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PubMedDate not supplied

[The possibility of colonizing the intestines of white mice with Lactobacillus acidophilus during bacterial therapy].

The study revealed the possibility, on principle, for L. acidophilus strain VKM V-2020 D to colonize the intestine of white mice with the preservation of the viability of lactobacilli subjected to the action of antibiotics. The culture of this strain, isolated from the animals, showed the stability of its biological properties: resistance to polymyxin M, kanamycin, cyprofloxacin, nalidixic acid (including acquired resistance to rifampicin), as well as pronounced antagonism with respect to Vibrio cholerae. Good prospects for the use of L. acidophilus strain VKM V-2020 D for further studies regarding its use for prophylaxis and therapy were noted.

Animals↗

PubMed1991

High efficiency transformation of Tolypocladium geodes conidiospores to phleomycin resistance.

A convenient and efficient transformation system has been developed for the filamentous fungus Tolypocladium geodes. In contrast to most of the commonly described techniques requiring prior preparation of protoplasts or spheroplasts, this method leads to high efficiency transformation of T. geodes conidiospores following moderate lytic enzyme treatment. Competent cells so obtained are still resistant to osmotic pressure and can be stored frozen without loss of viability. The highest transformation frequency (3-5 x 10(3) transformants per microgram of DNA) was obtained with plasmid pUT737 containing the Sh ble gene conferring phleomycin resistance under the control of a strong promoter isolated from Trichoderma reesei. Southern hybridization revealed multiple integration sites of plasmid DNA into the T. geodes nuclear DNA despite the absence of homology between the transforming DNA and the recipient genome. Instability could not be detected for the phleomycin phenotype during more than five generations of mitotic growth under non-selective conditions.

Blotting, Southern↗

PubMed2002

Susceptibility of Candida albicans isolates from the oral cavities of HIV-positive patients to histatin-5.

STATEMENT OF PROBLEM: Oral surfaces, including the denture-fitting surface, may serve as a reservoir for disseminated candidal infections, particularly in immunocompromised hosts such as patients with AIDS. Histatins are a group of small, cationic antifungal peptides present in human saliva. There is limited information on the antifungal activity of peptides against Candida albicans isolates from HIV-positive patients. PURPOSE: This study investigated the fungicidal effects of histatin-5 against oral isolates of C. albicans from HIV-positive and HIV-negative patients. MATERIAL AND METHODS: An isolate of C. albicans from each of 2 HIV-positive patients (both male) and 3 HIV-negative patients (2 male and 1 female) was obtained. American Type Culture Collection 90028 served as a reference strain. All isolates were identified with sugar assimilation tests and the germ tube test. Fungicidal assays were performed on exponential C. albicans cells in the presence or absence of 0.315 to 50 microm of histatin-5. Numerical data were subjected to 1-way analysis of variance and Tukey's multiple range test (P<.05). RESULTS: Histatin-5 (50 microm) killed more than 95% of C. albicans isolates from HIV-negative patients and more than 90% of isolates from the reference strain. The same treatment induced 75.3% and 66.1% loss of viability in C. albicans isolates taken from HIV-positive patients (A1 and A2 cells, respectively). The difference between the fungicidal effects in the HIV-positive and HIV-negative groups was significant. (P<.05). CONCLUSION: Within the limited population of this study, C. albicans isolates from the oral cavities of HIV-positive patients were less sensitive to histatin-5 than oral isolates from HIV-negative patients.

AIDS-Related Opportunistic Infections↗

PubMed1994

Activity of aztreonam in pneumology, Part 2: Influence on phagocytosis and intracellular killing of human alveolar macrophages.

The study aim was to evaluate the activity of aztreonam on phagocytosis and intracellular killing of Staphylococcus aureus ATCC6538 by human alveolar macrophages. Drug concentrations of 1, 10, 25, 100 micrograms/ml were assayed in culture medium. Aztreonam induces dose-dependent phagocytosis up to 25 micrograms/ml concentrations; with a phagocytosis index (PIa) of 1.18 +/- 0.2 at 1 microgram/ml; of 1.27 +/- 0.2 at 10 micrograms/ml; of 1.42 +/- 0.3 at 25 micrograms/ml. No phagocytosis increase or inhibition, with unchanged cell viability compared to controls, is shown at 100 micrograms/ml aztreonam (PI 1.03 +/- 0.3). Intracellular killing acts in a similar way: the killing index (KIa) is 1.27 +/- 0.3 at 1 microgram/ml concentrations; 1.38 +/- 0.3 at 10 micrograms/ml; 1.61 +/- 0.4 at 25 micrograms/ml whereas at 100 micrograms/ml the KIa is 1.03 +/- 0.3. This study shows aztreonam's ability to stimulate macrophages' functional activity against a microorganism (S. aureus) which is not susceptible to its antibacterial activity.

