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At least 667 records · Page 37Linked to original sources
PubMed1996

Survey of prevalence of extended spectrum beta-lactamases among enterobacteriaceae.

During the first six months of 1990 and 1994 respectively, 3179 and 2721 non-repetitive strains of Enterobacteriaceae were isolated at the teaching hospital of Clermont-Ferrand. Extended-spectrum beta-lactamases were found in 147 isolates, mainly in Klebsiella pneumoniae (n = 73), Enterobacter aerogenes (n = 37) and Proteus mirabilis (n = 15). TEM-3/CTX-1, SHV-4/CAZ-5 and TEM-24/CAZ-6 were the prevalent enzymes. However, the most frequently involved enzyme in 1990 was TEM-3 (48.6%) whereas in 1994 it was SHV-4 (56.0%). Two salient features emerged from this study: the high frequency of TEM-3 production in P. mirabilis and the production of SHV-4 enzyme, heretofore observed solely in K. pneumoniae, in two other species, E. aerogenes and Escherichia coli.

Anti-Bacterial Agents↗
PubMed1998

Can susceptibility to an antimicrobial be restored by halting its use? The case of streptomycin versus Enterobacteriaceae.

To test the widespread view that resistance disappears in the absence of antimicrobial use, we tested streptomycin against 477 Enterobacteriaceae from the Royal London Hospital. Twenty per cent proved resistant although streptomycin is little used at the hospital and streptomycin resistance in gram-negative bacteria is caused by mechanisms that do not compromise the drugs that are used. Up to 70% of the observed resistance was associated with cross-resistance to spectinomycin and the presence of ant(3")-Ia, an integron-associated gene carried in Tn21-type transposons. This genetic organization may have conserved streptomycin resistance in the absence of direct selection pressure.

Anti-Bacterial Agents↗
PubMed1999

The post-exposure response of Enterobacteriaceae to ceftibuten.

The responses of ten isolates of Enterobacteriaceae to ceftibuten exposure were monitored by measuring several parameters. Post-antibiotic effect (PAE), control-related effective regrowth time (CERT) and post-antibiotic sub-MIC effect (PA-SME) were determined by bacterial enumeration carried out either by impedance in combination with viable counting (IMP/VC) or by impedance in combination with bioluminescence (IMP/BIOL). Kill curves were carried out by bioluminescence, viable counting and direct microscopy and post-exposure morphology was established. Ceftibuten primarily provoked filamentation. Over 24 h, kill of up to 3.6 log10 was evident by viable counting and direct microscopy at and above the MIC. Minimal kill, of up to 0.26 log10, was shown by bioluminescence. PAE was found to be method dependent, with statistical differences established by Student's t-test. PAE values of up to 0.48 h and 1.47 h (by IMP/BIOL and IMP/VC respectively) were not concentration dependent above 1 x MIC. CERT values were not method dependent, with values of up to 1.71 h also showing a lack of concentration dependence above 1 x MIC. PA-SME may reflect the situation in vivo more accurately than either PAE or CERT. In PAE and CERT studies the antibiotic is eliminated almost immediately, whereas in vivo there is gradual decrease in antibiotic levels. These persisting levels are reflected more accurately by PA-SME. Compared with PAE and CERT, significantly longer values, of up to 7.27 h, were obtained by PA-SME, although this parameter was also found to be method dependent. The results of the PA-SME studies, which may be the most clinically relevant pharmacodynamic parameter, confirm the appropriateness of the current once- or twice-daily dosing schedules despite the lack of PAE.

Ceftibuten↗
PubMed1999

Concurrent outbreaks of extended-spectrum beta-lactamase-producing organisms of the family Enterobacteriaceae in a Warsaw hospital.

The increasing use of broader-spectrum cephalosporins in the first half of the 1990s has become one of the major factors responsible for the high rate of selection of extended-spectrum beta-lactamase (ESBL)-producing microorganisms in Polish hospitals. Thirty-five isolates of seven different species of the family Enterobacteriaceae were identified as ESBL producers, over a 4 month period, in one of Warsaw's hospitals between the end of 1996 and the beginning of 1997. Sixteen per cent of all Klebsiella pneumoniae isolates, 16% of Citrobacter freundii isolates and 32% of Serratia marcescens isolates collected by the hospital microbiology laboratory at that time were expressing these enzymes. The majority of these (27 isolates) were found to express CTX-M-type ESBLs (pI 8.4). This outbreak was due to both plasmid dissemination among unrelated strains and clonal spread of some strains in several wards of the hospital. The remaining isolates produced ESBLs (pI 8.2) belonging to the SHV family of beta-lactamases and demonstrated a high degree of genetic diversity.

