Tobramycin, amikacin, sissomicin, and gentamicin resistant Gram-negative rods.
Sensitivities to gentamicin, sissomicin, tobramycin, and amikacin were compared in 196 gentamicin-resistant Gram-negative rods and in 212 similar organisms sensitive to gentamicin, mainly isolated from clinical specimens. Amikacin was the aminoglycoside most active against gentamicin-resistant organisms, Pseudomonas aeruginosa, klebsiella spp, Escherichia coli, Proteus spp, Providencia spp, and Citrobacter spp being particularly susceptible. Most of the gentamicin-resistant organisms were isolated from the urine of patients undergoing surgery. Gentamicin was the most active antibiotic against gentamicin-sensitive E coli, Proteus mirabilis, and Serratia spp. Pseudomonas aeruginosa and other Pseudomonas spp were most susceptible to tobramycin. (+info)
Automated food microbiology: potential for the hydrophobic grid-membrane filter.
Bacterial counts obtained on hydrophobic grid-membrane filters were comparable to conventional plate counts for Pseudomonas aeruginosa, Escherichia coli, and Staphylococcus aureus in homogenates from a range of foods. The wide numerical operating range of the hydrophobic grid-membrane filters allowed sequential diluting to be reduced or even eliminated, making them attractive as components in automated systems of analysis. Food debris could be rinsed completely from the unincubated hydrophobic grid-membrane filter surface without affecting the subsequent count, thus eliminating the possibility of counting food particles, a common source of error in electronic counting systems. (+info)
Anopheles gambiae Ag-STAT, a new insect member of the STAT family, is activated in response to bacterial infection.
A new insect member of the STAT family of transcription factors (Ag-STAT) has been cloned from the human malaria vector Anopheles gambiae. The domain involved in DNA interaction and the SH2 domain are well conserved. Ag-STAT is most similar to Drosophila D-STAT and to vertebrate STATs 5 and 6, constituting a proposed ancient class A of the STAT family. The mRNA is expressed at all developmental stages, and the protein is present in hemocytes, pericardial cells, midgut, skeletal muscle and fat body cells. There is no evidence of transcriptional activation following bacterial challenge. However, bacterial challenge results in nuclear translocation of Ag-STAT protein in fat body cells and induction of DNA-binding activity that recognizes a STAT target site. In vitro treatment with pervanadate (vanadate and H2O2) translocates Ag-STAT to the nucleus in midgut epithelial cells. This is the first evidence of direct participation of the STAT pathway in immune responses in insects. (+info)
Desulfocella halophila gen. nov., sp. nov., a halophilic, fatty-acid-oxidizing, sulfate-reducing bacterium isolated from sediments of the Great Salt Lake.
A new halophilic sulfate-reducing bacterium, strain GSL-But2T, was isolated from surface sediment of the Southern arm of the Great Salt Lake, UT, USA. The organism grew with a number of straight-chain fatty acids (C4-C16), 2-methylbutyrate, L-alanine and pyruvate as electron donors. Butyrate was oxidized incompletely to acetate. Sulfate, but not sulfite or thiosulfate, served as an electron acceptor. Growth was observed between 2 and 19% (w/v) NaCl with an optimum at 4-5% (w/v) NaCl. The optimal temperature and pH for growth were around 34 degrees C and pH 6.5-7.3, respectively. The generation time under optimal conditions in defined medium was around 28 h, compared to 20 h in complex medium containing yeast extract. The G+C content was 35.0 mol%. 16S rRNA gene sequence analysis revealed that strain GSL-But2T belongs to the family Desulfobacteriaceae within the delta-subclass of the Proteobacteria and suggested that strain GSL-But2T represents a member of a new genus. The name Desulfocella halophila gen. nov., sp. nov. is proposed for this organism. The type strain of D. halophila is strain GSL-But2T (= DSM 11763T = ATCC 700426T). (+info)
The influence of a diet rich in wheat fibre on the human faecal flora.
The effect on the faecal flora of adding wheat fibre to a controlled diet in four healthy volunteers for a 3-week period has been observed. No change in the concentration of the bacteria in the bacterial groups counted was found, although there was a slight increase in total output associated with increased faecal weight. The predominant organisms in all subjects were non-sporing anaerobes, but the dominant species in each subject was different and was unaffected by changing the diet. Similarly, the concentration of faecal beta-glucuronidase detected in two subjects was unaltered and the concentration of clostridia able to dehydrogenate the steroid nucleus found in one subject was unaltered. It is suggested that the faecal microflora is not primarily controlled by the presence of undigested food residues in the large bowel. (+info)
In vitro activities of aminomethyl-substituted analogs of novel tetrahydrofuranyl carbapenems.