Adjuvants, Immunologic↗

PubMed2000

Improved direct viable count procedure for quantitative estimation of bacterial viability in freshwater environments.

A direct viable count (DVC) procedure was developed which clearly and easily discriminates the viability of bacterial cells. In this quantitative DVC (qDVC) procedure, viable cells are selectively lysed by spheroplast formation caused by incubation with antibiotics and glycine. This glycine effect leads to swollen cells with a very loose cell wall. The viable cells then are lysed easily by a single freeze-thaw treatment. The number of viable cells was obtained by subtracting the number of remaining cells after the qDVC procedure from the total cell number before the qDVC incubation. This improved procedure should provide useful information about the metabolic potential of natural bacterial communities.

Bacteria↗

PubMed2005

Cyanide detoxification by recombinant bacterial rhodanese.

Cyanide is a major environmental pollutant of the chemical and metallurgical industries. Although extremely toxic, cyanide can enzymatically be converted to the less toxic thiocyanate by rhodaneses (thiosulfate:cyanide sulfurtransferases, EC 2.8.1.1). We engineered a genetic system to express high levels of recombinant Pseudomonas aeruginosa rhodanese (r-RhdA) in Escherichia coli, and used this organism to test the role of r-RhdA in cyanide detoxification. Inducible expression of the rhdA gene under the control of the hybrid T7-lacO promoter yielded active r-RhdA over a 4-h period, though r-RhdA-expressing E. coli showed decreased viability starting from 1 h post-induction. At this time, Western blot analysis and enzymatic assay showed r-RhdA partition between the cytoplasm (95%) and the periplasm (5%). The accessibility of thiosulfate to r-RhdA was a limiting step for the sulfur transfer reaction in the cellular system, but cyanide conversion to thiocyanate could be increased upon permeabilization of the bacterial membrane. Specific r-RhdA activity was higher in the whole-cell assay than in the in vitro assay with pure enzyme (2154 vs. 816 micromol min-1 mg-1 r-RhdA, respectively), likely reflecting enzyme stability. The r-RhdA-dependent cyanide detoxification resulted in increased resistance of r-RhdA overexpressing E. coli to 5 mM cyanide. Bacterial survival was paralleled by release of thiocyanate into the medium. Our results indicate that cyanide detoxification by engineered E. coli cells is feasible under laboratory conditions, and suggest that microbial rhodaneses may contribute to cyanide transformation in natural environments.

Biodegradation, Environmental↗

PubMed1998

Use of almond mesocarp for production of the entomopathogenic fungus Verticillium lecanii.

Almond mesocarp (AM) has been evaluated for production of Verticillium lecanii. Microbial flora of AM has been studied. After ground AM dilution plating, 5.3 x 10(5) +/- 2.6 x 10(4) fungal CFU.g-1 of dry AM were found. Common fungal saprophytes (Rhizopus sp. and Alternaria spp.) were found in more than 80% of the samples. Aspergillus sp. and yeasts were found less commonly. Rhizopus sp., Alternaria spp., and Aspergillus sp. inhibited growth of several V. lecanii; therefore, AM was treated with sterilization agents to eliminate endogenous mycoflora. Small samples (10 g) of AM saturated in distilled water treated with steam (120 degrees C and 100 kPa) were completely sterilized after 15 min. Ground AM incorporated on agar increased the biomass of V. lecanii compared with controls. This suggested AM as suitable substrate for the production of the fungus. In petri dishes, 9.7 x 10(7) +/- 2.9 x 10(7) conidia.g-1 of dry AM were produced after inoculating 10 conidia.g-1 of AM and incubating for 2 weeks. Viability of conidia produced was more than 90%. These conidia (5 x 10(4) conidia per larvae) caused Galleria mellonella mortality, calculated as median lethal time (LT50 5.3 +/- 1.6 days), that was significantly higher (F = 10.93; P < 0.05) than untreated controls (LT50 11.3 +/- 1.1 days). Larger scale tests have to be optimized before mass production.

