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At least 703 records · Page 39Linked to original sources
PubMed1990

Determination of taxonomic resolution capacity of conventional one-dimensional SDS-polyacrylamide gel electrophoresis of whole-cell proteins using Enterobacteriaceae.

The capacity of one-dimensional SDS-PAGE of whole bacterial cells to both separate and cluster taxonomic units is studied using members of Enterobacteriaceae as test material. The results show that intraspecies variation can be detected and on the other hand the degree of taxonomic divergence which still can be grouped together is determined. In addition the system has high tolerance to changes in cell culture conditions making the usage of SDS-PAGE suitable for applications where rapid and reliable bacterial identification is needed.

Bacterial Proteins↗
PubMed1994

Cloning and expression in Enterobacteriaceae of the extended-spectrum beta-lactamase gene from a Pseudomonas aeruginosa plasmid.

An extended-spectrum beta-lactamase, the gene for which is located on plasmid pMS350 in Pseudomonas aeruginosa strains, hydrolyzes carbapenems and other extended-spectrum beta-lactam antibiotics. We cloned the pMS350 beta-lactamase gene in an Escherichia coli K-12 strain using the vector plasmid pHSG398, and subcloned it into pMS360, a plasmid with a wide host-range. This resulted in the formation of the recombinant plasmid, pMS363, containing a 4.1-kb DNA insert that includes the extended-spectrum beta-lactamase gene. Plasmid pMS363 was introduced into the P. aeruginosa PAO strain or into six species of Enterobacteriaceae, and the specific activities of the beta-lactamase and MICs of various beta-lactam antibiotics were estimated. The cloned gene was capable of expression in these strains and caused resistance to carbapenem, penem and other beta-lactam antibiotics, with the exception of aztreonam.

Cloning, Molecular↗
PubMed1996

Crucial domains are conserved in Enterobacteriaceae porins.

With the recent resolution of the crystal structures of several bacterial porins, it is worthwhile to define the generality of their organization throughout the Enterobacteriaceae. The distribution of specific epitopes was analysed among various Gram-negative bacterial porins using anti-peptide antibodies specific to exposed, transmembrane spanning, or pore-forming regions of Escherichia coli porins. Anti-peptide antibodies which recognized the exposed epitopes indicated a great variability among the bacterial porins analysed. Interestingly, an antigenic site located in the internal loop L3 constricting the pore diameter was present in the majority of the bacterial porins tested. Two epitopes located in domains involved in subunit interaction were also highly conserved. The presence of these common peptides suggested a conservation of specific regions involved in the functional organization of the enterobacterial porins.

Amino Acid Sequence↗
PubMed2001

Enterobactin: the characteristic catecholate siderophore of Enterobacteriaceae is produced by Streptomyces species.(1).

Enterobactin is described in the literature as the typical iron-chelating compound (siderophore) produced by bacteria of the family Enterobacteriaceae. In the course of a HPLC with diode array detection screening programme for detection of novel secondary metabolites, enterobactin, its biosynthetic precursor 2,3-dihydroxy-N-benzoylserine and its linear dimer and trimer condensation products were found to be produced by two Streptomyces strains besides the trihydroxamate-type siderophores desferri-ferrioxamine B and E.

Chromatography, High Pressure Liquid↗
PubMed1982

Thin layer iso-electro focusing of intracellular bacterial protein in classification of some representatives of the families Enterobacteriaceae and Vibrionaceae.

Intracellular bacterial protein from some representatives of the families Enterobacteriaceae and Vibrionaceae has been investigated using thin layer iso-electric focusing in polyacrylamide gel. A marked difference between the protein patterns was observed between species within the same family. Carrying out the iso-electric focusing at pH range 3.5-9 gave a large number of protein bands. Increased resolution of the protein bands was obtained using iso-electric focusing at the pH range 4-6.5. Careful standardization of sample preparation, application and running conditions gave good reproducibility of intracellular proteins from bacterial subcultures.

Aeromonas↗
PubMed1985

Population analysis of susceptibility to cefotaxime in Enterobacteriaceae.

