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PubMedDate not supplied

[Anaerobic degradation of biphenyl by the facultative anaerobic strain Citrobacter freundi BS2211].

Using a synthetic medium supplemented with biphenyl (a polycyclic aromatic hydrocarbon), a new bacterial strain of Citrobacter freundii was isolated from enrichment cultures containing soil and industrial wastewater samples of the Serpukhov Condenser Factory. This strain was found to be capable of degrading biphenyl under anaerobic conditions in the course of nitrate reduction. When the initial concentration of biphenyl in culture medium equaled 150 mg/l, the culture with a titer of 10(9) cells/ml degraded up to 26-28% of biphenyl in 3 days (28 degrees C). At 250 mg/l, the culture with a titer of 10(7) cells/ml degraded 15% of biphenyl in 21 days. Approximately 10% of the substrate consumed was utilized completely, whereas the remainder underwent transformation.

Anaerobiosis↗
PubMed2002

Clinical features and antimicrobial susceptibility trends in Citrobacter freundii bacteremia.

This retrospective study investigated the clinical characteristics and antimicrobial susceptibilities of 36 cases of Citrobacter freundii bacteremia treated at the Taipei Veterans General Hospital from 1996 through 1999. The results showed that the predominant infection site was the intraabdominal region and the mortality was 22%. The resistance of C. freundii to most third-generation cephalosporins and broad-spectrum penicillins increased in both nosocomial and community-acquired C. freundii bacteremia during the study period, and the strategy of using a combination of antimicrobial agents to treat C. freundii infection was effective. This study also demonstrated the importance of appropriate antimicrobial therapy to the successful outcome of C. freundii bacteremia. The guidelines of the National Nosocomial Infections Surveillance System were followed to determine trends of resistance of C. freundii to various antimicrobial agents. The resistance of C. freundii to antibiotics in 1999 (n = 10), compared with the period from 1996 through 1998 (n = 26), increased 66% for ciprofloxacin, 36% for ticarcillin/clavulanate, 70% for piperacillin/tazobactam, and 62.8% for piperacillin, but remained uniformly susceptible to imipenem/cilastatin and the new fluoroquinolone (levofloxacin). This increase in resistance was attributable to the use of third-generation cephalosporin instead of first-generation cephalosporins. These findings indicate the need for new measures to facilitate the appropriate choice of antimicrobial agents for patients with C. freundii bacteremia.

Adult↗
PubMed2002

Comparison of an espB gene fecal polymerase chain reaction assay with bacteriologic isolation for detection of Citrobacter rodentium infection in mice.

PURPOSE: To develop a polymerase chain reaction (PCR) assay for specific detection of Citrobacter rodentium in fecal samples of mice and to compare this assay with bacterial isolation and identification methods. METHODS: The target sequence of the PCR assay was the espB gene encoding a secreted virulence factor. To facilitate visual identification during primary isolation on MacConkey agar containing ampicillin, C. rodentium ATCC type strain 51459 was transformed by use of a plasmid encoding the enhanced green fluorescent protein (EGFP) and ampicillin resistance. The EGFP-C. rodentium was inoculated into Swiss Webster (SW) mice to study the time course of detection of the organism by use of fecal PCR analysis, bacterial isolation, and development of colonic hyperplasia by light microscopy. Lactose-fermenting fluorescent bacterial colonies identified during primary isolation of fecal bacteria on MacConkey-ampicillin agar were identified by use of biochemical typing. RESULTS: Mice inoculated with EGFP-transformed C. rodentium developed colonic mucosal hyperplasia, characterized by a three-fold increase in colonic crypt height that peaked at post-inoculation day (PID) 14. The espB PCR assay detected as little as 0.3 colony-forming units of C. rodentium. The PCR assay was specific in that it did not detect the espB gene of Escherichia coli 0157. Results of in vivo studies in SW mice indicated that EGFP-C. rodentium could be detected by use of espB fecal PCR analysis in 100% of inoculated mice tested on PID 1, 3, 7, and 8, in 60% on PID 9, and in 20% on PID 10 (n = 5). Bacterial isolation from the same fecal samples detected the organism in 100% of the inoculated mice on PID 7, in 50% on PID 8, and in none on subsequent PID 9-14. The ability of the PCR assay to detect C. rodentium in fresh feces of inoculated mice was significantly better than that of bacterial isolation methods (Fisher-Irwin exact test, P < 0.01). At the time of peak colonic hyperplasia, the organism could no longer be cultivated or detected in mice by use of fecal PCR analysis. CONCLUSIONS: The EGFP-C. rodentium was capable of inducing transmissible murine colonic hyperplasia similar to that previously reported in SW mice. The PCR assay for detection of the espB gene sequence of C. rodentium in total fecal DNA was a more sensitive diagnostic assay than was bacterial isolation.

