1,721,055 research outputs found
A KLUYVERA-CRYOCRESCENS STRAIN FROM A GALLBLADDER INFECTION
Full text linkThe isolation and the identification of a pure-culture Kluyvera cryocrescens
strain in a gall.bladder pus specimen from a 76-year-old woman vcith acute cholecystitis
is described. This is the first Teported recovery of a K. cryocrescens
strain from such a sample
A NEW APPROACH TO USE OF BACTERIOLYTIC ENZYMES AS A TOOL FOR SPECIES IDENTIFICATION - SELECTION OF SPECIES-SPECIFIC INDICATOR STRAINS WITH BACTERIOLYTIC ACTIVITY TOWARDS ENTEROCOCCUS STRAINS
No full textWe describe the bacteriolytic activity of 377 group D Enterococcus isolates expressed towards 25 Enterococcus strains belonging to different species and Micrococcus luteus ATCC 4698. Of the 26 indicator strains used to reveal bacteriolytic activity, 5 were lysed by all of the strains of some species and were not lysed by all of the strains of other species. The use of these indicator strains allowed us to devise a new method to differentiate group D Enterococcus strains, based on qualitative analysis (lysis or no lysis of the indicator strains) of bacteriolytic activity. The bacteriolytic patterns obtained fell into six bacteriolytic groups corresponding (98% agreement) to species or groups of enterococci as determined by a comparison with data from a phenetic similarity study
ORTHO-NITROPHENYL-BETA-D-GALACTOPYRANOSIDE UREASE INDOLE BROTH, A NEW COMPOSITE TUBE MEDIUM FOR SALMONELLA SCREENING
No full textA new composite broth medium combining o-nitrophenyl-i-D-galactopyranoside (ONPG) and urease and
indole tests in a single tube is described. High-level agreement with individual conventional tests was recorded
in comparative studies with 2,412 cultures of members of the family Enterobacteriaceae, i.e., 100% agreement
with the exception of Hafnia spp. (96.3% agreement) for the ONPG test and Citrobacter, Enterobacter, and
Hafnia spp. (75, 86.4, and 98.2% agreement, respectively) for the urease test. The new medium seems
especially promising as a screen for Salmonella subgroup I which encompasses most pathogenic Salmonella
species other than the Arizona subgroup
MODIFIED MACCONKEY MEDIUM WHICH ALLOWS SIMPLE AND RELIABLE IDENTIFICATION OF PROVIDENCIA-STUARTII
No full textThis work describes a modified MacConkey medium (MCP medium) enabling the simple identification of Providencia stuartii, an emerging nosocomial pathogen. A total of 813 strains, belonging to the families Enterobacteriaceae and Pseudomonadaceae, were tested on MCP medium; all P. stuartii strains were phosphatase positive, as were 97.5% of Morganella morganii strains, in contrast with all other tested organisms. A simple discriminating test, such as the ornithine or citrate test, allowed identification of strains of these species. We have also compared the reliabilities of P. stuartii identification by commercial kits (API 20E system) by using a standard MacConkey or MCP medium. Sixteen and three-tenths percent of P. stuartii strains were misidentified by using the former procedure, while with the latter all strains were correctly identified. Finally, the MCP medium was used over a 6-month period in our routine clinical laboratory. Of a total of 1,278 seeded urine samples from elderly patients, we isolated 103 P. stuartii strains which were all correctly identified by coupling MCP medium and the API 20E system. Seventeen and one-half percent of these strains were misidentified when the API 20E system was used in combination with standard MacConkey medium
Bacterial acid phosphatase gene fusions useful as targets for cloning-dependent insertional inactivation
No full textModified Mc Conkey medium which allows simple and reliable identification of Providencia stuartii.
No full textT-MOD PATHWAY, A REDUCED SEQUENCE FOR IDENTIFICATION OF GRAM-NEGATIVE URINARY-TRACT PATHOGENS
Full text linkIn this paper, we describe a reduced sequence of identification that includes T-mod medium, a selective and
differential isolation medium which allows accurate presumptive identification of the most common gramnegative
bacteria encountered in urine samples. The present study, performed on bacteria isolated from 1,762
independent urine samples, has shown that a few selected tests (lysine and ornithine decarboxylase, urease and
trehalose fermentation tests) improve the identification accuracy of T-mod, making it possible both to identify
the less frequent species and to prevent some misidentifications of Klebsiella pneumoniae and Proteus mirabilis.