Population analysis of susceptibility to cefotaxime (CTX) in eight species of Enterobacteriaceae was carried out. One strain of each species was examined. The strains represented their individual species as regards natural susceptibility to ampicillin (A) and carbenicillin (Ca). Cephalothinase activity of the parental strains and strains selected on the plates with the highest concentration that allowed growth was determined by an ultraviolet assay. The populations of the A-susceptible/Ca-susceptible (A-s/Ca-s) species, Escherichia coli and Proteus mirabilis were homogeneous as regards susceptibility to CTX. The A-resistant/Ca-resistant (A-r/Ca-r) species, Klebsiella oxytoca and Citrobacter koseri, were less homogeneous, but in all four mentioned species no increase in cephalothinase activity was observed between the parental strains and the strains selected in the population analysis. The four A-r/Ca-s species, Enterobacter cloacae, Citrobacter freundii, Proteus vulgaris, and Morganella morganii, were heterogeneous. The frequency of CTX-r mutants was approx. 10(-6.5). The IC50 for CTX was 2(7.5)-2(8.5) times higher for the mutants than for the parental strains. The CTX resistance was maintained in subcultures of the strains. All four species had a very high increase in cephalothinase activity from parental strains to the strains selected in the population analysis. Only the enzyme of Proteus vulgaris was able to hydrolyze CTX.

Cefotaxime↗
PubMed1987

Failure to detect hydrogen-sulphide production in lactose/sucrose-fermenting Enterobacteriaceae, using triple sugar iron agar.

Triple Sugar Iron agar failed to detect hydrogen sulphide in 44 out of 69 hydrogen-sulphide producing strains of Enterobacteriaceae, which at the same time fermented lactose and/or sucrose. The species involved were Salmonella typhi, Salmonella enteritidis, Citrobacter freundii, Escherichia coli, and Proteus vulgaris. By contrast, no false-negative reactions were observed in 74 strains, which fermented neither lactose nor sucrose. Failure to detect hydrogen sulphide was probably due to acidification of the medium following the fermentation of carbohydrates. A medium without carbohydrates is preferable in diagnostic situations where hydrogen-sulphide detection is of great importance.

Citrobacter↗
PubMed1976

In vitro susceptibility of gentamicin-resistant Enterobacteriaceae and Pseudomonas aeruginosa to netilmicin and selected aminoglycoside antibiotics.

Netilmicin (Sch 20569), a semisynthetic aminoglycoside related to gentamicin C(1a), was evaluated in vitro in agar dilution testing against 224 different clinical isolates of gentamicin-resistant Enterobacteriaceae and Pseudomonas aeruginosa in parallel with amikacin, gentamicin, sisomicin, and tobramycin. Netilmicin showed a very high degree of activity against gentamicin-resistant organisms, but amikacin was more active in vitro, particularly against Providencia stuartii and P. aeruginosa. Sisomicin and tobramycin were consistently less active than either netilmicin or amikacin. Netilmicin was bactericidal in broth testing against P. aeruginosa. Netilmicin showed a greater difference between results with agar and broth dilution testing than did amikacin.

Aminoglycosides↗
PubMed1979

Lack of correlation between beta-lactamase production and susceptibility to cefamandole or cefoxitin among spontaneous mutants of Enterobacteriaceae.

A large number of cultures of gram-negative bacteria were examined for their susceptibility to various concentrations of cefamandole, cefoxitin, carbenicillin, and nalidixic acid. Heterogeneity of susceptibility was demonstrated in individual cultures to all of these antibiotics. Resistant clones isolated from cefamandole or cefoxitin plates were examined for beta-lactamase production. Approximately 13% of 262 resistant clones acquired the ability to produce a beta-lactamase. Examination of the substrate profile of the beta-lactamases from some of these clones revealed no change in the specific activity of these enzymes for cefamandole, cephaloridine, or compound 87/312 as compared with their parental enzymes. This study clearly shows that some resistant clones do not produce beta-lactamases, whereas some susceptible strains produced significant amounts of these enzymes. We conclude from these findings that little correlation exists between beta-lactamase production and decreased susceptibility to cefamandole or cefoxitin. The results suggest the possibility that characteristics other than beta-lactamase production may be responsible for resistance in Enterobacteriaceae.

Cefamandole↗
PubMed1979

Mecillinam-ampicillin synergism in experimental Enterobacteriaceae meningitis.