Animals↗
PubMedDate not supplied

[Plasmid localization and cloning of restriction modification genes from Citrobacter freundii 4111 strain].

Over 60 producing strains of restriction endonucleases type II have been found among 500 different strains, mostly Enterobacteriaceae. The strain Citrobacter freundii 4111 produces restriction endonuclease CfrBI, a new isoschisomer of StyI. The genes of the restriction-modification system CfrBI were located on the multicopy plasmid pZE8 containing the Co1E1-type replicon and cloned to E. coli K802. The deletion variant of 3.2-kb pZE8 which contains intact restriction-modification and a DNA fragment responsible for autonomous plasmid replication was selected among the recombinant plasmids. The strain with higher R. CfrBI production (at least 10,000,000 U/g cells, which is 500-fold higher than the wild strain) was constructed.

Citrobacter freundii↗
PubMed2004

Isolation of Citrobacter sp. mutants defective in decolorization of brilliant green by transposon mutagenesis.

To identify genes involved in the decolorization of brilliant green, we isolated random mutants generated by transposon insertion in brilliant green-decolorizing bacterium, Citrobacter sp. The resulting mutant bank yielded 19 mutants with a complete defect in terms of the brilliant green color removing ability. Southern hybridization with a Tn5 fragment as a probe showed a single hybridized band in 7 mutants and these mutants appeared to have insertions at different sites of the chromosome. Tn5-inserted genes were isolated and the DNA sequence flanking Tn5 was determined. By comparing these with a sequence database, putative protein products encoded by bg genes were identified as follows: bg 3 as a LysR-type regulatory protein; bg 11 as a MalG protein in the maltose transport system; bg 14 as an oxidoreductase; and bg 17 as an ABC transporter. The sequences deduced from the three bg genes, bg 2, bg 7 and bg 16, showed no significant similarity to any protein with a known function, suggesting that these three bg genes may encode unidentified proteins responsible for the decolorization of brilliant green.

ATP-Binding Cassette Transporters↗
PubMed2004

Improved borate method for the rapid distinction of glucosamine and galactosamine in an exopolysaccharide produced by Citrobacter sp.

An improved borate method for the quantitative distinction of glucosamine (GlcN) and galactosamine (GalN) in a mixture is presented which is based on the Elson-Morgan method with addition of sodium borate to differentiate colour formation by the two hexosamines. The r2 value and maximum deviation of the method based on calculations derived in this study were 0.9979 and 5.1 %, respectively. Using this method, the GlcN/GalN ratio in an exopolysaccharide (EPS) produced by Citrobacter sp. was found to change with time during the production process, with a maximum value at 9.8:1.

Borates↗
PubMed2005

Dizygotic twins discordant for early-onset Citrobacter koseri and group B streptococcal sepsis.

Early-onset neonatal sepsis is usually a multisystem fulminant illness with prominent respiratory symptoms, and typically the infant has acquired the organism from the maternal genital tract during the intrapartum period. In this article, we report a rare case of dizygotic twins where each individual suffered early-onset sepsis caused by a different pathogen. Group B streptococcal (GBS) sepsis was diagnosed in twin A 1 day after birth; sepsis and meningitis caused by Citrobacter koseri was diagnosed in twin B at the age of the 4 days. The mother developed pre-eclampsia and fever and the twins were delivered via cesarean section at 35 week's gestation. Twin A received ampicillin treatment for 14 days and recovered fully. Twin B was treated with ceftriaxone for 4 weeks and follow-up brain ultrasound revealed persistent enlargement of the bilateral-lateral ventricles. When empiric antibiotic is considered for the symptomatic twin of a sibling with early-onset GBS infection, samples of blood and cerebrospinal fluid (CSF) should be obtained for culture study before treatment. Adjustment of antibiotic treatment based on the results of cultures and CSF Gram stain and antibiotic susceptibility test is essential.

Adult↗
PubMed2005

Enteric fever-like illness caused by infection with citrobacter amalonaticus.