The proposed work flow agreed with conventional identification protocols to a 99.3% extent and allowed
identification of 87.4% of the isolates directly from the primary plate, 11.4% after 1 to 3 additional tests, and
1.2% after an identification gallery
NEW PLATE MEDIUM FOR SCREENING AND PRESUMPTIVE IDENTIFICATION OF GRAM-NEGATIVE URINARY-TRACT PATHOGENS
Full text linkA new selective, differential plating medium to screen the common gram-negative urinary tract pathogens is
described. The medium combines adonitol fermentation, phenylalanine deaminase, and P-glucuronidase tests
and allows the indole and cytochrome oxidase tests to be performed directly from the plates. High-level
agreement with individual conventional tests was recorded in comparative studies with 504 cultures of
gram-negative rods. There was 100% agreement, except for the Providencia spp. indole spot test (61.6%
agreement). Adonitol fermentation by Providencia species could not be determined. Escherichia coli, Klebsiella
pneumoniae, Proteus mirabilis, and Pseudomonas aeruginosa were identified with a high efficiency (100, 85.7,
83.5, and 100% agreement, respectively) without further testing. There was 96% overall agreement for the 267
infected urine samples tested
The use of Escherichia coli bearing a phoN gene for the removal of uranium and nickel from aqueous flows
No full textA Citrobacter sp. originally isolated from metal-polluted soil accumulates heavy metals via metalphosphate deposition utilizing inorganic phosphate liberated via PhoN phosphatase activity. Further strain development was limited by the non-transformability of this environmental isolate. Recombinant Escherichia coli DH5 alpha bearing cloned phoN or the related phoC acquired metal-accumulating ability, which was compared with that of the Citrobacter sp. with respect to removal of uranyl ion (UO2(2+)) from dilute aqueous flows and its deposition in the form of polycrystalline hydrogen uranyl phosphate (HUO2PO4). Subsequently, HUO2PO4-laden cells removed Ni2+ from dilute aqueous flows via intercalation of Ni2+ into the HUO2PO4 lattice. Despite comparable acid phosphatase activity in all three strains, the E. coli DH5 alpha (phoN) construct was superior to Citrobacter N14 in both uranyl and nickel accumulation, while the E. coli DH5 alpha (phoC) construct was greatly inferior in both respects. Expression of phosphatase activity alone is not the only factor that permits efficient and prolonged metal phosphate accumulation, and the data highlight possible differences in the PhoN and PhoC phosphatases, which are otherwise considered to be related in many respects
Low doses of Tetracycline trigger the E. coli growth: a case of hormetic response
Full text linkHormesis is a biphasic dose-response relationship, occurring when low concentrations of toxic agents elicit apparent improvements. In this work, the ability of sub-inhibitory concentrations of Tetracycline to induce hormetic response in a model organism was investigated. To this aim a reference strain of Escherichia coli, MG1655, was exposed to six decreasing doses of Tetracycline (between 0.12 and 0.00375 μg/ml), much lower than the Minimal Inhibitory Concentration (4 μg/ml). An hormetic increase was observed at the intermediate concentrations (0.015-0.03 μg/ml) of the tested range. The Colony Forming Unit number, indeed, rose up to 141% and 121% as compared to the control. At the highest (0.12 μg/ml) and lowest (0.00375 μg/ml) concentrations a slight decrease in CFU number was found. Results demonstrated that, in Escherichia coli, low concentrations of Tetracycline bias the bacterial numerical increase through a hormetic response; the dose-response curve describing this numerical increase is an U-inverted curve. Furthermore, these data confirm that hormesis is common to many - if not all - living systems, including bacteria; they underline the relevance of a deepened knowledge of both the effects and the possible consequences of exposure to low doses of contaminants
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