The in vitro activities of mecillinam, a new beta-amidinopenicillin, and ampicillin, alone and in combination, against an Escherichia coli strain and a Klebsiella pneumoniae strain were compared, and these results were correlated with their respective activities in vivo in experimental meningitis. The mecillinam-ampicillin combination was synergistic in vitro against both strains when tested by a modified checkerboard technique (bacteriostatic synergy). However when quantitative bactericidal synergy studies were made, the relative bactericidal rate of the combination was more rapid than that of either drug alone ("bactericidal synergy") against the Escherichia coli isolate only. In a rabbit model of Enterobacteriaceae meningitis, in vivo bactericidal activity correlated with results obtained in vitro. Both drugs were administered by continuous intravenous infusion for 8 h. Serum and cerebrospinal fluid antibiotic levels were similar to those achieved in humans. Cerebrospinal fluid bacterial concentrations (colony-forming units [CFU] per milliliter) were quantitatively titrated at 2-h intervals. Both drugs, alone or the combination, were ineffective against the K. pneumoniae strain in vivo (change in titer <1 log in 8 h). In contrast, the combination produced a markedly enhanced bactericidal effect against the E. coli strain (mean +/- standard deviation, decrease of log(10) CFU per milliliter of 3.65 +/- 1.02) compared with those of ampicillin alone (decrease of log(10) CFU per milliter of 0.07 +/- 0.8) and mecillinam alone (decrease of log(10) CFU per milliliter of 1.6 +/- 0.05) (P < 0.001). When bactericidal synergism can be demonstrated for mecillinam-ampicillin in vitro in a case of gram-negative-bacillary meningitis this combination may be useful in the therapy of the illness.

Amdinocillin↗
PubMed1980

GR-20263: a new aminothiazolyl cephalosporin with high activity against Pseudomonas and Enterobacteriaceae.

The in vitro activity of GR-20263, a new aminothiazolyl cephalosporin, was compared with the activities of other beta-lactam antibiotics by using 800 clinical bacterial isolates. GR-20263 was highly active (inhibition of 90% of the isolates between 0.03 and 1 microgram/ml) against the common Enterobacteriaceae and 5 to 20 times more active than cefuroxime, cefoxitin, and cephalothin. GR-20263 was three to six times less active than cefotaxime against Escherichia coli, Klebsiella pneumoniae, Salmonella, and Shigella, but three to four times more active than cefotaxime against Proteus vulgaris and Serratia marcescens. The activity of GR-20263 against Pseudomonas aeruginosa (with minimal inhibitory concentrations of 2 and 8 micrograms/ml for 90 and 100% of the isolates, respectively) was similar to that of tobramycin, 2 times that of cefsulodin, 5 times that of piperacillin, and 10 times that of cefotaxime. Against Haemophilus influenzae GR-20263 was three time more active than ampicillin. The beta-lactamase-producing strains were as susceptible to GR-20263 as the beta-lactamase-negative strains. GR-20263 was less active than cefotaxime and ampicillin against Staphylococcus aureus.

Ampicillin↗
PubMed1981

Inconsistency of synergy between the beta-lactamase inhibitor CP-45,899 and beta-lactam antibiotics against multiply drug-resistant Enterobacteriaceae and pseudomonas species.

Synergy between CP-45,899 and ampicillin or newer beta-lactam antibiotics against multiply drug-resistant Enterobacteriaceae and Pseudomonas species was inconsistent. In contrast, synergy between CP-45,899 and ampicillin against beta-lactamase-producing strains of Haemophilus influenzae type b and Bacteroides fragilis was consistent and marked.

Anti-Bacterial Agents↗
PubMed1982

In vitro activity of moxalactam and mecillinam, singly and in combination, against multi-drug-resistant Enterobacteriaceae and Pseudomonas species.

The in vitro interaction of moxalactam and mecillinam against multi-drug-resistant gram-negative enteric bacilli was studied by checkerboard microdilution susceptibility tests and by killing curve kinetics. Against Enterobacteriaceae, the combination was unpredictable; the frequencies of synergy, indifference, and antagonism were 11, 76, and 13%, respectively. Against Pseudomonas sp., the two drugs were consistently indifferent. Overall, the combination of moxalactam and mecillinam was no more active than moxalactam alone.

Amdinocillin↗
PubMed1982

In vitro susceptibility of cephalothin-resistant Enterobacteriaceae and Pseudomonas aeruginosa to Amikacin and selected new beta-lactam agents.

Amikacin was evaluated in vitro by agar dilution testing against 148 different clinical isolates of cephalothin-resistant Enterobacteriaceae and Pseudomonas aeruginosa in parallel with cephalothin, cefoxitin, moxalactam, N-formimidoyl thienamycin, ceftriaxone, and cefmenoxime. Cefsulodin was also evaluated against 39 isolates of P. aeruginosa. More than 80% of all isolates tested were also gentamicin resistant, as determined by disk testing. Moxalactam and amikacin had comparable high activities against Proteus species, Escherichia coli, Serratia species, and Providencia species, and both amikacin and N-formimidoyl thienamycin had comparably high activities against the Klebsiella-Enterobacter group. N-Formimidoyl thienamycin was the most active agent against P. aeruginosa, followed by cefsulodin and amikacin.