'Enteric fever' is a potentially fatal, severe systemic disease, which is encountered worldwide. Traditionally, enteric fever refers to a bacteremic illness caused by members of certain Salmonella serotypes, notably: Salmonella typhi, a Gram-negative bacterium, and to a lesser extent, Salmonella paratyphi A, B and C. In addition, other non-salmonella organisms may produce a syndrome clinically indistinguishable from "enteric fever". Brucella sp., Campylobacter sp., Edwardsiella tarda, Enterobacter Cloacae, Escherichia coli, Klebsiella pneumoniae, Providencia alcalifaciens, Pseudomonas sp., Serratia marcescens, Francisella sp. and Yersinia pp have been identified in enteric fever This is, to the best of the authors' knowledge, the first case of Citrobacter to be reported presenting as enteric fever in a normal host in Thailand.

Citrobacter↗
PubMed2006

Alkaline lipase production by Citrobacter freundii IIT-BT L139.

Around 150 lipase producing bacterial isolates were screened from the local soils enriched with oil. Citrobacrer freundii IIT-BT L139, an isolated microbial strain, produced lipase that had high activity (8.8 U/ml) at pH 9.0 and 40 degrees C. The 16S rDNA phylogenetic studies showed that Citrobacter freundii belongs to the family Enterobacteriaceae and later confirmed by the microbial identification. Suitable C and N sources for lipase production were deduced to be starch and peptone-urea, respectively. In a controlled fermenter (1 L), the lipase activity was found to increase by 36% (12 Uml(-1)). The variation of lipase activity, pH and dissolved oxygen (DO) during growth of the organism in the controlled batch fermenter were monitored. The rheological characteristics of the fermentation broth indicated that it behaved like a Newtonian fluid throughout the fermentation. The fermentation time was comparatively short (60 h). The lipase was also found to be substantially resistant to common detergents. This lipase was, thus, characterized as alkaline, thermostable and solvent stable, which was essentially desirable in pharmaceutical, detergent and other industrial applications or production.

Citrobacter freundii↗
PubMed1990

[Transpon Tn5 mutagenesis in Citrobacter].

When E. coli 1830/PJB4JI mating with four Citrobacter strains all were Kanamycin resistant, but a majority of KanrGens transconjugants were obtained from C-3-1. Among 3000 KanrGens 21 were auxotrophs, these are Lys-(1), Ura-(1), Arg-(2), Iso-(2), His-(2), Met-(1), Phe-(1), Tyr-(1), Ser-(1), Thr-(1), Leu-(3), Pro-(1), Ade-(3), Lac-(1), PJB4JI plasmid DNA were detected in parent strain E. coli 1830, but not in auxotrophs strains which carrying Tn5 induced mutations. Twenty auxotrophs chromosome DNA were hybridized with Tn5 DNA labeled with 32P respectively, all auxotrophs has positive reaction. Therefore, we concluded from genetic and physical data that auxotrophs resulted from Tn5 transposition from PJB4JI into C-3-1 chromosome.

Citrobacter↗
PubMed1988

[The structure of O-specific polysaccharide chains of lipopolysaccharides from Citrobacter 032 and Salmonella arizonae 064 (Arizona 29)].

On the basis of acid hydrolysis, methylation, Smith degradation, selective cleavage with anhydrous hydrogen fluoride, and 13C NMR analysis, the repeating unit of the O-specific polysaccharide of Citrobacter O32 was concluded to have the following structure: (Formula: see text). The repeating unit of the Salmonella arizonae O64 O-specific polysaccharide has the same structure lacking the O-acetyl group.

Antigens, Bacterial↗
PubMed1989

Genetic properties of plasmids isolated from pathogenic strain of Citrobacter freundii.

It was found that Citrobacter freundii SLJ10 strain was an etiological factor of swine diarrhoea in North Poland. This strain harboured a plasmid aggregate consisting of two plasmids-pEM4 responsible for virulence and pEM6 for selective advantage of the strain, determining resistance to tetracycline and production of bacteriocin. These two plasmids cooperated in conjugal transfer and formed an infective block of genetic information, which could be transferred to other strains of Enterobacteriaceae and cause their virulence.

Citrobacter↗
PubMed1989

Hydrogen production from glucose by Citrobacter freundii.