Fungi↗

PubMed1995

High sensitivity of Mycobacterium species to the bactericidal activity by polylysine.

Bactericidal effects of polylysine on different bacterial species were measured. Marked differences in sensitivity were observed. Based on the concentration of polylysine required to reduce cell viability by 50%, Mycobacterium smegmatis and Mycobacterium tuberculosis were found to be the most sensitive and Escherichia coli the most resistant. In addition, two Gram-positive organisms, Staphylococcus epidermidis and Streptococcus salivarius exhibited significant differences in sensitivity which suggests that the relationship between sensitivity towards polylysine and bacterial cell type is not necessarily a function of the overall cell envelope structure. The high sensitivity of mycobacteria suggests the possible use of polylysine, or a conjugate of polylysine and another agent in anti-mycobacterial drug design.

Anti-Bacterial Agents↗

PubMed1989

An improved procedure for enzymatic harvesting of highly purified canine venous endothelial cells for experimental small diameter vascular prostheses.

We developed a new device, the vein holder, to improve yield and purity of enzymatic harvests of venous endothelial cells. External jugular veins of mongrel dogs were dissected by a no-touch technique. In vitro length and circumference of the vein segments were decreased to about half of the in situ dimensions. The vein holder enabled mounting of the veins at 80% of their in situ length during endothelial cell harvesting. Trypan blue staining and scanning electron microscopic observations revealed that vein eversion as well as the new vein holder technique successfully removed the endothelium. Endothelial cell harvests by the eversion technique were, however, low and varied in size, viability, and purity. In contrast, the defined handling by the new vein holder technique regularly provided markedly increased amounts of endothelial cells. Most of the cells attached and developed cultures consisting of endothelial cells only, as shown by the uptake of DilAcLDL. Prostacyclin production of confluent cultures was similar to that of native veins. It is concluded that minimal handling, defined mounting, and prevention of overfilling the vein markedly improves endothelial cell harvests, providing greater amounts of viable and purified endothelial cells.

Animals↗

PubMed1981

Some observations on the activity of three antiseptics used as bladder irrigants in the treatment of urinary tract infection in patients with indwelling catheters.

A comparison has been made of the activity of three antiseptics that are used as bladder irrigants in the treatment of urinary tract infection in catheterised patients. At the concentrations and exposure times used for bladder irrigation, phenoxyethanol (2:4% v/v) proved to be highly bactericidal against urine-grown cells of all the common urinary pathogens tested. Chlorhexidine (200 microgram/ml) was active against Escherichia coli and produced significant reductions in the viability of Klebsiella pneumoniae, Proteus mirabilis and Pseudomonas aeruginosa but failed to eradicate Providencia stuartii. Exposure to noxythiolin (2.5% v/v) for 20 min had little effect in any of the bacteria, even though all strains tested had been recorded as noxythiolin-sensitive by conventional plate sensitivity tests. Contact with noxythiolin for periods of at least 1-2 hrs was necessary before extensive bactericidal activity was detected. These results provide an explanation of the poor clinical performance of noxythiolin that we have observed.

Anti-Infective Agents, Urinary↗

PubMed2004

In-vitro activity of nikkomycin Z alone and in combination with polyenes, triazoles or echinocandins against Aspergillus fumigatus.

The in-vitro activity of nikkomycin Z was investigated in combination with polyenes, triazoles or echinocandins against 20 clinical isolates of Aspergillus fumigatus with the fractional inhibitory concentration index (FICI) method. The drug interactions were classified as synergic (FICI < or = 0.5), no interaction (FICI > 0.5, but FICI < or = 4) or antagonistic (FICI > 4). The fungicidal activity of nikkomycin Z alone and in combination with a representative echinocandin (caspofungin) or triazole (voriconazole) was also examined with time-kill experiments and fungal cell viability assays. Two-drug combinations of nikkomycin Z with amphotericin B (FICI 3.59 +/- 0.57), amphotericin B lipid complex (FICI 3.95 +/- 0.74), liposomal amphotericin B (FICI 3.62 +/- 0.98), itraconazole (FICI 2.0 +/- 0.0), voriconazole (FICI 1.07 +/- 0.37), posaconazole (FICI 2.20 +/- 0.44) or ravuconazole (FICI 1.76 +/- 0.44) showed no interactions, but the pairwise combination of nikkomycin Z with caspofungin (FICI 0.22 +/- 0.19) or micafungin (FICI 0.35 +/- 0.27) showed synergic activity against A. fumigatus. Time-kill studies and fungal cell viability assays showed that neither nikkomycin Z nor caspofungin alone possessed fungicidal activity against A. fumigatus, whereas a combination of these two drugs at concentrations > or = 2 mg/L (> or = 0.031 x the concentration of drug that produced no visible growth) killed germinated conidia within 24 h in a concentration-dependent manner. These data suggest that two-drug combinations of nikkomycin Z with echinocandins, but not with polyenes and triazoles, have a synergic effect against A. fumigatus.

