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PubMed1997

Resistance to ciprofloxacin in pathogenic Enterobacteriaceae in England and Wales in 1996.

In 1996, 6% of Escherichia coli from extraintestinal infections were resistant to ciprofloxacin with minimum inhibitory concentrations (MICs) > or = 2 mg/l (high level resistance). Low level resistance (MIC 0.125-1 mg/l) was also identified in 7% of Salmonella typhi, 4% of S paratyphi A, and 4% of non-typhoidal salmonellas. However, resistance to ciprofloxacin was rarely identified in shigellas. For E coli, physicians should be aware that treatment failures may occur when patients with invasive illness are treated with ciprofloxacin before the results of laboratory sensitivity tests are available. For salmonellas an increasing number of treatment failures have been recorded for patients infected with strains with low level resistance. Because of the increasing incidence of Enterobacteriaceae with low level resistance to ciprofloxacin, it is recommended that for this group of organisms a breakpoint of 0.125 mg/l should be included in laboratory sensitivity tests.

Anti-Infective Agents↗
PubMed1995

A survey of the incidence of Salmonella species and Enterobacteriaceae in poultry feeds and feed components.

Between July 1990 and April 1991 the rate of contamination with Salmonella species of poultry feeds and feed components used by the Dutch feed industry was surveyed. Ten per cent of 360, 10 g samples of poultry feeds were found to be contaminated. Mash feeds, mostly used for layer-breeders, were far more frequently (21 per cent) contaminated than pelleted feeds (1.4 per cent). The rate of contamination of 130 samples of fish meal was 31 per cent, of 83 samples of meat and bone meal 4 per cent, 58 samples of tapioca 2 per cent and of 15 samples of maize grits 27 per cent. Twenty-eight serotypes of salmonellae were isolated, but no Salmonella enteritidis was found, despite the occurrence of an epidemic in poultry caused by this serotype since 1987. The serotypes isolated most frequently were not the same as those encountered in poultry flocks. The Enterobacteriaceae isolated from the feedstuffs were predominantly thermotrophic. They were shown to be useful markers of the rate of contamination with salmonellae and of the efficiency of decontamination of the feedstuffs by pelletisation.

Animal Feed↗
PubMed1984

Prevalence of extreme detergent resistance among the Enterobacteriaceae.

The detergent-resistance properties of 208 independent isolates of the Enterobacteriaceae have been examined. Of these bacterial strains, 200 were able to grow in the presence of greater than or equal to 5% sodium dodecyl sulfate, including all members of the Klebsielleae tribe. This resistance does not appear to be plasmid encoded. It is proposed that detergent-resistant organisms be termed saponotolerant or saponophilic, by analogy with other microorganisms occupying harsh ecological niches. In contrast to their prevalent resistance to anionic detergents, not one of the 208 strains tested was found to grow in the presence of three different cationic detergents. This sensitivity to cationic detergents may be of significance in combating nosocomial infections.

Detergents↗
PubMed2005

Evolution of the NadR regulon in Enterobacteriaceae.

The NAD biosynthetic pathway and NAD transformations in E. coli and S. typhi are well characterized. Using comparative genomics methods we describe the NadR regulon in other Enterobacteriaceae, identity new candidate regulon members and demonstrate that even a very simple regulon covering an essential methabolic pathway could be different in closely related genomes.

Bacterial Proteins↗
PubMed1976

Genetic relatedness in the family Enterobacteriaceae.

Five criteria of genetic relatedness are considered. The first, transfer of plasmids between groups, is frequently not a good criterion, because transfer is possible between all genera of the Enterobacteriaceae and also to genera in other families. Though transfer to closely related groups is most frequent, host restriction and the properties of the plasmid may influence the transfer frequency as much as the relatedness of the donor and recipient. The second criterion is interspecies recombination (integration) of chromosomal genes transferred by Hfr strains. Crosses between closely related genera (E. coli and Shigella) gave high frequency of stable hybrids, but crosses between less related genera (E. coli and Salmonella) result in lower recombination, with the donor genes frequently integrated in nonallelic positions on the chromosome, or remaining as autonomous CCC-DNA. In crosses between distantly related genera such as E. coli and Proteus, all the donor DNA remained as CCC, with no detectable integration into the chromosome. Third, the linkage maps of different strains of a species such as E. coli or of closely related species are very similar. The linkage maps of E. coli and S. typhimurium are also similar, with one gene rearrangement, an inversion, distinguishing them. There are some indications of differences in gene order between E. coli and Yersinia and between E. coli and S. marcescens and considerable evidence for rearrangements in gene order between E. coli and P. mirabilis. No similarity between the linkage maps of E. coli and of nonenteric bacteria such as Pseudomonas was observed. Thus within the enteric bacteria there is striking similarity in order of genes between closely related genera, but major changes when less related genera, such as E. coli and P. mirabilis, are observed. are observed...