Bacterial Typing Techniques↗
PubMed2005

Emergence of plasmid-mediated resistance to quinolones in Enterobacteriaceae.

Although quinolone resistance results mostly from chromosomal mutations in Enterobacteriaceae, it may also be mediated by plasmid-encoded Qnr determinants. Qnr proteins protect DNA from quinolone binding and compromise the efficacy of quinolones such as nalidixic acid. Qnr proteins (QnrA-like, QnrB and QnrS) have been identified worldwide with a quite high prevalence among Asian isolates with a frequent association with clavulanic acid inhibited expanded-spectrum beta-lactamases and plasmid-mediated cephalosporinases. The qnrA genes are embedded in complex sul1-type integrons. A very recent identification of the origin of QnrA determinants in the water-borne species Shewanella algae underlines the role of the environment as a reservoir for this emerging threat. It may help to determine the location of in vivo transfer of qnrA genes. Further analysis of the role (if any) of quinolones for enhancing this gene transfer may be conducted. This could prevent the spread, if still possible, of this novel antibiotic resistance mechanism.

Amino Acid Sequence↗
PubMed1996

Prolyl aminopeptidase is also present in Enterobacteriaceae: cloning and sequencing of the Hafnia alvei enzyme-gene and characterization of the expressed enzyme.

The Hafnia alvei prolyl aminopeptidase gene (hpap) was cloned and sequenced, the expressed enzyme (HPAP) was purified to homogeneity and thoroughly characterized. An open reading frame of 1,281 bp was found to code for the enzyme, resulting in a protein of 427 amino acids with a molecular weight of 48,577. HPAP resembles the Aeromonas sobria enzyme, having 45% identity and the same distinctive properties with respect to size and substrate specificities. Both enzyme show similar chromatographic behavior, and HPAP could be purified following the procedure previously described for the Aeromonas enzyme. HPAP was found to be resistant to diisopropylphosphofluoridate as are most of the prolyl aminopeptidases hitherto described. In spite of this similarity, no inhibition by 1 mM p-chloromercuribenzoate solution could be detected. Significant inhibition was, however, observed when the enzyme was incubated with 3,4-dichloroisocoumarin. This study confirms the presence of two types of prolyl aminopeptidases, of which the Hafnia and Aeromonas enzymes constitute one group and the Bacillus, Neisseria, and Lactobacillus enzymes the other, and describes the cloning of the first prolyl aminopeptidase gene from an Enterobacteriaceae.

Aeromonas↗
PubMed1999

The phylogenetic position of Serratia, Buttiauxella and some other genera of the family Enterobacteriaceae.

The phylogenetic relationships of the type strains of 38 species from 15 genera of the family Enterobacteriaceae were investigated by comparative 16S rDNA analysis. Several sequences of strains from the genera Citrobacter, Erwinia, Pantoea, Proteus, Rahnella and Serratia, analysed in this study, have been analysed previously. However, as the sequences of this study differ slightly from the published ones, they were included in the analysis. Of the 23 enterobacterial genera included in an overview dendrogram of relatedness, members of the genera Xenorhabdus, Photorhabdus, Proteus and Plesiomonas were used as a root. The other genera formed two groups which could be separated, although not exclusively, by signature nucleotides at positions 590-649 and 600-638. Group A contains species of Brenneria, Buttiauxella, Citrobacter, Escherichia, Erwinia, Klebsiella, Pantoea, Pectobacterium and Salmonella. All seven type strains of Buttiauxella share 16S rDNA similarities greater than 99%. Group B embraces two phylogenetically separate Serratia clusters, a lineage containing Yersinia species, Rahnella aquatica, Ewingella americana, and also the highly related pair Hafnia alvei and Obesumbacterium proteus.

DNA, Ribosomal↗
PubMed2001

Samsonia erythrinae gen. nov., sp. nov., isolated from bark necrotic lesions of Erythrina sp., and discrimination of plant-pathogenic Enterobacteriaceae by phenotypic features.

Bacterial strains isolated from diseased erythrina (Erythrina sp.) trees in Martinique (French West Indies) were studied using phenotypic tests, 16S rDNA sequence analysis and DNA-DNA hybridization. Numerical analysis of phenotypic characteristics showed that these strains formed an homogeneous phenon among plant-pathogenic Enterobacteriaceae, and gave useful and updated information for the identification of these bacteria. Results of DNA-DNA hybridization indicated that strains from erythrina belonged to a discrete genomospecies (89-100% hybridization) and had low levels of DNA relatedness (2-33% hybridization) with reference strains of phytopathogenic Erwinia, Brenneria, Pectobacterium, Pantoea and Enterobacter species. 16S rDNA sequence analysis using three different methods revealed that the position of strain CFBP 5236T isolated from erythrina was variable in the different trees, so that strains from erythrina could not be assigned to any recognized genus. It is proposed that these strains are included in a new genus, Samsonia. The name Samsonia erythrinae is proposed for the new species. The G+C content of the DNA of the type strain, CFBP 5236T (= ICMP 13937T), is 57.0 mol%.