C. freundii, a member of Enterobacteriaceae was isolated from nearby sewage and characterised. With optimum conditions, its hydrogen production capacity and efficiency was tested in synthetic medium containing glucose as carbon and energy source. C. freundii was grown in a 51 fermentor under batch anaerobic conditions. The total production of gas was 8.91 in the volumetric ratio of 63% H2 and 37% CO2 in 11 hr from 30.8 g glucose. From 1 mole of glucose 1.286 mole of hydrogen was produced (YH2/s). The rate of gas production (rQ) and hydrogen production (rH2) was 0.71 and 0.45 1/hr respectively. The strain appears to be a better one for hydrogen production compared to the earlier Citrobacter spp reported.

Citrobacter↗
PubMed1989

[TNT-degrading enzyme of Citrobacter freundii and its regulation by carbon and nitrogen source].

It was detected that both NAD(P)H-linked reductase (TNT-Red) and NAD(P)+-linked TNT dehydrogenase (TNT-Deh) were present in TNT-degrading enzymes of Citrobacter freundii simultaneously. The time course of formation for the enzymes and the actions of coenzymes in enzymatic reaction of TNT have been studied. The effects of varied carbon and nitrogen sources on the regulation of the enzymes were different clearly. When the concentration of NH4Cl or urea in culture medium was more than 0.1 mol/L, the formation of both TNT reductase and TNT dehydrogenase was promoted. However, the formation of these enzymes was inhibited by KNO3 in culture. The production of both reductase and dehydrogenase was promoted by glucose. The sodium citrate was able to help the formation of the TNT dehydrogenase. The activity of the TNT reductase was increased when the concentration of sodium citrate was less than 0.5%, but when it was more than 0.5%, the activity of this enzyme was decreased rapidly.

Ammonium Chloride↗
PubMedDate not supplied

[Kinetic study of 3,4-dihydroxyphenyl-L-alanine synthesis in Citrobacter freundii cells immobilized in carrageenan].

A kinetic study was carried out of the enzymatic synthesis of 3,4-dihydroxyphenyl-L-alanine (DOPA) by the Citrobacter freundii 62 cells, possessing tyrosine-phenol-lyase (TPL) activity, immobilized in carrageenan, and optimum conditions of the reaction were found. The dependence of the TPL activity and its stability on the conditions of the DOPA synthesis was investigated. The TPL activity was higher and more stable in the immobilized cells as compared to free ones.

Bacteriological Techniques↗
PubMed1987

The morphology and nucleotide composition of DNA of Citrobacter phages.

Citrobacter phages 38/37, 31/37, 40/1 and 8/5, isolated from lysogenic cultures, were concentrated and purified by 2 cycles of differential centrifugation. Electron microscopy of the phages has shown that their particles have similar morphology and that they relate to the morphological group A1. The heads of the phages are hexagonal, 50 +/- 2 nm in diameter. The tail of the phage is straight, 112-152 nm in length, with a contracting sheath 11.5-12.5 nm wide. The tails of the phages 38/37 and 40/1 were found to be slightly longer in comparison with the phages 31/37 and 8/5. Chromatographic investigation of DNA preparations of the phages revealed the presence of 4 nitrous bases. Identification of the latter permitted us to relate them to common nitrous bases. DNA of the phages is double-stranded and belongs to a weakly expressed guanine-cytosine type. The content of guanine and cytosine in DNA of the phage 38/37 amounts to 56.68%, that of the phage 31/37 to 56.75, of the phage 40/1 to 57.36% and of the phage 8/5 to 55.58%. No substantial variations were observed in the DNA composition of the phages.

Bacteriophages↗
PubMed1986

[Ability of Citrobacter freundii strains isolated in acute intestinal infections to produce LT-enterotoxin].

C. freundii enteropathogenic strains were found to be capable of producing choleroform thermolabile enterotoxin. Thus, in the study of 96 C. freundii strains 38 enterotoxin-producing cultures (39.5%) were revealed by means of the molecular-biological techniques and 29 such cultures (30.0%), by means of the radioimmunoassay (RIA). 100% coincidence was noted in the results of tests for enterotoxigenicity, made by means of RIA or hybridization techniques with the use of the LT-probe containing a cloned fragment with the gene coding the synthesis of LT-enterotoxin in enterotoxigenic Escherichia coli. At the same time only 29 out of 38 Citrobacter strains found to be positive in the hybridization tests, yielded the positive result when tested in RIA for the presence of LT-enterotoxin. This fact should be taken into consideration in the determination of enterotoxin-producing cultures isolated in acute enteric infections, as the method of genetic probing is capable of bringing out the genetic information in bacteria even in the absence of its phenotypical expression.

Acute Disease↗