Bacterial Proteins↗
PubMed1977

Association of halogenated isoxazolylpenicillins with penicillinase-sensitive beta-lactam antibiotics. Microbiological evaluation on beta-lactamase-producing Enterobacteriaceae.

The validity of nonsimultaneous association of penicillinase-sensitive beta-lactam antibiotics with halogenated isoxazolylpenicillins was tested in various Enterobacteriaceae strains. With several bacterial strains, expecially if producers of beta-lactamase type IV, exposure of either the bacterial suspensions of the brothsupernatant to the isoxazolylpenicillins appears both in vivo and in vitro to reduce the extent of subsequent hydrolysis of penicillinase-sensitive beta-lactam antibiotics.

Animals↗
PubMed1979

Sensitivity of gentamicin-resistant Enterobacteriaceae to cefamandole and cefoxitin.

A collection of gentamicin-resistant Enterobacteriaceae strains was significantly more resistant to cefamandole than a species-matched collection of gentamicin-sensitive organisms. Cefamandole and gentamicin resistance could be simultaneously transferred by conjugation from four different species, Citrobacter freundii, Escherichia coli, Klebsiella pneumoniae and Serratia marcescens, to a recipient E. coli strain. Plasmids specifying linked resistance to cefamandole and gentamicin are thus commonly present in the environment of our medical center despite the fact that cefamandole has never been used here. Gentamicin-resistant organisms were not more resistant to cefoxitin than gentamicin-sensitive isolates. Conjugal transfer of cefoxitin resistance could not be demonstrated. Relative resistance to cefoxitin was nevertheless common among Enterobacter and Serratia isolates.

Cefamandole↗
PubMed1980

Antibacterial activity of HR-756, cefoxitin and cefuroxine against multiply antibiotic-resistant strains of Enterobacteriaceae and Pseudomonas aeruginosa.

The in vitro antibacterial activity of HR-756 compared to cefoxitin and cefuroxime. 122 multiresistant clinical isolates including Enterobacteriaceae (104) and P. aeruginosa (18), which present particular problems in antibiotic chemotherapy, were selected for study. HR-756 inhibited all the stains of S. marcescens, P. mirabilis and indole-positive Proteus spp. at a concentration of 1,3 and 12 micrograms/ml, respectively; beta-lactamase-producing strains were also susceptible. 90% of K. pneumoniae and more than half of the Enterobacter and P. aeruginosa were inhibited from the drug at a concentration 16 microgram/ml. Cefoxitin and cefuroxime were less active than HR-756. Cefoxitin was more effective against S. marcescens and P. mirabilis while the same was the case with cefuroxime against K. pneumoniae strains. The greater efficiency of HR-756 over cefoxitin and cefuroxime against these multiply resistant isolates seems to be due not only to its indifference to the beta-lactamases but also to its easier penetrability into the bacterial cell.

Bacteria↗
PubMed1980

Comparative in vitro activity of netilmicin, amikacin, tobramycin and sisomicin against gentamicin highly-resistant enterobacteriaceae.

Netilmicin was compared with sisomicin, tobramycin and amikacin against 65 recent clinical enterobacterial isolates found to be highly resistant to gentamicin (MIC larger than or equal to 80 microgram/ml). Netilmicin showed a high activity against 20 out of 65 strains tested. Most of the sensitive strains (60%) to netilmicin required a concentration of gentamicin equal or lower than 160 microgram/ml for inhibition. Amikacin proved to be extremely effective in all the organisms tested. Tobramycin was consistently less active than either netilmicin or amikacin and the same was the case with sisomicin. The MIC was determined in both solid and liquid media for 24 strains. Depending upon which aminoglycoside was used, we found that 10-30% of the enterobacteriaceae exhibited a twofold diminution of MIC when tested in broth as compared to agar, while the greater proportion of strains was characterized by a higher MIC tested in broth as compared to agar.

Amikacin↗
PubMed1982

In vitro comparative activity of moxalactam, GR 20263, and N-formimidoyl thienamycin to other beta-lactam antibiotics and tobramycin against enterobacteriaceae and staphylococci.