Base Composition↗
PubMed1977

Isolation of Enterobacteriaceae bacteriophage particles catalysing cell wall lipopolysaccharide degradation.

Using pairs of smooth and rough forms of Enterobacteriaceae, six smooth-specific bacteriophages were isolated from sewage and another was obtained from Dr Hedda Milch, Budapest. Upon incubation of the individual extracted (smooth) host cell wall lipopolysaccharides with the homologous purified viruses, liberation of reducing groups (i.e. of about di- to nonasaccharides) was observed in four cases, indicating the action of glycanases - but no liberation of acetic acid, indicating the absence of esterase activity. Under the electron microscope, all phages were seen to exhibit Bradley group B or C morphology and to carry tail spikes.

Bacteriophages↗
PubMed1979

Specificity of attachment of certain enterobacteriaceae to mammalian cells.

The specificity of adherence of various Enterobacteriaceae to different mammalian cells was studied in vitro. 3H-Labelled organisms of the same species isolated from various clinical sources differed significantly in their abilities to adhere to the same mammalian cells. Bacteria frequently adhered better to cells derived from sites other than those analogous to their original source. Bacteria did not display consistently 'high' or 'low' attachment to a variety of human and tissue-cultured cells and little selective adherence was demonstrable.

Adrenal Glands↗
PubMed1980

Fatty acid patterns in the classification of some representatives of the families Enterobacteriaceae and Vibrionaceae.

Twenty-three strains representing the families Enterobacteriaceae and Vibrionaceae were analysed for fatty acid composition of whole cells by means of glass capillary column gas chromatography. Among the several alternatives tested, cluster analysis based on data normalized to hexadecanoate and logarithmically transformed provided good separations of species, genera and families. Strains from the genera Salmonella, Escherichia, Proteus, Enterobacter, Klebsiella, Vibrio and Aeromonas were studied.

Chromatography, Gas↗
PubMed1980

Numerical and DNA: DNA reassociation analyses of Erwinia rubrifaciens and other members of the Enterobacteriaceae.

Phenetic data on 75 strains of Erwinia and other representative genera of the Enterobacteriaceae were collected and analysed using two numerical taxonomic methods. In both methods the same subclusters were recovered. The subclusters, however, were defined at different similarity levels and were classified into clusters of different composition. Erwinia rubrifaciens strains formed a very tight, homogeneous subcluster, completely distinct and readily distinguishable from other Erwinia and enterobacteria species studied. DNA: DNA hybridization between E. rubrifaciens and Erwinia and Shigella species were analysed to corroborate the numerical classifications. A good correlation between the numerical and DNA: DNA hybridization analyses was found and provided sufficient evidence for not supporting the previously proposed subspecific taxonomic position of E. rubrifaciens. The data clearly showed that E. rubrifaciens is a separate species in its own right. Based on the existence of very high genetic relatedness and high similarities in phenetic characters among E. rubrifaciens strains and the confinement of the pathogen to the state of California, the hypothesis is offered that E. rubrifaciens originated from a single source.

DNA, Bacterial↗
PubMed1985

Colicin E2 production and release by Escherichia coli K12 and other Enterobacteriaceae.

Previous work has shown that Escherichia coli K12 ColE2+ cells undergo a form of partial lysis and exhibit increases in lysophosphatidylethanolamine (lysoPE) and free fatty acid content due to activation of phospholipase A when induced to produce and release colicin E2. The increase in lysoPE content was assumed to be essential for efficient colicin release. These same characteristics are also presented by some natural ColE2+ isolates, and by other representatives of the Enterobacteriaceae after transformation with derivatives of a ColE2 plasmid. However, Salmonella typhimurium strains carrying ColE2 plasmids released colicin without partial lysis and without increasing their lysoPE content. A previously undetected minor phospholipid, which appeared in these and other strains only when they were induced to produce colicin, may be an important factor in colicin release. In ColE2+ E. coli K12, production of this new lipid was dependent on phospholipase A activation following expression of the ColE2 lysis gene. Some other ColE2+ strains did not respond to induction of colicin production in the same way as ColE2+ E. coli K12. These strains were less sensitive to inducer (mitomycin C) or unable to produce increased amounts of colicin in response to induction, or unable to degrade colicin once it was released. In general, the results suggest that colicin release occurs by the same or similar processes in the various strains tested, and support the continued use of E. coli K12 as the model strain for studying the mechanisms of colicin release.

