693 were isolated from cattle, 190 from sheep, 10 from hare, 9 from goats, 3 from swine and 3 from field mice (Apodemus sylvaticus); 150 were of cases of human infection. Of the 18 types presently recognized for the genus Brucella, 11 were identified within the sample. In animal strains, they were B. abortus biotypes 1, 2, 3, 4 and 9, B. suis biotypes 1 and 2, B. melitensis biotypes 1, 2 and 3, and B. ovis. All these types--except B. suis 2 and B. ovis--were identified within the human strains. Of these 11 types, 3 were widely predominant both in man and animals: B. abortus biotypes 1 and 3 and B. melitensis biotype 3, which together total 84.2% of the sample's strains. The results also emphasized the preference of B. abortus, B. melitensis and B. ovis for a decided animal host: 99.4% of the bovine strains were B. abortus, 98.1% of those isolated from ewes and goats were B. melitensis, and all the B ovis strains were from cases of ram epididymitis. Of the 150 human strains, 115 were B. melitensis, 33 B. abortus and 2 B. suis. These data were discussed from a taxonomical and epidemiological point of view.

The present paper summarizes results concerning a mild isolation method of Mycobacterium lepraemurium and M. bovis-BCG from host tissues, and describes the application of such a method in purifying M. leprae (M1) from either infected armadillo tissues or human skin biopsies. This isolation method consists of homogenization, two-phase partition in dextranpolyethylene glycol and finally sedimentation in sucrose gradient using a unit gravity chamber. Such a purified M1 preparation appears to be devoid of host-tissue contaminants as examined by light and electron microscopy as well as by a radioimmuno spot test. The results indicate that the present method is mild enough to allow the purification of M1 from infected host tissues with in vivo conservation of antigenicity and viability of the bacilli.

Twenty clinical isolates of ampicillin- and carbenicillin-resistant or susceptible (two strains) Gram-negative rods, producing at least one beta-lactamase, were examined for susceptibility to a combination of ampicillin or carbenicillin with clavulanic acid (enzymatic inhibitor). Synergy was evaluated by the reduction of the beta-lactam agar dilution MIC and by the measurement of intracellular AYP using firefly bioluminescence. The potentiation effect of clavulanic acid was variable, depending on resistance levels, species and types of beta-lactamase (TEM, SHV-1, CARB, OXA, MAL and Cpase). The synergy was significant, with 10 mg/l of inhibitor for all the strains producing TEM-1, TEM-2 and Carb-2 except for one strain of Serratia marcescens (TEM-2). The synergy was weak for Levinea strains (Citrobacter diversus biotype b), biosynthesizing specific penicillinases as MAL-1. No potentiation effect was observed for strains producing a cephalosporinase, such as Escherichia coli and Pseudomonas aeruginosa. This effect appeared to be variable for strains producing the oxacillin-hydrolysing enzyme (OXA-1), such as E. coli and P. aeruginosa. A positive correlation was clearly demonstrated between the MIC values and the intracellular ATP concentration in bacteria within 2 h. The opportunity of using the firefly assay for the rapid determination of synergy between beta-lactam antibiotics and clavulanic acid is discussed.

Microcristalline cellulose (cellulose Avicel, Merck) supported growth of Trichoderma harzianum and induced production of cellulases in liquid cultures. After 50 h growth, the total cellulasic activities present in both the supernatant and the mycelium were 3,000 IU/l of carboxymethyl cellulose, 400 IU/l of filter paper activity, and 4 IU/l of cotton activity corresponding to 1.7 g/l of proteins. Cellulase production could be increased by a preliminary treatment of cellulose, and pH regulation during growth. The influence of inoculum concentration was studied and an optimum of 3 x 10(7) conidia/g dry weight of substrate was demonstrated. Using a synthetic culture medium, a soluble factor of germination was demonstrated which could be leached out by 3 successive washings of conidia.

In the mouse foot pas, deoxyfructo-serotonin (DFS) shows a definite inhibitory effect on the multiplication of M. leprae in Dapsone-sensitive as well as Dapsone-resistant cases. In clinical trials, based on 7 cases treated with DFS for an average period of 6 months, the beneficial effects of DFS are observed after a few weeks of treatment in BB cases, and after a few months in LL cases. In addition to clear improvements in the appearance of the skin (regression and healing of nodules, almost complete disappearance of infiltration, etc) one observes in the majority of cases a rapid improvement in the bacteriological and morphological indexes, the latter falling to 0%. In the course of these studies, no single suggestion of intolerance was detected.

A total of 129 strains of Haemophilus influenzae were tested for susceptibility to twelve antibiotics. Capsular serotypes and biotypes were determined, and the relation between these parameters and minimal inhibitory concentrations (MIC) were analysed. Non-capsulated strains were more susceptible to streptomycin than capsulated ones. The distribution of MIC of chloramphenicol among biotypes was different. The distribution of MIC of penicillin G, tetracycline and chloramphenicol among sources of isolation was also different. Therefore the strains did not have the same origin, and one should look at the concept of organotropism for H. influenzae.