The in vitro activities of moxalactam, GR 20263, and N-formimidoyl thienamycin were compared to those of cephalothin, cefazolin, cefamandole, cefoxitin, and tobramycin against 152 strains of Enterobacteriaceae and staphylococci. The results showed that moxalactam, GR 20263, and N-formimidoyl thienamycin each had significantly improved activity toward the gram-negative organisms tested compared to the other beta-lactams and tobramycin. N-formimidoyl thienamycin was particularly impressive with respect to its activity toward Staphylococcus aureus and S. epidermidis as compared to moxalactam, GR 20263 and the older beta-lactam drugs.

Anti-Bacterial Agents↗
PubMed1984

Comparison of in vitro activities of eight new beta-lactam compounds against cephalothin-resistant Enterobacteriaceae from hospital patients.

The in vitro antibacterial activity of eight newer beta-lactam antibiotics (mecillinam, piperacillin, mezlocillin, cefoxitin, cefotaxime, moxalactam, ceftriaxone and ceftazidime) was determined against 87 cephalothin-resistant strains of Enterobacteriaceae isolated during 6 months in a general hospital. Ceftriaxone, cefotaxime, moxalactam and ceftazidime proved to be highly active; only a minority of strains required higher concentrations than 0.125 microgram/ml for inhibition of growth. Cefoxitin, mecillinam, mezlocillin and piperacillin were less active. Mecillinam displayed greater efficacy against Escherichia coli, Klebsiella and Enterobacter spp., while the same was the case for piperacillin against Proteus mirabilis and Serratia marcescens, and for cefoxitin against indole-positive Proteus spp. The production of beta-lactamase was correlated with a reduced activity of mecillinam, mezlocillin and piperacillin but not of cefoxitin or the other beta-lactamase-stable cephalosporins. However, some strains, mainly those of Proteus, Enterobacter and Serratia, though resistant to mecillinam, mezlocillin and piperacillin did not produce beta-lactamases. This observation might indicate that ceftriaxone, moxalactam, cefotaxime and ceftazidime, besides their indifference to beta-lactamases, are characterized also by a high degree of intrinsic activity.

Anti-Bacterial Agents↗
PubMed1992

Cefonicid versus cefuroxime: an in vitro study of 1,000 Enterobacteriaceae.

Cefuroxime and cefonicid, two common representatives of the second-generation cephalosporins, were compared for their spectrum of activity against 1,000 isolates of gram-negative Enterobacteriaceae. Cefuroxime had an overall advantage of 6.3% over cefonicid. Upon investigation, we found that this was mainly due to Escherichia coli: 11.2% of the E. coli strains proved resistant to cefonicid whilst only 0.4% were cefuroxime resistant.

Cefonicid↗
PubMed1992

Distribution of beta lactamases in Enterobacteriaceae: indoor versus outdoor strains.

The distribution of beta-lactamases of indoor and outdoor origin was studied over a 9-month period. We consecutively selected 37 indoor and 48 outdoor strains of the following genera of the Enterobacteriaceae family: Escherichia (species coli), Enterobacter, Proteus, and Klebsiella. All isolates were resistant to amoxicillin and/or cephalothin and/or cefamandole. All strains showed beta-lactamase activity. We characterized the enzymes by an isoelectric focusing method and by a disc diffusion test. For both indoor and outdoor isolates we found that plasmid-mediated beta-lactamases were encountered mostly in the E. coli and Klebsiella species, whereas chromosomally mediated enzymes predominated in the Proteus and Enterobacter species. No significant difference in distribution of beta-lactamases could be found comparing both groups, but it was noted that chromosomally mediated beta-lactamases predominated in the Department of Urology, while plasmid-mediated beta-lactamases prevailed in other departments (p less than 0.05).

Drug Resistance, Microbial↗
PubMedDate not supplied

In vitro activity of cefpirome against beta-lactamase-inducible and stably derepressed Enterobacteriaceae.

Most members of the Enterobacteriaceae and Pseudomonas aeruginosa possess an inducible chromosomal class I beta-lactamase. Bacterial strains which produce high levels of beta-lactamase constitutively can be isolated from infections; these derepressed mutants are responsible for resistance to third-generation cephalosporins and ureidopenicillins. Minimum inhibitory concentrations of cefpirome, a fourth-generation cephalosporin, and other beta-lactam antibiotics were determined for a series of mutants of Citrobacter freundii, Enterobacter cloacae, Morganella morganii, Proteus vulgaris and Serratia marcescens with inducible stably derepressed or basal expression of chromosomal class I beta-lactamases. All the antibiotics tested were almost equally active against beta-lactamase-inducible organisms and their basal mutants. Imipenem and cefpirome showed better activity against derepressed mutants than third-generation cephalosporins and ureidopenicillins.