Aminoglycosides↗

PubMedDate not supplied

Fragmentation of the ribosome to investigate RNA-ligand interactions.

RNA molecules perform a variety of important and diverse functions and, therefore, an understanding of their structure and interaction with proteins and ligands is essential. Large RNA molecules (for example, the ribosomal RNAs) are complex and hence reports describing their fragmentation into functional subdomains has provided a means for their detailed analysis. We present here an in vivo approach to study RNA-ligand interactions. This is based on the concept that an RNA fragment could mimic a drug-binding site present on the intact molecule. Overexpression of the fragment would sequester the drug thereby permitting the continued functioning of the ribosome and, thus, ensuring cell viability. Accordingly, a fragment of 16S rRNA encompassing the spectinomycin-binding domain in helix 34 (nucleotides 1046-1065 and 1191-1211) was cloned and in vivo expression resulted in drug resistance. Furthermore, an RNA fragment lacking flanking sequences to helix 34 was also selected from among a pool of random rRNA fragments and shown to confer spectinomycin resistance. A similar in vitro approach is also described for the analysis of rRNA molecules that interact with the yeast elongation factor 3 (EF-3).

Anti-Bacterial Agents↗

PubMed1986

[Virulence, viability and antibiotic sensitivity of the causative agent of plague growing on nutrient media at 28 and 37 degrees C].

A comparative study of virulence, viability and antibiotic sensitivity of Y. pestis strains grown at 28 degrees C and 37 degrees C in yeast-casein medium, yeast medium with Hottinger's meat digest and yeast medium with protein hydrolysate obtained from sunflower seed groats has been made. These media have been found to be suitable for the prolonged cultivation of Y. pestis at 28 degrees C and 37 degrees C, for the determination of its sensitivity to antibiotics, as well as for the preservation of Y. pestis cultures.

Animals↗

PubMed1998

Clarification of small volume microbial suspensions in an ultrasonic standing wave.

The removal of Saccharomyces cerevisiae and Escherichia coli from 2.5 ml suspensions in ultrasonic standing wave formed at 1 or 3 MHz has been characterized. The standing wave was set up by a plane transducer and reflector mounted in the vertical plane. Cells in the ultrasonic field first concentrated in vertical planes at half wavelength separations. The ultrasound was then pulsed to allow clumps of concentrated cells to sediment in a controlled way during the short 'off' intervals. Yeast removal from suspension at a concentration of 3 x 10(9) ml-1 (14% volume v/v) was 99.5% in a total time of 4.5 min. Almost total (99.5%) clarification of prokaryote (E. coli) suspension was achieved here for the first time in a standing wave field. The clarification of a 1.3 x 10(11) ml-1 (16% v/v) E. coli suspension occurred over 11.5 min. The period decreased to 7 min in the presence of a polycationic flocculant, polyethyleneimine. The implications of the results for design of systems to further reduce clarification times are discussed. Removal efficiency for both S. cerevisiae and E. coli decreased with decrease in cell concentration. This concentration dependence is shown not to be simply a consequence of acoustic interaction between single cells. Flow cytometry of stained cells detected no loss of cell viability arising from the ultrasonic procedure.

Bacteriological Techniques↗

PubMed1998

High hydrostatic pressure come-up time and yeast viability.