Chromatography, Thin Layer↗
PubMed1991

An IS1-like element is responsible for high-level synthesis of extended-spectrum beta-lactamase TEM-6 in Enterobacteriaceae.

Resistance of Escherichia coli strain HB251 to the newer beta-lactam antibiotics, in particular ceftazidime and aztreonam, results from production of the extended-spectrum beta-lactamase TEM-6. The corresponding structural gene, bla(T)-6, and its promoter region were amplified by the polymerase chain reaction. Analysis of the sequence of the amplification product showed that bla(T)-6 differed by two nucleotide substitutions from bla(T)-1, the gene encoding TEM-1 penicillinase in plasmid pBR322. The mutations led to the substitution of a lysine for a glutamic acid at position 102 and of a histidine for an arginine at position 162 of the unprocessed TEM-1 protein. The presence of a 116 bp DNA insert upstream from bla(T)-6 resulted in the creation of hybrid promoter P6 in which the -10 region was that of TEM-1 promoter P3 whereas the -35 canonical sequence TTGACA was provided by the right end of the insert. P6 was found to be 10 times more active than P3 and to confer higher levels of antibiotic resistance upon the host. Analysis of the sequence of the insert indicated that the 116 bp fragment is related to insertion sequence IS1 but differs from it by three internal deletions that removed regions encoding the transposase. The distribution of the IS1-like element in clinical isolates of Enterobacteriaceae was studied by the polymerase chain reaction and by DNA-DNA hybridization. The element appeared to be widespread and was detected in strains producing TEM-6 or other TEM variants.

Base Sequence↗
PubMed1993

Immunological relatedness of the LamB proteins among members of Enterobacteriaceae.

We have studied the immunological relatedness of LamB proteins from a wide range of enterobacterial species, using antibodies directed against denatured Escherichia coli K12 and Klebsiella pneumoniae LamB proteins (LamBE.c. and LamBK.p., respectively), and anti-peptide antibodies directed against 10 distinct loops of LamB from E. coli K12 predicted to protrude either side of the outer membrane. We have shown that a protein immunologically related to LamBE.c. and LamBK.p. was present in all members of Enterobacteriaceae tested. A protein recognized by several anti-peptide antibodies was identified in E. coli, Shigella sonnei, Salmonella typhimurium and Kleb. pneumoniae, as well as in two Citrobacter species, two Enterobacter species and Kluyvera ascorbata. The recognition patterns obtained with the anti-peptide antibodies were in agreement with the LamB protein sequence data available. They indicated that the cell surface and also the periplasmic loops of LamB are subject to great antigenic variability.

Amino Acid Sequence↗
PubMed1985

Contribution of the traT gene to serum resistance among clinical isolates of enterobacteriaceae.

Antimicrobial resistance plasmids containing the traT gene confer resistance to serum bactericidal activity upon some laboratory strains of Escherichia coli. We have examined the DNA of Enterobacteriaceae from human extraintestinal infections to determine the frequency of traT-like genes. DNA sequences homologous with traT were found among 58% of Escherichieae but among none of the Klebsielleae or Proteeae tested and were found as frequently among serum-sensitive E. coli as among serum-resistant strains. Sequences related to traT were always associated with large plasmids. The potential contribution of traT-containing plasmids to serum resistance of clinical isolates is discussed.

Blood Bactericidal Activity↗
PubMed1985

Effect of microwave energy on the metabolism of Enterobacteriaceae.

The effect of microwave irradiation on the metabolism of 94 strains of Enterobacteriaceae was studied. Sixteen substrates were used and the results obtained with microwave irradiation were compared with those given by conventional biochemical tests. There was good correlation between the methods but not sufficient to enable accurate identification of unknown species. However, microwave irradiation considerably increased the enzymatic activity of bacterial suspensions and the results obtained could form the basis for a rapid method of microbial identification.

Carbohydrate Metabolism↗
PubMed1987

Antigenic relationships among type-1 fimbriae of Enterobacteriaceae revealed by immuno-electronmicroscopy.

Antigenic relationships among type-1 fimbriae of 40 strains of Enterobacteriaceae representing 19 species and seven genera were determined by immuno-electronmicroscopy. Ten distinct antigenic groups were distinguished. Intra- and inter-generic relationships were observed although some antigenic groups were species-specific only. Antigenic relationships among type-1 fimbriae are more complex than have been reported hitherto.

Antigens, Bacterial↗