Anti-Bacterial Agents↗
PubMed1986

Resistance to beta-lactams in Enterobacteriaceae: distribution of phenotypes related to beta-lactamase production.

Phenotypes of susceptibility to amoxycillin (Amo), ticarcillin (Tic), cephalothin (Ctn) were determined in 1366 isolates of Enterobacteriaceae by disk method and beta-lactamases were identified in 243 strains belonging to different phenotypes of amoxycillin-resistant strains. AmoR TicR CtnS strains (25%) were penicillinase producers and all of them were susceptible to the combination amoxycillin/clavulanic acid (Amo/CA) and ticarcillin/clavulanic acid (Tic/CA). Amo1/R TicS CtnR strains (12%) were cephalosporinase producers and resistance to Amo/CA was observed, except for Proteus vulgaris. AmoR TicR CtnR strains (18%) often produced two beta-lactamases (penicillinase and cephalosporinase) and they were resistant to Amo/CA; in this group, susceptibility to Tic/CA depends on the nature and the amount of the beta-lactamase produced, except for Serratia marcescens for which antibiotic resistance is probably due to other mechanisms. Tic/CA resistance was mainly found in Serratia marcescens (41%) and Enterobacter cloacae (36%).

Amoxicillin↗
PubMed2005

Lipopolysaccharide inner core oligosaccharide structure and outer membrane stability in human pathogens belonging to the Enterobacteriaceae.

In the Enterobacteriaceae, the outer membrane is primarily comprised of lipopolysaccharides. The lipopolysaccharide molecule is important in mediating interactions between the bacterium and its environment and those regions of the molecule extending further away from the cell surface show a higher amount of structural diversity. The hydrophobic lipid A is highly conserved, due to its important role in the structural integrity of the outer membrane. Attached to the lipid A region is the core oligosaccharide. The inner core oligosaccharide (lipid A proximal) backbone is also well conserved. However, non-stoichiometric substitutions of the basic inner core structure lead to structural variation and microheterogeneity. These include the addition of negatively charged groups (phosphate or galacturonic acid), ethanolamine derivatives, and glycose residues (Kdo, rhamnose, galactose, glucosamine, N-acetylglucosamine, heptose, Ko). The genetics and biosynthesis of these substitutions is beginning to be elucidated. Modification of heptose residues with negatively charged molecules (such as phosphate in Escherichia coli and Salmonella and galacturonic acid in Klebsiella pneumoniae) has been shown to be involved in maintaining membrane stability. However, the biological role(s) of the remaining substitutions is unknown.

Cell Membrane↗
PubMed1977

The use of biotyping of Enterobacteriaceae as an evaluation of the isolation efficacy of laboratory animals.

2 sets of data are given of biotyping the Enterobacteriaceae from the faecal flora of SPF rats and cats housed with different isolation arrangements. The method is presented as an evaluation of the isolation efficiency of laboratory animals. Biotypes which were determined on almost every occasion belonged to the resident flora of the animals while those found occasionally represented contamination. Contaminating bacteria are cleared from an SPF breeding unit by colonization resistance and the continuous efflux of animals from the unit. A parameter of isolation efficacy is the number of different biotypes determined in time. With optimal isolation arrangements a stable bacterial flora of permanently colonized biotypes is obtained in the animals.

Animals↗
PubMed2003

Plasmid-mediated extended-spectrum beta-lactamase-producing strains of Enterobacteriaceae isolated from diabetes foot infections in a Brazilian diabetic center.

We bacteriologically analyzed 156 species of Enterobacteriaceae, isolated from 138 patients with community-acquired diabetic foot ulcers, in a prospective study made at a diabetic center and at the Federal University of Ceará, Brazil, from March, 2000, to November, 2001. The samples were cultured using selective media, and identification, susceptibility tests and detection of plasmid-mediated-extended-spectrum-beta-lactamase (ESBL) producing strains were made with conventional and automated methods. The most frequently occurring pathogens were K. pneumoniae (21.2%), Morganella morganii (19.9%) and E. coli (15.4%). High resistance rates were noted for ampicillin, first generation cephalosporin, trimethoprim/sulfamethoxazole, tetracycline, amoxicillin-clavulanic acid and chloramphenicol. ESBL-producing strains were detected in 6% of the patients. Resistance among gram-negative bacteria has become increasingly common, even in community-acquired infections.

Anti-Bacterial Agents↗