The effects of the come-up time at selected pressures (50 to 689 MPa) on Saccharomyces cerevisiae and Zygosaccharomyces bailii viability were evaluated at 21 degrees C. For Z. bailii the effects of the water activity (a(w)) of the suspension media and the stage of the growth cycle were also investigated. Pressure come-up times exerted an important effect on the yeast survival fraction, decreasing counts as pressure increased. An increased sensitivity to pressure treatments was observed with yeast cells from the exponential growth phase. Lethality increased as a(w) of the suspension media increased. For an a(w) of 0.98 and cells from the stationary growth phase, pressure treatments at less than 200 MPa had no effect on Z. bailii viability; however, no survivors (< 10 CFU/ml) were observed in treatments applied only for the time needed to reach pressures greater than 517 MPa. Yeast survivor curves showed an excellent fit (r > 0.996) when described by a phenomenological model based on the Fermi equation, S(P) = 1/¿1 + exp[(P - Pc)/k]¿, where S(P) is the survival fraction, P is the pressure, Pc is a critical pressure corresponding to 50% survival, and k is a constant representing the steepness of the curve.

Colony Count, Microbial↗

PubMed2001

Effect of low-temperature, high-pressure treatment on the survival of Escherichia coli O157:H7 and Salmonella in unpasteurized fruit juices.

The destructive effect of high pressure (615 MPa) combined with low temperature (15 degrees C) on various strains of Escherichia coli O157:H7 and various serovars of Salmonella in grapefruit, orange, apple, and carrot juices was investigated. The three-strain cocktail of E. coli O157:H7 (SEA13B88, ATCC 43895, and 932) was found to be most sensitive in grapefruit juice (8.34-log reduction) and least in apple juice (0.41-log reductions) when pressurized at 615 MPa for 2 min at 15 degrees C. Correspondingly, no injured survivor was detected in grapefruit and carrot juices under similar treatment conditions. No Salmonella spp. were detected in a 2-min pressure treatment (615 MPa, 15 degrees C) of grapefruit and orange fruit juices. Except for Enteritidis, all four serovars tested in the present study have viability loss of between 3.92- and 5.07-log reductions when pressurized in apple juice at 615 MPa for 2 min at 15 degrees C. No injured cells were recovered from grapefruit and orange juices, whereas the same treatment demonstrated reduction in numbers of Salmonella serovars Agona and Muenchen in apple juices and to a lesser extent with Typhimurium, Agona, and Muenchen in carrot juice. The present study demonstrated that low-temperature, high-pressure treatment has the potential to inactivate E. coli O157:H7 strains and different Salmonella spp. in different fruit juices.

Beverages↗

PubMed1981

Tissue disaggregation of human kidney cells followed by purification on isokinetic and isopyknic gradients.

Five normal human kidneys were disaggregated with three combinations of enzymes. The combination of collagenase 0.5 mg per ml of 11 additional kidneys. The viability of cells in suspension ranged from 75 to 94 per cent with a mean viability of 85.3 +/- 1.6 per cent. Disaggregated kidney cells were fractionated in isopyknic and isokinetic gradients. After isokinetic sedimentation, kidney tubule cells were predominantly in fraction 22 +/- 1 whereas lymphocytes were consistently located in fraction 8 +/- 1. Kidney epithelial cells were enriched to a 90.4 +/- 2.2 per cent (79.0 to 96.0 per cent) purity by isokinetic gradient centrifugation. Controlled rate freezing of cells provided material for repeated experiments, and short-term tissue culture before cell separation increased the proportion of viable cells in suspension.

Cell Count↗

PubMed2007

Transfer of bacteria between biomaterials surfaces in the operating room--an experimental study.

Bacterial adhesion to and transfer between surfaces is a complicated process. With regard to the success of biomaterials implants, studies on bacterial adhesion and transfer should not be confined to biomaterials surfaces in the human body, but also encompass surfaces in the operating room, where the origin of many biomaterials related infections is found. The purpose of this study was to quantify the transfer of Staphylococcus aureus, Staphylococcus epidermidis, and Propionibacterium acnes from one operating room material to another, while accounting for surface hydrophobicity and roughness, moistness and application of friction during transfer. The tested operating room materials were gloves, broaches (orthopaedic drills), theatre gowns, and light handles. As a possible clinical intervention method to prevent transfer, it was investigated whether dipping the gloves in a chlorhexidine splash-basin affected the viability of the transferred bacteria. Transfer (moist and without friction) was demonstrated to some extent with all bacterial strains and with every material, ranging from 17% to 71%, and was influenced by the bacterial strain, moistness of the inoculum, the application of friction, and the characteristics of both the donating and the receiving surface. Dipping the glove material in 4% or 0.4% chlorhexidine solutions killed all bacteria present, regardless of whether surfaces were dried or moist and thus prevented transfer.

Bacteria↗