CL 188,624, CL 190,294, and CL 191,121 are novel aminomethyl tetrahydrofuranyl (THF)-1 beta-methylcarbapenems. The in vitro antibacterial activities of these THF carbapenems were evaluated and compared with those of biapenem, imipenem, and meropenem against 554 recent clinical isolates obtained from geographically distinct medical centers across North America. The antibacterial activities of the THF carbapenems were equivalent to that of biapenem, and the THF carbapenems were slightly more active than imipenem and less active than meropenem against most of the members of the family Enterobacteriaceae but lacked significant activity against Pseudomonas isolates. In general, CL 191,121 was two- to fourfold more active than CL 188,624 and CL 190,294 against the staphylococcal and enterococcal isolates tested. CL 191,121 was twofold less active than imipenem against methicillin-susceptible staphylococci and was as activity as imipenem against Enterococcus faecalis isolates. Biapenem and meropenem were two- and fourfold less active than CL 191,121, respectively, against the methicillin-susceptible staphylococci and E. faecalis. All the carbapenems displayed equivalent good activities against the streptococci. Biapenem was slightly more active than the other carbapenems against Bacteroides fragilis isolates. Time-kill curve studies demonstrated that the THF carbapenems were bactericidal in 6 h against Escherichia coli and Staphylococcus aureus isolates. The postantibiotic effect exerted by CL 191,121 was comparable to or slightly longer than that of imipenem against isolates of S. aureus, E. coli, and Klebsiella pneumoniae. (+info)
Antimicrobial activities of synthetic bismuth compounds against Clostridium difficile.
Clostridium difficile is a major nosocomial pathogen responsible for pseudomembranous colitis and many cases of antibiotic-associated diarrhea. Because of potential relapse of disease with current antimicrobial therapy protocols, there is a need for additional and/or alternative antimicrobial agents for the treatment of disease caused by C. difficile. We have synthesized a systematic series of 14 structurally simple bismuth compounds and assessed their biological activities against C. difficile and four other gastrointestinal species, including Helicobacter pylori. Here, we report on the activities of six compounds that exhibit antibacterial activities against C. difficile, and some of the compounds have MICs of less than 1 microgram/ml. Also tested, for comparison, were the activities of bismuth subcitrate and ranitidine bismuth citrate obtained from commercial sources. C. difficile and H. pylori were more sensitive both to the synthetic bismuth compounds and to the commercial products than were Escherichia coli, Pseudomonas aeruginosa, and Proteus mirabilis, and the last three species were markedly resistant to the commercial bismuth salts. Testing with human foreskin fibroblast cells revealed that some of the synthetic compounds were more cytotoxic than others. Killing curves for C. difficile treated with the more active compounds revealed rapid death, and electron microscopy showed that the bismuth of these compounds was rapidly incorporated by C. difficile. Energy dispersive spectroscopy X-ray microanalysis of C. difficile cells containing electron-dense material confirmed the presence of internalized bismuth. Internalized bismuth was not observed in C. difficile treated with synthetic bismuth compounds that lacked antimicrobial activity, which suggests that the uptake of the metal is required for killing activity. The nature of the carrier would seem to determine whether bismuth is transported into susceptible bacteria like C. difficile. (+info)
3-Hydroxylaminophenol mutase from Ralstonia eutropha JMP134 catalyzes a Bamberger rearrangement.
3-Hydroxylaminophenol mutase from Ralstonia eutropha JMP134 is involved in the degradative pathway of 3-nitrophenol, in which it catalyzes the conversion of 3-hydroxylaminophenol to aminohydroquinone. To show that the reaction was really catalyzed by a single enzyme without the release of intermediates, the corresponding protein was purified to apparent homogeneity from an extract of cells grown on 3-nitrophenol as the nitrogen source and succinate as the carbon and energy source. 3-Hydroxylaminophenol mutase appears to be a relatively hydrophobic but soluble and colorless protein consisting of a single 62-kDa polypeptide. The pI was determined to be at pH 4.5. In a database search, the NH2-terminal amino acid sequence of the undigested protein and of two internal sequences of 3-hydroxylaminophenol mutase were found to be most similar to those of glutamine synthetases from different species. Hydroxylaminobenzene, 4-hydroxylaminotoluene, and 2-chloro-5-hydroxylaminophenol, but not 4-hydroxylaminobenzoate, can also serve as substrates for the enzyme. The enzyme requires no oxygen or added cofactors for its reaction, which suggests an enzymatic mechanism analogous to the acid-catalyzed Bamberger rearrangement. (+info)