Amikacin↗
PubMed1983

Isolation of trimethoprim-resistant, sulfonamide-susceptible Enterobacteriaceae from urinary tract infections.

The isolation of trimethoprim-resistant, sulfonamide-susceptible Enterobacteriaceae causing urinary tract infections is reported. The appearance of these strains followed the introduction of trimethoprim alone for use as treatment. Trimethoprim resistance was attributable to plasmids or transposons less frequently in sulfonamide-susceptible Escherichia coli isolates than in sulfonamide-resistant strains.

Drug Resistance, Microbial↗
PubMed1983

Early synergistic interaction between semisynthetic penicillins and aminoglycosidic aminocyclitols against Enterobacteriaceae.

Time-kill curves were used to assess the relative in vitro efficacy of the early interaction of three semisynthetic penicillins with two aminoglycosides against 48 Enterobacteriaceae strains. The most efficacious combinations were piperacillin plus amikacin, which demonstrated synergism (greater than or equal to 2 logs of increased kill after 7 h of incubation) against 43 of 48 (90%) strains, and piperacillin plus gentamicin, which exhibited synergism against 25 of 48 (52%) strains. With the combinations of carbenicillin or ticarcillin plus amikacin or gentamicin, early synergistic killing was demonstrated against only 12 to 29% of the strains.

Amikacin↗
PubMed1984

Enhanced in vitro bactericidal activity of amikacin or gentamicin combined with three new extended-spectrum cephalosporins against cephalothin-resistant members of the family Enterobacteriaceae.

The in vitro bactericidal interactions of three new extended-spectrum cephalosporins (ceftriaxone, ceftizoxime, or ceftazidime) in combination with gentamicin or amikacin were compared against 40 recent nosocomial bloodstream Enterobacteriaceae isolates by the timed-kill curve technique. All of the study strains were cephalothin resistant, and 56% were resistant to cefamandole. Combinations of aminoglycosides plus ceftriaxone or ceftizoxime exhibited an enhanced bactericidal effect with the highest frequency (approximately 85 to 90%), whereas gentamicin-ceftazidime combinations demonstrated the lowest frequency (for 60% of assays, P less than 0.0005 against the nonceftazidime regimens). The enhanced bactericidal effects occurred within readily achievable drug levels in serum for all of the single antibiotic constituents. No bactericidal antagonism was observed. There was no discernible relationship between the relative in vitro susceptibilities of the 40 study isolates to ceftazidime and the potential for gentamicin-ceftazidime combinations to demonstrate enhanced bactericidal activity. In 14 of the 40 study strains (35%) all six drug combinations tested demonstrated an enhanced bactericidal effect. In nearly 50% of bactericidal interactions which resulted in enhanced bactericidal effect at 24 h, such enhanced killing was clearly demonstrable by 4 h of incubation. These results delineate a frequent and rapid enhancement of in vitro bactericidal activity between three new extended-spectra cephalosporins and aminoglycosides against nosocomial members of the family Enterobacteriaeceae.

Amikacin↗
PubMed1985

Inoculum effect of beta-lactam antibiotics on Enterobacteriaceae.

Seven beta-lactam antibiotics were studied for both their antimicrobial activity and the degree to which they produced inoculum effect on Escherichia coli, Klebsiella pneumoniae, and Salmonella typhimurium. Aztreonam, cefoperazone, and ceftazidime were poorly bactericidal, caused marked bacterial filamentation, and exhibited a large inoculum effect on E. coli, K. pneumoniae, and S. typhimurium. Cefotaxime and ceftriaxone were more rapidly bactericidal, caused only a moderate amount of filamentous forms, and exhibited a modest inoculum effect, while cefoxitin and imipenem both were rapidly bactericidal and exhibited only a minimal-to-no-inoculum effect. The inoculum effect did not correlate with drug stability during incubation with the bacteria. Inoculum effect on these species of the family Enterobacteriaceae appears to be a manifestation of increase in optical density secondary to the development of filamentous bacterial forms with an increase in bacterial mass during exposure to antibiotics which are not rapidly bactericidal. These observations have a clear significance for the susceptibility testing of beta-lactam antibiotics when turbidity is used as a parameter to determine presence of bacterial growth.

Anti-Bacterial Agents↗